WPF LinearGradientBrush StartPoint EndPoint GradientStop Offset Color

<Window x:Class="WpfApp144.MainWindow"
        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:WpfApp144"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.Resources>
        <local:SizeConverter x:Key="sizeConverter"/>
    </Window.Resources>
    <Grid>
        <Ellipse x:Name="RotatableEllipse" 
                 Width="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,
                       AncestorType={x:Type Window}},Converter={StaticResource sizeConverter},ConverterParameter=1.2}"
                 Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,
                       AncestorType={x:Type Window}},Converter={StaticResource sizeConverter},ConverterParameter=1.2}"
                 Stroke="Black" 
                 StrokeThickness="2"
                 RenderTransformOrigin="0.5,0.5"
                 MouseDown="Ellipse_MouseDown"
                 MouseMove="Ellipse_MouseMove"
                 MouseUp="Ellipse_MouseUp">
            <Ellipse.Fill>
                <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
                    <GradientStop Offset="0.0" Color="Blue"/>
                    <GradientStop Offset="0.2" Color="Blue"/>
                    <GradientStop Offset="0.2" Color="Orange"/>
                    <GradientStop Offset="0.4" Color="Orange"/>
                    <GradientStop Offset="0.4" Color="Yellow"/>
                    <GradientStop Offset="0.49" Color="Yellow"/>
                    <GradientStop Offset="0.49" Color="Red"/>
                    <GradientStop Offset="0.51" Color="Red"/>
                    <GradientStop Offset="0.51" Color="Yellow"/>
                    <GradientStop Offset="0.6" Color="Yellow"/>
                    <GradientStop Offset="0.6" Color="Green"/>
                    <GradientStop Offset="0.8" Color="Green"/>
                    <GradientStop Offset="0.8" Color="Cyan"/>
                    <GradientStop Offset="1.0" Color="Cyan"/>
                </LinearGradientBrush>
            </Ellipse.Fill>
            <Ellipse.RenderTransform>
                <RotateTransform x:Name="EllipseRotateTransform" Angle="0" />
            </Ellipse.RenderTransform>
        </Ellipse>
    </Grid>
</Window>

 

 

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp144
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private bool isRotating = false;
        private Point startPoint;

        public MainWindow()
        {
            InitializeComponent();
            this.Title = EllipseRotateTransform.Angle.ToString("N2");
        }

        private void Ellipse_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                isRotating = true;
                startPoint = e.GetPosition(RotatableEllipse);
                RotatableEllipse.CaptureMouse();
            }
        }

        private void Ellipse_MouseMove(object sender, MouseEventArgs e)
        {
            if (isRotating)
            {
                Point currentPoint = e.GetPosition(RotatableEllipse);
                double deltaX = currentPoint.X - startPoint.X;
                double deltaY = currentPoint.Y - startPoint.Y;

                // Calculate the angle of rotation
                double angle = Math.Atan2(deltaY, deltaX) * 180 / Math.PI;

                // Apply the rotation
                EllipseRotateTransform.Angle = angle;
                this.Title = angle.ToString("N2");
            }
        }

        private void Ellipse_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if (isRotating)
            {
                isRotating = false;
                RotatableEllipse.ReleaseMouseCapture();
            }
        }
    }

    public class SizeConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            double dValue = 0.0, paramValue = 0.0;
            if(double.TryParse(value?.ToString(), out dValue)  && double.TryParse(parameter?.ToString(),out paramValue))
            {
                return dValue / paramValue;
            }
            return 0;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}