canvas(3)

NAME

Tk::Canvas - Create and manipulate Canvas widgets

SYNOPSIS

$canvas = $parent->Canvas(?options?);

STANDARD OPTIONS

-background -highlightthickness -insertwidth -state -borderwidth -insertbackground -relief -tile -cur sor -insertborderwidth -selectbackground -takefocus -highlightbackground -insertofftime -selectborder width -xscrollcommand -highlightcolor -inserton time -selectforeground -yscrollcommand

WIDGET-SPECIFIC OPTIONS

Name: closeEnough
Class: CloseEnough
Switch: -closeenough

Specifies a floating-point value indicating how close
the mouse cursor must be to an item before it is con
sidered to be ``inside'' the item. Defaults to 1.0.

Name: confine
Class: Confine
Switch: -confine

Specifies a boolean value that indicates whether or
not it should be allowable to set the canvas's view
outside the region defined by the scrollRegion argu ment. Defaults to true, which means that the view
will be constrained within the scroll region.

Name: height
Class: Height
Switch: -height

Specifies a desired window height that the canvas wid
get should request from its geometry manager. The
value may be specified in any of the forms described
in the "COORDINATES" section below.

Name: scrollRegion
Class: ScrollRegion
Switch: -scrollregion

Specifies a list with four coordinates describing the
left, top, right, and bottom coordinates of a rectan
gular region. This region is used for scrolling pur
poses and is considered to be the boundary of the
information in the canvas. Each of the coordinates
may be specified in any of the forms given in the
"COORDINATES" section below.

Name: state
Class: State
Switch: -state

Modifies the default state of the canvas where state
may be set to one of: normal, disabled, or hidden.
Individual canvas objects all have their own state
option, which overrides the default state. Many
options can take separate specifications such that the
appearance of the item can be different in different
situations. The options that start with "active" con
trol the appearence when the mouse pointer is over it,
while the option starting with "disabled" controls the
appearence when the state is disabled.

Name: width
Class: width
Switch: -width

Specifies a desired window width that the canvas wid
get should request from its geometry manager. The
value may be specified in any of the forms described
in the "COORDINATES" section below.

Name: xScrollIncrement
Class: ScrollIncrement
Switch: -xscrollincrement

Specifies an increment for horizontal scrolling, in
any of the usual forms permitted for screen distances.
If the value of this option is greater than zero, the
horizontal view in the window will be constrained so
that the canvas x coordinate at the left edge of the
window is always an even multiple of xScrollIncrement;
furthermore, the units for scrolling (e.g., the change
in view when the left and right arrows of a scrollbar
are selected) will also be xScrollIncrement. If the value of this option is less than or equal to zero,
then horizontal scrolling is unconstrained.

Name: yScrollIncrement
Class: ScrollIncrement
Switch: -yscrollincrement

Specifies an increment for vertical scrolling, in any
of the usual forms permitted for screen distances. If
the value of this option is greater than zero, the
vertical view in the window will be constrained so
that the canvas y coordinate at the top edge of the
window is always an even multiple of yScrollIncrement;
furthermore, the units for scrolling (e.g., the change
in view when the top and bottom arrows of a scrollbar
are selected) will also be yScrollIncrement. If the value of this option is less than or equal to zero,
then vertical scrolling is unconstrained.

DESCRIPTION

The Canvas method creates a new window (given by the $can
vas argument) and makes it into a canvas widget. Addi
tional options, described above, may be specified on the
command line or in the option database to configure
aspects of the canvas such as its colors and 3-D relief.
The canvas command returns its $canvas argument. At the
time this command is invoked, there must not exist a win
dow named $canvas, but $canvas's parent must exist.

Canvas widgets implement structured graphics. A canvas
displays any number of items, which may be things like
rectangles, circles, lines, and text. Items may be manip
ulated (e.g. moved or re-colored) and callbacks may be
associated with items in much the same way that the bind
method allows callbacks to be bound to widgets. For exam
ple, a particular callback may be associated with the
<Button-1> event so that the callback is invoked whenever button 1 is pressed with the mouse cursor over an item.
This means that items in a canvas can have behaviors
defined by the Callbacks bound to them.

DISPLAY LIST

The items in a canvas are ordered for purposes of display,
with the first item in the display list being displayed
first, followed by the next item in the list, and so on.
Items later in the display list obscure those that are
earlier in the display list and are sometimes referred to
as being ``on top'' of earlier items. When a new item is created it is placed at the end of the display list, on
top of everything else. Widget methods may be used to rearrange the order of the display list.

Window items are an exception to the above rules. The
underlying window systems require them always to be drawn
on top of other items. In addition, the stacking order of
window items is not affected by any of the canvas methods;
you must use the raise and lower Tk widget methods
instead.

ITEM IDS AND TAGS

Items in a canvas widget may be named in either of two
ways: by id or by tag. Each item has a unique identifying
number which is assigned to that item when it is created.
The id of an item never changes and id numbers are never
re-used within the lifetime of a canvas widget.

Each item may also have any number of tags associated with
it. A tag is just a string of characters, and it may take
any form except that of an integer. For example, ``x123''
is OK but ``123'' isn't. The same tag may be associated
with many different items. This is commonly done to group
items in various interesting ways; for example, all
selected items might be given the tag ``selected''.

The tag all is implicitly associated with every item in
the canvas; it may be used to invoke operations on all
the items in the canvas.

The tag current is managed automatically by Tk; it applies to the current item, which is the topmost item whose drawn area covers the position of the mouse cursor. If the
mouse is not in the canvas widget or is not over an item,
then no item has the current tag.

When specifying items in canvas methods, if the specifier
is an integer then it is assumed to refer to the single
item with that id. If the specifier is not an integer,
then it is assumed to refer to all of the items in the
canvas that have a tag matching the specifier. The symbol
tagOrId is used below to indicate that an argument speci fies either an id that selects a single item or a tag that
selects zero or more items.

tagOrId may contain a logical expressions of tags by using operators: '&&', '||', '^' '!', and parenthezised subex
pressions. For example:

$c->find('withtag', '(a&&!b)|(!a&&b)');

or equivalently:

$c->find('withtag', 'a^b');

will find only those items with either "a" or "b" tags,
but not both.

Some methods only operate on a single item at a time; if
tagOrId is specified in a way that names multiple items, then the normal behavior is for the methods is to use the
first (lowest) of these items in the display list that is
suitable for the method. Exceptions are noted in the
method descriptions below.

COORDINATES

All coordinates related to canvases are stored as float
ing-point numbers. Coordinates and distances are speci
fied in screen units, which are floating-point numbers
optionally followed by one of several letters. If no let
ter is supplied then the distance is in pixels. If the
letter is m then the distance is in millimeters on the
screen; if it is c then the distance is in centimeters; i
means inches, and p means printers points (1/72 inch).
Larger y-coordinates refer to points lower on the screen;
larger x-coordinates refer to points farther to the right.

TRANSFORMATIONS

Normally the origin of the canvas coordinate system is at
the upper-left corner of the window containing the canvas.
It is possible to adjust the origin of the canvas coordi
nate system relative to the origin of the window using the
xview and yview methods; this is typically used for scrolling. Canvases do not support scaling or rotation of
the canvas coordinate system relative to the window coor
dinate system.

Individual items may be moved or scaled using methods
described below, but they may not be rotated.

INDICES

Text items support the notion of an index for identifying
particular positions within the item.

Indices are used for methods such as inserting text,
deleting a range of characters, and setting the insertion
cursor position. An index may be specified in any of a
number of ways, and different types of items may support
different forms for specifying indices.

In a similar fashion, line and polygon items support index
for identifying, inserting and deleting subsets of their
coordinates. Indices are used for commands such as
inserting or deleting a range of characters or coordi
nates, and setting the insertion cursor position. An index
may be specified in any of a number of ways, and different
types of items may support different forms for specifying
indices.

