用perfmon简单分析GDI+性能和代码的一点小改进
Paint事件被触发了多少次？比较简单的方式，我们自己做一个perfmon能用的counter。看代码：
1
private void button1_Click(object sender, EventArgs e)
2
{
3
4 if (!PerformanceCounterCategory.Exists("GDI+ Monitor"))
5
{
6 CounterCreationDataCollection ccdc = new CounterCreationDataCollection();
7
8 CounterCreationData totalPaint = new CounterCreationData();
9 totalPaint.CounterName = "# operator executed";
10 totalPaint.CounterHelp = "Counts of OnPaint events called";
11 totalPaint.CounterType = PerformanceCounterType.NumberOfItems32;
12
13 ccdc.Add(totalPaint);
14
15 PerformanceCounterCategory.Create("GDI+ Monitor", "Some counters for GDI+ objects", PerformanceCounterCategoryType.MultiInstance, ccdc);
16
}
17
}
private void button1_Click(object sender, EventArgs e)2
{3
4
if (!PerformanceCounterCategory.Exists("GDI+ Monitor"))5
{6
CounterCreationDataCollection ccdc = new CounterCreationDataCollection();7
8
CounterCreationData totalPaint = new CounterCreationData();9
totalPaint.CounterName = "# operator executed";10
totalPaint.CounterHelp = "Counts of OnPaint events called";11
totalPaint.CounterType = PerformanceCounterType.NumberOfItems32;12
13
ccdc.Add(totalPaint);14
15
PerformanceCounterCategory.Create("GDI+ Monitor", "Some counters for GDI+ objects", PerformanceCounterCategoryType.MultiInstance, ccdc);16
}17
}好，点一下button1之后，我们就可以在perfmon中看到GDI+ Monitor这个category了，然后只有一个counter，就是# operator executed
然后在winform中增加这么一段：
paintcall = new PerformanceCounter(); paintcall.CategoryName = "GDI+ Monitor"; paintcall.CounterName = "# operator executed"; paintcall.MachineName = "."; paintcall.ReadOnly = false;好了，代码里面可以用paintcall这个变量了。我们现在的需求是监视Paint被触发了多少次，那么可以在代码中这么写：
1 Graphics g2 = e.Graphics;
2
3 Bitmap bmp = new Bitmap(this.Width, this.Height);
4 Graphics g = Graphics.FromImage(bmp);
5
6 paintcall.Increment();
7
8 Rectangle r = new Rectangle(0, 0, this.Width, this.Height);
9 g.FillRectangle(new LinearGradientBrush(r, Color.Red, Color.Blue, LinearGradientMode.BackwardDiagonal), r);
10
11 g2.DrawImage(bmp, new Point(0, 0));
12
13 g.Dispose();
14 g = null;
15
16 bmp.Dispose();
17 bmp = null;
Graphics g2 = e.Graphics;2
3
Bitmap bmp = new Bitmap(this.Width, this.Height);4
Graphics g = Graphics.FromImage(bmp);5
6
paintcall.Increment();7
8
Rectangle r = new Rectangle(0, 0, this.Width, this.Height);9
g.FillRectangle(new LinearGradientBrush(r, Color.Red, Color.Blue, LinearGradientMode.BackwardDiagonal), r);10
11
g2.DrawImage(bmp, new Point(0, 0));12
13
g.Dispose();14
g = null;15
16
bmp.Dispose();17
bmp = null;看上面第6行，这句会把paint call增加一。当然，其他方法有很多，这里不写了。
好，跑一下perfmon，然后把我们新增加的counter add上，嗯，可以看到当窗口无效的时候，计数器就增加了。
有一个小的细节，当窗口稍微改动大小的时候，你会发现Paint被调用了多次，这个实在很郁闷。so，稍微做点手脚：
1 private bool resize = false;
2 private void Form1_ResizeEnd(object sender, EventArgs e)
3 {
4 resize = false;
5 this.Invalidate();
6 }
7
8 private void Form1_ResizeBegin(object sender, EventArgs e)
9 {
10 resize = true;
11 }
private bool resize = false;2
private void Form1_ResizeEnd(object sender, EventArgs e)3
{4
resize = false;5
this.Invalidate();6
}7
8
private void Form1_ResizeBegin(object sender, EventArgs e)9
{10
resize = true;11
}然后我们修改一下Paint事件的代码如下：
1 private void Form1_Paint(object sender, PaintEventArgs e)
2 {
3 if (true == resize) return;
4
5 Graphics g2 = e.Graphics;
6
7 Bitmap bmp = new Bitmap(this.Width, this.Height);
8 Graphics g = Graphics.FromImage(bmp);
9
10 paintcall.Increment();
11
12 Rectangle r = new Rectangle(0, 0, this.Width, this.Height);
13 g.FillRectangle(new LinearGradientBrush(r, Color.Red, Color.Blue, LinearGradientMode.BackwardDiagonal), r);
14
15 g2.DrawImage(bmp, new Point(0, 0));
16
17 g.Dispose();
18 g = null;
19
20 bmp.Dispose();
21 bmp = null;
22 }
private void Form1_Paint(object sender, PaintEventArgs e)2
{3
if (true == resize) return;4
5
Graphics g2 = e.Graphics;6
7
Bitmap bmp = new Bitmap(this.Width, this.Height);8
Graphics g = Graphics.FromImage(bmp);9
10
paintcall.Increment();11
12
Rectangle r = new Rectangle(0, 0, this.Width, this.Height);13
g.FillRectangle(new LinearGradientBrush(r, Color.Red, Color.Blue, LinearGradientMode.BackwardDiagonal), r);14
15
g2.DrawImage(bmp, new Point(0, 0));16
17
g.Dispose();18
g = null;19
20
bmp.Dispose();21
bmp = null;22
}注意第三行，我们判断，如果在resize过程中，那么就直接返回。这样，虽然界面像白板一样，但是却少了很多Paint操作，从性能上会好不少。
posted on 2007-11-13 16:54:00 by juqiang 评论(4) 阅读(5062)