WPF Binding to RotateTransform.Angle does not work

Question

I am trying to make a simple app where I bounce an image around the screen and rotate it. I want the rotation speed to be dynamic and change whenever the image hits one of the sides of the containing window. So, I was trying to figure out how to dynamically change the speed of the rotation and perhaps even the direction. I am experimenting with passing in a speed value and dynamically changing the rotation with an animation.

Anyway, I am trying to just test the ability to dynamically change the rotation by animating the AngleProperty and binding to the Angle in the XAML. I must be doing something wrong, because the image won't rotate.

Any help with this would be GREATLY appreciated !!

Thanks, Curtis

Here is my XAML:

<UserControl x:Class="Scooter.Bug"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             DataContext="{Binding RelativeSource={RelativeSource Self}}"
             Loaded="Bug_OnLoaded"
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
        <Image x:Name="_image" Source="Images/Author.png" RenderTransformOrigin="0.5, 0.5">
        <Image.RenderTransform>
            <RotateTransform Angle="{Binding Angle}"/>
        </Image.RenderTransform>    
        </Image>
    </Grid>
</UserControl>

Here is my code-behind:

using System;
using System.Windows;
using System.Windows.Media.Animation;

namespace Scooter
{
    public partial class Bug
    {
        public static readonly DependencyProperty SpinSpeedProperty = DependencyProperty.Register("SpinSpeed", typeof (TimeSpan), typeof (Bug), new PropertyMetadata(default(TimeSpan)));
        public static readonly DependencyProperty AngleProperty = DependencyProperty.Register("Angle", typeof (double), typeof (Bug), new PropertyMetadata(default(double)));

        public Bug()
        {
            InitializeComponent();
        }

        void _timer_Tick(object sender, EventArgs e)
        {
            Angle = Angle >= 360 ? 0 : Angle + 1;
        }

        public TimeSpan SpinSpeed
        {
            get { return (TimeSpan) GetValue(SpinSpeedProperty); }
            set { SetValue(SpinSpeedProperty, value); }
        }

        public double Angle
        {
            get { return (double) GetValue(AngleProperty); }
            set { SetValue(AngleProperty, value); }
        }

        private void Bug_OnLoaded(object sender, RoutedEventArgs e)
        {
            DoubleAnimation animation = new DoubleAnimation
            {
                From = 0,
                To = 360,
                RepeatBehavior = RepeatBehavior.Forever,
                Duration = SpinSpeed
            };

            _image.BeginAnimation(AngleProperty, animation);
        }
    }
}

Answer 1

You're calling BeginAnimation() on the Image, but using AngleProperty from Bug.

You could either use BeginAnimation() on the RotateTransform

_image.RenderTransform.BeginAnimation(RotateTransform.AngleProperty, animation);

or call BeginAnimation() on your control:

this.BeginAnimation(AngleProperty, animation);