C# winform-.NET Compact Framework 3.5中的OnPaint

我目前正在一个智能设备项目中制作一个曲线进度条。我重写了OnPaint函数

protected override void OnPaint(PaintEventArgs e)
        {
            gx = e.Graphics;
// Draw the original curved progress bar
            int intPosition1 = m_NumberOfSpoke;

            for (int intCounter1 = 0; intCounter1 < m_NumberOfSpoke; intCounter1++)
            {
                intPosition1 = intPosition1 % m_NumberOfSpoke;
                DrawLine(e.Graphics,
                         GetCoordinate(m_CenterPoint, m_InnerCircleRadius, m_Angles[intPosition1]),
                         GetCoordinate(m_CenterPoint, m_OuterCircleRadius, m_Angles[intPosition1]),
                         Color.DarkGray, m_SpokeThickness);
                intPosition1++;
            }

     // Draw a part of the progress bar to reflect the changing current value(such as 30%)
   int intPosition = CurrentValue;

                for (int intCounter1 = 0; intCounter1 < CurrentValue; intCounter1++)
                {
                    intPosition = intPosition % CurrentValue;
                    DrawLine(gx,
                             GetCoordinate(m_CenterPoint, m_InnerCircleRadius, m_Angles[intPosition]),
                             GetCoordinate(m_CenterPoint, m_OuterCircleRadius, m_Angles[intPosition]),
                             Color.Yellow, m_SpokeThickness);
                    intPosition++;
                }

        base.OnPaint(e);



        }

在Override OnPaint（）函数中，我用深灰色绘制了弯曲的进度条，并用黄色绘制了进度条的一部分，以反映进度条不断变化的值（例如30%）。但是，当值不断变化时，我可以看到进度条的部分颜色变为黄色。但是，弯曲的进度条本身也会重新绘制。有人知道如何避免在值更改时重新绘制原始曲线进度条吗？因此，当值发生变化时，它仅用黄色重新绘制进度条的一部分，而不是用灰色重新绘制原始进度条。下面是我在OnPaint函数中使用的代码

protected override void OnPaint(PaintEventArgs e)
        {
            gx = e.Graphics;
// Draw the original curved progress bar
            int intPosition1 = m_NumberOfSpoke;

            for (int intCounter1 = 0; intCounter1 < m_NumberOfSpoke; intCounter1++)
            {
                intPosition1 = intPosition1 % m_NumberOfSpoke;
                DrawLine(e.Graphics,
                         GetCoordinate(m_CenterPoint, m_InnerCircleRadius, m_Angles[intPosition1]),
                         GetCoordinate(m_CenterPoint, m_OuterCircleRadius, m_Angles[intPosition1]),
                         Color.DarkGray, m_SpokeThickness);
                intPosition1++;
            }

     // Draw a part of the progress bar to reflect the changing current value(such as 30%)
   int intPosition = CurrentValue;

                for (int intCounter1 = 0; intCounter1 < CurrentValue; intCounter1++)
                {
                    intPosition = intPosition % CurrentValue;
                    DrawLine(gx,
                             GetCoordinate(m_CenterPoint, m_InnerCircleRadius, m_Angles[intPosition]),
                             GetCoordinate(m_CenterPoint, m_OuterCircleRadius, m_Angles[intPosition]),
                             Color.Yellow, m_SpokeThickness);
                    intPosition++;
                }

        base.OnPaint(e);



        }

protected override void OnPaint（PaintEventArgs e）
{
gx=e.图形；
//绘制原始曲线进度条
int intPosition1=m_个辐条；
for（int-intCounter1=0；intCounter1

我曾尝试使用Override OnBackgroundPaint绘制原始曲线进度条作为背景，以避免在OnPaint中重新绘制它，但它不起作用。加载表单时，我看不到任何内容。有什么想法吗

提前谢谢你的帮助

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这是对实际屏幕的大量抽绳调用，很可能会导致闪烁。您应该通过创建一个后缓冲区来加倍缓冲区，对其执行所有绘图操作，然后通过调用

DrawBitmap

沿着以下几行将其显示到屏幕上：

protected override void OnPaint(PaintEventArgs e)
{
    using(var buffer = new Bitmap(this.Width, this.Height))
    using(var gx = Graphics.FromImage(buffer))
    {
        // for loops to draw to gx
        ....

        e.Graphics.DrawBitmap(buffer, ...);
    }

}

我也非常倾向于不做上面提到的事情，而是缓存缓冲区，以防止每次调用时产生位图的垃圾

Bitmap m_buffer;
Gramphic m_gx;

protected override void OnPaint(PaintEventArgs e)
{
    if(m_buffer == null)
    {
        m_buffer = new Bitmap(this.Width, this.Height))
        m_gx = Graphics.FromImage(buffer))
    }

    // clear the backbuffer with a FillRect

    // for loops to draw to m_gx
    ....

    e.Graphics.DrawBitmap(m_buffer, ...);
}

我甚至可能会更进一步，如果控件的灰色部分总是相同的，并执行“三重缓冲”，保留带有灰色绘制的图像的缓存版本，然后在OnPaint中，将其显示在图形上，绘制黄色，然后显示在屏幕上

Bitmap m_buffer;
Bitmap m_backimage;
Gramphic m_gx;

protected override void OnPaint(PaintEventArgs e)
{
    if(m_buffer == null)
    {
        m_backimage = new Bitmap(this.Width, this.Height);
        var g = Graphics.FromImage(m_backImage);
        // for loop to draw the grey stuff to g
        ....

        m_buffer = new Bitmap(this.Width, this.Height))
        m_gx = Graphics.FromImage(buffer))
    }

    m_gx.DrawImage(m_backImage);

    // for loop to draw *just the yellow* to m_gx
    ....

    e.Graphics.DrawBitmap(m_buffer, ...);
}

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您可能还需要覆盖OnResize和其他一些东西，再加上扩展Dispose来清理这些成员级GDI对象，但性能会更好，而且不会闪烁。

谢谢您的帮助，Chris。最终，我解决了这个问题。请问您是否了解Compact Framework中的线程技术？因为我现在有个问题。