[AGGPas, fpGUI] Use CopyImage method
lazarus / 39-Graphics

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Roland57 · 2026-02-24 15:37

Hello everybody.

I would like to use a static background (a PNG image) for my clock. I
use CopyImage method of TAgg2D, and TFpgImage.

It works, but the colors are not as expected. (Compare the pictures
attached.)

Would you see what is wrong in my code?

Regards.

Roland

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dergen · 2026-02-27 08:33

Check RGBA <> BGRA or Transparent copying bug.

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Graeme · 2026-03-17 11:37

Just so others benefit from the answer, I've explained it in the link
below. The static.png image is a PNG with 16-bit colour channels -
something not used often. 99.99% of images normally use 8-bit colour
channels. fpGUI doesn't officially support reading and displaying
16-bit colour channel images, as there simply hasn't been a need for
it. Convert it to 8-bit channels using something like The GIMP and
then it renders fine.

https://github.com/graemeg/fpGUI/issues/164#issuecomment-4074196192

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Roland57 · 2026-03-18 05:04

Thank you Graeme. Glad that my program is fixed.

For information, here is how I converted the image with ImageMagick:

$ file static.png
static.png: PNG image data, 400 x 400, 16-bit/color RGBA, non-
interlaced
$ magick static.png PNG32:static2.png
$ file static2.png
static2.png: PNG image data, 400 x 400, 8-bit/color RGBA, non-
interlaced

But later I found I could create directly 8-bit/color image:
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   png :=
TFPWriterPNG.Create;  png.WordSized := FALSE;