I got an invalid image error with the png image. jng worked fine, thank you.

The show is running on a minipc with Intel Celeron M 373 @ 1000 Mhz and a HP LP2475w 1200x1920 px monitor. Fading in from alpha 20 to 255 in 30 steps takes about 6 seconds, showing also horizontally moving stripes.

I have a slideshow using DisplayImage for drawing on a TPaintBox. Now I want to fade-in/fade-out images. How do I do that?
I tried something like Image.DrawAlpha(Image.BoundsRect, PaintBox.Canvas, 0, 0) in a loop where alphachannel values increases/decreased. It doesn't work.

Graphics is not my cup of tea, obviously. Besides drawing the image on itself I forgot to call canvas.updatecanvasstate.
Of course the probability of me causing the error was high. Nevertheless I posted this report because in this case one would expect an exception handling the setting of a width or the mapping table to a negative length.

Vampyre 0.26.4
FPC 2.4.1
WinXP sp3

Image.BoundsRect: 1920x1200
PaintBox.ClientRect: 682x633

CommonRect (103, 0, 682, 529)

Calling ImageCanvas.DrawStretchAlpha(Image.BoundsRect, ImageCanvas, CommonRect, rfBicubic)
results in a runtime error 201 in ImagingFormats.BuildMappingTable line 1611 SetLength(Result, DstWidth) because DstWidth has a negative value.

Do you have a quick fix please?

Yes, it can be opened. After refresing the list the correct filisize is shown. Files are appr. 500 KB.

WinXP SP3, Lazarus 9.28.2, Vampyre 26.4
With demo LCLImager I converted a jpg file to A8R8G8B8 format and saved it as jng file. Windows explorer shows an incorrect file size of 0 KB (whereas file properties show the correct file size).

I have jpeg photo's which are converted to A8R8G8B8 because I need an alpha channel. In which extension should the resulting image be saved so quality is preserved best? Or should I convert to another format?