Question

我想知道是否有人可以向我解释如何在.net紧凑框架中双重缓冲一个完整的表单。我已经找到了双缓冲的例子，但我似乎无法使其中任何一个工作。

我们创建了一个包含多个表单的应用程序。这些形式中的一些确实需要很长时间在屏幕上绘制，这导致闪烁。为了让您对我们的应用程序有所了解，我将解释其中一种形式。此表单包含用户控件，一些面板，文本框和按钮。 usercontrol具有自定义绘图的面板（在屏幕上绘制文本和图像（具有透明度））。甚至其中一些面板包含其他面板也可以做同样的事情。面板也有自定义绘图，因为我们在屏幕上绘制文字，带有一些效果等。每个面板都需要时间来绘制，这意味着如果我们在3x3网格中有9个面板，它们将被绘制并以随机顺序显示，而不是同时显示所有面板。文本绘图等也是如此。我们希望表格中的所有内容同时显示。

所以我的问题是，我可以创建一个执行双缓冲的“超级”类，在完整形式的内存中绘图吗？

我可以从中扩展我的当前表格而不必改变我的控件，面板，图像等等吗？

由于

Answer 1

我不确定你的确切表单的复杂性以及它上面的所有控件，但是我已经实现了一个基类DoubleBufferableControl类，您可以从中扩展它以创建双缓冲的自定义控件。我用自定义绘图创建了许多控件，它们都将它用作基类。

您可以将此类用作控件的基类，这些控件具有自定义绘制以避免闪烁。在您的子类中，请确保在构造函数中将DoubleBuffered设置为true。

    /// <summary>
/// Implements the functionality for a control that can be double buffered
/// </summary>
public class DoubleBufferableControl : ScrollableControl
{
    public event BufferedPaintEventHandler BufferedPaint;
    private bool doubleBuffered;
    private Bitmap backBuffer;
    private Size oldSize;

    /// <summary>
    /// Gets or sets whether this control will use double buffering
    /// </summary>
    public bool DoubleBuffered
    {
        get
        {
            return doubleBuffered;
        }
        set
        {
            if (value && !doubleBuffered && Width > 0 && Height > 0)
            {
                backBuffer = new Bitmap(Width, Height);
            }
            else if(!value && doubleBuffered)
            {
                backBuffer.Dispose();
                backBuffer = null;
            }

            doubleBuffered = value;
        }
    }

    /// <summary>
    /// Gets the off screen image used for double buffering
    /// </summary>
    public Bitmap BackBuffer
    {
        get
        {
            return backBuffer;
        }
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DoubleBufferableControl"/> class.
    /// </summary>
    public DoubleBufferableControl()
    {
        AutoScroll = false;
        doubleBuffered = DefaultDoubleBuffered;
        oldSize = Size;
    }

    #region Designer
    private bool DefaultDoubleBuffered = false;
    protected virtual bool ShouldSerializeDoubleBuffered()
    {
        return !this.doubleBuffered.Equals(DefaultDoubleBuffered);
    }
    protected void ResetDoubleBuffered()
    {
        DoubleBuffered = DefaultDoubleBuffered;
    }
    #endregion

    /// <summary>
    /// Raises the Paint event
    /// </summary>
    /// <param name="e">A PaintEventArgs that represents event data</param>
    protected override sealed void OnPaint(PaintEventArgs e)
    {
        if (doubleBuffered)
        {
            DoubleBufferedPaintEventArgs pe = new DoubleBufferedPaintEventArgs(CreateGraphics(), e.ClipRectangle);
            OnPaint(pe);
            pe.Graphics.Dispose();
            e.Graphics.DrawImage(backBuffer, e.ClipRectangle, e.ClipRectangle, GraphicsUnit.Pixel);
            base.OnPaint(e);
        }
        else
        {
            DoubleBufferedPaintEventArgs pe = new DoubleBufferedPaintEventArgs(e.Graphics, e.ClipRectangle);
            OnPaint(pe);
            base.OnPaint(e);
        }
    }

    /// <summary>
    /// Raises the Paint event for child classes that are to be double buffered
    /// </summary>
    /// <param name="e"></param>
    protected virtual void OnPaint(DoubleBufferedPaintEventArgs e)
    {
        if (BufferedPaint != null)
            BufferedPaint(this, e);
    }

    /// <summary>
    /// Paints the background of the control
    /// </summary>
    /// <param name="e">A PaintEventArgs object that contains event data</param>
    protected override void OnPaintBackground(PaintEventArgs e)
    {
        // do not use arg, because can't control back/screen
        Graphics gfx = CreateGraphics();
        gfx.Clear(BackColor);
        gfx.Dispose();
    }

    /// <summary>
    /// Raises the Resize event
    /// </summary>
    /// <param name="e">An EventArgs that represents event data</param>
    protected override void OnResize(System.EventArgs e)
    {
        if (Size != oldSize) // Stupid control gets resized when like anything happens to the parent form
        {
            if (doubleBuffered)
            {
                if (backBuffer != null)
                    backBuffer.Dispose();

                backBuffer = new Bitmap(Width != 0 ? Width : 1, Height != 0 ? Height : 1);
            }
        }
        oldSize = Size;

        base.OnResize(e);
    }

    /// <summary>
    /// Creates the Graphics for the control
    /// </summary>
    /// <param name="backBuffer">True to bypass the buffer and get the control graphics</param>
    /// <returns></returns>
    public virtual Graphics CreateGraphics(bool bypass)
    {
        if(bypass || !doubleBuffered)
            return base.CreateGraphics();
        else
            return Graphics.FromImage(backBuffer);
    }
    public virtual new Graphics CreateGraphics()
    {
        return CreateGraphics(false);
    }
}

你需要这些：

/// <summary>
/// Provides data for the DoubleBufferedControl.Paint event
/// </summary>
public class DoubleBufferedPaintEventArgs : PaintEventArgs
{
    /// <summary>
    /// Initializes a DoubleBufferedPaintEventArgs
    /// </summary>
    /// <param name="g">The Graphics object to paint to;  If the control is double buffered, the graphics object is for the buffer otherwise the screens graphics is used</param>
    /// <param name="clip">The region in which to paint</param>
    public DoubleBufferedPaintEventArgs(Graphics g, Rectangle clip) : base(g, clip) { }
}
public delegate void BufferedPaintEventHandler(object sender, DoubleBufferedPaintEventArgs args);

我通常从这个类继承，覆盖OnPaintBackground方法并将其实现留空。然后，我在OnPaint方法中实现了所有自定义绘图。

.NET Compact Framework上的双缓冲

1 个答案: