c# - 抓取位图图像(Winforms)并转换为 WPF 图像失败

Question

我从外部摄像头抓取图像。 winforms 应用程序到目前为止工作。现在我需要将它传输到 WPF。因此，我像这样将位图图像转换为 WPF:

    GrabHandler frameCallbackDelegate;
    void frameCallBack(IntPtr lpUserData, ref VCECLB_FrameInfoEx frameInfo)
    {
        if (frameInfo.dma_status != 0) return;

        // fill image
        Rectangle rect = new Rectangle(0, 0, image.Width, image.Height);

        BitmapData bmdata = image.LockBits(rect, ImageLockMode.ReadWrite, image.PixelFormat);

        UInt32 outputBitDepth;
        IntPtr stride = new IntPtr(bmdata.Stride);

        VCECLB_Error err = NativeFunctions.VCECLB_UnpackRawPixelsEx(ref pRawPixelInfo, frameInfo.lpRawBuffer, bmdata.Scan0, ref stride, VCECLB_Output_Format.VCECLB_EX_FMT_TopDown | VCECLB_Output_Format.VCECLB_EX_FMT_3Channel, out outputBitDepth);

        image.UnlockBits(bmdata);



        Dispatcher.Invoke(new Action(() =>
        {
            // Convert bitmap to WPF-Image
            var bmp = new Bitmap(image);
            var hBitmap = bmp.GetHbitmap();

            ImageSource wpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
                        hBitmap,
                        IntPtr.Zero,
                        Int32Rect.Empty,
                        BitmapSizeOptions.FromEmptyOptions());

            image_LowLight.Source = wpfBitmap;

            DeleteObject(hBitmap);
            image.Dispose();
            }));
        GC.Collect();


    }


    private void StartGrab(object sender, RoutedEventArgs e)
    {
        start_button.IsEnabled = true;
        stop_button.IsEnabled = false;

        frameCallbackDelegate = new GrabHandler(frameCallBack);
        m_ImageAquisition.StartGrab(frameCallbackDelegate);
    }

当我第一次从 StartGrab 进入 frameCallBack 时，image.Width 和 image.Height 有一个有效值(不是 0)并且看起来是正确的。当第二次输入 frameCallBack 时，所有图像数据(宽度和高度)均为 0，因此 rect 会出错。

我使用 Dispatcher.Invoke 获取有效位图图像的方式有问题吗？

谢谢!

Answer 1

避免在稍后由 Dispatcher 执行的 Action() 中使用 volatile 数据。

像这样重构你的代码:

   GrabHandler frameCallbackDelegate;
    void frameCallBack(IntPtr lpUserData, ref VCECLB_FrameInfoEx frameInfo)
    {
        if (frameInfo.dma_status != 0) return;

        // fill image
        Rectangle rect = new Rectangle(0, 0, image.Width, image.Height);

        BitmapData bmdata = image.LockBits(rect, ImageLockMode.ReadWrite, image.PixelFormat);

        UInt32 outputBitDepth;
        IntPtr stride = new IntPtr(bmdata.Stride);

        VCECLB_Error err = NativeFunctions.VCECLB_UnpackRawPixelsEx(ref pRawPixelInfo, frameInfo.lpRawBuffer, bmdata.Scan0, ref stride, VCECLB_Output_Format.VCECLB_EX_FMT_TopDown | VCECLB_Output_Format.VCECLB_EX_FMT_3Channel, out outputBitDepth);

        image.UnlockBits(bmdata);

        // Convert bitmap to WPF-Image
        var bmp = new Bitmap(image);
        var hBitmap = bmp.GetHbitmap();

        ImageSource wpfBitmap =
            System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
                        hBitmap,
                        IntPtr.Zero,
                        Int32Rect.Empty,
                        BitmapSizeOptions.FromEmptyOptions());

        DeleteObject(hBitmap);
        image.Dispose();

        Dispatcher.Invoke(new Action(() =>
        {
            image_LowLight.Source = wpfBitmap;
        }));
        GC.Collect();
    }