绑定到BitmapImage

Question

    public class Thumbnail : INotifyPropertyChanged
    {
        public BitmapImage testimage { get; set; }
        Thumbnail()
        {
            testimage = new BitmapImage(new Uri("http://www.diseno-art.com/news_content/wp-content/uploads/2012/09/2013-Jaguar-F-Type-1.jpg"));
        }
    }

以及自定义控件中的图像元素：

<Image x:Name="previewImage" x:FieldModifier="public" Margin="8" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Source="{Binding Path=thumbnail.testimage}" Stretch="Fill" />

当我创建一个控件时，我会这样做：

MyControl MC = new MyControl();
MC.DataContext = new Thumbnail();

和图像没有出现-为什么？

Answer 1

XAML：

<Image x:Name="previewImage" x:FieldModifier="public" Margin="8" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Source="{Binding Path=testimage}" Stretch="Fill" />

代码(清洁剂)：

 public class Thumbnail : INotifyPropertyChanged
        {
            private BitmapImage tmpbmp;
            public BitmapImage testimage { get { return tmpbmp; } set { tmpbmp = value; OnPropertyChanged("testimage"); } }
            public Thumbnail()
            {
                tmpbmp = new BitmapImage(new Uri("http://www.diseno-art.com/news_content/wp-content/uploads/2012/09/2013-Jaguar-F-Type-1.jpg"));
            }


            public event PropertyChangedEventHandler PropertyChanged;

            protected virtual void OnPropertyChanged(string propertyName)
            {
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                    handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }

Answer 2

缩略图类没有公共构造函数，不实现INotifyPropertyChanged成员(在您的示例中根本不需要)。而XAML应是：

<Image x:Name="previewImage" x:FieldModifier="public" Margin="8" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Source="{Binding Path=testimage}" Stretch="Fill" />