delphi to lazarus ...?

[Pegasus_Seiya]

hi


how to convert this code to lazarus.

Code: [Select]



procedure FindAlphaChannel(Dest, Image0, Image1: TBitmap; Bk1, Bk2: Cardinal);
var
 Index   : Integer;
 ScanIndx: Integer;

 BackValue1: Real;
 BackValue2: Real;

 Pixel1: Real;
 Pixel2: Real;

 Pixel : Real;
 Alpha : Real;

 Read0: PCardinal;
 Read1: PCardinal;
 Write: PCardinal;

 Color: Cardinal;
begin
 BackValue1:= Pixel2GrayEx(Bk1);
 BackValue2:= Pixel2GrayEx(Bk2);

 if (Image0.PixelFormat <> pf32bit) then Image0.PixelFormat:= pf32bit;
 if (Image1.PixelFormat <> pf32bit) then Image1.PixelFormat:= pf32bit;

 Dest.Width := Image0.Width;
 Dest.Height:= Image0.Height;
 if (Dest.PixelFormat <> pf32bit) then Dest.PixelFormat:= pf32bit;

 for ScanIndx:= 0 to Dest.Height - 1 do
  begin
   Read0:= Image0.Scanline[ScanIndx];
   Read1:= Image1.Scanline[ScanIndx];
   Write:= Dest.Scanline[ScanIndx];

   for Index:= 0 to Dest.Width - 1 do
    begin
     // retreive source grayscale pixels
     Pixel1:= Pixel2GrayEx(Read0^);
     Pixel2:= Pixel2GrayEx(Read1^);

     // calculate alpha-value and original pixel
     ExtractAlpha(Pixel1, Pixel2, BackValue1, BackValue2, Alpha, Pixel);

     // convert normalized pixel to color index
     Color:= Round(Pixel * 255.0);
     // prepare a 24-bit RGB color
     Color:= Color or (Color shl 8) or (Color shl 16);
     // add alpha-channel to 24-bit RGB color and write it to destination
     Write^:= Color or (Round(Alpha * 255.0) shl 24);

     // move through pixels
     Inc(Read0);
     Inc(Read1);
     Inc(Write);
    end;
  end;
end;                  


thanks

[Danail]

What hapens when you simply copy- paste it ?

[Legolas]

http://wiki.lazarus.freepascal.org/Developing_with_Graphics
http://www.lazarus.freepascal.org/index.php?name=PNphpBB2&file=viewtopic&t=3178&highlight=

[Pegasus_Seiya]

What hapens when you simply copy- paste it ?

It's don't work because lazarus bitmap don't suport Scanline, but I don't want to use LazIntfImage.

Do you know how to use scanline on lazarus for windows?


thanks

[Pegasus_Seiya]

http://wiki.lazarus.freepascal.org/Developing_with_Graphics
http://www.lazarus.freepascal.org/index.php?name=PNphpBB2&file=viewtopic&t=3178&highlight=

Hi

I don't understand this example =/

DO you know how to make a Tbitmap unit with suport Scanline ?

I'm using Lazarus for windows.


thanks

[Legolas]

No (simple) way, IMHO. You either need to create a wrapper for GDI32.dll from scratch (HUGE work) or to use another package, eg. LazIntfImage.

[Pegasus_Seiya]

No (simple) way, IMHO. You either need to create a wrapper for GDI32.dll from scratch (HUGE work) or to use another package, eg. LazIntfImage.

ok

can you explain me how to convert that code with LazIntfImage?

thanks

[theo]

Row := Bitmap.Scanline[y];
Row

• //<- Pixel with TBitmap.Scanline

 
SrcIntfImg.Colors[px,py] //<-Pixel with TLazIntfImage

See Demo in "A fading example" in http://wiki.lazarus.freepascal.org/Developing_with_Graphics

[Pegasus_Seiya]

Row := Bitmap.Scanline[y];
Row

• //<- Pixel with TBitmap.Scanline

 
SrcIntfImg.Colors[px,py] //<-Pixel with TLazIntfImage

See Demo in "A fading example" in http://wiki.lazarus.freepascal.org/Developing_with_Graphics

hi

Bitmap.Scanline[y]; = TPointer.

