如何通过在 wpf 中选择笔划来缩放形状

Question

我是 WPF 新手，我想通过选择笔画来缩放椭圆。我已设置 IsManipulationEnabled=true 但事件未触发。下面是我的代码

 <Path Stretch="Fill" Stroke="Black" ManipulationDelta="Path_ManipulationDelta" 
      IsManipulationEnabled="True" StrokeThickness="4">
        <Path.Data>
            <EllipseGeometry Center="0,0"   RadiusX="200" RadiusY="200"/>
        </Path.Data>
    </Path>

请帮忙。enter image description here

Answer 1

下面是一些可能会给您一些想法的代码：

在此示例中，我使用了一些基本的鼠标事件 MouseDown、MouseMove 和 MouseUp，以便我可以检测用户何时单击 Path，当他们开始拖动鼠标时。

XAML

<Window x:Class="WpfApp4.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApp4"
    Title="MainWindow"
    Width="800"
    Height="450"
    UseLayoutRounding="True">
    <Grid>
        <Canvas x:Name="Canvas">
            <Path x:Name="CirclePath"
                MouseDown="OnMouseDown"
                MouseMove="OnMouseMove"
                MouseUp="OnMouseUp"
                Stretch="Fill"
                Stroke="Black"
                StrokeThickness="4">
                <Path.Data>
                    <EllipseGeometry x:Name="EllipseGeometry"
                        Center="0,0"
                        RadiusX="100"
                        RadiusY="100" />
                </Path.Data>
            </Path>
        </Canvas>
    </Grid>
</Window>

在 OnMouseDown 处理程序中，我检查鼠标左键是否按下，然后捕获鼠标并获取鼠标相对于 Canvas 的位置。

接下来，在 OnMouseMove 处理程序中，如果左键仍然按下 - 用户正在拖动 - 我将获得新的鼠标位置并根据旧鼠标位置计算偏移量。然后我更新 EllipseGeometry 以反映鼠标偏移量。

最后，在 OnMouseUp 处理程序中，我释放鼠标捕获。

代码隐藏

using System.Windows;
using System.Windows.Input;

namespace WpfApp4
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private Point oldMousePosition;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void OnMouseDown(object sender, MouseButtonEventArgs e)
        {
            if(e.ChangedButton != MouseButton.Left) return;
            Mouse.Capture(CirclePath);
            oldMousePosition = e.GetPosition(Canvas);
        }

        private void OnMouseMove(object sender, MouseEventArgs e)
        {
            if (e.LeftButton != MouseButtonState.Pressed) return;

            var newMousePosition = e.GetPosition(Canvas);
            var offset = newMousePosition - oldMousePosition;

            EllipseGeometry.RadiusX += offset.X / 2;
            EllipseGeometry.RadiusY += offset.Y / 2;

            oldMousePosition = newMousePosition;
        }

        private void OnMouseUp(object sender, MouseButtonEventArgs e)
        {
            Mouse.Capture(null);
        }
    }
}

希望对您有所帮助。

Answer 2

XAML
     XAML
<Window x:Class="WidgetWpf.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:WidgetWpf"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">   
    <Viewbox>
        <Grid Name="MainGrid">           

            <Ellipse x:Name="DottedCircle" Width="200" Height="200"  Stroke="White" StrokeThickness="2"   Opacity="0.90" StrokeDashArray="4 4"
                     MouseDown="DottedCircle_MouseDown"
                     MouseMove="DottedCircle_MouseMove"
                     MouseUp="DottedCircle_MouseUp"
                     MouseEnter="DottedCircle_MouseEnter"
                     MouseLeave="DottedCircle_MouseLeave"  
                     />            
        </Grid>    
    </Viewbox>

</Window>
//Here is my code behind 

    public partial class MainWindow : Window
    {
        #region Variables
        MatrixTransform transform;
        Point OldMousePosition;
        Point NewMousePosition;
        double[] Dimensions = new double[2];
        Rect rect = new Rect();
        bool IsResizeMode;
        bool IsDragAndDropMode;

        #endregion
        public MainWindow()
        {
            InitializeComponent();
        }

        private void DottedCircle_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (e.ChangedButton != MouseButton.Left) return;
            Mouse.Capture(DottedCircle);
            OldMousePosition = e.GetPosition(MainGrid);
        }

        private void DottedCircle_MouseMove(object sender, MouseEventArgs e)
        {

            DottedCircle.ToolTip = e.GetPosition(MainGrid);
            if (e.LeftButton != MouseButtonState.Pressed) return;
            var NewMousePosition = e.GetPosition(MainGrid);         
            var offset = NewMousePosition-OldMousePosition;

            #region working by co-ordinate

            //get center of grid

            double dicisionPoint=0.0 ;
            double CP_X = MainGrid.ActualWidth / 2;
            double CP_Y = MainGrid.ActualHeight / 2;

            //1 st co-ordinate
            if(NewMousePosition.X>CP_X && NewMousePosition.Y<CP_Y)
            {
                dicisionPoint = offset.X;
            }
            //2nd cordinate
            else if (NewMousePosition.X < CP_X && NewMousePosition.Y < CP_Y)
            {
                dicisionPoint = -offset.X;
            }
            else if (NewMousePosition.X < CP_X && NewMousePosition.Y > CP_Y)
            {
                dicisionPoint = offset.Y;
            }
            else if (NewMousePosition.X > CP_X && NewMousePosition.Y > CP_Y)
            {
                dicisionPoint = offset.Y;
            }


            if (DottedCircle.Width+ dicisionPoint < InnerCircle.Width)
            {
                DottedCircle.Fill = new SolidColorBrush(Colors.Transparent);
                DottedCircle.Width += dicisionPoint;
                DottedCircle.Height += dicisionPoint;
            }
            else if (DottedCircle.Width+ dicisionPoint>= InnerCircle.Width) { DottedCircle.Fill = new SolidColorBrush(Colors.Red); }
            #endregion



            OldMousePosition = NewMousePosition;
            DottedCircle.ToolTip = offset.X+ "__" + offset.Y;
        }

        private void DottedCircle_MouseUp(object sender, MouseButtonEventArgs e)
        {
            Mouse.Capture(null);
            DottedCircle.Style = null;
        }

        private void DottedCircle_MouseEnter(object sender, MouseEventArgs e)
        {
            DottedCircle.Stroke = new SolidColorBrush( Colors.Blue);
            DottedCircle.Style = (Style)Application.Current.Resources["DiffPathStyle"];
        }

        private void DottedCircle_MouseLeave(object sender, MouseEventArgs e)
        {
            DottedCircle.Stroke = new SolidColorBrush(Colors.White);
            DottedCircle.Style = null;
        }
    }

如何通过在 wpf 中选择笔划来缩放形状

How to scale a shape by selecting its stroke in wpf

wpf

wpf-controls