Text items support the following forms for an index; if
you define new types of text-like items, it would be
advisable to support as many of these forms as practical.
Note that it is possible to refer to the character just
after the last one in the text item; this is necessary
for such tasks as inserting new text at the end of the
item. Lines and Polygons don't support the insertion cur
sor and the selection. Their indices are supposed to be
even always, because coordinates always appear in pairs.

number

A decimal number giving the position of the desired
character within the text item. 0 refers to the first
character, 1 to the next character, and so on. If
indexes are odd for lines and polygons, they will be
automatically decremented by one. A number less than
0 is treated as if it were zero, and a number greater
than the length of the text item is treated as if it
were equal to the length of the text item. For poly
gons, numbers less than 0 or greater then the length
of the coordinate list will be adjusted by adding or
substracting the length until the result is between
zero and the length, inclusive.

end Refers to the character or coordinate just after the

last one in the item (same as the number of characters
or coordinates in the item).

insert

Refers to the character just before which the inser
tion cursor is drawn in this item. Not valid for lines
and polygons.

sel.first

Refers to the first selected character in the item.
If the selection isn't in this item then this form is
illegal.

sel.last

Refers to the last selected character in the item. If
the selection isn't in this item then this form is
illegal.

[x,y]

Refers to the character or coordinate at the point
given by x and y, where x and y are specified in the
coordinate system of the canvas. If x and y lie out
side the coordinates covered by the text item, then
they refer to the first or last character in the line
that is closest to the given point. The Tcl string
form "@x,y" is also allowed.

DASH PATTERNS

Many items support the notion of an dash pattern for out
lines.

The first possible syntax is a list of integers. Each ele
ment represents the number of pixels of a line segment.
Only the odd segments are drawn using the "outline" color.
The other segments are drawn transparant.

The second possible syntax is a character list containing
only 5 possible characters [.,-_ ]. The space can be used
to enlarge the space between other line elements, and can
not occur as the first position in the string. Some exam
ples:

-dash . = -dash [2,4]
-dash - = -dash [6,4]
-dash -. = -dash [6,4,2,4]
-dash -.. = -dash [6,4,2,4,2,4]
-dash '. ' = -dash [2,8]
-dash ',' = -dash [4,4]

The main difference of this syntax with the previous is
that it it shape-conserving. This means that all values in
the dash list will be multiplied by the line width before
display. This assures that "." will always be displayed as
a dot and "-" always as a dash regardless of the line
width.

On systems where only a limited set of dash patterns, the
dash pattern will be displayed as the most close dash pat
tern that is available. For example, on Windows only the
first 4 of the above examples are available. The last 2
examples will be displayed identically as the first one.

WIDGET METHODS

The Canvas method creates a widget object. This object
supports the configure and cget methods described in Tk::options which can be used to enquire and modify the
options described above. The widget also inherits all the
methods provided by the generic Tk::Widget class.

The following additional methods are available for canvas
widgets:

$canvas->addtag(tag, searchSpec, ?arg, arg, ...?)

For each item that meets the constraints specified by
searchSpec and the args, add tag to the list of tags associated with the item if it isn't already present
on that list. It is possible that no items will sat
isfy the constraints given by searchSpec and args, in which case the method has no effect. This command
returns an empty string as result. SearchSpec and arg's may take any of the following forms:

above tagOrId

Selects the item just after (above) the one
given by tagOrId in the display list. If
tagOrId denotes more than one item, then the last (topmost) of these items in the display
list is used.

all Selects all the items in the canvas.

below tagOrId

Selects the item just before (below) the one
given by tagOrId in the display list. If
tagOrId denotes more than one item, then the first (lowest) of these items in the display
list is used.

closest x y ?halo? ?start?

Selects the item closest to the point given by
x and y. If more than one item is at the same
closest distance (e.g. two items overlap the
point), then the top-most of these items (the
last one in the display list) is used. If
halo is specified, then it must be a non-nega
tive value. Any item closer than halo to the
point is considered to overlap it. The start
argument may be used to step circularly
through all the closest items. If start is
specified, it names an item using a tag or id
(if by tag, it selects the first item in the
display list with the given tag). Instead of
selecting the topmost closest item, this form
will select the topmost closest item that is
below start in the display list; if no such
item exists, then the selection behaves as if
the start argument had not been specified.

enclosed x1 y1 x2 y2

Selects all the items completely enclosed
within the rectangular region given by x1, y1,
x2, and y2. X1 must be no greater then x2 and y1 must be no greater than y2.

overlapping x1 y1 x2 y2

Selects all the items that overlap or are
enclosed within the rectangular region given
by x1, y1, x2, and y2. X1 must be no greater then x2 and y1 must be no greater than y2.

withtag tagOrId

Selects all the items given by tagOrId.

$canvas->bbox(tagOrId, ?tagOrId, tagOrId, ...?)

Returns a list with four elements giving an approxi
mate bounding box for all the items named by the
tagOrId arguments. The list has the form ``x1 y1 x2 y2'' such that the drawn areas of all the named ele
ments are within the region bounded by x1 on the left,
x2 on the right, y1 on the top, and y2 on the bottom. The return value may overestimate the actual bounding
box by a few pixels. If no items match any of the
tagOrId arguments or if the matching items have empty bounding boxes (i.e. they have nothing to display)
then an empty string is returned.

$canvas->bind(tagOrId?, sequence? ?,callback?)

This method associates callback with all the items given by tagOrId such that whenever the event sequence given by sequence occurs for one of the items the
callback will be invoked. This method is similar to
the bind method except that it operates on items in a
canvas rather than entire widgets. See Tk::bind for
complete details on the syntax of sequence and the substitutions performed on callback before invoking it. If all arguments are specified then a new binding
is created, replacing any existing binding for the
same sequence and tagOrId (if the first character of command is ``+'' then command augments an existing binding rather than replacing it). In this case the
return value is an empty string. If callback is omit ted then the method returns the callback associated with tagOrId and sequence (an error occurs if there is no such binding). If both callback and sequence are omitted then the method returns a list of all the
sequences for which bindings have been defined for
tagOrId.

The only events for which bindings may be
specified are those related to the mouse and
keyboard (such as Enter, Leave, ButtonPress, Motion, and KeyPress) or virtual events. The handling of events in canvases uses the cur
rent item defined in "ITEM IDS AND TAGS"
above. Enter and Leave events trigger for an item when it becomes the current item or
ceases to be the current item; note that these
events are different than Enter and Leave events for windows. Mouse-related events are
directed to the current item, if any. Key
board-related events are directed to the focus
item, if any (see the focus method below for
more on this). If a virtual event is used in
a binding, that binding can trigger only if
the virtual event is defined by an underlying
mouse-related or keyboard-related event.

It is possible for multiple bindings to match
a particular event. This could occur, for
example, if one binding is associated with the
item's id and another is associated with one
of the item's tags. When this occurs, all of
the matching bindings are invoked. A binding
associated with the all tag is invoked first,
followed by one binding for each of the item's
tags (in order), followed by a binding associ
ated with the item's id. If there are multi
ple matching bindings for a single tag, then
only the most specific binding is invoked. A
continue in a callback terminates that subrou tine, and a break method terminates that sub
routine and skips any remaining callbacks for
the event, just as for the bind method.

If bindings have been created for a canvas
window using the CanvasBind method, then they are invoked in addition to bindings created
for the canvas's items using the bind method.
The bindings for items will be invoked before
any of the bindings for the window as a whole.

$canvas->canvasx(screenx?, gridspacing?)

Given a window x-coordinate in the canvas screenx,
this method returns the canvas x-coordinate that is
displayed at that location. If gridspacing is speci fied, then the canvas coordinate is rounded to the
nearest multiple of gridspacing units.

$canvas->canvasy(screeny, ?gridspacing?)

Given a window y-coordinate in the canvas screeny this method returns the canvas y-coordinate that is dis
played at that location. If gridspacing is specified, then the canvas coordinate is rounded to the nearest
multiple of gridspacing units.

$canvas->coords(tagOrId ?x0,y0 ...?)

