TImage colors incorrect

[Jonny]

Create an empty form with this code in FormCreate:

Code: Pascal  [Select][+][-]

1. var
2.   aImage: TImage;
3. procedure TfrmMain.FormCreate(Sender: TObject);
4. var
5.    aBitmap: TBitmap;
6. begin
7.   aImage := TImage.Create(frmMain);
8.   aImage.Parent := frmMain;
9.   aImage.Width := 500;
10.   aImage.Height := 500;
11.   aBitmap := TBitmap.Create;
12.   aBitmap.Width := 500;
13.   aBitmap.Height := 500;
14.   aBitmap.Canvas.Brush.Color := clRed;
15.   aBitmap.Canvas.FillRect(0,0,500,500);
16.   aBitmap.Canvas.Brush.Color := clBlue;
17.   aBitmap.Canvas.FillRect(150,150,350,350);
18.   aImage.Canvas.Draw(0,0,aBitmap);
19.   aBitmap.SaveToFile('/tmp/test.bmp');
20. end;
21.  

Expected result:
  TImage on form = red background with blue box
  Saved bitmap file  = red background with blue box

Actual result:
  TImage on form = blue background with red box ** !!! **
  Saved bitmap file  = red background with blue box

See attachments.

Why is the image on the form incorrect?

[wp]

Your Lazarus/FPC version? ("Help" > "About Lazarus")? IIRC, there were old versions in which red and blue were exchanged.

[Jonny]

Code: [Select]

$ ./fpc -iW
3.3.1-17259-g904c25745c-dirty

Lazarus 4.99 (rev main_4_99-813-g9eb9286e45) FPC 3.3.1 x86_64-linux-qt5

Is there a way to check affected versions?

[wp]

And which Linux distribution is this?

[Jonny]

MX Linux 23 - based on Debian 12 - built GTK2 and QT5 x86-64 executables and both have the same issue.

[Jonny]

Just updated to latest trunk. The issue persists. Is it my code or an ongoing error in trunk? Should I drop down to last stable or fixes branch?

[jamie]

Try setting the pixel format of the bitmap to 32bits before setting the width and height of it.

[bytebites]

Unable to reproduce. (Linux Mint).

[Jonny]

Try setting the pixel format of the bitmap to 32bits before setting the width and height of it.

Code: Pascal  [Select][+][-]

1. var
2.   aImage: TImage;
3. procedure TfrmMain.btnDrawClick(Sender: TObject);
4. var
5.    aBitmap: TBitmap;
6. begin
7.   aImage := TImage.Create(frmMain);
8.   aImage.Parent := frmMain;
9.   aImage.Width := 500;
10.   aImage.Height := 500;
11.   aBitmap := TBitmap.Create;
12.   aBitmap.PixelFormat := pf32bit;
13.   aBitmap.Width := 500;
14.   aBitmap.Height := 500;
15.   aBitmap.Canvas.Brush.Color := clRed;
16.   aBitmap.Canvas.FillRect(0,0,500,500);
17.   aBitmap.Canvas.Brush.Color := clBlue;
18.   aBitmap.Canvas.FillRect(150,150,350,350);
19.   aImage.Canvas.Draw(0,0,aBitmap);
20.   aBitmap.SaveToFile('/tmp/test.bmp');
21. end;
22.  

Thanks, but no change, the TBitmap is always correct, it is the colors on TImage that are still inverted.

[Khrys]

Does the output of the following two lines (the raw image descriptions) differ?

Code: Pascal  [Select][+][-]

1. WriteLn(aImage.Picture.Bitmap.RawImage.Description.AsString());
2. WriteLn(aBitmap.RawImage.Description.AsString());

From the screenshots it seems like the channel order is being swapped somewhere (RGB / BGR - red is interpreted as blue and vice versa). Try drawing a green  (clFuchsia)  square, it should stay green in both versions if this is the culprit.

[Jonny]

Code: [Select]

Format=ricfRGBA HasPalette->False HasMask->False Depth=24 Width=500 Height=500 BitOrder=riboReversedBits ByteOrder=riboLSBFirst LineOrder=riloTopToBottom LineEnd=rileDWordBoundary BitsPerPixel=32 BytesPerLine->2000 RedPrec=8 RedShift=16 GreenPrec=8 GreenShift=8 BluePrec=8 BlueShift=0 AlphaPrec=0 AlphaShift=0 ~~~mask~~~ MaskBitsPerPixel=1 MaskShift=0 MaskLineEnd=rileDWordBoundary MaskBitOrder=riboReversedBits MaskBytesPerLine->64 ~~~palette~~~ PaletteColorCount=0 PaletteBitsPerIndex=0 PaletteShift=0 PaletteLineEnd=rileTight PaletteBitOrder=riboBitsInOrder PaletteByteOrder=riboLSBFirst PaletteBytesPerLine->0

Format=ricfRGBA HasPalette->False HasMask->False Depth=32 Width=500 Height=500 BitOrder=riboReversedBits ByteOrder=riboLSBFirst LineOrder=riloTopToBottom LineEnd=rileDWordBoundary BitsPerPixel=32 BytesPerLine->2000 RedPrec=8 RedShift=16 GreenPrec=8 GreenShift=8 BluePrec=8 BlueShift=0 AlphaPrec=8 AlphaShift=24 ~~~mask~~~ MaskBitsPerPixel=1 MaskShift=0 MaskLineEnd=rileDWordBoundary MaskBitOrder=riboReversedBits MaskBytesPerLine->64 ~~~palette~~~ PaletteColorCount=0 PaletteBitsPerIndex=0 PaletteShift=0 PaletteLineEnd=rileTight PaletteBitOrder=riboBitsInOrder PaletteByteOrder=riboLSBFirst PaletteBytesPerLine->0

The differences are:

Code: [Select]

Depth=24
Depth=32

AlphaPrec=0 AlphaShift=0
AlphaPrec=8 AlphaShift=24

All green drawing is fine, it is indeed RGB vs BGR. Very strange, everything else on my display is fine. Just files that I compile with FPC.

[lainz]

Please try with BGRABitmap, and BGRAControls if you can...

To know if that bug affect these packages as well...

Thanks

[Jonny]

Please try with BGRABitmap, and BGRAControls if you can...

Hmm, are these external packages? I cannot find them in the normal FPC/Lazarus installation.

[lainz]

Please try with BGRABitmap, and BGRAControls if you can...

Hmm, are these external packages? I cannot find them in the normal FPC/Lazarus installation.

Yes these are external. Try with OPM (online package manager).

Basically to test install both packages and drop a TBCButton for example and change the color of normal state In the object inspector..

[Jonny]

Same issue with TBGRABitmap - blue and red reversed on screen, exporting bitmap image is fine.

Code: Pascal  [Select][+][-]

1. procedure TfrmMain.btnDrawClick(Sender: TObject);
2. var
3.    aBitmap: TBGRABitmap;
4. begin
5.   aImage := TImage.Create(frmMain);
6.   aImage.Parent := frmMain;
7.   aImage.Width := 500;
8.   aImage.Height := 500;
9.   aBitmap := TBGRABitmap.Create;
10.   aBitmap.SetSize(500,500);
11.   aBitmap.Canvas.Brush.Color := clRed;
12.   aBitmap.Canvas.FillRect(0,0,500,500);
13.   aBitmap.Canvas.Brush.Color := clBlue;
14.   aBitmap.Canvas.FillRect(150,150,350,350);
15.   aImage.Picture.Bitmap.Assign(aBitmap);
16.   aBitmap.SaveToFile('/tmp/test.bmp');
17. end;
18.