减少VCL花费的CPU时间 [英] Reduce CPU time spent in VCL

问题描述

有一个MIDI播放器播放的音符为precisely尽可能是很重要的。我从来没有完全成功在于，总是指责定时器（见previous螺纹：的如何prevent提示中断定时器）。最近我获得了ProDelphi，开始测量究竟消耗了多少时间。其结果是相当惊人的，见下面的例子code。

It is important for a MIDI player to playback the notes as precisely as possible. I never quite succeeded in that, always blaming the timer (see a previous thread: How to prevent hints interrupting a timer). Recently I acquired ProDelphi and started measuring what exactly consumed that much time. The result was quite surprising, see the example code below.

procedure TClip_View.doMove (Sender: TObject; note, time, dure, max_time: Int32);
var x: Int32;
begin
{$IFDEF PROFILE}Profint.ProfStop; Try; Profint.ProfEnter(@self,1572 or $58B20000); {$ENDIF}
   Image.Picture.Bitmap.Canvas.Pen.Mode := pmNot;
   Image.Picture.Bitmap.Canvas.MoveTo (FPPos, 0);
   Image.Picture.Bitmap.Canvas.LineTo (FPPos, Image.Height);
   x := time * GPF.PpM div MIDI_Resolution;
   Image.Picture.Bitmap.Canvas.Pen.Mode := pmNot;
   Image.Picture.Bitmap.Canvas.MoveTo (x, 0);
   Image.Picture.Bitmap.Canvas.LineTo (x, Image.Height);
   FPPos := x;
//   Bevel.Left := time * GPF.PpM div MIDI_Resolution;
{$IFDEF PROFILE}finally; Profint.ProfExit(1572); end;{$ENDIF}
end; // doMove //

的测量（不含在Intel i7-920调试code，2,7Ghz）：

The measurements are (without debug code on an Intel i7-920, 2,7Ghz):

如图所示
1. 95微秒为code


2. 当一切除了现在注释掉的语句注释掉5.609毫秒（ Bevel.Left：= ）


3. 0.056毫秒，当所有code是由替换X：=时间* GPF.PpM格MIDI_Resolution;

1. 95 microseconds for the code as shown
2. 5.609 milliseconds when all is commented out except for the now commented out statement (Bevel.Left :=)
3. 0.056 microseconds when all code is replaced by x := time * GPF.PpM div MIDI_Resolution;

只是围绕一个锥搬家费用60倍，CPU只是作为一个绘图画布。这让我感到惊讶。测量1的结果非常发声（还有比这只是更会），但2和3未。我需要某种形式的反馈给用户什么的球员现在正在处理，一些线路在钢琴卷是接受的方式。在我的上房减少了定时事件循环的C​​PU周期的追求，我有一些问题：

Just moving around a Bevel costs 60 times as much CPU as just drawing on a Canvas. That surprised me. The results of measurement 1 are very audible (there is more going on than just this), but 2 and 3 not. I need some form of feedback to the user as what the player now is processing, some sort of line over a piano roll is the accepted way. In my never ending quest of reducing CPU cycles in the timed-event loop I have some questions:

• 为什么围绕一个斜角的成本是多少时间？
动

• 有降低比上一个位图吸引更多的CPU周期的方式？


• 有图纸时减少闪烁的方式？

推荐答案

您将无法改变世界，也不VCL也不支持Windows。我怀疑你是问得多那些...

You won't be able to change the world, nor VCL nor Windows. I suspect you are asking to much to those...

恕我直言，你最好改变一点点你的架构：

IMHO you should better change a little bit your architecture:

• 声音处理应在一个（或多个）分隔线程（s）和不应该在所有链接到UI（例如不脱离其发送GDI消息）;


• UI刷新应使用定时器与一个500毫秒的分辨率（半秒刷新听起来有足够的反应），而不是每次有变化。进行

也就是说，编曲不会刷新的用户界面，但用户界面将定期向音序器是什么其当前状态。这将是恕我直言更加顺畅。

That is, the sequencer won't refresh the UI, but the UI will ask periodically the sequencer what is its current status. This will be IMHO much smoother.

要回答你的问题的确切：

To answer your exact questions:

• 移动锥实际上是发送一些GDI消息，并且渲染将通过使用临时位图GDI堆栈（GDI32.DLL）进行;


• 尝试使用更小的位图，或者尝试使用Direct X的缓冲区映射;


• 尝试 DoubleBuffered：= TRUE 您TForm.OnCreate事件，或者使用专用的组件（ TPaintBox ）与整个成分含量的全球位图，用类似的东西为消息 WM_ERASEBKGND 。

• "Moving a bevel" is in fact sending several GDI messages, and the rendering will be made by the GDI stack (gdi32.dll) using a temporary bitmap;
• Try to use a smaller bitmap, or try using a Direct X buffer mapping;
• Try DoubleBuffered := true on your TForm.OnCreate event, or use a dedicated component (TPaintBox) with a global bitmap for the whole component content, with something like that for the message WM_ERASEBKGND.

有些code：

   procedure TMyPaintBox.WMEraseBkgnd(var Message: TWmEraseBkgnd);
   begin
     Message.Result := 1; // no erasing is necessary after this method call
   end;

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