將圖像值綁定到wpf和c中的路徑＃

Question

我正在努力將值綁定到路徑ImageSource。當我嘗試設置新值時，我得到NullReferenceError。 我當前的代碼是：

在MainWindow.xaml路徑代碼以下

<Path x:Name="PPButton" Data="M110,97 L155,123 
     C135,150 135,203 153,227 
     L112,255 
     C80,205 80,150 110,97" 
     Stretch="none" MouseEnter="Path_MouseEnter_1" MouseLeave="Path_MouseLeave_1" > 
      <Path.Fill> 
       <ImageBrush ImageSource="{Binding ImageSource}"/> 
      </Path.Fill> 
    </Path> 

上MainWindow.xaml.cs在那裏我得到錯誤，我評論的背後Path_mouseEnter_1

Image image; 
private void Path_MouseEnter_1(object sender, MouseEventArgs e) 
     { 
      image.ImageSource = new Uri("/RoundUI;component/sadface.png", UriKind.Relative); // This "An unhandled exception of type 'System.NullReferenceException' occurred in RoundUI.exe" 
     } 

     private void Path_MouseLeave_1(object sender, MouseEventArgs e) 
     { 
      image.ImageSource = new Uri("/RoundUI;component/smileface.png", UriKind.Relative); 
     } 

類，其中約束值應該採取：

public class Image : INotifyPropertyChanged 
    { 
     public event PropertyChangedEventHandler PropertyChanged; 

     private string title; 
     private Uri imageSource; 

     public Uri ImageSource 
     { 
      get 
      { 
       return imageSource; 
      } 
      set 
      { 
       imageSource = value; 
       if (PropertyChanged != null) 
       { 
        PropertyChanged(this, new PropertyChangedEventArgs("ImageSource")); 
       } 
      } 
     } 

     public void OnPropertyChanged(string name) 
     { 
      PropertyChangedEventHandler handler = PropertyChanged; 
      if (handler != null) 
      { 
       handler(this, new PropertyChangedEventArgs(name)); 
      } 
     } 
    } 

Answer 1

在代碼後面的喲你必須使用完整的Pack URIs，包括前綴pack://application:,,,。而且你不應該指定UriKind.Relative。

private void Path_MouseEnter_1(object sender, MouseEventArgs e) 
{ 
    image.ImageSource = new Uri("pack://application:,,,/RoundUI;component/sadface.png"); 
} 

---

編輯：看來你在這裏混淆了一些東西。現在它可能也許會更容易不的圖像刷的ImageSource屬性綁定，而是直接在代碼中設置它的背後，如圖this answer你前面的問題：

<Path x:Name="PPButton" ... 
     MouseEnter="Path_MouseEnter_1" MouseLeave="Path_MouseLeave_1" > 
    <Path.Fill> 
     <ImageBrush/> 
    </Path.Fill> 
</Path> 

後面的代碼：

private void Path_MouseEnter_1(object sender, MouseEventArgs e) 
{ 
    var imageBrush = PPButton.Fill as ImageBrush; 
    image.ImageSource = new Uri("pack://application:,,,/RoundUI;component/sadface.png"); 
}