Article #16385: Keeping a glyph's transparent area transparent.

 Question and Answer Database
FAQ1385D.txt Keeping a glyph's transparent area transparent.
Category :VCL
Platform :All
Product :All 32 bit
Question:
Under some video modes, the transparent area of the standard
TBitBtn glyphs turns gold or maroon. How can I keep the standard
TBitBtn's glyph transparent?
Answer:
The following example demonstrates a technique where the
transparent portion of the glyph is filled with the background color
of the button, making the glyph appear transparent.
Example:
function InitStdBitBtn(BitBtn : TBitBtn;
kind : TBitBtnKind) : bool;
var
Bm1 : TBitmap;
Bm2 : TBitmap;
begin
Result := false;
if Kind = bkCustom then exit;
Bm1 := TBitmap.Create;
case Kind of
bkOK : Bm1.Handle := LoadBitmap(hInstance, 'BBOK');
bkCancel : Bm1.Handle := LoadBitmap(hInstance, 'BBCANCEL');
bkHelp : Bm1.Handle := LoadBitmap(hInstance, 'BBHELP');
bkYes : Bm1.Handle := LoadBitmap(hInstance, 'BBYES');
bkNo : Bm1.Handle := LoadBitmap(hInstance, 'BBNO');
bkClose : Bm1.Handle := LoadBitmap(hInstance, 'BBCLOSE');
bkAbort : Bm1.Handle := LoadBitmap(hInstance, 'BBABORT');
bkRetry : Bm1.Handle := LoadBitmap(hInstance, 'BBRETRY');
bkIgnore : Bm1.Handle := LoadBitmap(hInstance, 'BBIGNORE');
bkAll : Bm1.Handle := LoadBitmap(hInstance, 'BBALL');
end;
Bm2 := TBitmap.Create;
Bm2.Width := Bm1.Width;
Bm2.Height := Bm1.Height;
bm2.Canvas.Brush.Color := ClBtnFace;
bm2.Canvas.BrushCopy(Rect(0, 0, bm2.Width, bm2.Height),
Bm1,
Rect(0, 0, Bm1.width, Bm1.Height),
bm1.canvas.pixels[0,0]);
bm1.Free;
LockWindowUpdate(BitBtn.Parent.Handle);
BitBtn.Kind := kind;
BitBtn.Glyph.Assign(bm2);
LockWindowUpdate(0);
bm2.Free;
Result := true;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
InitStdBitBtn(BitBtn1, bkOk);
end;
7/16/98 4:31:28 PM

Last Modified: 01-SEP-99