Program crashing with no debug info while creating a PNG on Linux/GTK2
lazarus / 39-Graphics

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mhainze · 2018-09-06 21:20

Was on Fedora 28 x86_64, tested on both stable (via .rpm) and trunk
(via fpcupdeluxe) versions of Lazarus.

Sample code:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   // create
thumbnail  thumb := TPortableNetworkGraphic.Create;  thumb.Width :=
r.Width; // r = TRect  thumb.Height := r.Height; 
thumb.Canvas.AntialiasingMode := amOn;  thumb.Canvas.StretchDraw(r,
orig.Graphic); // orig = loaded TPicture  thumb.SaveToFile(Target);
Unfortunately I've switched back to Windows so can't do much for
replication or testing, just a heads up.  Fails on .JPG creation, too
IIRC.  Stepping through shows the fail consistently (on just some
files; being private files I can't provide them) at the StretchDraw
operation.  This is inside of a separate thumbnailer thread.  I can
StretchDraw onto a visible canvas from the main thread just fine. 
Possibly related to needing a system handle?  I tried various tricks
to force a handle but none solved the problem.

Also having problems with .ICO files (at least) stored as Glyphs in
speedbuttons being glitched or missing.  So for some reason the
graphics format parser on Linux is not at parity with Windows.