GTK3 distorts colors?

[wschulte]

When using the LoadFromFile method from TPicture I get totally wrong colors when compiling with the GTK3 widget-set. See gtk3.jpg. When compiling for GTK2 is displays normal (gtk2.jpg).
What am I doing wrong ?

Attached the sources in problemsrc.zip.

BTW. also in QT5 the picture displays normal. It is only in GTK3 that the colors get weird.

FPC 3.2.2
Lazarus 2.2.2.0
libgtk-3.so.0.2404.16
Distro: Linux Mint 20.3 Una

[bytebites]

widgets_unit.pas" was not found

[dseligo]

It looks like red and blue are mutally changed.

[winni]

Already in the bugreports:

https://bugs.openjdk.org/browse/JDK-8271398?attachmentSortBy=dateTime

[Zoran]

Already in the bugreports:

https://bugs.openjdk.org/browse/JDK-8271398?attachmentSortBy=dateTime

But... this is JDK bugreports?!

[Thaddy]

Indeed, this is not related to FPC or Lazarus.

[wschulte]

widgets_unit.pas" was not found

Sorry,  forgot those 2. They are in this attachment.

[wschulte]

Indeed, this is not related to FPC or Lazarus.

When searching for my problem, I found indeed another case of swapped channels in GTK4, but it was related to PNG (https://gitlab.gnome.org/GNOME/gtk/-/issues/4616). Somehow I thought it unrelated to my issue, but now .. it looks the same. Though I find it peculiar that I am the first one to stumble over this in Lazarus. So I guess also GTK4 has the same issue.

[wschulte]

 
Did some further research with the same program as from post #6 and it gets a bit confusing. I tried to load some different graphical formats from the same picture, converted with GIMP to other formats. In GTK2 all pictures display normal, but on GTK3:

• .jpg gets displayed distorted, probably the blue and red channel are swapped
• .png either gets displayed distorted as the .jpg or not displayed at all. Looks like it depends on the size of the picture: small ones were displayed, albeit distorted, bigger ones (like my trial pic) didn't get displayed at all without any warning.
• .ico gets displayed okay !
• .bmp becomes a totally weird picture on display

I am a complete layman when it comes to graphical formats so I attach the base picture here (poep.jpg), which I used to produce the other formats.

Perhaps important too: when I run the program in with GTK3 it produces a huge amount of output to stdout of what looks like debug messages:

Code: Pascal  [Select][+][-]

1. Focused
2. GtkEventResize: Form1:TForm1 Send=0 x=757 y=365 w=200 h=200
3. other changes state=00015480 mask=00015400
4. GtkEventResize: Form1:TForm1 Send=1 x=757 y=365 w=200 h=200
5. GtkEventResize: Form1:TForm1 Send=1 x=757 y=365 w=200 h=200
6. GtkEventResize: Form1:TForm1 Send=0 x=757 y=365 w=309 h=362
7. GetStyleWithName creating style widget memo
8. GtkEventResize: Form1:TForm1 Send=1 x=758 y=365 w=309 h=362
9. GtkEventResize: Form1:TForm1 Send=1 x=758 y=366 w=309 h=362
10. GtkEventResize: Form1:TForm1 Send=1 x=758 y=367 w=309 h=362
11. GtkEventResize: Form1:TForm1 Send=1 x=758 y=368 w=309 h=362
12. GtkEventResize: Form1:TForm1 Send=1 x=758 y=369 w=309 h=362
13.  

Do I have the right GTK3 library (3.24.0 in the repository) ? I downloaded it from the standard repository of Mint ...

[AmatCoder]

When using the LoadFromFile method from TPicture I get totally wrong colors when compiling with the GTK3 widget-set. See gtk3.jpg. When compiling for GTK2 is displays normal (gtk2.jpg).
What am I doing wrong ?

You are doing nothing wrong. Just the LCL-Gtk3 implementation from Lazarus is buggy and/or incomplete.

This confuses you because you are thinking: "...if works with Gtk2 then it should work with Gtk3..."

But they are completely different for drawing:
Gtk2 uses the old GDK drawing API.
Gtk3 uses Cairo.

Edit: A quick example. No support for RGB formats here.