Clear canvas and set transparent
lazarus / 39-Graphics

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lainz · 2011-04-14 18:10

See the attached picture / Attached 7z file (requires BGRABitmap as
installed package).

Compile and run lazgui_test.

If you go over the 'ToolButton' you will see that is painted.

But if you leave the 'ToolButton' area isn't cleared, and text is
drawn over the previous drawing.

I need to clear the previous drawing and only draw text in a
transparent area (to see the background gradient).

I tried to use ACanvas.Clear:

(lazguiwin7.pas line 60):
Code: [Select]if AState = lgNormal then begin
    bmp:= TBGRABitmap.Create(ARect.Right,ARect.Bottom);
    ACanvas.Clear; // This clear the drawing, but isn't transparent,
and used in this way produces flickering
end
But the background isn't transparent, it is filled with clDefault.

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eny · 2011-04-14 18:45

You are 'abusing' the paintboxes and assume that they work like
controls.

The easiest fix: repaint all elements of the 'toolbar' when something
changes and do it in the right order: first the 'toolbar paintbox' and
then all 'button paintboxes'.

BTW: case statement