Question

以下是代码的外观。

void ApplyFilter()
{
    this.filterOperationInProgress = true;
    WriteableBitmap wBmp = new WriteableBitmap(0, 0);
    wBmp = LocalWriteableBitmap.Clone();
    NokiaFilters nf = new NokiaFilters(wBmp, FilterName.Mango);
    wBmp = nf.render().Result;
    this.filterOperationInProgress = false;
}

NokiaFilter Class：

class NokiaFilters
{
    WriteableBitmap wb;
    FilterName filtername = FilterName.NoFilter;
    public NokiaFilters(WriteableBitmap wbm1, FilterName filtername1)
    {
        wb = wbm1;
        filtername = filtername1;
    }

    public async Task<WriteableBitmap> render()
    {
        MemoryStream memstream = new MemoryStream(wb.ToByteArray());
        if (memstream == null)
            return wb;
        //Mango
        else if (filtername == FilterName.Mango)
        {
            memstream.Position = 0;
            // Create a source to read the image from PhotoResult stream
            using (var source = new StreamImageSource(memstream))
            {
                // Create effect collection with the source stream
                using (var filters = new FilterEffect(source))
                {
                    // Initialize the filter 
                    ContrastFilter contrastfilter = new ContrastFilter(0.16);
                    HueSaturationFilter saturationfilter = new HueSaturationFilter(-0.01, -0.53);

                    LomoFilter lomofilter = new LomoFilter(0.5, 0.5, LomoVignetting.Low, LomoStyle.Yellow);
                    // Add the filter to the FilterEffect collection
                    filters.Filters = new List<IFilter> { contrastfilter, saturationfilter, lomofilter };

                   // Create a target where the filtered image will be rendered to
                   var target = new WriteableBitmap((int)wb.PixelWidth, (int)wb.PixelHeight);

                   // Create a new renderer which outputs WriteableBitmaps
                   using (var renderer = new WriteableBitmapRenderer( filters,target))
                   {
                       // Render the image with the filter(s)
                       try
                       {
                           target  = await renderer.RenderAsync().AsTask().ConfigureAwait(false);                                                            
                       }
                       catch (System.InvalidOperationException inv)
                       { }
                       catch { }

                       // Set the output image to Image control as a source
                       return target;
                   }
               }
           }
       }

       return wb;
   }
}

我的用户界面完全卡住，甚至后退按钮都没有响应。当我停止调试器时，代码指向

wBmp = nf.render().Result;

在此之前开始执行的语句是

target  = await renderer.RenderAsync().AsTask().ConfigureAwait(false);

我是并行编程的新手。我经常搜索，发现死锁在这种情况下很常见。我相信这也是一个僵局的情况。我怎么解决这个问题？

更新

更换后

wBmp = nf.render().Result;

带

wBmp = await nf.render().ConfigureAwait(false);

我得到了HRESULT：在

后的catch {}中出现0x8004C00F错误

target  = await renderer.RenderAsync().AsTask().ConfigureAwait(false);

这是stacktrace：

at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Nokia.Graphics.Imaging.WriteableBitmapRenderer.<<RenderAsync>b__0>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
   at SomeApp.NokiaFilters.<render>d__f.MoveNext()

Answer 1

解决了它。

替换

MemoryStream memstream = new MemoryStream(wb.ToByteArray());

与

MemoryStream memstream = new MemoryStream(); wb.SaveJpeg(memstream, wb.PixelWidth, wb.PixelHeight, 0, 100);

Answer 2

您是否在没有ConfigureAwait(false);的情况下尝试等待？是this.filterOperationInProgress是否与UI绑定？如果是这样，可能会出现“更改UI”的情况，而不是在UI线程上。

编辑：wb是否有效 - PixelWidth和PixelHeight是否大于或等于存储在MemoryStream中的图片？

HRESULT：使用Nokia Imaging sdk时为0x8004C00F

2 个答案: