C# bitblt位图渲染控件

Question

我从事一个小型实时项目，其中非常需要快速位图渲染技术。我需要每秒在图片框中显示许多(数百)个小块，我从 pinvoke.net 中找到了 bitblt 示例网站。

我使用 while 循环(现在是无限循环)来检索特定位图，然后调用 Invalidate() 方法来触发 Paint 事件。

这是我的代码:

    protected override void OnPaint(PaintEventArgs e)
    {
        IntPtr pTarget = e.Graphics.GetHdc();
        IntPtr pSource = CreateCompatibleDC(pTarget);
        IntPtr pOrig = SelectObject(pSource, bmp.GetHbitmap());
        BitBlt(pTarget, 0, 0, bmp.Width, bmp.Height, pSource, 0, 0, TernaryRasterOperations.SRCCOPY);
        DeleteObject(pOrig);
        DeleteDC(pSource);
        e.Graphics.ReleaseHdc(pTarget);
    }
    private void Display()
    {
        while (true)
        {
            frame = desktopDuplicator.GetLatestFrame();
            if (frame != null)
            {
                bmp = frame.DesktopImage;//retrieve image.
                this.Invoke(new Action(() => this.Invalidate()));//trigger the repaint event
            }

        }
    }

它在几秒钟内工作正常，然后我在这一行收到一个 System.ArgumentException:

BitBlt(pTarget, 0, 0, bmp.Width, bmp.Height, pSource, 0, 0, TernaryRasterOperations.SRCCOPY);

有人知道这里出了什么问题吗？我一直在释放已使用的资源(在绘画事件中)...为什么会出现此错误？

提前致谢。

Answer 1

Does anyone have an idea what is wrong here? i keep releasing the used resources(in the paint event)...why i'm getting this error?

实际上您没有释放所有使用的资源，特别是bmp.GetHbitmap() 调用返回的位图句柄。正确的顺序是将原始默认位图句柄选回设备上下文，然后删除您的位图句柄，如 SelectObject documentation 中所述。 :

This function returns the previously selected object of the specified type. An application should always replace a new object with the original, default object after it has finished drawing with the new object.

IntPtr targetDC = e.Graphics.GetHdc();
IntPtr sourceDC = CreateCompatibleDC(targetDC);
IntPtr sourceBitmap = bmp.GetHbitmap();
IntPtr originalBitmap = SelectObject(sourceDC, sourceBitmap);
BitBlt(targetDC, 0, 0, bmp.Width, bmp.Height, sourceDC, 0, 0, TernaryRasterOperations.SRCCOPY);
SelectObject(sourceDC, originalBitmap);
DeleteObject(sourceBitmap);
DeleteDC(sourceDC);
e.Graphics.ReleaseHdc(targetDC);