本文共 1635 字，大约阅读时间需要 5 分钟。

今天在网上看有些人的文章，很是不怎么样。实在忍不住了。

 

简单的写了一下下。

 

 

 

鼠标拖拽旋转。任意角度。。

 

 

Public Class Form1

    Dim bmp As Bitmap    Dim bmpsize As Single    Dim gr As Graphics    Dim pb As Point    Dim po As PointF

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        bmpsize = Math.Sqrt(Me.Icon.Width ^ 2 + Me.Icon.Height ^ 2)        bmp = New Bitmap(CInt(bmpsize), CInt(bmpsize))        gr = Graphics.FromImage(bmp)        po = New PointF((bmpsize - Me.Icon.Width) / 2, (bmpsize - Me.Icon.Height) / 2)        gr.DrawIcon(Me.Icon, po.X, po.Y)        PictureBox1.Image = bmp    End Sub

    Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown

        pb = e.Location    End Sub

    Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove

        If Not pb = Point.Empty Then            'O/-----------B            '  /             '   /            '    /            '    E            Dim vOB, vOE As Windows.Vector            vOB = New Windows.Vector(bmpsize / 2, bmpsize / 2) - New Windows.Vector(pb.X, pb.Y)            vOE = New Windows.Vector(bmpsize / 2, bmpsize / 2) - New Windows.Vector(e.X, e.Y)            '可以用叉乘求面积，正负号代表旋转方向，而后正弦定理求角度，            Dim O As Double = Windows.Vector.AngleBetween(vOB, vOE)            '若角度为有效值            gr.TranslateTransform(bmpsize / 2, bmpsize / 2)         '移动坐标至图像中心            gr.RotateTransform(O)                                   '按角度旋转            gr.TranslateTransform(-bmpsize / 2, -bmpsize / 2)       '移回            gr.Clear(Color.Transparent)                             '清除原有图像            gr.DrawIcon(Me.Icon, po.X, po.Y)                        '绘制新图像            PictureBox1.Image = bmp            pb = e.Location        End If

    End Sub

    Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp

        pb = Point.Empty    End Sub

End Class

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