C# UWP-图像不'；当它引用的图像文件发生更改时，不能更改内容

我正在尝试拍摄视频快照并用滚动条预览它。假设我们有

bohemian.mp4

，我的应用程序将在某个点拍摄快照并保存到

bohemian.png

。这是前面提到的部分

xaml:

public CommandEventHandler<double> UpdateSnapshotCmd
        {
            get
            {
                return new CommandEventHandler<double>(
                    async (second) => await UpdateSnapshotPreview(second)
                    );
            }
        }

public async Task UpdateSnapshotPreview(double second)
        {
            try
            {
                if (mp4 == null)
                {
                    mp4 = await StorageFile.GetFileFromPathAsync(mp4Path);
                }

                var imgName = Path.ChangeExtension(mp4.Name, ".png");

                StorageFile imgFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync(imgName, CreationCollisionOption.ReplaceExisting);

                MediaComposition mediaComposition = new MediaComposition();
                MediaClip mediaClip = await MediaClip.CreateFromFileAsync(mp4);
                mediaComposition.Clips.Add(mediaClip);
                
                var interval = TimeSpan.FromSeconds(second);
                var thumbnail = await mediaComposition.GetThumbnailAsync(interval, 
                    1024, 768, VideoFramePrecision.NearestKeyFrame);

                using (var randomAccess = await imgFile.OpenAsync(FileAccessMode.ReadWrite))
                using (var destStream = randomAccess.AsStream())
                using (var sourceStream = thumbnail.AsStream())
                {
                    await sourceStream.CopyToAsync(destStream);
                }

                mp3ViewerModel.ImagePath = imgFile.Path;
            }
            catch (Exception ex)
            {
                await new MessageDialog(ex.Message).ShowAsync();
            }
            
        }

出于调试目的，我会让

按钮

处理我的

命令

查看模型：

public CommandEventHandler<double> UpdateSnapshotCmd
        {
            get
            {
                return new CommandEventHandler<double>(
                    async (second) => await UpdateSnapshotPreview(second)
                    );
            }
        }

public async Task UpdateSnapshotPreview(double second)
        {
            try
            {
                if (mp4 == null)
                {
                    mp4 = await StorageFile.GetFileFromPathAsync(mp4Path);
                }

                var imgName = Path.ChangeExtension(mp4.Name, ".png");

                StorageFile imgFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync(imgName, CreationCollisionOption.ReplaceExisting);

                MediaComposition mediaComposition = new MediaComposition();
                MediaClip mediaClip = await MediaClip.CreateFromFileAsync(mp4);
                mediaComposition.Clips.Add(mediaClip);
                
                var interval = TimeSpan.FromSeconds(second);
                var thumbnail = await mediaComposition.GetThumbnailAsync(interval, 
                    1024, 768, VideoFramePrecision.NearestKeyFrame);

                using (var randomAccess = await imgFile.OpenAsync(FileAccessMode.ReadWrite))
                using (var destStream = randomAccess.AsStream())
                using (var sourceStream = thumbnail.AsStream())
                {
                    await sourceStream.CopyToAsync(destStream);
                }

                mp3ViewerModel.ImagePath = imgFile.Path;
            }
            catch (Exception ex)
            {
                await new MessageDialog(ex.Message).ShowAsync();
            }
            
        }

---

当我选中保存的文件夹时，

png

文件被更改为

Slider.Value

但应用程序中的

Image

只响应了一次。如何修复此问题？

我认为，因为文件路径保持不变，所以导致

图像的行为相同，尽管内容不同或
OnPropertyChanged
调用不同

因此，我在视图模型中找到了一个解决方案：

public CommandEventHandler<double> UpdateSnapshotCmd
        {
            get
            {
                return new CommandEventHandler<double>(
                    async (second) => await UpdateSnapshotPreview(second)
                    );
            }
        }

public async Task UpdateSnapshotPreview(double second)
        {
            try
            {
                if (mp4 == null)
                {
                    mp4 = await StorageFile.GetFileFromPathAsync(mp4Path);
                }

                var imgName = Path.ChangeExtension(mp4.Name, ".png");

                StorageFile imgFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync(imgName, CreationCollisionOption.ReplaceExisting);

                MediaComposition mediaComposition = new MediaComposition();
                MediaClip mediaClip = await MediaClip.CreateFromFileAsync(mp4);
                mediaComposition.Clips.Add(mediaClip);
                
                var interval = TimeSpan.FromSeconds(second);
                var thumbnail = await mediaComposition.GetThumbnailAsync(interval, 
                    1024, 768, VideoFramePrecision.NearestKeyFrame);

                using (var randomAccess = await imgFile.OpenAsync(FileAccessMode.ReadWrite))
                using (var destStream = randomAccess.AsStream())
                using (var sourceStream = thumbnail.AsStream())
                {
                    await sourceStream.CopyToAsync(destStream);
                }

                mp3ViewerModel.ImagePath = imgFile.Path;
            }
            catch (Exception ex)
            {
                await new MessageDialog(ex.Message).ShowAsync();
            }
            
        }

StorageFile imgFile=wait ApplicationData.Current.TemporaryFolder.CreateFileAsync（imgName，
CreationCollisionOption.ReplaceExisting）；

改为：

StorageFile imgFile=wait ApplicationData.Current.TemporaryFolder.CreateFileAsync（imgName，
CreationCollisionOption.GenerateUniqueName）；

但是，这将创建一堆
png
，看起来很难看。我想知道是否有任何替代解决方案可以重复使用第一个也是唯一的
png
？
使用a来监视文件的更改：
这是正确的，我建议使用解码图像绑定到视图，这样您也不必将图像保存到文件，只需创建一个图像源变量并为其赋值并绑定相同的值，这样当滑块更改时，图像源可以直接更新，而无需保存到文件