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 }
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;
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;
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 }
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 }
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。