Fastest way to draw pixels in FireMonkey

问题

I have made the following code:

procedure TForm15.Button1Click(Sender: TObject);
var
  Bitmap1: TBitmap;
  im: TImageControl;
  Color: TColor;
  Scanline: PAlphaColorArray;
  x,y,i: Integer;
begin
  for i:= 1 to 100 do begin
    im:= ImageControl1;
    Bitmap1:= TBitmap.Create(100,100);
    try
      for y:= 0 to 99 do begin
        ScanLine:= Bitmap1.ScanLine[y];
        for x:= 0 to 99 do begin
          ScanLine[x]:= Random(MaxInt);
        end;
      end;
      ImageControl1.Canvas.BeginScene;
      ImageControl1.Canvas.DrawBitmap(Bitmap1, RectF(0,0,Bitmap1.Width, Bitmap1.Height)
                                     ,im.ParentedRect,1,true);
      ImageControl1.Canvas.EndScene;
    finally
      Bitmap1.Free;
    end;
  end;
end;

Is there a faster way to draw pixels in Firemonkey?
I aim to make a demo program using Conway's game of life.

回答1:

All the time is spent performing these two lines of code:

ImageControl1.Canvas.BeginScene;
ImageControl1.Canvas.EndScene;

You can delete all the code that works with the bitmap and the code that actually draws the bitmap and it makes not one iota of difference to the runtime. In other words, the bottleneck is the scene code not the bitmap code. And I see no way for you to optimise that.

My test code looked like this:

Stopwatch := TStopwatch.StartNew;
for i:= 1 to 100 do begin
  ImageControl1.Canvas.BeginScene;
  ImageControl1.Canvas.EndScene;
end;
ShowMessage(IntToStr(Stopwatch.ElapsedMilliseconds));

This has the same elapsed time as your code, 1600ms on my machine. If you remove the BeginScene, DrawBitmap and EndScene calls then your code runs in 3ms on my machine.

回答2:

Here is a faster way to do that :

     procedure TForm2.Button1Click(Sender: TObject);
     var i,j: integer;
     begin
       for i := 0 to 200 do
       for j := 0 to 200 do ImageControl1.Bitmap.ScanLine[i][j]:=Random(Maxlongint);
       ImageControl1.Bitmap.BitmapChanged;
     end;

Quick and Optimized !...

回答3:

You can optimize your code like this:

procedure TForm15.Button1Click(Sender: TObject);
var
  Bitmap1: TBitmap;
  im: TImageControl;
  Color: TColor;
  ScanLine: PAlphaColorArray;
  x,y,i: Integer;
begin
  Bitmap1:= TBitmap.Create(100,100);
  try
    for i:= 1 to 100 do begin
      im:= ImageControl1;
      Scanline := PAlphaColorArray(Bitmap1.StartLine);
      for x := 0 to Bitmap1.Width * Bitmap1.Height do
        ScanLine[x] := Random(MaxInt);
      ImageControl1.Canvas.BeginScene;
      ImageControl1.Canvas.DrawBitmap(Bitmap1, RectF(0,0,Bitmap1.Width, Bitmap1.Height)
                                     ,im.ParentedRect,1,true);
      ImageControl1.Canvas.EndScene;
   end;
 finally
   Bitmap1.Free;
 end;
end;

Removed:

calling try finally in loop
creating TBitmap in loop
calling TBitmap.ScanLine method

来源：https://stackoverflow.com/questions/8988131/fastest-way-to-draw-pixels-in-firemonkey

标签

Delphi

delphi-xe2

firemonkey