Question

任务：我有一个简单的任务：在椭圆的中心周围的椭圆内移动针。它将成为角度指示器/控制器。

状态：

当左侧按钮在椭圆内部向下时，我想根据鼠标位置移动此针。

这没关系。

如果释放鼠标左键，我想停止移动。

没关系。

我的问题：

但问题是如果我用鼠标左键退出椭圆区域（即偶然地移动针头），那么它就是“保持”。如果您在鼠标左键向上的情况下返回椭圆，则针将像点击一样移动。所以我需要的是当我的鼠标离开椭圆时禁用“拖动”，无论鼠标左键是否被点击。此时，如果针被“锁定”，则需要进入椭圆外部，单击鼠标左键，并通过输入椭圆区域按住它。如果您现在释放鼠标左键，它将恢复正常/想要的行为。

这是我的XAML“代码”：

<Window x:Class="test_gauge.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">
    <Grid MouseLeftButtonUp="Grid_MouseLeftButtonUp">
        <Ellipse Name="ellipse1" Fill="#FFF4F4F5" HorizontalAlignment="Left" Height="100" Stroke="Black" VerticalAlignment="Top" Width="100" Canvas.Left="0" Canvas.Top="0" Margin="280,180,0,0" MouseMove="onEllipseMouseMove" MouseLeftButtonDown="onEllipseMouseLeftPressed" MouseLeftButtonUp="onEllipseMouseLeftReleased" MouseLeave="onEllipseMouseLeave"/>
        <Canvas Margin="257,145,10,10" MouseLeftButtonUp="Canvas_MouseLeftButtonUp_1">
            <Thumb Name="myThumb" Canvas.Left="73" Canvas.Top="85" RenderTransformOrigin="0,0">
                <Thumb.RenderTransform>
                    <RotateTransform/>
                </Thumb.RenderTransform>
                <Thumb.Template>
                    <ControlTemplate>
                        <Line Name="needle_line" X1="0" Y1="0" X2="50" Y2="0" StrokeThickness="2" Stroke="Black" MouseLeave="needle_line_MouseLeave"/>
                    </ControlTemplate>
                </Thumb.Template>
            </Thumb>
            <TextBox Name="txtbxAngle" Height="23" Canvas.Left="168" TextWrapping="Wrap" Text="TextBox" Canvas.Top="25" Width="72"/>
        </Canvas>
    </Grid>
</Window>

然后是C＃“代码”：

public partial class MainWindow : Window
{
    /* Angle control stuff */
    public bool bNeedlePressed = false;
    public double refreshedAngle = 0;

    public MainWindow()
    {
        InitializeComponent();
    }

    private void onEllipseMouseMove(object sender, MouseEventArgs e)
    {
        if (bNeedlePressed)
        {
            // This will get the mouse cursor relative to the upper left corner of your ellipse.
            // Note that nothing will happen until you are actually inside of your ellipse.
            Point curPoint = e.GetPosition(ellipse1);

            // Assuming that your ellipse is actually a circle.
            Point center = new Point(ellipse1.Width / 2, ellipse1.Height / 2);

            // A bit of math to relate your mouse to the center...
            Point relPoint = new Point(curPoint.X - center.X, curPoint.Y - center.Y);

            /* Process new angle */
            refreshedAngle = Math.Atan2(relPoint.Y, relPoint.X) * 180 / Math.PI;
            txtbxAngle.Text = ((int)(refreshedAngle)).ToString();

            /* Apply new angle */
            var transform = myThumb.RenderTransform as RotateTransform;
            transform.Angle = refreshedAngle;
        }
    }

    private void onEllipseMouseLeftPressed(object sender, MouseButtonEventArgs e)
    {
        bNeedlePressed = true;
    }
    private void Canvas_MouseLeftButtonUp_1(object sender, MouseButtonEventArgs e)
    {
        bNeedlePressed = false;
    }

    private void onEllipseMouseLeftReleased(object sender, MouseButtonEventArgs e)
    {
        bNeedlePressed = false;
    }

    private void onEllipseMouseLeave(object sender, MouseEventArgs e)
    {
        //bNeedlePressed = false;
    }

    private void needle_line_MouseLeave(object sender, MouseEventArgs e)
    {
        //bNeedlePressed = false;
    }

    private void Grid_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        bNeedlePressed = false;
    }
}

正如您所看到的，它使用不同的事件，但没有一个可以做到。嗯，我相信至少有一个，但我不知道哪一个。

如果您有任何想法，请随时回答：）

Answer 1

您可以管理鼠标离开事件

    private void Grid_MouseLeave(object sender, MouseEventArgs e)
    {
        bNeedlePressed = false;
    }

在XAML中声明

<Grid MouseLeftButtonUp="Grid_MouseLeftButtonUp" MouseLeave="Grid_MouseLeave" MouseEnter="Grid_MouseEnter">

鼠标进入

    private void Grid_MouseEnter(object sender, MouseEventArgs e)
    {
        bNeedlePressed = e.LeftButton == MouseButtonState.Pressed;
    }

鼠标左键按钮在需要时不会被触发

1 个答案: