[英]How to crop an FMX TBitmap
I receive a bitmap via TCameraComponent.SampleBufferReady event.我通过 TCameraComponent.SampleBufferReady 事件收到一个位图。 Then I need to crop the received image so that I get a, for instance, recangular image.
然后我需要裁剪接收到的图像,以便我得到一个,例如,矩形图像。
I calculate the necessary parameters in the following method:我用以下方法计算必要的参数:
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:我找到了 @RRUZ delphi-how-do-i-crop-a-bitmap-in-place的答案,但它需要一个 VCL API 句柄并且使用 Windows GDI 函数:
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.我的项目使用的是FMX,未来打算移植到Android平台。 So I am expecting to get problems if I use handles.
因此,如果我使用句柄,我预计会出现问题。 How can I solve this problem?
我怎么解决这个问题?
Assuming you can guarantee that InBitmap and OutBitMap exist (if not, you can handle error checking yourself)假设你可以保证 InBitmap 和 OutBitMap 存在(如果没有,你可以自己处理错误检查)
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.它与原始版本相同,但使用 Firemonkey CopyFromBitmap,它类似于 Windows 中的 BitBlt。
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