WPF设置传参、点击按钮改变长度

前台代码

 <!--  通过传递ElementName  -->
 <Button
     x:Name="btn1"
     Width="200"
     Height="27"
     Command="{Binding Command}"
     CommandParameter="{Binding ElementName=btn1}" />

 <!--  通过传递自身  -->
 <Button
     Grid.Row="1"
     Width="200"
     Height="27"
     Command="{Binding Command2}"
     CommandParameter="{Binding RelativeSource={RelativeSource Mode=Self}}" />

 <!--  通过传递Width Width是只读的，这种方法行不通，哪怕设置双向也不行，-->
 <Button
     Grid.Row="2"
     Width="200"
     Height="27"
     Command="{Binding Command3}"
     CommandParameter="{Binding RelativeSource={RelativeSource Self}, Path=Width,UpdateSourceTrigger=PropertyChanged}" />

后台代码

 private DelegateCommand<Button> _Command;
 public DelegateCommand<Button> Command =>
     _Command ?? (_Command = new DelegateCommand<Button>(ExecuteCommand, CanExecuteCommand));

 private void ExecuteCommand(object parameter)
 {
     var btn = parameter as Button;
     btn.Width = 500;
 }

 private DelegateCommand<Button> _Command2;
 public DelegateCommand<Button> Command2 =>
     _Command2 ?? (_Command2 = new DelegateCommand<Button>(ExecuteCommand2));

 private void ExecuteCommand2(object parameter)
 {
     var btn = parameter as Button;
     btn.Width = 500;
 }

 private DelegateCommand<double> _Command3;
 public DelegateCommand<double> Command3 =>
     _Command3 ?? (_Command3 = new DelegateCommand<double>(ExecuteCommand3));

 private void ExecuteCommand3(double parameter)
 {
     Application.Current.Dispatcher.Invoke(() =>
     {
        var width=parameter;
         width = 500;
     });
 }  

 private bool CanExecuteCommand(object parameter)
 {
     return true;
 }

第三种报错，因为Width是只读的，你可以传递一个实体，然后修改实体的属性，但是传递的参数本身应该是只读的，这是我个人的理解，如果能直接传递宽度实现宽度改变的，希望留下代码，一起交流