Question

当我在Windows Phone 8中调用等待PhotoCaptureDevice.OpenAsync（..）时，相机应用会抛出InvalidOperationException。

System.InvalidOperationException：由于操作无效对象的当前状态。在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务） System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）在System.Runtime.CompilerServices.TaskAwaiter`1.GetResult（）at JPMC.Controls.CaptureTaskLauncher.d_6.MoveNext（）---堆栈结束从抛出异常的先前位置追踪--- at System.Runtime.CompilerServices.AsyncMethodBuilderCore.b_0（对象状态）}

但是还有一件事就是每当我第一次运行相机测试时它会完美地工作，即PhotoCaptureDevice正确初始化，但是当我从另一个页面返回到Camera测试时，它会给出上面提到的错误。那么，任何人都可以帮我解决这个问题吗？

由于

Answer 1

您是否尝试在离开页面之前使用PhotoCaptureDevice.Close（）和Dispose（）来释放资源？

Answer 2

 private static PhotoCaptureDevice d = null;
        public static async Task<bool> InitializeCamera(CameraSensorLocation sensorLocation)
        {
            bool catchValue = true;
            try
            {
                Windows.Foundation.Size initialResolution = new Windows.Foundation.Size(640, 480);
                Windows.Foundation.Size previewResolution = new Windows.Foundation.Size(640, 480);
                Windows.Foundation.Size captureResolution = new Windows.Foundation.Size(640, 480);
                d = await PhotoCaptureDevice.OpenAsync(sensorLocation, initialResolution);
                await d.SetPreviewResolutionAsync(previewResolution);
                await d.SetCaptureResolutionAsync(captureResolution);               
                d.SetProperty(KnownCameraGeneralProperties.PlayShutterSoundOnCapture, true);
                MemoryStream stream = new MemoryStream();                
                CameraCaptureSequence sequence = d.CreateCaptureSequence(1);
                sequence.Frames[0].CaptureStream = stream.AsOutputStream();
                await d.PrepareCaptureSequenceAsync(sequence);                
                await sequence.StartCaptureAsync();                            
                if (stream.Length > 0)
                {
                    d.Dispose();
                    d = null;
                    stream.Dispose();
                    stream = null;
                    return true;
                }
                else
                {
                    d.Dispose();
                    d = null;
                    stream.Dispose();
                    stream = null;
                }
                return false;
            }
            catch (Exception ex)
            {
                catchValue = false;
            }
            if (!catchValue)
            {
                Windows.Foundation.Size initialResolution = new Windows.Foundation.Size(640, 480);
                Windows.Foundation.Size previewResolution = new Windows.Foundation.Size(640, 480);
                Windows.Foundation.Size captureResolution = new Windows.Foundation.Size(640, 480);

                 d = await PhotoCaptureDevice.OpenAsync(sensorLocation,initialResolution);

                await d.SetPreviewResolutionAsync(previewResolution);
                await d.SetCaptureResolutionAsync(captureResolution);

                d.SetProperty(KnownCameraGeneralProperties.PlayShutterSoundOnCapture, true);
                MemoryStream stream = new MemoryStream();

                CameraCaptureSequence sequence = d.CreateCaptureSequence(1);
                sequence.Frames[0].CaptureStream = stream.AsOutputStream();
                await d.PrepareCaptureSequenceAsync(sequence);

                await sequence.StartCaptureAsync();

                if (stream.Length > 0)
                {
                    d.Dispose();
                    d = null;
                    stream.Dispose();
                    stream = null;
                    return true;
                }
                else
                {
                    d.Dispose();
                    d = null;
                    stream.Dispose();
                    stream = null;
                }
                return false;
            }
            return false;

        }

WP8中的PhotoCaptureDevice中的InvalidOperationException

2 个答案: