TIP #260: Add Underline Option to Canvas Text Items

Title:Add Underline Option to Canvas Text Items
Version:$Revision: 1.4 $
Author:Donal K. Fellows <donal dot k dot fellows at manchester dot ac dot uk>
Created:Wednesday, 04 January 2006


This TIP proposes adding an -underline option to the Tk canvas widget's text items.


If you're simulating a label (or button or ...) widget using a canvas, it is useful to be able to underline a single character of a piece of text. Although this can be done in various ways using font measure to work out where to start drawing, it would be far easier if we could use Tk's own built-in underlining engine (which also gets other font-related issues correct too, and correcting for them is more difficult than it ought to be given that Tk already knows what to do anyway).

Proposed Change

The canvas widget's text items shall gain an additional option, -underline which shall take an integer value (-1 being the default "no underline" value) describing which character position in the text to underline, just as with the -underline option provided by the label widget (and elsewhere). As with all canvas items, no specific support for modification through the option database shall be provided, but otherwise the option shall be exactly as described in the options manual page.


This document has been placed in the public domain.

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