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Timage transparenty on transparent form

Robert_MP
Robert_MP asked
on
Medium Priority
269 Views
Last Modified: 2010-04-05
Hello developers

I have successfully created a TImage with transparency using this code:

  Image1.Picture.Bitmap.TransparentColor :=  Image1.Picture.Bitmap.Canvas.Pixels[50,300];    
  Image1.Picture.Bitmap.TransparentMode := tmFixed;
  Image1.Transparent := true;

This works fine.

Secondy I need my form to be transparent, which is done using this code:

procedure TForm.FormCreate(Sender: TObject);
var
  hRgn: Cardinal;
  i: Integer;
begin
 //Transparentform
  with FormProducts do
  begin
    BorderStyle := bsNone;
    hRgn := CreateRectRgn(0, 0, 0, 0);
    for i := 0 to ControlCount - 1 do
      with Controls[i].BoundsRect do
        CombineRgn(hRgn, hRgn, CreateRectRgn(Left, Top, Right, Bottom), RGN_OR);
    SetWindowRgn(handle, hRgn, True);
  end;
end;

Which also works. The problems arise when these snippets are combined. The image doesn't show the graphics behind the form, but shows the color the form was before it became transparent. Any idea how to get around this problem?

My main task is to create a form which isn't triangular. I need some of the edges to be round and follow the shape of some images. If anyone has a different idea to do this it would also be most welcome.
Comment
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Mihai StancescuSoftware Engineer

Commented:
Try to put the transparent color of the form to the color that remains visible.

Regards,
Mishu
CERTIFIED EXPERT
Commented:
You need to intercept the WM_EraseBkgnd message passed to the form. something like:

type
  TMyTransparentForm = Class(TCustomForm)
...
  private
    procedure WMEraseBkgnd(var Message: TWmEraseBkgnd); message WM_ERASEBKGND;
...  
  end;

...
procedure TForm1.WMEraseBkgnd(var Message: TWmEraseBkgnd);
begin
  Message.Result:= 1;
end;
...

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