Load PNG, scale, draw to canvas with transparency
lazarus / 39-Graphics

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Thomas Munk · 2013-10-21 19:15

Is there a build-in way to do the following:
(or do I need an external library?)




(1)  Load a 32-bit PNG-image (with alpha transparency) from disk


(2) Scale this image (up or down) to another in-memory-image, using a
quality interpolation, keeping alpha


(3) Draw this in-memory-image to the Form's Canvas, blending with the
background (using alpha)




If I didn't need (2) then everything works fine with
TPortableNetworkGraphic and Form.Canvas.Draw...

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User137 · 2013-10-22 03:43

The "quality interpolation" part is not possible without external
library, or manual pixel calculations. You can try BGRABitmap library,
as it is commonly hinted on these forums.