What is the fastest way to check if two Tbitmaps are the same?
delphi, delphi-2009
Solution
You can save both Bitmaps to TMemoryStream and compare using CompareMem:
function IsSameBitmap(Bitmap1, Bitmap2: TBitmap): Boolean;
var
Stream1, Stream2: TMemoryStream;
begin
Assert((Bitmap1 <> nil) and (Bitmap2 <> nil), 'Params can''t be nil');
Result:= False;
if (Bitmap1.Height <> Bitmap2.Height) or (Bitmap1.Width <> Bitmap2.Width) then
Exit;
Stream1:= TMemoryStream.Create;
try
Bitmap1.SaveToStream(Stream1);
Stream2:= TMemoryStream.Create;
try
Bitmap2.SaveToStream(Stream2);
if Stream1.Size = Stream2.Size Then
Result:= CompareMem(Stream1.Memory, Stream2.Memory, Stream1.Size);
finally
Stream2.Free;
end;
finally
Stream1.Free;
end;
end;
begin
if IsSameBitmap(MyImage1.Picture.Bitmap, MyImage2.Picture.Bitmap) then
begin
// your code for same bitmap
end;
end;
I did not benchmark this code X scanline, if you do, please let us know which one is the fastest.
Problem
Is there a better way than examine them pixel by pixel?