问题

Question

问题

我试图在游标移动时将线条绘制到游标当前位置。我已尝试将以下代码添加到表单中的 MouseMove 事件中;然而，没有任何改变。我已经能够成功画出这条线，但不管我做什么，我似乎都无法让线跟随鼠标。此外，如果能够使用可靠的代码实现这一目标而不使用计时器（为了资源），那将是很好的，但无论有效，都可以。

代码

该程序只是一个空白表格。到目前为止，这是我获得的所有代码（这是所有代码）：

Public Class drawing

Public xpos = MousePosition.X
Public ypos = MousePosition.Y

Public Sub DrawLineFloat(ByVal e As PaintEventArgs)
    ' Create pen.
    Dim blackPen As New Pen(Color.Black, 2)
    ' Create coordinates of points that define line.
    Dim x1 As Single = xpos
    Dim y1 As Single = ypos
    Dim x2 As Single = 100
    Dim y2 As Single = 100
    ' Draw line to screen.
    e.Graphics.DrawLine(blackPen, x1, y1, x2, y2)
End Sub

Private Sub drawing_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
    DrawLineFloat(e)
End Sub
End Class

正如您所看到的，我尝试修改 MouseMove 事件的代码，但它失败了（我只是包括它，所以你可以看到之前的尝试）。提前感谢您的帮助。

Answer 1

这将满足您的需求：

private Point? startPoint;
protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);
    if (startPoint.HasValue)
    {
        Graphics g = e.Graphics;
        using (Pen p = new Pen(Color.Black, 2f))
        {
            g.DrawLine(p, startPoint.Value, new Point(100, 100));
        }
    }
}

protected override void OnMouseMove(MouseEventArgs e)
{
    base.OnMouseMove(e);

    this.startPoint = e.Location;
    this.Invalidate();
}

this指的是Form个实例。

使用http://converter.telerik.com/

将代码翻译为Vb.Net

Private startPoint As System.Nullable(Of Point)
Protected Overrides Sub OnPaint(e As PaintEventArgs)
    MyBase.OnPaint(e)
    If startPoint.HasValue Then
        Dim g As Graphics = e.Graphics
        Using p As New Pen(Color.Black, 2F)
            g.DrawLine(p, startPoint.Value, New Point(100, 100))
        End Using
    End If
End Sub

Protected Overrides Sub OnMouseMove(e As MouseEventArgs)
    MyBase.OnMouseMove(e)

    Me.startPoint = e.Location
    Me.Invalidate()
End Sub

VB.Net（WinForms）绘制一条线来跟随光标

问题

代码

1 个答案: