画法闪烁

Question

考虑下面的paint函数(简化)：

public void paint(object sender, PaintEventArgs e)
{
    base.OnPaint(e);

    Graphics g = e.Graphics;

    BufferedGraphicsContext context = BufferedGraphicsManager.Current;
    BufferedGraphics buffer = context.Allocate(g, e.ClipRectangle);

    buffer.Graphics.Clear(Color.PaleVioletRed);

    // skip drawing if cond is true (condition is not relevant)
    if(!cond)
    {
        try
        {
          // l is some List<p>
          foreach(Point p in l)
          { 
             // ...calculate X and Y... (not relevant)

             buffer.Graphics.FillEllipse(new SolidBrush(Color.Blue), p.X,p.Y, Point.SIZE,Point.SIZE);
           }                                          
         }

         catch {} // some exception handling (not relevant)

         finally{
            buffer.Render(g);
         }
    }                
    buffer.Render(g);
}

请注意，上面的代码或多或少是伪代码。我希望使用BufferedGraphics对象，闪烁就会消失。一开始，我认为这个画图方法会花很长的时间，但事实大概并非如此(每次调用我都测量了4-7毫秒)。如果我将cond设置为true，它仍然闪烁，尽管画图方法几乎不需要时间。很重要的一点是，paint-method将在面板上绘制，并且我使用计时器使面板大约每50ms无效一次。我如何才能最终消除闪烁？

Answer 1

只需尝试在构造函数中设置该属性：

this.DoubleBuffered = true;

那么你就不需要BufferedGraphics的东西了：

public void paint(object sender, PaintEventArgs e)
{
  base.OnPaint(e);

  Graphics g = e.Graphics;       
  g.Clear(Color.PaleVioletRed);

  // skip drawing if cond is true (condition is not relevant)
  if(!cond)
  {
    // l is some List<p>
    foreach(Point p in l)
    { 
      // ...calculate X and Y... (not relevant)  
      g.FillEllipse(new SolidBrush(Color.Blue), p.X,p.Y, Point.SIZE,Point.SIZE);
    }                                          
  }
}