Is it possible to remove hideous outline around a TSpeedButton glyph?

Question

I've run into a bit of a snag, is it just me or can you not assign an image from a resource to TSpeedButton's glyph without a hideous black outline as shown below?

I've assigned it exactly the same way for the TImage component and I'm getting the result needed.

I've been searching for quite a while but no one seems to have this bizarre and annoying problem.

Here's my source code for the form below:

procedure TForm3.Button1Click(Sender: TObject);
var r : tresourcestream; png : tpngimage;
begin
  r := tresourcestream.CreateFromID(hinstance,34,'cardimage');
  png := tpngimage.Create;  
  png.LoadFromStream(r);  
  png.AssignTo(image1.Picture.bitmap);  
  png.AssignTo(speedbutton1.glyph);  
  png.Free;  
  r.Free;  
end;

34 is the image of type 'cardimage' that relates to the image being shown in the picture if you haven't guessed already.

Leandroleaning

The issue is clearly that the alpha channel is ignored in the left picture. – Halflight

Generally, you should call X.Assign(Y), not Y.AssignTo(X). If TX doesn't know how acquire attributes from a TY, it will defer to TY by calling Y.AssignTo(X) automatically. But if TY doesn't know how to assign itself to a TX, it won't defer to the target object. – Cnidoblast

Answer 1

The issue is clearly that the alpha channel is ignored in the left picture. Now, the TSpeedButton.Glyph property is a TBitmap, so it might be problematic to preserve the PNG alpha channel. For example,

var
  png: TPNGImage;
begin
  png := TPngImage.Create;
  png.LoadFromFile('C:\Users\Andreas Rejbrand\Pictures\alpha.png');
  SpeedButton1.Glyph.Assign(png); // or png.AssignTo(SpeedButton1.Glyph);

produces

One partial solution is to pre-blend the PNG image:

var
  png: TPNGImage;
  bm: TBitmap;
begin
  png := TPngImage.Create;
  png.LoadFromFile('C:\Users\Andreas Rejbrand\Pictures\alpha.png');
  bm := TBitmap.Create;
  bm.SetSize(png.Width, png.Height);
  bm.Canvas.Brush.Color := Self.Color;
  bm.Canvas.FillRect(Rect(0, 0, bm.Width, bm.Height));
  bm.Canvas.Draw(0, 0, png);
  SpeedButton1.Glyph.Assign(bm);

Halflight

Thanks, @Ken. But there might be a better solution. – Halflight

I would +1 if I could lol, but Thanks works a treat! It's only being used for a school project, and was just annoying my eyes lol but thanks yet again! :D – Leandroleaning

pre-blending's going to gîte you some grief somewhere down the line. – Binomial

Nit-pick :) guess you don't need a second bitmap, can draw directly to the button glyph.. – Topology

@Sertac: Oh, yes, quite true. – Halflight

FWIW, I am personally going to rewrite TSpeedButton to have proper PNG support. Some day. When I have time.... [grins] – Baeza

Very nice, this is something that should be native. Amazing even in XE2 the buttons still dont support PNG by default. – Swordplay