Big issue with Timage/TBitmap, PNG under Linux
lazarus / 39-Graphics

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BeanzMaster · 2020-05-11 15:20

Hi to all, i've made a little freecell clone with Lazarus 2.0.8 , it
work like a charm under Windows 10 64 bit. But under Linux the image
are black.

So why a little simple project like this, don't work properly under
Linux ? 
How to do for fixing Bitmap drawing with linux in a simply way?

You can download full source for testing here :  https://my.pcloud.com
/publink/show?code=XZMgRdkZLuwYrHbIbfQLcG9WH8zvWumgVgnX


Thanks in advance

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circular · 2020-05-11 17:07

Hi there

PixelFormat is buggy. Do not modify it.

When accessing pixels, read the RawImage description to know where the
channels are:
Code: Delphi  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  function
NegateBitmap(SrcBmp : TBitmap) : TBitmap; Var  bytesPerPixel,
redOffset, greenOffset, blueOffset: byte;  DstPtr : PByte;  x,y :
Integer; begin   Result := TBitmap.Create;   Result.Assign(srcBmp); 
 Result.BeginUpdate;   bytesPerPixel :=
Result.RawImage.Description.BitsPerPixel div 8;   redOffset :=
Result.RawImage.Description.RedShift div 8;   greenOffset :=
Result.RawImage.Description.GreenShift div 8;   blueOffset :=
Result.RawImage.Description.BlueShift div 8;   {$IFNDEF
ENDIAN_LITTLE}   redOffset := bytesPerPixel - 1 - redOffset; 
 greenOffset := bytesPerPixel - 1 - greenOffset;   blueOffset :=
bytesPerPixel - 1 - blueOffset;   {$ENDIF}   for y :=  0 to
Result.Height - 1 do   begin     DstPtr :=
Result.RawImage.GetLineStart(y);     for x := 0 to Result.Width - 1
do     begin;       (DstPtr+blueOffset)^ := not (DstPtr+blueOffset)^; 
     (DstPtr+greenOffset)^ := not (DstPtr+greenOffset)^;     
 (DstPtr+redOffset)^ := not (DstPtr+redOffset)^;       inc(DstPtr,
bytesPerPixel);     end;   end;   Result.EndUpdate; end;

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BeanzMaster · 2020-05-11 18:34

Hi, thanks for the tips but the problem is not wiht the negate
functions

So if pixelformat is buggy with Linux how to display transparent
bitmap correctly ?

I hope this bug will solve in next version 2.2 of Lazarus.

Thanks

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circular · 2020-05-11 20:21

Quote from: BeanzMaster on May 11, 2020, 08:34:57 pmHi, thanks for the
tips but the problem is not wiht the negate functions Well it is with
the Negate function as well because it relies on the pixel format.

QuoteSo if pixelformat is buggy with Linux how to display transparent
bitmap correctly ?With BGRABitmap?

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wp · 2020-05-11 21:06

Great game! You should put it on the Application Gallery

In Linux I get rid of the black images when I set all PixelFormats to
pf24bit or do not set it at all. For the NegateBitmap procedure I use
an intermedate LazIntfImage for safety.

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BeanzMaster · 2020-05-12 15:46

Quote from: wp on May 11, 2020, 11:06:50 pmGreat game! You should put
it on the Application Gallery

In Linux I get rid of the black images when I set all PixelFormats to
pf24bit or do not set it at all. For the NegateBitmap procedure I use
an intermedate LazIntfImage for safety.

Thanks wp, yes by uses pf24bit it work, and the copymode to. But on
Windows copymode don't work. I'll make test with pf24bit. And yes why
not tu put it in the Application Gallery. I've also made the
possibility to select and move more than one card