Bgrabitmap fast textrect

[Onur2x]

Hello   
I need to write grid-like text on bgrabitmap, but it takes a long time. where am i doing wrong my code is below.

Code: Pascal  [Select][+][-]

1.  
2. Procedure Tform1.button1click(Sender: Tobject);
3. var
4. a:Tbgrabitmap;
5. i,r,c,roww,colw,x,y:integer;
6.  initialtime, elapsedtime: DWord;
7. Begin
8.   a:=Tbgrabitmap.Create;
9.   a.SetSize(self.Width,self.Height);
10.   a.Fill(colortobgra(clred));
11.   initialtime := GetTickCount;
12.   roww:=0;
13.   x:=0;
14.   y:=0;
15.   for i:=0 to 250 do
16.   begin
17.     colw:=0;
18.     roww:=roww+30;
19.     for c:=0 to 5 do
20.     begin
21.      colw:=colw+80;
22.       a.TextRect(rect(x,y,colw,roww),i.ToString,taCenter,tlCenter,colortobgra(clblack));
23.       x:=colw;
24.     end;
25.     y:=roww;
26.   End;
27.    elapsedtime := GetTickCount - initialtime;
28.    WriteLn(IntToStr(elapsedtime));
29. End;      
30.  

[circular]

Hello Onur2x,

There are various possible problems:
- the rectangles are bigger than necessary
- the font rendering is in itself too slow
- the text outside the visible area is drawn needlessly

For the first problem, you can fix the size of the rectangles by writing the code in a simpler way.

For the second, you can use a lighter text rendering by setting the FontQuality property.

For the third, you can check if the area is actually visible.

Drawing text is generally a slow process though. If all of these are not enough, I suggest to store in a cache the rendered cells. At a next rendering phase, you can reuse the cache those that are still visible and free the unused cache.

Code: Pascal  [Select][+][-]

1. procedure Tform1.button1click(Sender: Tobject);
2. const
3.   roww = 30;
4.   colw = 80;
5. var
6.   a: TBGRABitmap;
7.   r, c, x, y: integer;
8.   cellRect: TRect;
9. Begin
10.   a:=TBGRABitmap.Create;
11.   a.SetSize(self.ClientWidth, self.ClientHeight); // use client size
12.   a.Fill(CSSRed); // use BGRA constants
13.   a.FontQuality:= fqSystemClearType; // less precision but faster
14.   y:=0;
15.   for r:=0 to 250 do
16.   begin
17.     x:=0;
18.     for c:=0 to 5 do
19.     begin
20.       cellRect := RectWithSize(x, y, colw, roww); // specify size
21.       // check if cell actually visible
22.       if cellRect.IntersectsWith(ClientRect) then
23.         a.TextRect(cellRect, r.ToString, taCenter, tlCenter, BGRABlack);
24.       x += colw;
25.     end;
26.     y += roww;
27.   End;
28.   ... // do something with the bitmap
29.   a.free; // free memory
30. End;

[Onur2x]

Thank you very much, the program is a little more relaxed, but unfortunately it is not quite fast. It takes longer when you draw with canvas or canvasbgra

[circular]

Another approach, if you don't need some special characters, is to use BGRAFreeType. This will render font polygons directly, without going though a system call to render the text.