Query or modify the coordinates that define an item.
If no coordinates are specified, this method returns a
list whose elements are the coordinates of the item
named by tagOrId. If coordinates are specified, then they replace the current coordinates for the named
item. If tagOrId refers to multiple items, then the first one in the display list is used.

$canvas->create(type, x, y, ?x, y, ...?, ?option, value, ...?)

Create a new item in $canvas of type type. The exact format of the arguments after type depends on type, but usually they consist of the coordinates for one or
more points, followed by specifications for zero or
more item options. See the subsections on individual
item types below for more on the syntax of this
method. This method returns the id for the new item.

$canvas->dchars(tagOrId, first, ?last?)

For each item given by tagOrId, delete the characters, or coordinates, in the range given by first and last, inclusive. If some of the items given by tagOrId
don't support Text items interpret first and last as indices to a character, line and polygon items inter
pret them indices to a coordinate (an x,y pair).
within the item(s) as described in "INDICES" above.
If last is omitted, it defaults to first. This method returns an empty string.

$canvas->delete(?tagOrId, tagOrId, ...?)

Delete each of the items given by each tagOrId, and
return an empty string.

$canvas->dtag(tagOrId, ?tagToDelete?)

For each of the items given by tagOrId, delete the tag given by tagToDelete from the list of those associated with the item. If an item doesn't have the tag tag_
ToDelete then the item is unaffected by the method. If tagToDelete is omitted then it defaults to tagOrId. This method returns an empty string.

$canvas->find(searchCommand, ?arg, arg, ...?)

This method returns a list consisting of all the items
that meet the constraints specified by searchCommand and arg's. SearchCommand and args have any of the forms accepted by the addtag method. The items are
returned in stacking order, with the lowest item
first.

focus
$canvas->focus(?tagOrId?)

Set the keyboard focus for the canvas widget to the
item given by tagOrId. If tagOrId refers to several items, then the focus is set to the first such item in
the display list that supports the insertion cursor.
If tagOrId doesn't refer to any items, or if none of them support the insertion cursor, then the focus
isn't changed. If tagOrId is an empty string, then
the focus item is reset so that no item has the focus.
If tagOrId is not specified then the method returns
the id for the item that currently has the focus, or
an empty string if no item has the focus.

Once the focus has been set to an item, the
item will display the insertion cursor and all
keyboard events will be directed to that item.
The focus item within a canvas and the focus
window on the screen (set with the focus
method) are totally independent: a given item
doesn't actually have the input focus unless
(a) its canvas is the focus window and (b) the
item is the focus item within the canvas. In
most cases it is advisable to follow the focus
widget method with the CanvasFocus method to set the focus window to the canvas (if it
wasn't there already).

$canvas->gettags(tagOrId)

Return a list whose elements are the tags associated
with the item given by tagOrId. If tagOrId refers to more than one item, then the tags are returned from
the first such item in the display list. If tagOrId doesn't refer to any items, or if the item contains no
tags, then an empty string is returned.

$canvas->icursor(tagOrId, index)

Set the position of the insertion cursor for the
item(s) given by tagOrId to just before the character whose position is given by index. If some or all of
the items given by tagOrId don't support an insertion cursor then this method has no effect on them. See
"INDICES" above for a description of the legal forms
for index. Note: the insertion cursor is only dis
played in an item if that item currently has the key
board focus (see the widget method focus, below), but
the cursor position may be set even when the item
doesn't have the focus. This method returns an empty
string.

$canvas->index(tagOrId, index)

This method returns a decimal string giving the numer
ical index within tagOrId corresponding to index. Index gives a textual description of the desired posi
tion as described in "INDICES" above. Text items
interpret index as an index to a character, line and
polygon items interpret it as an index to a coordinate
(an x,y pair). The return value is guaranteed to lie
between 0 and the number of characters, or coordi
nates, within the item, inclusive. If tagOrId refers to multiple items, then the index is processed in the
first of these items that supports indexing operations
(in display list order).

$canvas->insert(tagOrId, beforeThis, string)

For each of the items given by tagOrId, if the item
supports text or coordinate, insertion then string is
inserted into the item's text just before the charac
ter, or coordinate, whose index is beforeThis. Text items interpret beforethis as an index to a charac ter, line and polygon items interpret it as an index
to a coordinate (an x,y pair). For lines and polygons
the string must be a valid coordinate sequence. See
"INDICES" above for information about the forms
allowed for beforeThis. This method returns an empty string.

$canvas->itemcget(tagOrId, option)

Returns the current value of the configuration option
for the item given by tagOrId whose name is option. This method is similar to the cget method except that
it applies to a particular item rather than the widget
as a whole. Option may have any of the values
accepted by the create method when the item was cre
ated. If tagOrId is a tag that refers to more than
one item, the first (lowest) such item is used.

$canvas->itemconfigure(tagOrId, ?option?, ?value?, ?option, value, ...?)

This method is similar to the configure method except
that it modifies item-specific options for the items
given by tagOrId instead of modifying options for the overall canvas widget. If no option is specified,
returns a list describing all of the available options
for the first item given by tagOrId (see Tk::options for information on the format of this list). If
option is specified with no value, then the method returns a list describing the one named option (this
list will be identical to the corresponding sublist of
the value returned if no option is specified). If one or more option-value pairs are specified, then the method modifies the given widget option(s) to have the
given value(s) in each of the items given by tagOrId;
in this case the method returns an empty string. The
options and values are the same as those permissible in the create method when the item(s) were created;
see the sections describing individual item types
below for details on the legal options.

$canvas->lower(tagOrId, ?belowThis?)

Move all of the items given by tagOrId to a new posi tion in the display list just before the item given by
belowThis. If tagOrId refers to more than one item then all are moved but the relative order of the moved
items will not be changed. BelowThis is a tag or id;
if it refers to more than one item then the first
(lowest) of these items in the display list is used as
the destination location for the moved items. Note:
this method has no effect on window items. Window
items always obscure other item types, and the stack
ing order of window items is determined by the raise
and lower methods of the widget, not the raise and lower methods for canvases. This method returns an
empty string.

$canvas->move(tagOrId, xAmount, yAmount)

Move each of the items given by tagOrId in the canvas coordinate space by adding xAmount to the x-coordinate of each point associated with the item and yAmount to the y-coordinate of each point associated with the
item. This method returns an empty string.

$canvas->postscript(?option, value, option, value, ...?)

Generate a Postscript representation for part or all
of the canvas. If the -file option is specified then
the Postscript is written to a file and an empty
string is returned; otherwise the Postscript is
returned as the result of the method. If the inter
preter that owns the canvas is marked as safe, the
operation will fail because safe interpreters are not
allowed to write files. If the -channel option is specified, the argument denotes the name of a channel
already opened for writing. The Postscript is written
to that channel, and the channel is left open for fur
ther writing at the end of the operation. The
Postscript is created in Encapsulated Postscript form
using version 3.0 of the Document Structuring Conven
tions. Note: by default Postscript is only generated
for information that appears in the canvas's window on
the screen. If the canvas is freshly created it may
still have its initial size of 1x1 pixel so nothing
will appear in the Postscript. To get around this
problem either invoke the update method to wait for
the canvas window to reach its final size, or else use
the -width and -height options to specify the area of the canvas to print. The option-value argument pairs provide additional information to control the genera
tion of Postscript. The following options are sup
ported:

-colormap => hashRef

HashRef must be a reference to a hash variable or an anonymous hash that specifies a color
mapping to use in the Postscript. Each value
of the hash must consist of Postscript code to
set a particular color value (e.g. ``1.0 1.0
0.0 setrgbcolor''). When outputting color information in the Postscript, Tk checks to
see if there is a key in the hash with the
same name as the color. If so, Tk uses the
value of the element as the Postscript method
to set the color. If this option hasn't been
specified, or if there isn't a key in hashRef for a given color, then Tk uses the red,
green, and blue intensities from the X color.

