Delphi code using ScanLine
lazarus / 39-Graphics

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lainz · 2013-02-04 16:42

Hi, I have this code that works with Delphi, and it uses ScanLine that
there's no available on lazarus, how I can convert it?

See attached file.

Code: [Select]// Dan de pixels zelf. Blijkbaar bestaat een icoon uit
4x4 tiles van
      // 8x8 pixels.
      for y := 0 to 31 do
      begin
        ScanLine := Icon.ScanLine[y];

        for x := 0 to 31 do
        begin
          // Bereken de tile-index
          t := ((y shr 1) and not 3) + x shr 3;
          // Vermenigvuldig deze met 32 (32 bytes per tile) en tel er
de
          // byte-index binnen de tile bij op. Doordat alles zo mooi
met
          // machten van twee werkt kunnen we zelfs de modulo
vervangen door
          // 'and'.
          i := (t shl 5) + ((x shr 1) and 3) + ((y and 7) shl 2);
          // Lees de juiste nibble uit de tile-data
          b := Banner.TileData[i];
          if x and 1 = 1 then
            b := b shr 4
          else
            b := b and $F;

          // Pixel zetten
          ScanLine^[x] := Palette[b];
        end;
      end;
Thanks.

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howardpc · 2013-02-04 17:16

The wiki suggests this:

"Since Lazarus has no TBitmap.ScanLines property, the best way to
access the pixels of an image in a fast way for both reading and
writing is by using TLazIntfImage. The TBitmap can be converted to a
TLazIntfImage by using TBitmap.CreateIntfImage() and after modifying
the pixels it can be converted back to a TBitmap by using
TBitmap.LoadFromIntfImage(); Here's the sample on how to create
TLazIntfImage from TBitmap, modify it and then go back to the
TBitmap."

Code: [Select]uses
  ...GraphType, IntfGraphics, LCLType, LCLProc,  LCLIntf ...

procedure TForm1.Button4Click(Sender: TObject);
var
  b: TBitmap;
  t: TLazIntfImage;
begin
  b := TBitmap.Create;
  try
    b.LoadFromFile('test.bmp');
    t := b.CreateIntfImage;

    // Read and/or write to the pixels
    t.Colors[10,20] := colGreen;

    b.LoadFromIntfImage(t);
  finally
    t.Free;
    b.Free;
  end;
end;

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circular · 2013-02-04 17:22

Well, you can use BGRABitmap of course.

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dcelso · 2013-02-04 17:35

uses
  ...GraphType, IntfGraphics, LCLType, LCLProc,  LCLIntf ...

procedure TForm1.Button4Click(Sender: TObject);
var
  bmp: TBitmap;
  t: TLazIntfImage;
begin
  bmp := TBitmap.Create;
  try
    bmp.LoadFromFile('test.bmp');
    t := b.CreateIntfImage;

for y := 0 to 31 do
      begin
        ScanLine := t.getdatalinestart(y);

        for x := 0 to 31 do
        begin
          // Bereken de tile-index
          t := ((y shr 1) and not 3) + x shr 3;
          // Vermenigvuldig deze met 32 (32 bytes per tile) en tel er
de
          // byte-index binnen de tile bij op. Doordat alles zo mooi
met
          // machten van twee werkt kunnen we zelfs de modulo
vervangen door
          // 'and'.
          i := (t shl 5) + ((x shr 1) and 3) + ((y and 7) shl 2);
          // Lees de juiste nibble uit de tile-data
          b := Banner.TileData;
          if x and 1 = 1 then
            b := b shr 4
          else
            b := b and $F;

          // Pixel zetten
          ScanLine^ := Palette;
        end;
      end;

    bmp.LoadFromIntfImage(t);
  finally
    t.Free;
    bmp.Free;
  end;
end;

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lainz · 2013-02-04 18:44

Thanks to all, I will try the different solutions.