Windows Phone 8中BitmapImage/Image控件的内存消耗

Question

我正在测试一个WP8应用程序和它的图像查看器来显示许多图像,我发现应用程序的内存消耗正在提高,并希望找到如何解决它.

我已经从网上阅读了一些文章,但这些文章提供的解决方案不适用于我的应用,请阅读以下历史记录.

首先,我发现文章" Windows Phone 7的图像提示 "并下载其样本进行清洁图像缓存测试,它使用的是1张图像.

然后出于测试目的,我使用应用程序内的15个离线图像编译此应用程序,并设置为"内容",请从此处下载测试应用程序.

我的测试步骤是:

(1) Launch app
(2) Go to Image Caching page
(3) Enable checkbox "Avoid Image Caching"
(4) Continuously tapping button Show/Clear
(5) Keep watching the memory status textblock at the bottom

当我测试我的应用程序时,内存正在提升,如16.02MB =>显示(19.32MB)=>清除(16.15MB)=>显示(20.18MB)=>清除(17.03MB)...等和内存即使离开缓存页面再次进入缓存页面也不会被释放.似乎文章" Windows Phone 7的图像提示 "的解决方案仅适用于1个图像.

这是" Windows Phone 7的图像提示 "解决方案的xaml和代码隐藏.

[Caching.xaml]

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <StackPanel Orientation="Horizontal" VerticalAlignment="Top">
                <ToggleButton Content="Show" Width="150" Checked="ShowImageClicked" Unchecked="ClearImageClicked"/>
                <CheckBox x:Name="cbAvoidCache" Content="Avoid Image Caching"/>
            </StackPanel>
            <Image x:Name="img" Grid.Row="2" Width="256" Height="192"/>
            <TextBlock x:Name="tbMemory" Grid.Row="2" Text="Memory: " VerticalAlignment="Bottom" Style="{StaticResource PhoneTextLargeStyle}"/>
        </Grid>

[Caching.xaml.cs]

public partial class Caching : PhoneApplicationPage
{
    public Caching()
    {
        InitializeComponent();

        DispatcherTimer timer = new DispatcherTimer();
        timer.Interval = TimeSpan.FromMilliseconds(500);
        timer.Start();
        timer.Tick += delegate
        {
            GC.Collect();
            tbMemory.Text = string.Format("Memory: {0} bytes", DeviceExtendedProperties.GetValue("ApplicationCurrentMemoryUsage"));
        };
    }

    private int nIndex = 1;
    BitmapImage bitmapImageFromUri = new BitmapImage();
    private void ShowImageClicked(object sender, RoutedEventArgs e)
    {
        string strImage = string.Format("../ImagesAsContent/{0:D2}.jpg", nIndex);
        bitmapImageFromUri.UriSource = new Uri(strImage, UriKind.Relative);
        img.Source = bitmapImageFromUri;

        nIndex++;
        if (nIndex > 15)
        {
            nIndex = 1;
        }

        (sender as ToggleButton).Content = "Clear";
    }

    private void ClearImageClicked(object sender, RoutedEventArgs e)
    {
        if (cbAvoidCache.IsChecked == true)
        {
            // set the UriSource to null in order to delete the image cache
            BitmapImage bitmapImageFromUri = img.Source as BitmapImage;
            bitmapImageFromUri.UriSource = null;
        }
        img.Source = null;
        (sender as ToggleButton).Content = "Show";
    }
}

我也尝试搜索任何其他解决方案,一些测试结果如下.

(1)文章" [wpdev] BitmapImage内存泄漏 ":它提供了2个解决方案,一个是DisposeImage API,另一个是将BitmapImage源设置为null,如下所示.另外文章让我们知道我们必须小心事件处理程序附加/分离,但是我的测试应用程序在缓存页面中没有事件处理程序.

[DisposeImage]

private void DisposeImage(BitmapImage image)
{
    if (image != null)
    {
        try
        {
            using (var ms = new MemoryStream(new byte[] { 0x0 }))
            {
                image.SetSource(ms);
            }
        }
        catch (Exception)
        {
        }
    }
}

[设为null]

BitmapImage bitmapImage = image.Source as BitmapImage;
bitmapImage.UriSource = null;
image.Source = null;

(2)文章" Windows phone:带有图像内存不足的列表框 ":它提供了一个API"DisposeImage",与下面的(1)相比差别不大,但是这也行不通,我还是得到了内存提高症状.

public static void DisposeImage(BitmapImage image)
{
    Uri uri= new Uri("oneXone.png", UriKind.Relative);
    StreamResourceInfo sr=Application.GetResourceStream(uri);
    try
    {
     using (Stream stream=sr.Stream)
     {
      image.DecodePixelWidth=1; //This is essential!
      image.SetSource(stream);
     }
    }
    catch
    {}
}

(3)文章" 找不到内存泄漏 ":它提供了与上述相同的2个解决方案,也提到了孤立存储图像无法重现的问题,但是我的测试应用程序的图像来自隔离存储.

(4)我还尝试了1000张图片,当应用程序依次显示190张图片时,测试结果是应用程序崩溃,请参阅下面的Windows Phone Application Analysis Graphics获取内存.

最后,感谢您耐心阅读我的问题和历史,我一直在努力寻找解决方案多天.如果您有任何线索或解决方案,请告诉我.

谢谢.

Answer 1

我正在处理同样的问题，我认为，最终，实际上我找到了解决方法，我不是专业程序员，但这是我的解决方案：

  public Task ReleaseSingleImageMemoryTask(MyImage myImage, object control)
    {
        Pivot myPivot = control as Pivot;
        Task t = Task.Factory.StartNew(() =>
        {
            Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                if (myImage.img.UriSource != null)
                {
                    myImage.img.UriSource = null;
                    DisposeImage(myImage.img);
                }
                PivotItem it = (PivotItem)(myPivot.ItemContainerGenerator.ContainerFromIndex(myImage.number % 10));
                Image img = FindFirstElementInVisualTree<Image>(it);
                if (img != null)
                {
                    img.Source = null;
                    GC.Collect();
                }
            });
            myImage.released = true;
        });
        return t;
    } 


private T FindFirstElementInVisualTree<T>(DependencyObject parentElement) where T : DependencyObject
    {
        var count = VisualTreeHelper.GetChildrenCount(parentElement);
        if (count == 0)
            return null;

        for (int i = 0; i < count; i++)
        {
            var child = VisualTreeHelper.GetChild(parentElement, i);

            if (child != null && child is T)
            {
                return (T)child;
            }
            else
            {
                var result = FindFirstElementInVisualTree<T>(child);
                if (result != null)
                    return result;
            }
        }
        return null;
    }

    private void DisposeImage(BitmapImage img)
    {
        if (img != null)
        {
            try
            {
                using (var ms = new MemoryStream(new byte[] { 0x0 }))
                {
                    img = new BitmapImage();
                    img.SetSource(ms);
                }
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine("ImageDispose FAILED " + e.Message);
            }
        }
    }

希望这有帮助:)