-colormode => mode

Specifies how to output color information.
Mode must be either color (for full color out put), gray (convert all colors to their grayscale equivalents) or mono (convert all colors
to black or white).

-file => fileName

Specifies the name of the file in which to
write the Postscript. If this option isn't
specified then the Postscript is returned as
the result of the method instead of being
written to a file.

-fontmap => hashRef

HashRef must be a reference to a hash variable or an anonymous hash that specifies a font
mapping to use in the Postscript. Each value
of the hash must consist of an array reference
with two elements, which are the name and
point size of a Postscript font. When out
putting Postscript commands for a particular
font, Tk checks to see if hashRef contains a value with the same name as the font. If
there is such an element, then the font infor
mation contained in that element is used in
the Postscript. Otherwise Tk attempts to
guess what Postscript font to use. Tk's
guesses generally only work for well-known
fonts such as Times and Helvetica and Courier,
and only if the X font name does not omit any
dashes up through the point size. For exam
ple, -*-Courier-Bold-R-Normal--*-120-* will work but *Courier-Bold-R-Normal*120* will not;
Tk needs the dashes to parse the font name).

-height => size

Specifies the height of the area of the canvas
to print. Defaults to the height of the can
vas window.

-pageanchor => anchor

Specifies which point of the printed area of
the canvas should appear over the positioning
point on the page (which is given by the
-pagex and -pagey options). For example, -pageanchor=>n means that the top center of the area of the canvas being printed (as it
appears in the canvas window) should be over
the positioning point. Defaults to center.

-pageheight => size

Specifies that the Postscript should be scaled
in both x and y so that the printed area is
size high on the Postscript page. Size con sists of a floating-point number followed by c
for centimeters, i for inches, m for millime
ters, or p or nothing for printer's points
(1/72 inch). Defaults to the height of the
printed area on the screen. If both -page
height and -pagewidth are specified then the scale factor from -pagewidth is used (non-uni form scaling is not implemented).

-pagewidth => size

Specifies that the Postscript should be scaled
in both x and y so that the printed area is
size wide on the Postscript page. Size has the same form as for -pageheight. Defaults to the width of the printed area on the screen.
If both -pageheight and -pagewidth are speci fied then the scale factor from -pagewidth is used (non-uniform scaling is not implemented).

-pagex => position

Position gives the x-coordinate of the posi tioning point on the Postscript page, using
any of the forms allowed for -pageheight. Used in conjunction with the -pagey and
-pageanchor options to determine where the printed area appears on the Postscript page.
Defaults to the center of the page.

-pagey => position

Position gives the y-coordinate of the posi tioning point on the Postscript page, using
any of the forms allowed for -pageheight. Used in conjunction with the -pagex and
-pageanchor options to determine where the printed area appears on the Postscript page.
Defaults to the center of the page.

-rotate => boolean

Boolean specifies whether the printed area is to be rotated 90 degrees. In non-rotated out
put the x-axis of the printed area runs along
the short dimension of the page (``portrait''
orientation); in rotated output the x-axis
runs along the long dimension of the page
(``landscape'' orientation). Defaults to
non-rotated.

-width => size

Specifies the width of the area of the canvas
to print. Defaults to the width of the canvas
window.

-x => position

Specifies the x-coordinate of the left edge of
the area of the canvas that is to be printed,
in canvas coordinates, not window coordinates.
Defaults to the coordinate of the left edge of
the window.

-y => position

Specifies the y-coordinate of the top edge of
the area of the canvas that is to be printed,
in canvas coordinates, not window coordinates.
Defaults to the coordinate of the top edge of
the window.

$canvas->raise(tagOrId, ?aboveThis?)

Move all of the items given by tagOrId to a new posi tion in the display list just after the item given by
aboveThis. If tagOrId refers to more than one item then all are moved but the relative order of the moved
items will not be changed. AboveThis is a tag or id;
if it refers to more than one item then the last (top
most) of these items in the display list is used as
the destination location for the moved items. Note:
this method has no effect on window items. Window
items always obscure other item types, and the stack
ing order of window items is determined by the raise
and lower widget commands, not the raise and lower methods for canvases. This method returns an empty
string.

$canvas->scale(tagOrId, xOrigin, yOrigin, xScale, yScale)

Rescale all of the items given by tagOrId in canvas
coordinate space. XOrigin and yOrigin identify the origin for the scaling operation and xScale and yScale identify the scale factors for x- and y-coordinates,
respectively (a scale factor of 1.0 implies no change
to that coordinate). For each of the points defining
each item, the x-coordinate is adjusted to change the
distance from xOrigin by a factor of xScale. Simi larly, each y-coordinate is adjusted to change the
distance from yOrigin by a factor of yScale. This method returns an empty string.

$canvas->scan(option, args)

This method is used to implement scanning on canvases.
It has two forms, depending on option:

$canvas->scanMark(x, y)

Records x and y and the canvas's current view;
used in conjunction with later scanDragto method. Typically this method is associated
with a mouse button press in the widget and x
and y are the coordinates of the mouse. It
returns an empty string.

$canvas->scanDragto(x, y, ?gain?.)

This method computes the difference between
its x and y arguments (which are typically
mouse coordinates) and the x and y arguments
to the last scanMark method for the widget. It then adjusts the view by 10 times the dif
ference in coordinates. This method is typi
cally associated It then adjusts the view by
gain times the difference in coordinates,
where gain defaults to 10. This command is
typically associated with mouse motion events
in the widget, to produce the effect of drag
ging the canvas at high speed through its win
dow. The return value is an empty string.

$canvas->select(option, ?tagOrId, arg?)

Manipulates the selection in one of several ways,
depending on option. The method may take any of the
forms described below. In all of the descriptions
below, tagOrId must refer to an item that supports
indexing and selection; if it refers to multiple
items then the first of these that supports indexing
and the selection is used. Index gives a textual
description of a position within tagOrId, as described in "INDICES" above.

$canvas->selectAdjust(tagOrId, index)

Locate the end of the selection in tagOrId
nearest to the character given by index, and
adjust that end of the selection to be at
index (i.e. including but not going beyond
index). The other end of the selection is
made the anchor point for future selectTo
method calls. If the selection isn't cur
rently in tagOrId then this method behaves the same as the selectTo widget method. Returns an empty string.

$canvas->selectClear

Clear the selection if it is in this widget.
If the selection isn't in this widget then the
method has no effect. Returns an empty
string.

$canvas->selectFrom(tagOrId, index)

Set the selection anchor point for the widget
to be just before the character given by index
in the item given by tagOrId. This method
doesn't change the selection; it just sets
the fixed end of the selection for future
selectTo method calls. Returns an empty
string.

$canvas->selectItem

Returns the id of the selected item, if the
selection is in an item in this canvas. If
the selection is not in this canvas then an
empty string is returned.

$canvas->selectTo(tagOrId, index)

Set the selection to consist of those charac
ters of tagOrId between the selection anchor point and index. The new selection will
include the character given by index; it will
include the character given by the anchor
point only if index is greater than or equal
to the anchor point. The anchor point is
determined by the most recent selectAdjust or selectFrom method calls for this widget. If the selection anchor point for the widget
isn't currently in tagOrId, then it is set to the same character given by index. Returns an
empty string.

$canvas->type(tagOrId)

Returns the type of the item given by tagOrId, such as rectangle or text. If tagOrId refers to more than one item, then the type of the first item in the display
list is returned. If tagOrId doesn't refer to any
items at all then an empty string is returned.

$canvas->xview(?args?)

This method is used to query and change the horizontal
position of the information displayed in the canvas's
window. It can take any of the following forms:

$canvas->xview

Returns a list containing two elements. Each
element is a real fraction between 0 and 1;
together they describe the horizontal span
that is visible in the window. For example,
if the first element is .2 and the second ele
ment is .6, 20% of the canvas's area (as
defined by the -scrollregion option) is offscreen to the left, the middle 40% is visible
in the window, and 40% of the canvas is offscreen to the right. These are the same val
ues passed to scrollbars via the -xscrollcom mand option.

