Retrieving Bounding Box Coordinates
When we talked about the scrolling
region of a Canvas, we saw an example of the bbox
method. The bbox
method
returns a list with four elements that define the area in which all
the specified tags exist. The example used the special
"all"
tag, which refers to every item in the
Canvas. This was how we used it to define our scrolling region. You
can specify more than one tag/ID to search for as follows:
($x1, $y1, $x2, $y2) = $canvas->bbox("blue", "red");
Assuming that you have been assigning the tags
"blue"
and "red"
to color items
appropriately, this code would return the region in the Canvas that
encloses all blue and red items.
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