Question

不好意思，因为我的英语不好。我试图通过在计时器刻度处理函数中设置Paint事件处理程序在picturebox上绘制一条旋转线：

View()
{
InitializeComponent();
ViewModel vm = new ViewMode();
this.BindingContext= vm;
}

标有“1”的行在时间过程中执行得越来越慢。这是下面的“绘图”功能代码：

private void timer1_Tick(object sender, EventArgs e)
    {
        pictureBox1.Invalidate();
        pictureBox1.Paint += new PaintEventHandler(Draw);//1
        foreach (Line line in lines)//array "lines" contains just 16 objects
        {
            //calculating new coordinates ...
        }
    }

请你们告诉我，我该如何解决这个问题？谢谢！

Answer 1

不要在timer1_Tick中执行pictureBox1.Paint + = new PaintEventHandler（Draw）; // 1。在表单加载中执行一次。否则，每次Paint事件都会多次调用Draw（），调用次数也会增加。

Answer 2

试试这个

private void timer1_Tick(object sender, EventArgs e)
    {
        Graphics g = pictureBox1.CreateGraphics();
        foreach (Point line in lines)
        {
            g.DrawLine(new Pen(Brushes.Black, 5f), line.P1, line.P2);
            g.FillEllipse(Brushes.Red, line.P1.X - 2.5f, line.P1.Y - 2.5f, 5, 5);
            g.FillEllipse(Brushes.Red, line.P2.X - 2.5f, line.P2.Y - 2.5f, 5, 5);
            g.DrawEllipse(new Pen(Brushes.Red, 5f), line.P1.X, line.P1.Y, 1, 1);
            g.DrawEllipse(new Pen(Brushes.Red, 5f), line.P2.X, line.P2.Y, 1, 1);
        }
    }

如果它不显示效果，则在循环后添加以下行

pictureBox1.Invalidate();

Answer 3

除了解决其他答案中已经指出的事件处理程序问题之外，我还会在代码中更改一些内容。

首先，为什么要创建这么多Pen？把它们带出循环：

void Draw(object sender, PaintEventArgs e)
{
    var blackPen = new Pen(Brushes.Black, 5f);
    var redPen = new Pen(Brushes.Red, 5f);

    foreach (Line line in lines)
    {
        e.Graphics.DrawLine(blackPen, line.P1, line.P2);
        e.Graphics.FillEllipse(Brushes.Red, line.P1.X - 2.5f, line.P1.Y - 2.5f, 5, 5);
        e.Graphics.FillEllipse(Brushes.Red, line.P2.X - 2.5f, line.P2.Y - 2.5f, 5, 5);
        e.Graphics.DrawEllipse(redPen, line.P1.X, line.P1.Y, 1, 1);
        e.Graphics.DrawEllipse(redPen, line.P2.X, line.P2.Y, 1, 1);
    }
}

嗯，现在，请注意Pen实施IDisposable。养成处理完这些物品的习惯;这样，您将确定性地释放基础非托管资源，而不是GC决定：

void Draw(object sender, PaintEventArgs e)
{
    using (var blackPen = new Pen(Brushes.Black, 5f))
    using (var redPen = new Pen(Brushes.Red, 5f))
    {
        foreach (Line line in lines)
        {
            e.Graphics.DrawLine(blackPen, line.P1, line.P2);
            e.Graphics.FillEllipse(Brushes.Red, line.P1.X - 2.5f, line.P1.Y - 2.5f, 5, 5);
            e.Graphics.FillEllipse(Brushes.Red, line.P2.X - 2.5f, line.P2.Y - 2.5f, 5, 5);
            e.Graphics.DrawEllipse(redPen, line.P1.X, line.P1.Y, 1, 1);
            e.Graphics.DrawEllipse(redPen, line.P2.X, line.P2.Y, 1, 1);
        }
    }
}

此外，您甚至可以考虑将Pen缓存为实例变量;

class MyControl: ..., IDisposable
{
     private readonly Pen blackPen = new Pen(Brushes.Black, 5f));
     private readonly Pen redPen = new Pen(Brushes.Red, 5f));

     void Draw(object sender, PaintEventArgs e)
     {
         foreach (Line line in lines)
         {
            e.Graphics.DrawLine(blackPen, line.P1, line.P2);
            e.Graphics.FillEllipse(Brushes.Red, line.P1.X - 2.5f, line.P1.Y - 2.5f, 5, 5);
            e.Graphics.FillEllipse(Brushes.Red, line.P2.X - 2.5f, line.P2.Y - 2.5f, 5, 5);
            e.Graphics.DrawEllipse(redPen, line.P1.X, line.P1.Y, 1, 1);
            e.Graphics.DrawEllipse(redPen, line.P2.X, line.P2.Y, 1, 1);
        }
    }

    private void Dispose(bool disposing)
    {
         ....
         if (disposing)
         {
             ....
             blackPen.Dispose(;)
             redPen.Dispose();
         }
    }
}

Answer 4

看起来你的问题是pictureBox1.Paint += new PaintEventHandler(Draw);所以当paint事件触发第一个滴答时它在第二个刻度上没有做任何事情它会在第500个刻度重新绘制一次它重新绘制499次

你需要做的是

private void configure()
{
    pictureBox1.Paint += new PaintEventHandler(pictureBox1_OnPaint);
}
private void timer1_Tick(object sender, EventArgs e)
{
    pictureBox1.Invalidate();
}
private void pictureBox1_OnPaint(object sender, PaintEventArgs e)
{
    foreach (Line line in lines)//array "lines" contains just 16 objects
    {
        //calculating new coordinates ...
        e.Graphics.DrawLine(new Pen(Brushes.Black, 5f), line.P1, line.P2);
        e.Graphics.FillEllipse(Brushes.Red, line.P1.X - 2.5f, line.P1.Y - 2.5f, 5, 5);
        e.Graphics.FillEllipse(Brushes.Red, line.P2.X - 2.5f, line.P2.Y - 2.5f, 5, 5);
        e.Graphics.DrawEllipse(new Pen(Brushes.Red, 5f), line.P1.X, line.P1.Y, 1, 1);
        e.Graphics.DrawEllipse(new Pen(Brushes.Red, 5f), line.P2.X, line.P2.Y, 1, 1);
    }
}

更详细一点，因为您显然不了解事件处理程序的工作原理

pictureBox1.Paint += new PaintEventHandler(pictureBox1_OnPaint);

读取当绘制事件发生时我想让你每次调用该命令时调用pictureBox1_OnPaint，你将该方法调用的额外实例添加到你的程序中

pictureBox1.Paint += new PaintEventHandler(pictureBox1_OnPaint);
pictureBox1.Paint += new PaintEventHandler(pictureBox1_OnPaint);

说当Paint发生时你想要两次调用pictureBox1_OnPaint。它永远不会触发事件，调用Invalidate()会触发事件。

所以你需要做的是初始化表单时（这可能是构造函数，初始化事件，如（Form.Load）或类似的地方告诉表单你希望它与paint事件做什么时它发生在

pictureBox1.Paint += new PaintEventHandler( action );

但只做一次

然后在你的计时器调用Invalidate上，以便触发事件

因为每次paint事件触发时都会出现tick上的逻辑，那么你也可以将它添加到handers动作中，而不是通过行集合两次

执行图片框绘制事件处理程序变得越来越慢

4 个答案: