线条如何从画布中检测并在 WPF 中删除 [关闭]

Question

我在Canvas 中有很多行。我只想检测哪一行被点击，并想从 WPF 中Canvas 的子级删除它？任何解决方案 谢谢。

Answer 1

首先，您需要为您的画布添加一个 MouseLeftButtonDown 事件，并为您的 WPF 添加一个 KeyDown 事件。

    public MainWindow()
    {
        InitializeComponent();
        MyCanvas.MouseLeftButtonDown += MyCanvas_MouseLeftButtonDown;
        this.KeyDown += MainWindow_KeyDown;
    }

当您的鼠标左键单击其中一行时，它应该突出显示所选内容。当它点击其他东西时，它应该取消突出显示之前的选择。

    private Line _selectedLine;
    private void MyCanvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        object testPanelOrUi = InputHitTest(e.GetPosition(this)) as FrameworkElement;

        // if the selection equals _selectedLine, i.e. the line has been selected already
        if (Equals(testPanelOrUi, _selectedLine)) return;

        // The selection is different.
        // if _selectedLine is not null, revert color change.
        if (_selectedLine != null)
        {
            UnHighlightSelection();
        }

        // if testPanelOrUi is not a line.
        if (!(testPanelOrUi is Line)) return;

        // The selection is different and is a line.
        _selectedLine = (Line) testPanelOrUi;
        HighlightSelection(_selectedLine);
    }

您的HighlightSelection() 和UnHighlightSelection() 可能类似于以下内容：

    private void HighlightSelection(Line selectedob)
    {
        selectedob.Stroke = Brushes.Red;
    }

    private void UnHighlightSelection()
    {
        //if nothing has been selected yet.
        if (_selectedLine == null) return;

        _selectedLine.Stroke = Brushes.Black;
        _selectedLine = null;
    }

然后您可以定义您的Delete 和KeyDown 操作。当按下 Delete 键时，选择应该被删除。

    private void MainWindow_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Delete)
        {
            DeleteLine();
        }
    }

    public void DeleteLine()
    {
        //if nothing has been selected yet.
        if (_selectedLine == null) return;

        //if the selection has been deleted.
        if (!MyCanvas.Children.Contains(_selectedLine)) return;

        UnHighlightSelection();
        MyCanvas.Children.Remove(_selectedLine);
    }