Question

在我的Windows Phone 8应用程序中，我有一个LongListSelector的页面，该页面绑定到1000个对象的列表，这些对象具有base64string的图像属性。现在为了显示图像，我编写了这个转换器，将bas64string转换为stream。

public object Convert(object value, Type targetType, object parameter,  System.Globalization.CultureInfo culture)
{
    if (!value.ToString().Contains("http://"))
    {
        string str = value.ToString();
        byte[] bytes = Converter.FromBase64String(str);

        using (MemoryStream stream = new MemoryStream(bytes))
        {
            stream.Seek(0, SeekOrigin.Begin);

            BitmapImage image = new BitmapImage();
            image.SetSource(stream); 
            bytes = null;
            var memoryusage = string.Format("Memory: {0} bytes", 
            DeviceExtendedProperties.GetValue("ApplicationCurrentMemoryUsage"));
            Debug.WriteLine(memoryusage);
            return image;
        }
    }
    else
    { 
        return null;
    }
}

这就是记忆：

    Memory: 92549120 bytes
    Memory: 92946432 bytes
    Memory: 92946432 bytes
    Memory: 92946432 bytes
    Memory: 92946432 bytes
    Memory: 93192192 bytes
    Memory: 93192192 bytes
    Memory: 96079872 bytes
    Memory: 100700160 bytes
    Memory: 100700160 bytes
    Memory: 109568000 bytes
    Memory: 111734784 bytes
    Memory: 142852096 bytes
    Memory: 143056896 bytes
    Memory: 143056896 bytes
    Memory: 143261696 bytes
    Memory: 140791808 bytes
    Memory: 141103104 bytes
    Memory: 141529088 bytes
    Memory: 142151680 bytes
    Memory: 146784256 bytes
    Memory: 146784256 bytes
    Memory: 155066368 bytes
    Memory: 156368896 bytes

当内存等于或大于此156368896字节的某些字节时，应用程序将与EngineExecutionException崩溃。一旦我得到“OutOfMemoryException：

image.SetSource(stream);

显然这是一个记忆问题。我需要清除图像缓存但是如何？我在这个答案https://stackoverflow.com/a/12267163/1949475中看到了这个链接，但是我无法使用它。

注意：并非所有图像都同时显示，并且在我返回并再次返回页面后，应用程序占用了大量内存，从而更改要在LongListSelector中显示的数据。

Answer 1

在转换器类中设置

非常重要

BitmapImage image = new BitmapImage(); 
image.DecodePixelType = DecodePixelType.Logical; 
image.CreateOptions = BitmapCreateOptions.BackgroundCreation; 
image.CreateOptions = BitmapCreateOptions.DelayCreation; 
image.DecodePixelWidth = 56; 
image.DecodePixelHeight = 100;

如何在Windows Phone 8中释放图像缓存/内存？

1 个答案: