向表单添加控件的速度缓慢

Question

为什么油漆要花这么长时间？

public Form1()
    {
        InitializeComponent();
        SuspendLayout();
        double scale = ClientSize.Width / 11;
        for (int i = 1; i < 10; i++)
        {
            for (int j = 1; j < 10; j++)
            {
                everybox[i - 1, j - 1] = new TextBox
                                             {
                                                 Location = new Point((int)(scale * i), (int)(scale * j)),
                                                 Size = new Size((int)scale - 2, (int)scale - 2),
                                                 Multiline = true
                                             };
                Controls.Add(everybox[i - 1, j - 1]);
            }
        }
        ResumeLayout();
    }


private void Form1_Paint(object sender, PaintEventArgs e)
    {
        float scale = ClientSize.Width / 11;
        Graphics g = this.CreateGraphics();
        int counter = 0;
        for (float i = scale; i <= this.ClientSize.Width - scale; i += scale)
        {
            counter++;
            if ((counter - 1) % 3 != 0)
            {
                g.DrawLine(new Pen(Color.Black), new Point((int)i, (int)scale),
                           new Point((int)i, ClientSize.Width - (int)scale));
                g.DrawLine(new Pen(Color.Black), new Point((int)scale, (int)i),
                           new Point(ClientSize.Width - (int)scale, (int)i));
            }
            else
            {
                g.DrawLine(new Pen(Color.Black, 3f), new Point((int)i, (int)scale),
                           new Point((int)i, ClientSize.Width - (int)scale));
                g.DrawLine(new Pen(Color.Black, 3f), new Point((int)scale, (int)i),
                           new Point(ClientSize.Width - (int)scale, (int)i));
            }
        }
    }

这是相当烦人的，并且会导致明显的滞后。 everybox 是一个 TextBox[9,9] 对象。

Answer 1

根据我的评论，更改

Graphics g = this.CreateGraphics();

为：

e.Graphics

Answer 2

Paint 肯定会被多次调用，如果您收到太多调用，则可能与这段代码无关。有助于提高该特定位的性能的一件事是尝试减少您所做的工作量...

    Graphics g = e.Graphics;
    Pen bp = new Pen(Color.Black, 3f);
    Point start = new Point(0,0);
    Point stop = new Point(0,0);

    for (float i = scale; i <= this.ClientSize.Width - scale; i += scale)
    {
        int iAsInt = (int)i;
        int scaleAsInt = (int)scale;
        int w = ClientSize.Width;
        counter++;

        if ((counter - 1) % 3 != 0)
        {
            start.X = iAsInt;
            start.Y = scaleAsInt;
            stop.X = iAsInt;
            stop.Y = w-scaleAsInt;
            g.DrawLine(Pens.Black, start, stop);
            start.X = scaleAsInt;
            start.Y = iAsInt;
            stop.X = w-scaleAsInt;
            stop.Y = iAsInt;
            g.DrawLine(Pens.Black, start, stop);
            // Note: this looks like more work, but it is actually less
            // your code still has to make all the assignments in addition to 
            // newing up the points (and later having to garbage collect them)
        }
        else
        {
            // TODO: reuse the start/stop points here
            g.DrawLine(bp, new Point(iAsInt, scaleAsInt), new Point(iAsInt, w - scaleAsInt);
            g.DrawLine(bp, new Point(scaleAsInt, iAsInt), new Point(w - scaleAsInt, iAsInt));
        }
    }

要专门停止线条的过度绘制，请查看 PaintEventArgs 的 ClipRectangle 成员。如果线条的一部分落在剪辑矩形的区域内，请重新绘制它。

Answer 3

一个可能的原因是您试图绘制太多重量级组件。如果我的数学正确，您将重绘 9 * 9 * 9 * 9 = 6561 个对象。 WinForms 的设计并不支持以有效的方式重绘那么多组件。

您可能需要考虑是否真的需要在 WinForms 中使用那么多重量级图形组件。可能有更轻的组件，或者您可以根据上下文切换到 XNA（它具有相机、视图等 - 所有这些都减少了需要重绘的对象数量）或 WPF。

Answer 4

您发布的代码导致绘制事件触发 81 次 (9*9)。对于添加到表单的每个控件一次。任何更多的时间都是由于某些使表单无效的原因，例如鼠标在其上移动、另一个窗口在其上移动或表单大小调整。您未向我们展示的某些代码可能是有原因的。