get the shape after applying geometry

Question

hi i have applied a render tranform to a System.Windows.Shapes.Line and i don't know how to get line X1, Y1, X2, Y2 after transform.
any help will be appreciated,
thanks in advance.

Answer 1

Hi, code in C#.NET:

    using System;
    using System.ComponentModel;
    using System.Runtime.CompilerServices;
    using System.Windows;
    using System.Windows.Input;
    using System.Windows.Interactivity;
    using System.Windows.Media;
    using System.Windows.Shapes;

    namespace WpfApp1
    {

    namespace WpfApp036
    {
      public class ViewModel : INotifyPropertyChanged
      {
        internal Line MyLine { get; set; }
        public double Angle { get; set; } = -10;
        public Point Point1 { get; set; }
        public Point Point2 { get; set; }
        public ICommand Cmd { get => new RelayCommand(CmdExec); }

        internal void CmdExec(object obj)
        {
          if (MyLine == null) return;
          Angle += 10;
          OnPropertyChanged(nameof(Angle));
          MyLine.LayoutTransform = new RotateTransform(Angle);
          var TransMatrix = MyLine.LayoutTransform.Value;
          Point1 = TransMatrix.Transform(new Point(MyLine.X1, MyLine.Y1));
          OnPropertyChanged(nameof(Point1));
          Point2 = TransMatrix.Transform(new Point(MyLine.X2, MyLine.Y2));
          OnPropertyChanged(nameof(Point2));
        }

        #region PropertyChanged
        public event PropertyChangedEventHandler PropertyChanged;
        internal void OnPropertyChanged([CallerMemberName] string propName = "") =>
         PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));
        #endregion
      }

      public class LineBehavior : Behavior<Line>
      {
        protected override void OnAttached()
        {
          var vm = AssociatedObject.DataContext as ViewModel;
          vm.MyLine = AssociatedObject;
          vm.CmdExec(null);
        }
      }
      public class RelayCommand : ICommand
      {
        private readonly Predicate<object> _canExecute;
        private readonly Action<object> _action;
        public RelayCommand(Action<object> action) { _action = action; _canExecute = null; }
        public RelayCommand(Action<object> action, Predicate<object> canExecute) { _action = action; _canExecute = canExecute; }
        public void Execute(object o) => _action(o);
        public bool CanExecute(object o) => _canExecute == null ? true : _canExecute(o);
        public event EventHandler CanExecuteChanged
        {
          add { CommandManager.RequerySuggested += value; }
          remove { CommandManager.RequerySuggested -= value; }
        }
      }
    }
}

Answer 2

Hi, you can catch reference to line and use transformation matrix. Try following demo:

<Window x:Class="Window036"  
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"  
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"  
        xmlns:local="clr-namespace:WpfApp1.WpfApp036"  
        xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"  
        mc:Ignorable="d"  
        Title="Window036" Height="450" Width="800">  
  <Window.DataContext>  
    <local:ViewModel/>  
  </Window.DataContext>  
  <Canvas>  
    <StackPanel Orientation="Horizontal">  
      <Button Content="Transform"  Command="{Binding Cmd}"/>  
      <StackPanel>  
        <StackPanel Orientation="Horizontal">  
          <Label Content="Angle:"/>  
          <Label Content="{Binding Angle}"/>  
        </StackPanel>  
        <StackPanel Orientation="Horizontal">  
          <Label Content="Point 1 X:"/>  
          <Label Content="{Binding Point1.X}"/>  
        </StackPanel>  
        <StackPanel Orientation="Horizontal">  
          <Label Content="Point 1 Y:"/>  
          <Label Content="{Binding  Point1.Y}"/>  
        </StackPanel>  
        <StackPanel Orientation="Horizontal">  
          <Label Content="Point 2 X:"/>  
          <Label Content="{Binding  Point2.X}"/>  
        </StackPanel>  
        <StackPanel Orientation="Horizontal">  
          <Label Content="Point 2 Y:"/>  
          <Label Content="{Binding  Point2.Y}"/>  
        </StackPanel>  
      </StackPanel>  
    </StackPanel>  
    <Line X1="230" X2="400" Y1="50" Y2="80" StrokeThickness="3" Stroke="Red">  
      <i:Interaction.Behaviors>  
        <local:LineBehavior/>  
      </i:Interaction.Behaviors>  
    </Line>  
  </Canvas>  
</Window>  

-----------------------------------------------------------------

Imports System.ComponentModel  
Imports System.Runtime.CompilerServices  
Imports System.Windows.Interactivity  
  
Namespace WpfApp036  
  
  Public Class ViewModel  
    Implements INotifyPropertyChanged  
    Friend Property MyLine As Line  
    Public Property Angle As Double = -10  
    Public Property Point1 As Point  
    Public Property Point2 As Point  
    Public ReadOnly Property Cmd As ICommand = New RelayCommand(AddressOf CmdExec)  
  
    Friend Sub CmdExec(obj As Object)  
      If MyLine Is Nothing Then Exit Sub  
      Angle += 10  
      OnPropChanged(NameOf(Angle))  
      MyLine.LayoutTransform = New RotateTransform(Angle)  
      Dim TransMatrix = MyLine.LayoutTransform.Value  
      Point1 = TransMatrix.Transform(New Point(MyLine.X1, MyLine.Y1))  
      OnPropChanged(NameOf(Point1))  
      Point2 = TransMatrix.Transform(New Point(MyLine.X2, MyLine.Y2))  
      OnPropChanged(NameOf(Point2))  
    End Sub  
  
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged  
    Friend Sub OnPropChanged(<CallerMemberName> Optional propName As String = "")  
      RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propName))  
    End Sub  
  End Class  
  
  Public Class LineBehavior  
    Inherits Behavior(Of Line)  
    Protected Overrides Sub OnAttached()  
      Dim vm = TryCast(AssociatedObject.DataContext, ViewModel)  
      vm.MyLine = AssociatedObject  
      vm.CmdExec(Nothing)  
    End Sub  
  End Class  
  
End Namespace