$canvas->xviewMoveto(fraction)

Adjusts the view in the window so that frac_
tion of the total width of the canvas is offscreen to the left. Fraction must be a frac tion between 0 and 1.

$canvas->xviewScroll(number, what)

This method shifts the view in the window left
or right according to number and what. Number must be an integer. What must be either units or pages or an abbreviation of one of these.
If what is units, the view adjusts left or right in units of the xScrollIncrement option, if it is greater than zero, or in units of
one-tenth the window's width otherwise. If
what is pages then the view adjusts in units of nine-tenths the window's width. If number
is negative then information farther to the
left becomes visible; if it is positive then
information farther to the right becomes visi
ble.

$canvas->yview(?args?)

This method is used to query and change the vertical
position of the information displayed in the canvas's
window. It can take any of the following forms:

$canvas->yview

Returns a list containing two elements. Each
element is a real fraction between 0 and 1;
together they describe the vertical span that
is visible in the window. For example, if the
first element is .6 and the second element is
1.0, the lowest 40% of the canvas's area (as
defined by the -scrollregion option) is visi ble in the window. These are the same values
passed to scrollbars via the -yscrollcommand option.

$canvas->yviewMoveto(fraction)

Adjusts the view in the window so that frac_
tion of the canvas's area is off-screen to the
top. Fraction is a fraction between 0 and 1.

$canvas->yviewScroll(number, what)

This method adjusts the view in the window up
or down according to number and what. Number must be an integer. What must be either units or pages. If what is units, the view adjusts up or down in units of the yScrollIncrement option, if it is greater than zero, or in
units of one-tenth the window's height other
wise. If what is pages then the view adjusts in units of nine-tenths the window's height.
If number is negative then higher information
becomes visible; if it is positive then lower
information becomes visible.

OVERVIEW OF ITEM TYPES

The sections below describe the various types of items
supported by canvas widgets. Each item type is character
ized by two things: first, the form of the create method
used to create instances of the type; and second, a set
of configuration options for items of that type, which may
be used in the create and itemconfigure methods. Most items don't support indexing or selection or the methods
related to them, such as index and insert. Where items do support these facilities, it is noted explicitly in the
descriptions below. At present, text, line and polygon
items provide this support. For lines and polygons the
indexing facility is used to manipulate the coordinates of
the item.

ARC ITEMS

Items of type arc appear on the display as arc-shaped
regions. An arc is a section of an oval delimited by two
angles (specified by the -start and -extent options) and displayed in one of several ways (specified by the -style
option). Arcs are created with methods of the following
form:

$canvas->createArc(x1, y1, x2, y2, ?option, value, op

tion, value, ...?)

The arguments x1, y1, x2, and y2 give the coordinates of two diagonally opposite corners of a rectangular region
enclosing the oval that defines the arc. After the coor
dinates there may be any number of option-value pairs, each of which sets one of the configuration options for
the item. These same option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options are supported for arcs:

-dash => pattern
-activedash => pattern
-disableddash => pattern

This option specifies dash patterns for the normal
state, the active state, and the disabled state of an
arc item. pattern may have any of the forms accepted by Tk_GetDash. If the dash options are omitted then the default is a solid outline.

-dashoffset => offset

The starting offset into the pattern provided by the
-dash option. -dashoffset is ignored if there is no -dash pattern.

-extent => degrees

Specifies the size of the angular range occupied by
the arc. The arc's range extends for degrees degrees counter-clockwise from the starting angle given by the
-start option. Degrees may be negative. If it is greater than 360 or less than -360, then degrees mod ulo 360 is used as the extent.

-fill => color
-activefill => color
-disabledfill => color

Specifies the color to be used to fill the arc region
in its normal, active, and disabled states, Color may
have any of the forms accepted by Tk_GetColor. If color is an empty string (the default), then then the
arc will not be filled.

-outline => color
-activeoutline => color
-disabledoutline => color

This option specifies the color that should be used to
draw the outline of the arc in its normal, active and
disabled states. Color may have any of the forms
accepted by Tk_GetColor. This option defaults to black. If color is specified as undef then no outline is drawn for the arc.

-outlinestipple => bitmap
-activeoutlinestipple => bitmap -disabledoutlinestipple => bitmap

This option specifies stipple patterns that should be
used to draw the outline of the arc in its normal,
active and disabled states. Indicates that the out
line for the arc should be drawn with a stipple
pattern; bitmap specifies the stipple pattern to use,
in any of the forms accepted by Tk_GetBitmap. If the -outline option hasn't been specified then this option has no effect. If bitmap is an empty string (the
default), then the outline is drawn in a solid fash
ion.

-start => degrees

Specifies the beginning of the angular range occupied
by the arc. Degrees is given in units of degrees mea sured counter-clockwise from the 3-o'clock position;
it may be either positive or negative.

-state => state

Modifies the state of the arc item where state may be
set to one of: normal, disabled, hidden or "". If set
to empty, the state of the canvas itself is used. An
arc item may also be in the "active" state if the
mouse is currently over it. Many options can take
separate specifications in normal, active and disabled
states such that the appearance of the item can be
different in each state.

-stipple => bitmap
-activestipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to fill the the arc in its normal, active and
disabled states. bitmap specifies the stipple pattern to use, in any of the forms accepted by Tk_GetBitmap. If the -fill option hasn't been specified then this
option has no effect. If bitmap is an empty string
(the default), then filling is done in a solid fash
ion.

-style => type

Specifies how to draw the arc. If type is pieslice (the default) then the arc's region is defined by a
section of the oval's perimeter plus two line seg
ments, one between the center of the oval and each end
of the perimeter section. If type is chord then the arc's region is defined by a section of the oval's
perimeter plus a single line segment connecting the
two end points of the perimeter section. If type is
arc then the arc's region consists of a section of the
perimeter alone. In this last case the -fill option
is ignored.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the arc item is updated on the screen.

-width => outlineWidth
-activewidth => outlineWidth -disabledwidth => outlineWidth

Specifies the width of the outline to be drawn around
the arc's region, in its normal, active and disabled
states. outlineWidth may be in any of the forms described in the "COORDINATES" section above. If the
-outline option has been specified as undef then this option has no effect. Wide outlines will be drawn
centered on the edges of the arc's region. This
option defaults to 1.0.

BITMAP ITEMS

Items of type bitmap appear on the display as images with
two colors, foreground and background. Bitmaps are cre
ated with methods of the following form:

$canvas->createBitmap(x, y, ?option, value, option, val

ue, ...?)

The arguments x and y specify the coordinates of a point
used to position the bitmap on the display (see the
-anchor option below for more information on how bitmaps are displayed). After the coordinates there may be any
number of option-value pairs, each of which sets one of the configuration options for the item. These same
option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options
are supported for bitmaps:

-anchor => anchorPos

AnchorPos tells how to position the bitmap relative to the positioning point for the item; it may have any
of the forms accepted by Tk_GetAnchor. For example, if anchorPos is center then the bitmap is centered on the point; if anchorPos is n then the bitmap will be drawn so that its top center point is at the position
ing point. This option defaults to center.

-background => color
-activebackground => color -disabledbackground => color

Specifies the color to use for each of the bitmap's
'0' valued pixels in its normal, active and disabled
states. Color may have any of the forms accepted by
Tk_GetColor. If this option isn't specified, or if it is specified as undef, then nothing is displayed where
the bitmap pixels are 0; this produces a transparent
effect.

-bitmap => bitmap
-activebitmap => bitmap
-disabledbitmap => bitmap

Specifies the bitmaps to display in the item in its
normal, active and disabled states. Bitmap may have
any of the forms accepted by Tk_GetBitmap.

-foreground => color
-activeforeground => bitmap -disabledforeground => bitmap

Specifies the color to use for each of the bitmap's
'1' valued pixels in its normal, active and disabled
states. Color may have any of the forms accepted by
Tk_GetColor and defaults to black.

