'直線の描画
'頂点はLabelコントロールで表示して、マウスドラッグで移動できるように
Public Class Form1
Private beginPoint As Point 'マウスドラッグ開始点記録用
Private myPen As New Pen(Brushes.Magenta, 5) '直線用のPen
Private myPoints As New List(Of Point) '頂点座標群記録用
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
Call MyInitialize()
End Sub
'初期化
Private Sub MyInitialize()
'初期座標設定
myPoints = New List(Of Point)(New Point() {
New Point(0, 0),
New Point(150, 40),
New Point(80, 100),
New Point(100, 150)})
'頂点表示用のLabel作成
For i = 0 To myPoints.Count - 1
Call MakeLabel(myPoints(i), i)
Next
'直線を描画
Call MyDrawLines()
End Sub
'左クリック時の処理
Private Sub MyMouseDown(sender As Object, e As MouseEventArgs)
beginPoint = e.Location
End Sub
'マウスドラッグ中処理
Private Sub MyMouseMove(sender As Object, e As MouseEventArgs)
If e.Button = Windows.Forms.MouseButtons.Left Then
Dim myLabel = DirectCast(sender, Label)
Dim newLocate As Point
newLocate = New Point(e.X - beginPoint.X + myLabel.Location.X,
e.Y - beginPoint.Y + myLabel.Location.Y)
myLabel.Location = newLocate
myPoints(myLabel.Tag) = newLocate
Call MyDrawLines()
End If
End Sub
'直線を描画
Private Sub MyDrawLines()
Dim canvas As New Bitmap(Me.PictureBox1.Width, Me.PictureBox1.Height)
Dim g As Graphics = Graphics.FromImage(canvas)
g.DrawLines(myPen, myPoints.ToArray)
g.Dispose()
Me.PictureBox1.Image = canvas
End Sub
''' <summary>
''' 頂点表示用のLabel作成
''' </summary>
''' <param name="locate">頂点座標</param>
''' <param name="number">通し番号(何番目の頂点なのか識別用)</param>
''' <returns></returns>
Private Function MakeLabel(locate As Point, number As Integer) As Point
Dim myLabel = New Label()
With myLabel
.Width = 10
.Height = 10
.BackColor = Color.Black
.Location = locate
.Tag = number 'Tagに通し番号を記録
End With
Me.PictureBox1.Controls.Add(myLabel)
'マウスイベント時の処理追加
AddHandler myLabel.MouseDown, AddressOf MyMouseDown
AddHandler myLabel.MouseMove, AddressOf MyMouseMove
End Function
End Class
![[11]](https://s.yimg.jp/i/jp/blog/p3/images/paging_for2.gif){kind=small}
