[fpc-devel] FPImage to LCL. How to do it?

[Mattias Gaertner]

On 2/24/25 20:22, Giuliano Colla via fpc-devel wrote:
> I have an application where I need to rotate an image for displaying in 
> an LCL image. The image is a clock face, the image to rotate is each of 
> the hands.
> I can get the bitmap from the source LCL image, and copy the rectangle 
> from the LCL image canvas to the FPImage canvas.
> I can rotate it, but I'm unable to copy back the resulting image to the 
> LCL canvas, because I'm told that the  TFPImageCanvas is an 
> "incompatible type" with TCanvas.

If you have a FPImage canvas, then you should have a TFPCustomImage.
Preferably a LazIntfImage, preferably initialized to the same format as 
the LCL widgetset.

uses ..., IntfGraphics, LCLType, LCLIntf;

var
   LazImg: TLazIntfImage;
   BitmapHnd, DummyHnd: HBITMAP;
   LCLCanvas: TCanvas;
   RotatedWidth, RotatedHeight, x, y: Integer;
begin
   LCLCanvas:=Canvas;
   RotatedWidth:=100;
   RotatedHeight:=100;
   x:=0;
   y:=0;

   // create a memory image
   LazImg := TLazIntfImage.Create(0,0,[]);
   LazImg.DataDescription := GetDescriptionFromDevice(LCLCanvas.Handle,
      RotatedWidth,RotatedHeight);
   // draw the rotated image to the LazImg ...

   // create the widgetset bitmap
   LazImg.CreateBitmaps(BitmapHnd, DummyHnd, True);
   StretchBlt(LCLCanvas.Handle,x,y,LazImg.Width,LazImg.Height,
       BitmapHnd, 0,0,LazImg.Width,LazImg.Height, LCLCanvas.CopyMode);
end;

Mattias