Problem with TLazIntfImage : works with windows but not with linux
lazarus / 39-Graphics

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Axxel · 2011-03-21 22:09

Hi 

Sorry for advance for my english because I'm french.

I Try this code source usin the TLazIntfImage to work with scanlines
like delphi.

This code allow to force the red channel at the maximum. (I took it
form this example :
http://wiki.lazarus.freepascal.org/Developing_with_Graphics )

Code: [Select]procedure TForm1.FadeIn2(aBitMap: TBitMap);
 var
   IntfImg1, IntfImg2: TLazIntfImage;
   ImgHandle,ImgMaskHandle: HBitmap;
   FadeStep: Integer;
   px, py: Integer;
   CurColor: TFPColor;
   TempBitmap: TBitmap;
   Row1, Row2: PRGBTripleArray;
 begin
   IntfImg1:=TLazIntfImage.Create(0,0);
   IntfImg1.LoadFromBitmap(aBitmap.Handle,aBitmap.MaskHandle);

   IntfImg2:=TLazIntfImage.Create(0,0);
   IntfImg2.LoadFromBitmap(aBitmap.Handle,aBitmap.MaskHandle);

   TempBitmap:=TBitmap.Create;

   //with Scanline-like
   for FadeStep:=1 to 32 do begin
     for py:=0 to IntfImg1.Height-1 do begin
       Row1 := IntfImg1.GetDataLineStart(py); //like Delphi
TBitMap.ScanLine
       Row2 := IntfImg2.GetDataLineStart(py); //like Delphi
TBitMap.ScanLine
       for px:=0 to IntfImg1.Width-1 do begin
         Row2^[px].rgbtRed:= 255;
         Row2^[px].rgbtGreen := (FadeStep * Row1^[px].rgbtGreen) shr
5; // Fading
         Row2^[px].rgbtBlue := (FadeStep * Row1^[px].rgbtBlue) shr 5;
       end;
     end;
     IntfImg2.CreateBitmaps(ImgHandle,ImgMaskHandle,false);

     TempBitmap.Handle:=ImgHandle;
     TempBitmap.MaskHandle:=ImgMaskHandle;
     Canvas.Draw(0,0,TempBitmap);
   end;

   IntfImg1.Free;
   IntfImg2.Free;
   TempBitmap.Free;
 end;


I compile it under widows and this is a success !

http://img823.imageshack.us/img823/7431/winrl.jpg

An now I compile it under Ubuntu 10.10 and i have this result :

http://img689.imageshack.us/img689/6290/linuxf.jpg

I've tried a lot of things but unsuccessful 

Everyone have an idea how can we works with the scanlines under linux
without this bug ?

I thought there is a bug into the linux LCL no 

Thank you for advance!

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theo · 2011-03-21 22:42

Quote from: Axxel on March 21, 2011, 11:09:04 pm(I took it form this
example : http://wiki.lazarus.freepascal.org/Developing_with_Graphics
)

I read there:

QuoteIf you know that the TBitmap is using blue 8bit, green 8bit, red
8bit you can directly access the bytes, which is somewhat faster:
I guess you don't know this.
Maybe it's not 24bpp but 32bpp or something else.
You could try with an array of TRGBQuad.

It's probably easier to do it like the first example in "Fading
example", then you don't have to worry about pixelformats.

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circular · 2011-03-22 00:38

Or you can use BGRABitmap, I made it for this

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Marc · 2011-03-22 10:07

You falsely assume that all rawimages have the same data format.
Where on windows a pixel might be stored as a 3-byte RGB, it might be
stored completely different on linux. It can be stored in 4 bytes, but
also in 2 bytes (5-5-5) if your screen depth is only 16 bits.
Look at the IntfImage RawImageDescription  how the pixels are really
stored.

When accessing raw image data, never assume the pixel layout.

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Axxel · 2011-03-26 15:57

Hi.

Thanks ! It works wery well now with the TRGBQuad