wpf ellipse rotatetransform mousedown mousemove mouseup vector

<Window x:Class="WpfApp148.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:WpfApp148"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Ellipse x:Name="elp"
                 Width="500"
                 Height="500"                 
                 RenderTransformOrigin="0.5,0.5">
            <Ellipse.RenderTransform>
                <RotateTransform x:Name="rotateTransform" />
            </Ellipse.RenderTransform>
            <Ellipse.Fill>
                <LinearGradientBrush StartPoint="0,0"
                                     EndPoint="0,1">
                    <GradientStop Color="Cyan" Offset="0.0"/>
                    <GradientStop Color="Cyan" Offset="0.2"/>
                    <GradientStop Color="Orange" Offset="0.2"/>
                    <GradientStop Color="Orange" Offset="0.4"/>
                    <GradientStop Color="Yellow" Offset="0.4"/>
                    <GradientStop Color="Yellow" Offset="0.49"/>
                    <GradientStop Color="Red" Offset="0.49"/>
                    <GradientStop Color="Red" Offset="0.51"/>
                    <GradientStop Color="Yellow" Offset="0.51"/>
                    <GradientStop Color="Yellow" Offset="0.6"/>
                    <GradientStop Color="Green" Offset="0.6"/>
                    <GradientStop Color="Green" Offset="0.8"/>
                    <GradientStop Color="Blue" Offset="0.8"/>
                    <GradientStop Color="Blue" Offset="1.0"/>
                </LinearGradientBrush>
            </Ellipse.Fill>
        </Ellipse>
    </Grid>
</Window>





//cs
using System;
using System.Collections.Generic;
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 WpfApp148
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private bool isDragging = false;
        private Point startPoint;

        public MainWindow()
        {
            InitializeComponent(); 
            elp.MouseDown += elp_MouseDown;
            elp.MouseMove += elp_MouseMove;
            elp.MouseUp += elp_MouseUp;
        }

        private void elp_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                isDragging = true;
                startPoint = e.GetPosition(this);
                elp.CaptureMouse();
            }
        }

        private void elp_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDragging && e.LeftButton == MouseButtonState.Pressed)
            {
                Point currentPoint = e.GetPosition(this);

                // 创建起始向量和当前向量
                Vector startVector = Point.Subtract(startPoint, new Point(elp.RenderTransformOrigin.X * elp.ActualWidth + elp.Margin.Left, elp.RenderTransformOrigin.Y * elp.ActualHeight + elp.Margin.Top));
                Vector currentVector = Point.Subtract(currentPoint, new Point(elp.RenderTransformOrigin.X * elp.ActualWidth + elp.Margin.Left, elp.RenderTransformOrigin.Y * elp.ActualHeight + elp.Margin.Top));

                // 计算两个向量之间的夹角
                double angle = Vector.AngleBetween(startVector, currentVector);

                // 根据向量叉积判断旋转方向
                double crossProduct = startVector.X * currentVector.Y - startVector.Y * currentVector.X;
                if (crossProduct < 0)
                {
                    //angle = -angle;
                }

                var newAngle = rotateTransform.Angle + angle;
                if(newAngle>1080)
                {
                    newAngle -= 1080;
                }
                else if(newAngle<-360)
                {
                    newAngle = -360;
                }

                // 更新旋转变换的角度
                rotateTransform.Angle =newAngle;
                this.Title = rotateTransform.Angle.ToString("N2");
                startPoint = currentPoint;
            }
        }

        private void elp_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Released)
            {
                isDragging = false;
                elp.ReleaseMouseCapture();
            }
        }
    }
}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

//xaml
<Window x:Class="WpfApp148.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:WpfApp148"
        WindowState="Maximized"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Ellipse x:Name="elp"
                 Width="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"
                 Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"                 
                 RenderTransformOrigin="0.5,0.5">
            <Ellipse.RenderTransform>
                <RotateTransform x:Name="rotateTransform" />
            </Ellipse.RenderTransform>
            <Ellipse.Fill>
                <LinearGradientBrush StartPoint="0,0"
                                     EndPoint="0,1">
                    <GradientStop Color="Cyan" Offset="0.0"/>
                    <GradientStop Color="Cyan" Offset="0.2"/>
                    <GradientStop Color="Orange" Offset="0.2"/>
                    <GradientStop Color="Orange" Offset="0.4"/>
                    <GradientStop Color="Yellow" Offset="0.4"/>
                    <GradientStop Color="Yellow" Offset="0.49"/>
                    <GradientStop Color="Red" Offset="0.49"/>
                    <GradientStop Color="Red" Offset="0.51"/>
                    <GradientStop Color="Yellow" Offset="0.51"/>
                    <GradientStop Color="Yellow" Offset="0.6"/>
                    <GradientStop Color="Green" Offset="0.6"/>
                    <GradientStop Color="Green" Offset="0.8"/>
                    <GradientStop Color="Blue" Offset="0.8"/>
                    <GradientStop Color="Blue" Offset="1.0"/>
                </LinearGradientBrush>
            </Ellipse.Fill>
        </Ellipse>
    </Grid>
</Window>

//cs
using System;
using System.Collections.Generic;
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 WpfApp148
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private bool isDragging = false;
        private Point startPoint;

        public MainWindow()
        {
            InitializeComponent(); 
            elp.MouseDown += elp_MouseDown;
            elp.MouseMove += elp_MouseMove;
            elp.MouseUp += elp_MouseUp;
        }

        private void elp_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                isDragging = true;
                startPoint = e.GetPosition(this);
                elp.CaptureMouse();
            }
        }

        private void elp_MouseMove(object sender, MouseEventArgs e)
        {
            if (isDragging && e.LeftButton == MouseButtonState.Pressed)
            {
                Point currentPoint = e.GetPosition(this);

                // 创建起始向量和当前向量
                Vector startVector = Point.Subtract(startPoint, new Point(elp.RenderTransformOrigin.X * elp.ActualWidth + elp.Margin.Left, elp.RenderTransformOrigin.Y * elp.ActualHeight + elp.Margin.Top));
                Vector currentVector = Point.Subtract(currentPoint, new Point(elp.RenderTransformOrigin.X * elp.ActualWidth + elp.Margin.Left, elp.RenderTransformOrigin.Y * elp.ActualHeight + elp.Margin.Top));

                //Vector startVector = Point.Subtract(startPoint, new Point(elp.RenderTransformOrigin.X * elp.ActualWidth, elp.RenderTransformOrigin.Y * elp.ActualHeight));
                //Vector currentVector = Point.Subtract(currentPoint, new Point(elp.RenderTransformOrigin.X * elp.ActualWidth, elp.RenderTransformOrigin.Y * elp.ActualHeight));

                // 计算两个向量之间的夹角
                double angle = Vector.AngleBetween(startVector, currentVector);

                // 根据向量叉积判断旋转方向
                double crossProduct = startVector.X * currentVector.Y - startVector.Y * currentVector.X;
                if (crossProduct < 0)
                {
                    //angle = -angle;
                }

                var newAngle = rotateTransform.Angle + angle;
                if(newAngle>1080)
                {
                    newAngle -= 1080;
                }
                else if(newAngle<-360)
                {
                    newAngle = -360;
                }

                // 更新旋转变换的角度
                rotateTransform.Angle =newAngle;
                this.Title = rotateTransform.Angle.ToString("N2");
                startPoint = currentPoint;
            }
        }

        private void elp_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Released)
            {
                isDragging = false;
                elp.ReleaseMouseCapture();
            }
        }
    }
}