Question

过去一周左右，我一直在Silverlight中使用图像编辑器。这是我第一次遇到它，我仍然没有完全了解数据绑定和datacontext或mvvm。我有一个旋转方法，我希望能够将角度值从我的MainPage.xaml上的文本框传递给方法。我的初始值设置为90，当我单击它时，我的函数将图像旋转90度。文本框在运行时为空，显然也没有更新我的旋转角度。

MainPage.xaml中

<Grid DataContext="{Binding Path=Project}" Height="70" Name="grid1" Width="200">
   <Grid.RowDefinitions>
      <RowDefinition Height="35" />
      <RowDefinition Height="35" />
   </Grid.RowDefinitions>
   <Grid.ColumnDefinitions>
      <ColumnDefinition Width="84*" />
      <ColumnDefinition Width="57*" />
      <ColumnDefinition Width="59*" /> 
   </Grid.ColumnDefinitions>

<Button Command="{Binding Path=RotateCWElementCommand}"
      Height="30" Name="btnRotCW" Width="30" Grid.Column="2" Margin="15,0,14,5" Grid.Row="1">
<Image Source="../Assets/Images/Icons/object-rotate-right.png" Grid.Column="1"
      Grid.Row="4" Height="20" HorizontalAlignment="Left" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="20" />
</Button>

<TextBlock FontWeight="Bold" HorizontalAlignment="Left" Margin="10,10,0,8" Text="Rotate" VerticalAlignment="Center" />
<TextBlock FontWeight="Bold" HorizontalAlignment="Left" Margin="34,9,0,10" Text="Angle:" VerticalAlignment="Center" Grid.Row="1" />
<TextBox Text="{Binding Path=RotateElement.Angle, Mode=TwoWay}" Height="24" Name="textBox1" Width="52" Grid.Column="1" Margin="0,6,5,5" Grid.Row="1" />
</Grid>

（相关代码） Project.cs -

namespace ImageEditor.Client.BLL
{
public class Project : INotifyPropertyChanged
{

            #region Properties
            private RotateTransform rotateElement;
      public RotateTransform RotateElement
      {
        get { return rotateElement; }
        set
        {
            rotateElement = value;
            NotifyPropertyChanged("RotateElement");

        }
    }

        #endregion
    #region Methods


    private void RotateCWElement(object param)
    {
        FrameworkElement element = this.SelectedElement;
        RotateTransform RotateElement = new RotateTransform();

        RotateElement.Angle = 90;
        RotateElement.CenterX = element.ActualWidth * 0.5;
        RotateElement.CenterY = element.ActualHeight * 0.5;
        element.RenderTransform = RotateElement;


    }

我在这里做错了什么？是我的datacontext还是我的绑定路径是问题？它们应该是什么？格式化有点遗憾

Answer 1

用户界面不知道对象中的属性已更改，因为您只会在对象发生更改时通知，而不会通知其中的属性：

 private void RotateCWElement(object param) 
 { 
        FrameworkElement element = this.SelectedElement; 
        if (this.RotateElement == null) this.RotateElement = new RotateTransform(); 

        RotateElement.Angle = 90; 
        RotateElement.CenterX = element.ActualWidth * 0.5; 
        RotateElement.CenterY = element.ActualHeight * 0.5; 
        element.RenderTransform = RotateElement; 

        //tell the UI that this property has changed
        NotifyPropertyChanged("RotateElement"); 
 }

Silverlight - 我的datacontext / binding路径需要在这里？

1 个答案: