STR #1440

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STR #1440

Application:FLTK Library
Status:1 - Closed w/Resolution
Priority:2 - Low, e.g. a documentation error or undocumented side-effect
Scope:2 - Specific to an operating system
Subsystem:Core Library
Summary:CheckButton rendering under Xft messes up after calling value()
Created By:jeremy_henty
Assigned To:matt
Fix Version:Will Not Fix
Update Notification:

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Trouble Report Files:

Name/Time/Date Filename/Size top right image
#1 jeremy_henty
00:58 Sep 23, 2006
#2 jeremy_henty
01:15 Sep 23, 2006
bottom left image   bottom right image

Trouble Report Comments:

Name/Time/Date Text top right image
#1 jeremy_henty
00:58 Sep 23, 2006
If I call check_button->value() repeatedly the button's label gets corrupted - the letters get more and more blocky and ugly. Clicking the button fixes its appearance. It looks very much as if an antialiased string is being drawn on top of itself without being cleared first.

Confirmed with release 1.1.7 and SVN r5479 . Compiled on Linux 2.6 , gcc 3.4.3 , 6.8.2 with --enable-shared --enable-threads --enable-xft .

Demo code attached - two check buttons that set each other's value(). Click either one repeatedly and watch the other get its ugly on.
#2 jeremy_henty
01:13 Sep 23, 2006
I just confirmed it's an Xft thing - configure without --enable-xft and it's fine.  
#3 jeremy_henty
01:17 Sep 23, 2006
I uploaded a screenshot of the problem - I clicked 10-15 times on "Button 0" and you can see that "Button 1" is messed up.  
#4 matt
01:21 Sep 23, 2006
If you use antialiased fonts, the alpha blend ing accumulates. For check buttons and radion buttons, you must choose a box type that redraws the background of the widget (FL_FLAT_BOX for example). This issue is well known and can't be fixed without breaking existing code.  
bottom left image   bottom right image

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