-state => state

Modifies the state of the bitmap item where state may
be set to one of: normal, disabled, or hidden. An
bitmap item may also be in the "active" state if the
mouse is currently over it. Many options can take
separate specifications in normal, active and disabled
states such that the appearance of the item can be
different in each state.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the bitmap item is updated on the screen.

GRID ITEMS

Items of type grid are intended for producing a visual
reference for interpreting other items. They can be drawn
as either lines (with dash style) or as rectangular "dots"
at each grid point.

Items of type grid are unlike other items they always
cover the whole of the canvas, but are never enclosed by
nor overlap any area and are not near any point. That is
they are intended to be always visible but not "pickable",
as such they do support the "active" state. They are like
other items in that: multiple grids are permitted, they
can be raised and lowered relative to other items, they
can be moved and scaled. As yet grids do not apear in
PostScript output.

Grids have outline like configure options. Grids are cre
ated with methods of the following form:

$canvas->createGrid(x1, y1, x2, y2, ?option, value, op

tion, value, ...?)

The arguments x1, y1 give the origin of the grid. x2, and
y2 give the coordinates of the next grid point in their
respective directions. After the coordinates there may be
any number of option-value pairs, each of which sets one of the configuration options for the item. These same
option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options
are supported for grids:

-lines => boolean

If -lines is set to a true value then lines are drawn
for both X and Y grids in the style determined by
-dash. Otherwise retangular "dots" are drawn at each
grid point.

-dash => pattern
-disableddash => pattern

This option specifies dash patterns for the normal
state, and the disabled state of a grid item. pattern may have any of the forms accepted by Tk_GetDash. If the dash options are omitted then the default is a
solid outline.

-dashoffset => offset

The starting offset into the pattern provided by the
-dash option. -dashoffset is ignored if there is no -dash pattern.

-color => color
-disabledcolor => color

This option specifies the color that should be used to
draw the outline of the grid in its normal and dis
abled states. Color may have any of the forms
accepted by Tk_GetColor. This option defaults to black. If color is undef then no grid will be drawn.

-stipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to draw the outline of the rectangle in its nor
mal and disabled states. bitmap specifies the stipple pattern to use, in any of the forms accepted by
Tk_GetBitmap. If bitmap is an empty string (the default), then the outline is drawn in a solid fash
ion.

-state => state

Modifies the state of the rectangle item where state
may be set to one of: normal, disabled, or hidden.
Many options can take separate specifications in nor
mal and disabled states such that the appearance of
the item can be different in each state.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the grid item is updated on the screen.

-width => outlineWidth
-disabledwidth => outlineWidth

Specifies the width of the lines drawn by the grid or
the size (in both X and Y) of the dots, in its normal
and disabled states. This option defaults to 1.0.

IMAGE ITEMS

Items of type image are used to display images on a can
vas. Images are created with methods of the following
form:

$canvas->createImage(x, y, ?option, value, option, value,

...?)

The arguments x and y specify the coordinates of a point
used to position the image on the display (see the -anchor option below for more information). After the coordinates
there may be any number of option-value pairs, each of which sets one of the configuration options for the item.
These same option-value pairs may be used in itemconfigure methods to change the item's configuration. The following
options are supported for images:

-anchor => anchorPos

AnchorPos tells how to position the image relative to the positioning point for the item; it may have any
of the forms accepted by Tk_GetAnchor. For example, if anchorPos is center then the image is centered on the point; if anchorPos is n then the image will be drawn so that its top center point is at the position
ing point. This option defaults to center.

-image => name
-activeimage => name
-disabledimage => name

Specifies the name of the images to display in the
item in is normal, active and disabled states. This
image must have been created previously with the
imageCreate method.

-state => state

Modifies the state of the image item where state may
be set to one of: normal, disabled, or hidden. An
image item may also be in the "active" state if the
mouse is currently over it. Many options can take
separate specifications in normal, active and disabled
states such that the appearance of the item can be
different in each state.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item; it may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the image item is updated on the screen.

LINE ITEMS

Items of type line appear on the display as one or more
connected line segments or curves. Line items support
coordinate indexing operations using the canvas methods:
dchars, index, insert. Lines are created with methods of the following form:

$canvas->createLine(x1, y1..., xn, yn, ?option, value,

option, value, ...?)

The arguments x1 through yn give the coordinates for a
series of two or more points that describe a series of
connected line segments. After the coordinates there may
be any number of option-value pairs, each of which sets one of the configuration options for the item. These same
option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options
are supported for lines:

-arrow => where

Indicates whether or not arrowheads are to be drawn at
one or both ends of the line. Where must have one of
the values none (for no arrowheads), first (for an arrowhead at the first point of the line), last (for
an arrowhead at the last point of the line), or both
(for arrowheads at both ends). This option defaults
to none.

-arrowshape => shape

This option indicates how to draw arrowheads. The
shape argument must be a list with three elements,
each specifying a distance in any of the forms
described in the "COORDINATES" section above. The
first element of the list gives the distance along the
line from the neck of the arrowhead to its tip. The
second element gives the distance along the line from
the trailing points of the arrowhead to the tip, and
the third element gives the distance from the outside
edge of the line to the trailing points. If this
option isn't specified then Tk picks a ``reasonable''
shape.

-capstyle => style

Specifies the ways in which caps are to be drawn at
the endpoints of the line. Style may have any of the
forms accepted by Tk_GetCapStyle (butt, projecting, or round). If this option isn't specified then it
defaults to butt. Where arrowheads are drawn the cap
style is ignored.

-dash => pattern
-activedash => pattern
-disableddash => pattern

This option specifies dash patterns for the normal
state, the active state, and the disabled state of a
line item. pattern may have any of the forms accepted by Tk_GetDash. If the dash options are omitted then the default is a solid outline.

-dashoffset => offset

The starting offset into the pattern provided by the
-dash option. -dashoffset is ignored if there is no -dash pattern.

-fill => color
-activefill => color
-disabledfill => color

Specifies the color to be used to fill the line in its
normal, active, and disabled states. Color may have
any of the forms acceptable to Tk_GetColor. It may also be undef, in which case the line will be trans
parent. This option defaults to black.

-joinstyle => style

Specifies the ways in which joints are to be drawn at
the vertices of the line. Style may have any of the
forms accepted by Tk_GetCapStyle (bevel, miter, or round). If this option isn't specified then it
defaults to miter. If the line only contains two
points then this option is irrelevant.

-smooth => boolean

Boolean must have one of the forms accepted by Tk_Get Boolean. It indicates whether or not the line should be drawn as a curve. If so, the line is rendered as a
set of parabolic splines: one spline is drawn for the
first and second line segments, one for the second and
third, and so on. Straight-line segments can be gen
erated within a curve by duplicating the end-points of
the desired line segment.

-splinesteps => number

Specifies the degree of smoothness desired for curves:
each spline will be approximated with number line seg
ments. This option is ignored unless the -smooth
option is true.

-state => state

Modifies the state of the line item where state may be
set to one of: normal, disabled, or hidden. A line
item may also be in the "active" state if the mouse is
currently over it. Many options can take separate
specifications in normal, active and disabled states
such that the appearance of the item can be different
in each state.

-stipple => bitmap
-activestipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to fill the the line in its normal, active and
disabled states. bitmap specifies the stipple pattern to use, in any of the forms accepted by Tk_GetBitmap. If bitmap is an empty string (the default), then fill
ing is done in a solid fashion.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the line item is updated on the screen.

-width => lineWidth
-activewidth => lineWidth
-disabledwidth => lineWidth

Specifies the width of the line in its normal, active
and disabled states. lineWidth may be in any of the forms described in the "COORDINATES" section above.

Wide lines will be drawn centered on the path speci
fied by the points. If this option isn't specified
then it defaults to 1.0.

OVAL ITEMS

Items of type oval appear as circular or oval regions on
the display. Each oval may have an outline, a fill, or
both. Ovals are created with methods of the following
form:

$canvas->createOval(x1, y1, x2, y2, ?option, value, op

tion, value, ...?)

