Canvas

subclass of Widget
Classy::Canvas creates a canvas widget that supports undo and redo, save and load, selection and grouping. Most options and commands are identical to those of the standard Tk canvas.
Classy::Canvas reserves tags starting with an underscore (_) for internal use (temporary tags, grouping etc.). You should not add or remove such tags, except for the group names returned by the group method.

Canvas specific methods

pathname undo ?action? ?args?

Without arguments, this method will undo the previous action When action is provided, it can have the following values

check

insert a checkpoint

clear

clear undo buffer

add

add ?args? to undo buffer, they will be executed when undo is called

off

turn undo buffering of

on

turn undo buffering on

status

query state of undo

pathname redo

redo undone actions

pathname noundo ?args?

execute command without storing in undo buffer

pathname addtag tag searchCommand ?arg ...?

This command is identical to that of the standard canvas widget, but supports some extra searchcommanda:

items

all given items

tags

all items with one of the given tags

andtags

all items with all of the given tags

pathname find tag searchCommand ?arg ...?

This command is identical to that of the standard canvas widget, but supports some extra searchcommanda:

tags

all items with one of the given tags

andtags

all items with all of the given tags

pathname current ?item?

returns the current item. If current is given, it changes the the current item to the item given.

pathname save ?tag?

returns a list that can be used to restore the drawing in the canvas using a load command. This can be saved to a file for permanent storage. If tag is given, only items with tag $tag will be saved instead of all items.

pathname group searchcommand ?arg? ...

creates a new group, consisting of items found by the searchcommand. searchcommand has the same options as in the addtag method. The method returns the name of the group. The group name can be used as a tag, in order to perform actions on group members. Adding the group name as a tag to an item will add the item to the group.

pathname findgroup tagOrId

returns the main group of an item: This is the last one the item was added to. If tagOrId is a tag that refers to more than one item, the first (lowest) such item is used.

pathname cut ?tagOrId?

copies a description of the objects given by tagOrId to the clipboard

pathname copy ?tagOrId?

copies a description of the objects given by tagOrId to the clipboard

pathname paste

creates new objects from a description put on the clipboard by the copy or cut method

pathname print

pops up a print dialog and prints the current canvas.

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Peter De Rijk

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