在Canvas上根據變量改變Shape的位置

昨晚有朋友問：

引用

Hi，幫我講解一下WPF怎樣在Canvas或者Grid上根據變量改變 Shape的位置和形狀吧～

沒太理解問題在哪裡，不過看樣子是數據綁定方面不熟悉？

那 就寫個用到Canvas和數據綁定的例子吧。在VS2008裡新建一個WPF應用，然後把下面的Window1.xaml和 Window1.xaml.cs替換進去就行。

做出來的是像這樣的一個界面（是很丑啦 T T）

把Window裡 的根容器Grid分成上下兩行：上半部分放置用於控制和顯示坐標的控件；下半部分放置一個Canvas，裡 面放一個Rectangle。在TextBox裡輸入數字或者滑動ScrollBar都能夠改變Rectangle的位置。

也 就是隨便在VS2008的WPF Designer裡拖拖控件把界面拉出來：

Window1.xaml

Xml代碼

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Class="TestWpfCanvasShapeDataBinding.Window1"
    xmlns:Custom="http://schemas.microsoft.com/winfx/2006/xaml/composite-font"
    Title="Test Data Binding" Height="480" Width="230" >
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <TextBox Name="txtX" Margin="12,10,0,0" 

Height="23" Width="95"
                 VerticalAlignment="Top" HorizontalAlignment="Left"
                 Text="{Binding Path=RectX, Mode=TwoWay, 

UpdateSourceTrigger=PropertyChanged}" />
        <Label Name="lblX" Margin="12,40,0,0" Height="23" 

Width="95"
               VerticalAlignment="Top" HorizontalAlignment="Left"
               Content="{Binding Path=RectX}" />
        <Button Name="btnX" Margin="0,10,5,0" Height="23" 

Width="81"
                VerticalAlignment="Top" HorizontalAlignment="Right"
                Click="button1_Click" >
                Check X Value
        </Button>
        <ScrollBar Name="scbX" Margin="12,70,5,0" 

Height="20" Width="181"
                   VerticalAlignment="Top" Orientation="Horizontal"
                   Maximum="200" Value="{Binding Path=RectX, Mode=TwoWay}

" />
        
        <TextBox Name="txtY" Margin="12,120,0,0" 

Height="23" Width="95"
                 VerticalAlignment="Top" HorizontalAlignment="Left"
                 Text="{Binding Path=RectY, Mode=TwoWay, 

UpdateSourceTrigger=PropertyChanged}" />
        <Label Name="lblY" Margin="12,150,0,0" Height="23" 

Width="95"
               VerticalAlignment="Top" HorizontalAlignment="Left"
               Content="{Binding Path=RectY}" />
        <Button Name="btnY" Margin="0,120,5,0" Height="23" 

Width="81"
                VerticalAlignment="Top" HorizontalAlignment="Right"
                Click="button2_Click" >
                Check Y Value
        </Button>    
        <ScrollBar Name="scbY" Margin="12,180,5,0" 

Height="20" Width="181"
                   VerticalAlignment="Top" Orientation="Horizontal"
                   Value="{Binding Path=RectY, Mode=TwoWay}" 

Maximum="200" />
        
        <Canvas Margin="0,0,0,0" Grid.Row="1" >
            <Canvas.Background>
              <Custom:LinearGradientBrush EndPoint="1,0.5" 

StartPoint="0,0.5" >
                      <Custom:GradientStop Color="#FF337496" 

Offset="0" />
                      <Custom:GradientStop Color="#FF94E2EC" 

Offset="1" />
              </Custom:LinearGradientBrush>
            </Canvas.Background>
            <Rectangle Height="20" Width="20" 

Stroke="#FF301A87" Fill="#FF8169E6"
                       Canvas.Left="{Binding Path=RectX}"
                       Canvas.Top="{Binding Path=RectY}" />
        </Canvas>
    </Grid>
</Window>