The arguments x1, y1, x2, and y2 give the coordinates of two diagonally opposite corners of a rectangular region
enclosing the oval. The oval will include the top and
left edges of the rectangle not the lower or right edges.
If the region is square then the resulting oval is circu
lar; otherwise it is elongated in shape. After the coor
dinates there may be any number of option-value pairs, each of which sets one of the configuration options for
the item. These same option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options are supported for ovals:

-dash => pattern
-activedash => pattern
-disableddash => pattern

This option specifies dash patterns for the normal
state, the active state, and the disabled state of an
oval item. pattern may have any of the forms accepted by Tk_GetDash. If the dash options are omitted then the default is a solid outline.

-dashoffset => offset

The starting offset into the pattern provided by the
-dash option. -dashoffset is ignored if there is no -dash pattern.

-fill => color
-activefill => color
-disabledfill => color

Specifies the color to be used to fill the oval in its
normal, active, and disabled states. Color may have
any of the forms accepted by Tk_GetColor. If color is undef (the default), then then the oval will not be
filled.

-outline => color
-activeoutline => color
-disabledoutline => color

This option specifies the color that should be used to
draw the outline of the oval in its normal, active and
disabled states. Color may have any of the forms
accepted by Tk_GetColor. This option defaults to black. If color is undef then no outline will be drawn for the oval.

-outlinestipple => bitmap
-activeoutlinestipple => bitmap -disabledoutlinestipple => bitmap

This option specifies stipple patterns that should be
used to draw the outline of the oval in its normal,
active and disabled states. bitmap specifies the
stipple pattern to use, in any of the forms accepted
by Tk_GetBitmap. If the -outline option hasn't been specified then this option has no effect. If bitmap
is an empty string (the default), then the outline is
drawn in a solid fashion.

-state => state

Modifies the state of the oval item where state may be
set to one of: normal, disabled, or hidden. An oval
item may also be in the "active" state if the mouse is
currently over it. Many options can take separate
specifications in normal, active and disabled states
such that the appearance of the item can be different
in each state.

-stipple => bitmap
-activestipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to fill the the oval in its normal, active and
disabled states. bitmap specifies the stipple pattern to use, in any of the forms accepted by Tk_GetBitmap. If the -fill option hasn't been specified then this
option has no effect. If bitmap is an empty string
(the default), then filling is done in a solid fash
ion.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the oval item is updated on the screen.

-width => outlineWidth
-activewidth => outlineWidth -disabledwidth => outlineWidth

Specifies the width of the outline to be drawn around
the oval, in its normal, active and disabled states.
outlineWidth specifies the width of the outline to be drawn around the oval, in any of the forms described
in the "COORDINATES" section above.

If the -outline option hasn't been specified then this option has no effect. Wide outlines are drawn cen
tered on the oval path defined by x1, y1, x2, and y2. This option defaults to 1.0.

POLYGON ITEMS

Items of type polygon appear as polygonal or curved filled regions on the display. Polygon items support coordinate
indexing operations using the canvas methods: dchars,
index, insert. Polygons are created with methods of the following form:

$canvas->createPolygon(x1, y1, ..., xn, yn, ?option, val

ue, option, value, ...?)

The arguments x1 through yn specify the coordinates for
three or more points that define a closed polygon. The
first and last points may be the same; whether they are
or not, Tk will draw the polygon as a closed polygon.
After the coordinates there may be any number of
option-value pairs, each of which sets one of the configu ration options for the item. These same option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options are supported
for polygons:

-dash => pattern
-activedash => pattern
-disableddash => pattern

This option specifies dash patterns for the normal
state, the active state, and the disabled state of an
polygon item. pattern may have any of the forms
accepted by Tk_GetDash. If the dash options are omit ted then the default is a solid outline.

-dashoffset => offset

The starting offset into the pattern provided by the
-dash option. -dashoffset is ignored if there is no -dash pattern.

-fill => color
-activefill => color
-disabledfill => color

Specifies the color to be used to fill the polygon in
its normal, active, and disabled states. Color may
have any of the forms acceptable to Tk_GetColor. If color is undef then the polygon will be transparent.
This option defaults to black.

-joinstyle => style

Specifies the ways in which joints are to be drawn at
the vertices of the outline. Style may have any of
the forms accepted by Tk_GetCapStyle (bevel, miter, or round). If this option isn't specified then it
defaults to miter.

-outline => color
-activeoutline => color
-disabledoutline => color

This option specifies the color that should be used to
draw the outline of the polygon in its normal, active
and disabled states. Color may have any of the forms
accepted by Tk_GetColor. If color is undef then no outline will be drawn for the polygon. This option
defaults to undef (no outline).

-outlinestipple => bitmap
-activeoutlinestipple => bitmap -disabledoutlinestipple => bitmap

This option specifies stipple patterns that should be
used to draw the outline of the polygon in its normal,
active and disabled states. bitmap specifies the
stipple pattern to use, in any of the forms accepted
by Tk_GetBitmap. If the -outline option hasn't been specified then this option has no effect. If bitmap
is an empty string (the default), then the outline is
drawn in a solid fashion.

-smooth => boolean

Boolean must have one of the forms accepted by Tk_Get Boolean It indicates whether or not the polygon should be drawn with a curved perimeter. If so, the outline
of the polygon becomes a set of parabolic splines, one
spline for the first and second line segments, one for
the second and third, and so on. Straight-line seg
ments can be generated in a smoothed polygon by dupli
cating the end-points of the desired line segment.

-splinesteps => number

Specifies the degree of smoothness desired for curves:
each spline will be approximated with number line seg
ments. This option is ignored unless the -smooth
option is true.

-state => state

Modifies the state of the polygon item where state may
be set to one of: normal, disabled, or hidden. A
polygon item may also be in the "active" state if the
mouse is currently over it. Many options can take
separate specifications in normal, active and disabled
states such that the appearance of the item can be
different in each state.

-stipple => bitmap
-activestipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to fill the the polygon in its normal, active and
disabled states. bitmap specifies the stipple pattern to use, in any of the forms accepted by Tk_GetBitmap. If bitmap is an empty string (the default), then fill
ing is done in a solid fashion.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the polygon item is updated on the screen.

-width => outlineWidth
-activewidth => outlineWidth -disabledwidth => outlineWidth Specifies the width of the outline to be drawn around

the polygon, in its normal, active and disabled
states. outlineWidth may be in any of the forms described in the COORDINATES section above. Out_
lineWidth specifies the width of the outline to be drawn around the polygon, in any of the forms
described in the "COORDINATES" section above. If the
-outline option hasn't been specified then this option has no effect. This option defaults to 1.0.

Polygon items are different from other items such as
rectangles, ovals and arcs in that interior points are
considered to be ``inside'' a polygon (e.g. for pur
poses of the find closest and find overlapping meth ods) even if it is not filled. For most other item
types, an interior point is considered to be inside
the item only if the item is filled or if it has nei
ther a fill nor an outline. If you would like an
unfilled polygon whose interior points are not consid
ered to be inside the polygon, use a line item
instead.

RECTANGLE ITEMS

Items of type rectangle appear as rectangular regions on the display. Each rectangle may have an outline, a fill,
or both. Rectangles are created with methods of the fol
lowing form:

$canvas->createRectangle(x1, y1, x2, y2, ?option, value,

option, value, ...?)

The arguments x1, y1, x2, and y2 give the coordinates of two diagonally opposite corners of the rectangle (the
rectangle will include its upper and left edges but not
its lower or right edges). After the coordinates there
may be any number of option-value pairs, each of which sets one of the configuration options for the item. These
same option-value pairs may be used in itemconfigure meth ods to change the item's configuration. The following
options are supported for rectangles:

-dash => pattern
-activedash => pattern
-disableddash => pattern

This option specifies dash patterns for the normal
state, the active state, and the disabled state of a
rectangle item. pattern may have any of the forms
accepted by Tk_GetDash. If the dash options are omit ted then the default is a solid outline.

