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Draw text transparently on a canvas

I need to draw a text on a canvas.
Here are the problems:

1)TextOut draws a frame behind the text(like does a fillrect first and then draws the text over the rect). I only need to draw the text. I tried to make Canvas.Brush.Color:=clNone but that only made it white.

2)for the text to be seen without the mentioned frame, its colour should be the invert of the area around it. I remember this is done somehow with NOT operator, but I don't exatcly remember how.
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duke_n
Asked:
duke_n
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1 Solution
 
ITugayCommented:
Hi duke_n,
did you try  Canvas.Brush.Style = bsClear?

-----
Igor.
0
 
duke_nAuthor Commented:
My man you are a genius!

now what about the second problem?
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duke_nAuthor Commented:
ah, I found what I meant.

to set Canvas.Pen.Mode:=pmNot;

but it doesn't seem to affect the font.
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ITugayCommented:
Hi duke_n,
I'm not sure how to draw font directly using XOR or something like this. But you can try to draw it in memory bitmap and then use BitBlt API function to copy region to canvas you need.  BitBlt supports lot of raster operations codes, just take a look at Delphi's help.

-----
Igor.
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duke_nAuthor Commented:
this is really weird. I used this function many many times, but now nothing works:

var
BMp:TBitMap;
s:string;
pt:TPoint;
begin
  s:='Show me the  money' ;
  BMP:=TBitmap.Create;
  BMP.Width:=Canvas.TextWidth(s);
  BMP.Height:=Canvas.TextHeight(S) ;
  bmp.Canvas.Brush.Style:=bsClear;
  BMP.Canvas.TextOut(0,0,s);
  PT.x:=200;
  Pt.y:=50;
  Pt:=Image1.ClientToScreen(PT);
  if INteger(BitBlt(Image1.{Picture.Bitmap.}Canvas.Handle,Pt.x,Pt.y,BMP.Width,BMP.Height,BMP.Canvas.Handle,0,0,SRCERASE))<>0 then
    ShowMessage('Success');
  bmp.Free;


The weirdest thing is that it shows "Success" but it doesn't change the canvas.
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duke_nAuthor Commented:
HAHA, Got it


var
BMp:TBitMap;
s:string;
pt:TPoint;
begin
  s:='Show me the  money' ;
  BMP:=TBitmap.Create;
  BMP.Width:=Canvas.TextWidth(s);
  BMP.Height:=Canvas.TextHeight(S) ;
  bmp.Canvas.Brush.Style:=bsClear;
  BMP.Canvas.TextOut(0,0,s);
  Image1.Picture.Bitmap.Width:=Image1.Width;
  Image1.Picture.Bitmap.Height:=Image1.Width;
  PT.x:=200;
  Pt.y:=80;

  if INteger(BitBlt(Image1.Picture.Bitmap.Canvas.Handle,Pt.x,Pt.y,BMP.Width,BMP.Height,BMP.Canvas.Handle,0,0,SRCINVERT))<>0 then
    ShowMessage('Success');

  InvertRect(Image1.Picture.Bitmap.Canvas.Handle,RECT(Pt.x,Pt.y,Pt.x+BMP.Width,Pt.y+BMP.Height));
  bmp.Free;

end;
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duke_nAuthor Commented:
Thank you very much.

You have been of great help
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