如何在C＃中用鼠标画线

Question

我目前正在尝试以Visual Studio WPF形式制作一个pragram，它可以像在绘画中那样使用鼠标来绘制线条。 目前它正在绘制相同的旧线并继续绘制它，但是我想每次按鼠标左键时都绘制一条新线。 这是MainWindows.xaml.cs代码及其外观：

namespace DrawingLines
{

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private PathFigure _pathFigure = new PathFigure();
    PathFigureCollection _pathCollection = new PathFigureCollection();
    PathSegmentCollection _segments = new PathSegmentCollection();
    private PathGeometry _pathGeometry = new PathGeometry();

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        _pathFigure.Segments = _segments;
        _pathCollection.Add(_pathFigure);
        _pathGeometry.Figures = _pathCollection;
        myPath.Data = _pathGeometry;
    }

    private void Window_MouseMove(object sender, MouseEventArgs e)
    {
        if (e.LeftButton == MouseButtonState.Pressed)
        {
            LineSegment segment = new LineSegment();
            segment.Point = e.GetPosition(this);
            _pathFigure.Segments.Add(segment);
        }

    }

    private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        _pathFigure.StartPoint = e.GetPosition(this);
    }

    //private void Window_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
    //{

    //}

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        this.Close();

    }
}

}

这是MainWindow.xmal代码：

<Window x:Class="DrawingLines.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Joonistamine" Height="350" Width="525" Loaded="Window_Loaded" MouseMove="Window_MouseMove" MouseLeftButtonDown="Window_MouseLeftButtonDown" MouseRightButtonDown="Window_MouseRightButtonDown">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="53*" />
        <RowDefinition Height="258*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="124*" />
        <ColumnDefinition Width="379*" />
    </Grid.ColumnDefinitions>
    <Path Stroke="Black" StrokeThickness="1" Name="myPath" Grid.ColumnSpan="2" Grid.RowSpan="2" />
    <Button Content="Exit" Height="25" HorizontalAlignment="Left" Name="button1" VerticalAlignment="Top" Width="46" Click="button1_Click" BorderBrush="Red" Foreground="#FFFF1A1A" />
</Grid>

我究竟做错了什么？

Answer 1

在我看来，您是不断添加到PathSegment的过程，而在您开始新行时不会清除它（通过单击鼠标左键）。 因此，我会尝试这样做：

private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    _pathFigure.Segments.Clear();
    _pathFigure.StartPoint = e.GetPosition(this);
}

编辑：...，如果您希望它保留线并且它们不一定是连接的，则您需要为每条线使用单独的路径，因为每个路径都代表一个单独的连接形状。

为此，您需要以这种方式修改代码：

• 从您的XAML中删除路径
• 对于每个鼠标左键单击，创建一个新的Path并将其添加到网格（myGrid.Children.Add（myPath）
• 从鼠标移动到当前活动路径添加新点