| title | author | date | CreateTime | categories | 
| WPF 使用 RenderTargetBitmap 快速截图出现 COMException 提示 | lindexi | 2019-01-10 14:58:43 +0800 | 2019-01-10 14:46:27 +0800 | WPF | 
本文告诉大家一个最简单步骤让 RenderTargetBitmap 出现 COMException 提示
只需要在界面添加一个 ListView 绑定图片,然后在后台不断刷新列表就可以
<ListView Margin="10,10,10,10" ItemsSource="{Binding DeagernereDechuno}">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <Grid Margin="10,10,10,10">
                        <Image Source="{Binding}"></Image>
                    </Grid>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>在后台创建 DeagernereDechuno 列表
public ObservableCollection<ImageSource> DeagernereDechuno { get; set; }=new ObservableCollection<ImageSource>();在 Load 之后调用函数 WarwairJorkasou 不断截图
public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
            Loaded += (s, e) =>
            {
                 WarwairJorkasou();
            };
        }在 WarwairJorkasou 调用循环进行截图,很快就可以看到下面提示
System.Runtime.InteropServices.COMException: MILERR_WIN32ERROR异常堆栈
System.Runtime.InteropServices.COMException (0x88980003): MILERR_WIN32ERROR (异常来自 HRESULT:0x88980003)
   在 System.Windows.Media.Imaging.RenderTargetBitmap.FinalizeCreation()
   在 System.Windows.Media.Imaging.RenderTargetBitmap..ctor(Int32 pixelWidth, Int32 pixelHeight, Double dpiX, Double dpiY, PixelFormat pixelFormat)截图的代码
private async void WarwairJorkasou()
        {
            var ran = new Random();
            while (true)
            {
                await Task.Delay(10).ContinueWith(_ =>
                {
                    DeagernereDechuno.Clear();
                    var n = ran.Next(int.MaxValue / 10);
                    for (int i = n; i < n + 1000; i++)
                    {
                        try
                        {
                            DrawingVisual drawingVisual = new DrawingVisual();
                            DrawingContext drawingContext = drawingVisual.RenderOpen();
                            var text = new FormattedText(i.ToString(),
                                CultureInfo.GetCultureInfo("zh-cn"),
                                FlowDirection.LeftToRight,
                                new Typeface("Verdana"),
                                36, Brushes.Black);
                            drawingContext.DrawText(text,
                                new Point(0, 0));
                
                            drawingContext.Close();
                            var image = new RenderTargetBitmap((int) text.Width, (int) text.Height, 96, 96, PixelFormats.Pbgra32);
                            image.Render(drawingVisual);
                            DeagernereDechuno.Add(image);
                        }
                        catch (Exception e)
                        {
                            Console.WriteLine(e);
                        }
                    }
                }, TaskScheduler.FromCurrentSynchronizationContext());
            }
        }运行程序大概在 300M 左右就会出现 COMException 提示
System.Runtime.InteropServices.COMException (0x88980003): MILERR_WIN32ERROR (Exception from HRESULT: 0x88980003)RenderTargetBitmap throws COM exception when created too fast: MILERR_WIN32ERROR (Exception from HRESULT: 0x88980003)
代码请看 https://github.com/dotnet-campus/wpf-issues/tree/master/RenderTargetBitmapThrowsCOMExceptionWhenCreatedTooFast
    
    

