Shape.MouseDown 事件

项目
09/04/2008

更新：2007 年 11 月

当鼠标指针悬停在形状上且按下鼠标按钮时发生。

命名空间： Microsoft.VisualBasic.PowerPacks
程序集： Microsoft.VisualBasic.PowerPacks.Vs（在 Microsoft.VisualBasic.PowerPacks.Vs.dll 中）

语法

声明
<BrowsableAttribute(True)> _
Public Event MouseDown As MouseEventHandler
用法
Dim instance As Shape
Dim handler As MouseEventHandler

AddHandler instance.MouseDown, handler

[BrowsableAttribute(true)]
public event MouseEventHandler MouseDown

[BrowsableAttribute(true)]
public:
 event MouseEventHandler^ MouseDown {
    void add (MouseEventHandler^ value);
    void remove (MouseEventHandler^ value);
}

JScript 不支持事件。

备注

鼠标事件按以下顺序发生：

MouseEnter

MouseMove

MouseHover / MouseDown / MouseWheel

MouseUp

MouseLeave

有关如何处理事件的更多信息，请参见使用事件。

示例

下面的示例演示如何使用 MouseDown、MouseMove 和 MouseUp 事件在 RectangleShape 控件上绘制线条。此示例要求窗体上有一个名为 RectangleShape2 的 RectangleShape 控件。

Private mousePath = New System.Drawing.Drawing2D.GraphicsPath()

Private Sub RectangleShape2_MouseDown(ByVal sender As Object, _
  ByVal e As System.Windows.Forms.MouseEventArgs) Handles _
  RectangleShape2.MouseDown
    Dim mouseDownLocation As New Point(e.X + RectangleShape2.Left, _
      e.Y + RectangleShape2.Top)
    ' Clear the previous line.
    mousePath.Dispose()
    mousePath = New System.Drawing.Drawing2D.GraphicsPath()
    RectangleShape2.Invalidate()
    ' Add a line to the graphics path.
    mousePath.AddLine(mouseDownLocation, mouseDownLocation)
End Sub

Private Sub RectangleShape2_MouseMove(ByVal sender As Object, _
  ByVal e As System.Windows.Forms.MouseEventArgs) _
  Handles RectangleShape2.MouseMove
    Dim mouseX As Integer = e.X + RectangleShape2.Left
    Dim mouseY As Integer = e.Y + RectangleShape2.Top
    ' Add a line to the graphics path.
    mousePath.AddLine(mouseX, mouseY, mouseX, mouseY)
End Sub

Private Sub RectangleShape2_MouseUp(ByVal sender As Object, _
  ByVal e As System.Windows.Forms.MouseEventArgs) _
  Handles RectangleShape2.MouseUp
    Dim mouseUpLocation = New System.Drawing.Point(e.X + _
      RectangleShape2.Left, e.Y + RectangleShape2.Top)
    ' Add a line to the graphics path.
    mousePath.Addline(mouseUpLocation, mouseUpLocation)
    ' Force the shape to redraw.
    RectangleShape2.Invalidate()
End Sub

Private Sub RectangleShape2_Paint(ByVal sender As Object, _
  ByVal e As System.Windows.Forms.PaintEventArgs) _
  Handles RectangleShape2.Paint
    ' Draw the line.
    e.Graphics.DrawPath(System.Drawing.Pens.DarkRed, mousePath)
End Sub

private System.Drawing.Drawing2D.GraphicsPath mousePath = 
    new System.Drawing.Drawing2D.GraphicsPath();

private void rectangleShape2_MouseDown(object sender, 
    System.Windows.Forms.MouseEventArgs e)
{
    Point mouseDownLocation = new Point(e.X + rectangleShape2.Left, 
        e.Y + rectangleShape2.Top);
    // Clear the previous line.
    mousePath.Dispose();
    mousePath = new System.Drawing.Drawing2D.GraphicsPath();
    rectangleShape2.Invalidate();
    // Add a line to the graphics path.
    mousePath.AddLine(mouseDownLocation, mouseDownLocation);
}

private void rectangleShape2_MouseMove(object sender, 
    System.Windows.Forms.MouseEventArgs e)
{
    int mouseX = e.X + rectangleShape2.Left;
    int mouseY = e.Y + rectangleShape2.Top;
    // Add a line to the graphics path.
    mousePath.AddLine(mouseX, mouseY, mouseX, mouseY);
}

private void rectangleShape2_MouseUp(object sender, 
    System.Windows.Forms.MouseEventArgs e)
{
    System.Drawing.Point mouseUpLocation = 
        new System.Drawing.Point(e.X + rectangleShape2.Left, 
            e.Y + rectangleShape2.Top);
    // Add a line to the graphics path.
    mousePath.AddLine(mouseUpLocation, mouseUpLocation);
    // Force the shape to redraw.
    rectangleShape2.Invalidate();
}

private void rectangleShape2_Paint(object sender, 
    System.Windows.Forms.PaintEventArgs e)
{
    // Draw the line.
    e.Graphics.DrawPath(System.Drawing.Pens.DarkRed, mousePath);
}