如何将更改“刷新”到位图的ScanLine

Question

我目前正在尝试将镜像添加到我们的RotateBitmap例程中(来自http://www.efg2.com/Lab/ImageProcessing/RotateScanline.htm)。目前，伪代码中的这个示例(BitMapRotated是一个TBitmap)如下所示：

var
  RowRotatedQ: pRGBquadArray; //4 bytes

if must reflect then
begin
  for each j do
  begin
    RowRotatedQ := BitmapRotated.Scanline[j];
    manipulate RowRotatedQ
  end;
end;

if must rotate then
begin
  BitmapRotated.SetSize(NewWidth, NewHeight); //resize it for rotation
  ...
end;

如果我，必须旋转或反射，这是可行的。如果两者都做了，那么显然对SetSize的调用通过ScanLine使我以前的更改无效。我如何“刷新”或保存我的更改？我试着打电话给BitmapRotated.Handle、BitmapRotated.Dormant和设置BitmapRotated.Canvas.Pixels[0, 0]，但都没有成功。

编辑：，我发现了真正的问题--我正在用原始位图中的值覆盖我的更改。很抱歉这么做。

Answer 1

也许这并不是真正的答案，但这段代码在D2006和XE3中都有效，并给出了预期的结果。没有必要“冲洗”任何东西。

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  procedure RotateBitmap(const BitMapRotated: TBitmap);
  type
    PRGBQuadArray = ^TRGBQuadArray;
    TRGBQuadArray = array [Byte] of TRGBQuad;
  var
    RowRotatedQ: PRGBQuadArray;
    t: TRGBQuad;
    ix, iy: Integer;
  begin
    //first step
    for iy := 0 to BitMapRotated.Height - 1 do begin
      RowRotatedQ := BitMapRotated.Scanline[iy];
     // make vertical mirror
      for ix := 0 to BitMapRotated.Width div 2 - 1 do begin
        t := RowRotatedQ[ix];
        RowRotatedQ[ix] := RowRotatedQ[BitMapRotated.Width - ix - 1];
        RowRotatedQ[BitMapRotated.Width - ix - 1] := t;
      end;
    end;

    //second step
    BitMapRotated.SetSize(BitMapRotated.Width  + 50, BitMapRotated.Height + 50);
    //some coloring instead of rotation
    for iy := 0 to BitMapRotated.Height div 10 do begin
      RowRotatedQ := BitMapRotated.Scanline[iy];
      for ix := 0 to BitMapRotated.Width - 1 do
        RowRotatedQ[ix].rgbRed := 0;
    end;
  end;

var
  a, b: TBitmap;
begin
  a := TBitmap.Create;
  a.PixelFormat := pf32bit;
  a.SetSize(100, 100);
  a.Canvas.Brush.Color := clRed;
  a.Canvas.FillRect(Rect(0, 0, 50, 50));
  b := TBitmap.Create;
  b.Assign(a);
  RotateBitmap(b);
  Canvas.Draw(0, 0, a);
  Canvas.Draw(110, 0, b);