WPF - 使用鼠标事件在画布上绘图

Question

我在画布上处理鼠标事件时遇到问题.我想用鼠标绘制它,我想出了这些事件处理程序,但是当我开始绘图时它们什么都不做.

    private void paintSurface_MouseDown(object sender, MouseButtonEventArgs e)
    {
        if (e.ButtonState == MouseButtonState.Pressed)
            currentPoint = e.GetPosition(this);
    }

    private void paintSurface_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.LeftButton == MouseButtonState.Pressed)
        {
            Line line = new Line();

            line.Stroke = SystemColors.WindowFrameBrush;
            line.X1 = currentPoint.X;
            line.Y1 = currentPoint.Y;
            line.X2 = e.GetPosition(this).X;
            line.Y2 = e.GetPosition(this).Y;

            currentPoint = e.GetPosition(this);

            paintSurface.Children.Add(line);
        }
    }

你能告诉我什么缺失或者如何重写它以帮助我开始工作吗？

Answer 1

我愿意打赌你的画布没有接收鼠标事件,因为它的background属性被设置为透明

这对我来说很好.

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Canvas  Name="paintSurface" MouseDown="Canvas_MouseDown_1" MouseMove="Canvas_MouseMove_1" >
        <Canvas.Background>
            <SolidColorBrush Color="White" Opacity="0"/>
        </Canvas.Background>
    </Canvas>
</Window>


using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;
using System.Windows.Shapes;

namespace WpfApplication1
{
    public partial class MainWindow : Window
    {

        Point currentPoint = new Point();

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Canvas_MouseDown_1(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            if (e.ButtonState == MouseButtonState.Pressed)
                currentPoint = e.GetPosition(this);
        }

        private void Canvas_MouseMove_1(object sender, System.Windows.Input.MouseEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                Line line = new Line();

                line.Stroke = SystemColors.WindowFrameBrush;
                line.X1 = currentPoint.X;
                line.Y1 = currentPoint.Y;
                line.X2 = e.GetPosition(this).X;
                line.Y2 = e.GetPosition(this).Y;

                currentPoint = e.GetPosition(this);

                paintSurface.Children.Add(line);
            }
        }

    }
}

Answer 2

简单使用 InkCanvas

 <InkCanvas x:Name="InkCanvas" x:FieldModifier="public" Background="Transparent" Opacity="1" EditingMode="GestureOnly" ForceCursor="True" Cursor="Pen" >
                            <InkCanvas.DefaultDrawingAttributes>
                                <DrawingAttributes Color="White" Width="7" Height="7" />
                            </InkCanvas.DefaultDrawingAttributes>
                        </InkCanvas>