SrcIntfImg.Colors[px,py] = TPointer?


I need a  Pcardinal value, it will work?

thanks

[theo]

You don't need pointers for pixel access with TLazIntfImage, you just access the pixels array: SrcIntfImg.Colors[px,py]
It's very simple!

You're code above is buggy afaics.
This does nothing:

Code: [Select]

Image0.Scanline[ScanIndx] ;
 Image1.Scanline[ScanIndx];
 Vest.Scanline[ScanIndx];

What's "Vest" ?  Should be "Dest"?

[Pegasus_Seiya]

You don't need pointers for pixel access with TLazIntfImage, you just access the pixels array: SrcIntfImg.Colors[px,py]
It's very simple!

You're code above is buggy afaics.
This does nothing:

Code: [Select]

Image0.Scanline[ScanIndx] ;
 Image1.Scanline[ScanIndx];
 Vest.Scanline[ScanIndx];

What's "Vest" ?  Should be "Dest"?

hi



Sorry.



The correct code is this:

Code: [Select]



procedure FindAlphaChannel(Dest, Image0, Image1: TBitmap; Bk1, Bk2: Cardinal);
var
 Index   : Integer;
 ScanIndx: Integer;

 BackValue1: Real;
 BackValue2: Real;

 Pixel1: Real;
 Pixel2: Real;

 Pixel : Real;
 Alpha : Real;

 Read0: PCardinal;
 Read1: PCardinal;
 Write: PCardinal;

 Color: Cardinal;
begin
 BackValue1:= Pixel2GrayEx(Bk1);
 BackValue2:= Pixel2GrayEx(Bk2);

 if (Image0.PixelFormat <> pf32bit) then Image0.PixelFormat:= pf32bit;
 if (Image1.PixelFormat <> pf32bit) then Image1.PixelFormat:= pf32bit;

 Dest.Width := Image0.Width;
 Dest.Height:= Image0.Height;
 if (Dest.PixelFormat <> pf32bit) then Dest.PixelFormat:= pf32bit;

 for ScanIndx:= 0 to Dest.Height - 1 do
  begin
   Read0:= Image0.Scanline[ScanIndx];
   Read1:= Image1.Scanline[ScanIndx];
   Write:= Dest.Scanline[ScanIndx];

   for Index:= 0 to Dest.Width - 1 do
    begin
     // retreive source grayscale pixels
     Pixel1:= Pixel2GrayEx(Read0^);
     Pixel2:= Pixel2GrayEx(Read1^);

     // calculate alpha-value and original pixel
     ExtractAlpha(Pixel1, Pixel2, BackValue1, BackValue2, Alpha, Pixel);

     // convert normalized pixel to color index
     Color:= Round(Pixel * 255.0);
     // prepare a 24-bit RGB color
     Color:= Color or (Color shl 8) or (Color shl 16);
     // add alpha-channel to 24-bit RGB color and write it to destination
     Write^:= Color or (Round(Alpha * 255.0) shl 24);

     // move through pixels
     Inc(Read0);
     Inc(Read1);
     Inc(Write);
    end;
  end;
end;



[felipemdc]

I need a  Pcardinal value, it will work?

If it´s not a pointer just use @ operator. You have the sources to see what it is.

[Christian]

Since now Lazarus Bitmap schould support scanline with fpc 2.1.1

[theo]

Since now Lazarus Bitmap schould support scanline with fpc 2.1.1

What do you mean? Is this just your opinion ("it should") or
DOES it work now? If so, where did you read that?

[Pegasus_Seiya]

Lazarus will have scanline support?

 :roll: