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[BUG?] Timage

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Giuseppe Ridinò:
I really don't know if this is a bug, or it's me who doesn't understand it.
Take a TForm, with a Timage and a TButton.
This is the code of the TButton OnClick event:


--- Code: ---procedure TForm1.Button1Click(Sender: TObject);
var
  Vertex : array[0..3] of TPoint;
begin
  with Image1.Picture.Bitmap do
  begin
    Width  := ClientWidth;
    Height := ClientHeight;
    with Canvas do
    begin
        Brush.Style := bsSolid;
        // red square
        Vertex[0].X :=  0; Vertex[0].Y :=  0;
        Vertex[1].X := 20; Vertex[1].Y :=  0;
        Vertex[2].X := 20; Vertex[2].Y := 20;
        Vertex[3].X :=  0; Vertex[3].Y := 20;
        Brush.Color := clRed;
        Polygon(Vertex);
        // green square
        Vertex[0].X := 20; Vertex[0].Y := 20;
        Vertex[1].X := 40; Vertex[1].Y := 20;
        Vertex[2].X := 40; Vertex[2].Y := 40;
        Vertex[3].X := 20; Vertex[3].Y := 40;
        Brush.Color := clGreen;
        Polygon(Vertex);
    end;
  end;
end;
--- End code ---


Obviously when user click on the button, two squares are drawn, a red one on the top-left and a green one on the bottom-right of the Timage object.

In fact, in case (A) Timage has Left:=0; Top:=0; Width:=40; Height:=40; I get something like that:
RRBBX
RRBBX
BBGGX
BBGGX
XXXXX

Legend:
R=RED COLOR
G=GREEN COLOR
B=BLACK COLOR (canvas background)
X=form background (background)

But in case (B) Timage has Left:=10; Top:=10; Width:=40; Height:=40; I get something like that:
XXXXX
XRRBX
XRRBX
XBBGX
XXXXX

which IS NOT WHAT I EXPECTED  :shock:

I had expected something like that:
XXXXX
XRRBB
XRRBB
XBBGG
XBBGG

Am I wrong to expect that or what?
Thanks in advance to who will provide me with an explanation!  :wink:

Marc:
Hmm... I would have expected Image A in all cases. Since setting Top/Left of an image doesn't affect the internal image itself.

Giuseppe Ridinò:

--- Quote from: "Marc" ---... setting Top/Left of an image doesn't affect the internal image itself.
--- End quote ---

I agree.  :wink:
Maybe my "snapshots" are not clear.  :roll:
The top-left character represents always the top-left corner of the Tform, not of Timage which top-left character is always R.

Maybe I shoud provide with the full project sources.  :?:

Marc:
I think it has nothing to do with th epainting. Now it looks like your image isn't moved/sized right.

Giuseppe Ridinò:
Could BUG 360 be related to this problem?

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