How to crop an FMX TBitmap - delphi

Question

I receive a bitmap via TCameraComponent.SampleBufferReady event. Then I need to crop the received image so that I get a, for instance, recangular image.
I calculate the necessary parameters in the following method:
procedure TPersonalF.SampleBufferReady(Sender: TObject;
const ATime: TMediaTime);
var
BMP: TBitmap;
X, Y, W, H: Word;
begin
Try
BMP := TBitmap.Create;
CameraComponent.SampleBufferToBitmap(BMP, true);
if BMP.Width >= BMP.Height then //landscape
begin
W:=BMP.Height;
H:=W;
Y:=0;
X:=trunc((BMP.Width-BMP.Height)/2);
end
else //portrait
begin
W:=BMP.Width;
H:=W;
X:=0;
Y:=trunc((BMP.Height-BMP.Width)/2);
end;
CropBitmap(BMP, Image1.Bitmap, X,Y,W,H);
Finally
BMP.Free;
End;
end;
I found an answer by #RRUZ delphi-how-do-i-crop-a-bitmap-in-place, but it requires a VCL API handle and is uses a Windows GDI function:
procedure CropBitmap(InBitmap, OutBitMap: TBitmap; X, Y, W, H: Word);
begin
OutBitMap.PixelFormat := InBitmap.PixelFormat;
OutBitMap.Width := W;
OutBitMap.Height := H;
BitBlt(OutBitMap.Canvas.Handle, 0, 0, W, H, InBitmap.Canvas.Handle, X,
Y, SRCCOPY);
end;
My project is using FMX, and I plan to port it to Android platform in the future. So I am expecting to get problems if I use handles. How can I solve this problem?

Answer 1

Assuming you can guarantee that InBitmap and OutBitMap exist (if not, you can handle error checking yourself)
procedure CropBitmap(InBitmap, OutBitMap: TBitmap; X, Y, W, H: Word);
var
iRect : TRect;
begin
OutBitMap.PixelFormat := InBitmap.PixelFormat;
OutBitMap.Width := W;
OutBitMap.Height := H;
iRec.Left := 0;
iRect.Top := 0;
iRect.Width := W;
iRect.Height := H;
OutBitMap.CopyFromBitmap( InBitMap, iRect, 0, 0 );
end;
It is the same as the original but uses Firemonkey CopyFromBitmap which is similar to the Windows rather cryptically named BitBlt.