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Thread: Fast blit method for Lazarus RGB Graphics

  1. #1

    Fast blit method for Lazarus RGB Graphics

    Well, I know that the Laz guys hang out here now and again, and I can't find a good forum to post this code to so here will do and hopefully they pick it up. I'm using RGB Graphics in an application that I've been working on and found that there was no way to do a fast blit with transparency within it. That just plain sucked as I needed full transparency.

    After a bit of playing around I managed to get it to work, and the overall speed seems quite good. Below is my method for fast blits and the modifications needed to the TRGB32Bitmap to make use of it.

    [pascal]// Add this to rgbroutines.pas
    procedure BltRGB32Bitmap(Dst: TRGB32BitmapCore; X, Y: Integer;
    Src: TRGB32BitmapCore; TransparentColor: TRGB32Pixel);
    SrcX, SrcWidth, SrcY, SrcHeight: Integer;
    C, I: Integer;
    PS, PD: PRGB32Pixel;
    if (Dst = nil) or (Src = nil) then Exit;
    if (Dst.Width <= 0) or (Dst.Height <= 0) or (Src.Width <= 0) or (Src.Height <= 0) then Exit;
    if (X >= Dst.Width) or (Y >= Dst.Height) then Exit;
    if (X + Src.Width <= 0) or (Y + Src.Height <= 0) then Exit;

    SrcX := 0;
    SrcY := 0;
    SrcWidth := Src.Width;
    SrcHeight := Src.Height;

    if X < 0 then
    SrcX := -X;
    Inc(SrcWidth, X);
    X := 0;

    if Y < 0 then
    SrcY := -Y;
    Inc(SrcHeight, Y);
    Y := 0;

    if X + SrcWidth > Dst.Width then
    Dec(SrcWidth, X + SrcWidth - Dst.Width);
    if Y + SrcHeight > Dst.Height then
    Dec(SrcHeight, Y + SrcHeight - Dst.Height);

    for I := 0 to Pred(SrcHeight) do
    PS := Src.GetPixelPtrUnsafeInline(SrcX, SrcY + I);
    PD := Dst.GetPixelPtrUnsafeInline(X, Y + I);
    C := 0;
    while C < SrcWidth do
    if PS^<>TransparentColor then
    PD^ := PS^;

    [pascal]// Add this to TRGB32Bitmap in rgbgraphics.pas
    procedure TRGB32Bitmap.Blit(X, Y: Integer; ABitmap: TRGB32Bitmap;
    TransparentColor: TColor);
    BltRGB32Bitmap(Self, X, Y, ABitmap, ColorToRGB32PixelInline(TransparentColor));

    On another note, does anyone know how to speed up the standard PaintBox? Even with using RGB Graphics my drawing times are VERY VERY slow. I don't want to use SDL, OpenGL, or DirectX for this project as they would be MAJOR overkill. But, the paintbox in Lazarus is still too slow. The same code using Graphics32 in Delphi runs just fine on a paintbox yet with RGB in Lazarus its painfully slow when you hit a threshold of objects (system dependent). I can create a simple sample to show what I mean if anyone wants to take a look.

  2. #2

    Fast blit method for Lazarus RGB Graphics

    Graphics rendering in Lazarus is painfully slow, because it needs to work on much platforms. The best you can do is indeed use 3d accelleration, or as you already have noted use Graphics32 in Win.

  3. #3

    Fast blit method for Lazarus RGB Graphics

    I think this question is best posted on the Lazarus forums; I'm unexperienced with the LCL.


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