Canvas Attributes

Table 34-13 lists the attributes for the canvas widget. The table uses the resource name, which has capitals at internal word boundaries. In Tcl commands, the attributes are specified with a dash and are all lowercase.

Table 34-13. Canvas attribute resource names.

background	The normal background color.
borderWidth	The width of the border around the canvas.
closeEnough	Distance from mouse to an overlapping object.
confine	Boolean. True constrains the view to the scroll region.
cursor	Cursor to display when mouse is over the widget.
height	Height, in screen units, of canvas display.
highlightBackground	Focus highlight color when widget does not have focus.
highlightColor	Color for input focus highlight border.
highlightThickness	Width of highlight border.
insertBackground	Background for area covered by insert cursor.
insertBorderwidth	Width of cursor border. Nonzero for 3D effect.
insertOffTime	Time, in milliseconds the insert cursor blinks off.
insertOnTime	Time, in milliseconds the insert cursor blinks on.
insertWidth	Width of insert cursor. Default is 2.
relief	flat, sunken, raised, groove, solid, or ridge.
scrollIncrement	The minimum scrolling distance.
scrollRegion	Left, top, right, and bottom coordinates of the canvas.
selectBackground	Background color of selection.
selectForeground	Foreground color of selection.
selectBorderWidth	Width of selection border. Nonzero for 3D effect.
takeFocus	Controls focus changes from keyboard traversal.
width	Width in screen units for viewable area.
xScrollCommand	Tcl command prefix for horizontal scrolling.
xScrollIncrement	Distance for one scrolling unit in the X direction.
yScrollCommand	Tcl command prefix for vertical scrolling.
yScrollIncrement	Distance for one scrolling unit in the Y direction.

The scroll region of a canvas defines the boundaries of the canvas coordinate space. It is specified as four coordinates, x1 y1 x2 y2 where (x1, y1) is the top-left corner and (x2, y2) is the lower-right corner. If the confine attribute is true, then the canvas cannot be scrolled outside this region. It is OK to position canvas objects partially or totally off the scroll region; they just may not be visible. The scroll increment attributes determine how much the canvas is scrolled when the user clicks on the arrows in the scrollbar.

The closeEnough attribute indicates how far away a position can be from an object and still be considered to overlap it. This applies to the overlapping search criteria.