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The following procedure rotates a TBitmap 180 degrees:
procedure Rotate180(Bitmap:TBitmap);
type TRGBArray = array[0..0] of TRGBTriple;
pRGBArray = ^TRGBArray;
var countRows, countColumns: integer;
rowIn,rowOut:
pRGBArray;
tmpBitmap: TBitmap;
begin
// Create tmp bitmap
tmpBitmap:=TBitmap.Create;
// Adjust tmp bitmap size and pixelformat
with tmpBitmap do
begin
Width:=Bitmap.Width;
Height:=Bitmap.Height;
PixelFormat:=Bitmap.PixelFormat;
end;
// Use scanline to copy pixels from rowin to rowout in reverse order
for countRows:=0to Bitmap.Height-1 do
begin
rowIn:=Bitmap.ScanLine[countRows];
rowOut:=tmpBitmap.ScanLine[Bitmap.Height-countRows-1];
for countColumns:=0 to Bitmap.Width-1 do
rowOut[Bitmap.Width-countColumns-1]:=rowIn[countColumns];
end;
// Copy bitmap to source and free tmp bitmap
bitmap.assign(tmpBitmap);
tmpBitmap.free;
end;
