Canvas-compatible methods
We have tried to make the Slate a strict superset of the Tk canvas, in
order that it can be dropped into existing applications and those
applications then extended by using Slate's additional features. Here is
an overview of the Slate methods that implement the standard canvas
interface.
Methods extended to understand complex items
The following methods have been extended under complex item IDs:
- addtag tag searchSpec
- Add the tag tag to all items indicated by searchSpec.
searchSpec can have all the same formats as for the
find
method.
- bbox ?tagOrID? ....
- Return the bounding box of all items indicated by the arguments. Each
argument can either be an itemID or a tag.
- bind tagOrID ?sequence? ?command?
- Bind a command. With one argument, return the event sequences for
which there is a binding to tagOrID. If sequence is given,
return the command, if any, bound to the given tag or ID and event
sequence. If command is given, bind it to the given tag or ID and
event sequence.
- coords tagOrID ?x0 y0 ... ?
- With just the first argument, return the coordinates of the item
or (or the first found item if the argument is a tag). If coordinates are
given, set the item's coordinates to those values.
- create type ?x0 y0 ... ? ?option value ...?
- Create a new item and return its ID. If type starts with
a lower-case letter, create a simple (canvas) item; if not, create
a complex item. If the options include
-tag
with
tags returned by calling gettags
on a complex item, the new
item will be added to that complex item.
- delete ?tagOrID ...?
- Delete all indicated items. Each argument can be an item ID
or a tag.
- dtag tagOrID ?delete?
- If delete is not given, delete tag tagOrID from all
items indicated by tagOrID; else delete tag delete from all
items indicated by tagOrID.
- find searchSpec
- Return all items matching searchSpec. searchSpec
can have the following forms:
- above id: Return the item immediately above
id. Currently, this will not work if id is a tag.
- all: Return every root complex item, and every
item that is not a component of a complex item.
- below id: Return the item immediately below
id. Currently, this will not work if id is a tag.
- closest x y ?halo? ?start?: Return the item
closest to the point (x,y). Currently, this mode is not
working correctly.
- enclosed x0 x1 y0 y1: Return every complex item and
unparented simple item enclosed by the given region.
- overlapping x0 x1 y0 y1: Return every complex item and
unparented simple item that overlaps the given region.
- withtag tag: Return every complex item and every
unparented simple item with the given tag. If tag is
"current," return either the current simple item, or the complex
item which is the parent of that current simple item.
- gettags tagOrID
- Return the tags of the given item, or a matching item
if the argument is a tag.
- itemcget tagOrID option
- Read a configuration option of the given item, or a matching item
if the first argument is a tag.
- itemconfigure tagOrID ?option value ...?
- Set configuration options of the given item, or a matching item
if the first argument is a tag.
- lower tagOrID ?belowThis?
- Lower the given item, or a matching item
if the first argument is a tag, to the bottom of the display list,
or to just below belowThis if it is given.
- raise tagOrID ?aboveThis?
- Raise the given item, or a matching item
if the first argument is a tag, to the top of the display list,
or to just above aboveThis if it is given.
- move tagOrID ?x y?
- Move specified items by the given amount. The first argument
can either be a tag or an id.
- scale tagOrID ?xOrigin yOrigin xScale yScale?
- Scale specified items by the given amount. The first argument
can either be a tag or an id. Currently this does not work
if the first argument is a tag.
- type id
- Return the type of the given item.
Other methods
The following methods are forwarded directly to the canvas
and work correctly:
- canvasx screenx ?gridspacing?
- Convert a screen x coordinate into a canvas x coordinate
- canvasy screeny ?gridspacing?
- Convert a screen y coordinate into a canvas y coordinate
- focus ???
- Focus on an item
- postscript ???
- Generate a postscript representation of the canvas.
- scan option ?val? ...
- Scanning on an item???.
- xview ???
- Set the horizontal view for scrolling.
- yview ???
- Set the vertical view for scrolling.
The following methods are currently forwarded directly
to the canvas but need to be modified at some time to understand
complex item IDs:
- dchars id first ?last?
- Delete characters in a text item.
- icursor id index
- Set the insertion cursor.
- index id index
- Return the numerical value of a symbolic index.
- insert id beforeThis string
- Insert text at the insertion cursor.
- select option ?id? ?index?
- Manipulate the selection in a text item.
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Last updated: 96/12/11,
comments to: johnr@eecs.berkeley.edu