-dashoffset => offset

The starting offset into the pattern provided by the
-dash option. -dashoffset is ignored if there is no -dash pattern.

-fill => color
-activefill => color
-disabledfill => color

Specifies the color to be used to fill the rectangle
in its normal, active, and disabled states. Color may
be specified in any of the forms accepted by Tk_Get
Color. If color is undef (the default), then the rectangle will not be filled.

-outline => color
-activeoutline => color
-disabledoutline => color

This option specifies the color that should be used to
draw the outline of the rectangle in its normal,
active and disabled states. Color may have any of the
forms accepted by Tk_GetColor. This option defaults to black. If color is undef then no outline will be drawn for the rectangle.

-outlinestipple => bitmap
-activeoutlinestipple => bitmap -disabledoutlinestipple => bitmap

This option specifies stipple patterns that should be
used to draw the outline of the rectangle in its
normal, active and disabled states. bitmap specifies
the stipple pattern to use, in any of the forms
accepted by Tk_GetBitmap. If the -outline option hasn't been specified then this option has no effect.
If bitmap is an empty string (the default), then the
outline is drawn in a solid fashion.

-state => state

Modifies the state of the rectangle item where state
may be set to one of: normal, disabled, or hidden. A
rectangle item may also be in the "active" state if
the mouse is currently over it. Many options can take
separate specifications in normal, active and disabled
states such that the appearance of the item can be
different in each state.

-stipple => bitmap
-activestipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to fill the the rectangle in its normal, active
and disabled states. bitmap specifies the stipple
pattern to use, in any of the forms accepted by
Tk_GetBitmap. If the -fill option hasn't been speci fied then this option has no effect. If bitmap is an
empty string (the default), then filling is done in a
solid fashion.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the rectangle item is updated on the screen.

-width => outlineWidth
-activewidth => outlineWidth -disabledwidth => outlineWidth

Specifies the width of the outline to be drawn around
the rectangle, in its normal, active and disabled
states. OutlineWidth specifies the width of the out line to be drawn around the rectangle, in any of the
forms described in the "COORDINATES" section above.

If the -outline option hasn't been specified then this option has no effect. Wide outlines are drawn cen
tered on the rectangular path defined by x1, y1, x2,
and y2. This option defaults to 1.0.

TEXT ITEMS

A text item displays a string of characters on the screen
in one or more lines. Text items support indexing and
selection, along with the following text-related canvas
methods: dchars, focus, icursor, index, insert, select. Text items are created with methods of the following form:

$canvas->createText(x, y, ?option, value, option, value,

...?)

The arguments x and y specify the coordinates of a point
used to position the text on the display (see the options
below for more information on how text is displayed).
After the coordinates there may be any number of
option-value pairs, each of which sets one of the configuration options for the item. These same
option-value pairs may be used in itemconfigure methods to change the item's configuration. The following options
are supported for text items:

-anchor => anchorPos

AnchorPos tells how to position the text relative to the positioning point for the text; it may have any
of the forms accepted by Tk_GetAnchor. For example, if anchorPos is center then the text is centered on the point; if anchorPos is n then the text will be drawn such that the top center point of the rectangu
lar region occupied by the text will be at the posi
tioning point. This option defaults to center.

-fill => color
-activefill => color
-disabledfill => color

Specifies the color to be used to fill the text in its
normal, active, and disabled states. Color may have
any of the forms accepted by Tk_GetColor. If color is undef then the text will be transparent. If this
option isn't specified then it defaults to black.

-font => fontName

Specifies the font to use for the text item. FontName may be any string acceptable to Tk_GetFontStruct. If this option isn't specified, it defaults to a systemdependent font.

-justify => how

Specifies how to justify the text within its bounding
region. How must be one of the values left, right, or center. This option will only matter if the text is
displayed as multiple lines. If the option is omit
ted, it defaults to left.

-state => state

Modifies the state of the text item where state may be
set to one of: normal, disabled, or hidden. A text
item may also be in the "active" state if the mouse is
currently over it. Many options can take separate
specifications in normal, active and disabled states
such that the appearance of the item can be different
in each state.

-stipple => bitmap
-activestipple => bitmap
-disabledstipple => bitmap

This option specifies stipple patterns that should be
used to fill the the text in its normal, active and
disabled states. bitmap specifies the stipple pattern to use, in any of the forms accepted by Tk_GetBitmap. If bitmap is an empty string (the default) then the
text is drawn in a solid fashion.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-text => string

String specifies the characters to be displayed in the text item. Newline characters cause line breaks. The
characters in the item may also be changed with the
insert and delete methods. This option defaults to an empty string.

-updatecommand => command

Specifies a callback that is to be executed every time
the text item is updated on the screen.

-width => lineLength

Specifies a maximum line length for the text, in any
of the forms described in the "COORDINATES" section
above. If this option is zero (the default) the text
is broken into lines only at newline characters. How
ever, if this option is non-zero then any line that
would be longer than lineLength is broken just before a space character to make the line shorter than line_
Length; the space character is treated as if it were
a newline character.

WINDOW ITEMS

Items of type window cause a particular window to be dis
played at a given position on the canvas. Window items
are created with methods of the following form:

$canvas->createWindow(x, y?, -option=>value,

-option=>value, ...?)

The arguments x and y specify the coordinates of a point
used to position the window on the display (see the
-anchor option below for more information on how bitmaps are displayed). After the coordinates there may be any
number of option-value pairs, each of which sets one of the configuration options for the item. These same
option-value pairs may be used in itemconfigure method to change the item's configuration. The following options
are supported for window items:

-anchor => anchorPos

AnchorPos tells how to position the window relative to the positioning point for the item; it may have any
of the forms accepted by Tk_GetAnchor. For example, if anchorPos is center then the window is centered on the point; if anchorPos is n then the window will be drawn so that its top center point is at the position
ing point. This option defaults to center.

-height => pixels

Specifies the height to assign to the item's window.
Pixels may have any of the forms described in the
"COORDINATES" section above. If this option isn't
specified, or if it is specified as an empty string,
then the window is given whatever height it requests
internally.

-state => state

Modifies the state of the window item where state may
be set to one of: normal, disabled, or hidden.

-tags => tagList

Specifies a set of tags to apply to the item. TagList consists of a list of tag names, which replace any
existing tags for the item. TagList may be an empty list.

-updatecommand => command

Specifies a callback that is to be executed every time
the window item is updated on the screen.

-width => pixels

Specifies the width to assign to the item's window.
Pixels may have any of the forms described in the
"COORDINATES" section above. If this option isn't
specified, or if it is specified as an empty string,
then the window is given whatever width it requests
internally.

-window => $widget

Specifies the window to associate with this item. The
window specified by $widget must either be a child of
the canvas widget or a child of some ancestor of the
canvas widget. PathName may not refer to a top-level window.

Note: due to restrictions in the ways that windows
are managed, it is not possible to draw other graphi
cal items (such as lines and images) on top of window
items. A window item always obscures any graphics
that overlap it, regardless of their order in the dis
play list.

APPLICATION-DEFINED ITEM TYPES

It is possible for individual applications to define new
item types for canvas widgets using C code. See the docu
mentation for Tk_CreateItemType.

BINDINGS

Canvas has default bindings to allow scrolling if neces
sary: <Up>, <Down>, <Left> and <Right> (and their <Con
trol-*> counter parts). Further <Proir>, <Next>, <Home>
and <End>. These bindings allow you to navigate the same
way as in other widgets that can scroll.

CREDITS

Tk's canvas widget is a blatant ripoff of ideas from Joel
Bartlett's ezd program. Ezd provides structured graphics
in a Scheme environment and preceded canvases by a year or
two. Its simple mechanisms for placing and animating
graphical objects inspired the functions of canvases.

KEYWORDS

canvas, widget

perl v5.8.0 2000-03-31 CANVAS(1)