Mathematik, gedrehtes Bild an Rahmen anpassen

[Luckie]

Ich bekomme bei dem Code immer noch eine AV:

Delphi-Quellcode:

procedure TForm2.tbbRotateLeftClick(Sender: TObject);

  procedure RotateBitmap(const BitmapOriginal: TBitmap; BitmapRotated: TBitmap; const AngleOfRotation: DOUBLE);
  var
    jRotationAxis   : INTEGER;
    iRotationAxis   : INTEGER;
    cosTheta        : EXTENDED;
    i               : INTEGER;
    iOriginal       : INTEGER;
    iPrime          : INTEGER;
    j               : INTEGER;
    jOriginal       : INTEGER;
    jPrime          : INTEGER;
    RowOriginal     : PRGB32Array;
    RowRotated      : PRGB32Array;
    sinTheta        : EXTENDED;
  begin
    iRotationAxis := BitmapOriginal.Width div 2;
    jRotationAxis := BitmapOriginal.height div 2;
  // Get SIN and COS in single call from math library
    sincos(AngleOfRotation, sinTheta, cosTheta);

// If no math library, then use this:
// sinTheta := SIN(AngleOfRotation);
// cosTheta := COS(AngleOfRotation);

  // Step through each row of rotated image.
    for j := BitmapRotated.Height - 1 downto 0 do
    begin
      RowRotated := BitmapRotated.Scanline[j];
      jPrime := j - jRotationAxis;

      for i := BitmapRotated.Width - 1 downto 0 do
      begin
        iPrime := i - iRotationAxis;
        iOriginal := iRotationAxis + ROUND(iPrime * CosTheta - jPrime * sinTheta);
        jOriginal := jRotationAxis + ROUND(iPrime * sinTheta + jPrime * cosTheta);

      // Make sure (iOriginal, jOriginal) is in BitmapOriginal.  If not,
      // assign transparent color to corner points.
        if (iOriginal >= 0) and (iOriginal <= BitmapOriginal.Width - 1) and
          (jOriginal >= 0) and (jOriginal <= BitmapOriginal.Height - 1) then
        begin
        // Assign pixel from rotated space to current pixel in BitmapRotated
          RowOriginal := BitmapOriginal.Scanline[jOriginal];
          RowRotated[i] := RowOriginal[iOriginal]
        end
        else
        begin
          RowRotated[i].R := 0; // assign transparent color
          RowRotated[i].G := 0;
          RowRotated[i].B := 0
        end

      end
    end;
  end;

var
  BmpSrc, BmpDest   : TBitmap;
begin
  BmpSrc := TBitmap.Create;
  BmpDest := TBitmap.Create;
  try
    BmpSrc.Width := ImageEnVect1.layers[ImageEnVect1.LayersCurrent].Width;
    BmpSrc.Height := ImageEnVect1.layers[ImageEnVect1.LayersCurrent].Height;
    BmpDest.Width := ImageEnVect1.layers[ImageEnVect1.LayersCurrent].Width;
    BmpDest.Height := ImageEnVect1.layers[ImageEnVect1.LayersCurrent].Height;
    BmpSrc.Assign(ImageEnVect1.Bitmap);
    RotateBitmap(BmpSrc, BmpDest, DegToRad(10));
    ImageEnVect1.Bitmap.Assign(BmpDest);
  finally
    BmpSrc.Free;
    BmpDest.Free;
  end;
end;