VB.NET DrawImage to Transforma a square into a parallelogram.

Dobon_bitmapRotateTrans_01.vb

Public Class Form1

    Dim totalPlot As Bitmap
    Dim tg As Graphics
    Dim ulx, uly, urx, ury, llx, lly As Integer


    Private Sub plotSlider(ByVal startNo As Integer)
        '画像の一部を切り取って（トリミングして）表示する
        Debug.Print(startNo)
        Dim timeScale As Integer = 3

        Dim canvas As New Bitmap(410, 210) 'W=400,H=240
        Dim g As Graphics = Graphics.FromImage(canvas)
        Dim canvas3 As New Bitmap(600, 400) 'W=400,H=240
        Dim g3 As Graphics = Graphics.FromImage(canvas3)


        Dim srcRect As New Rectangle(startNo, 0, 400, 210)
        '描画する部分の範囲を決定する。ここでは、位置(0,0)、大きさ100x100で描画する
        Dim desRect As New Rectangle(0, 0, srcRect.Width, srcRect.Height)
        '画像の一部を描画する
        g.DrawImage(totalPlot, desRect, srcRect, GraphicsUnit.Pixel)
        g3.DrawImage(totalPlot, desRect, srcRect, GraphicsUnit.Pixel)
        Dim p As New Pen(Color.Red, 1)
        '位置(10, 20)に100x80の長方形を描く
        g.DrawRectangle(p, 0, 0, 399, 199)
        g3.DrawRectangle(p, 0, 0, 399, 199)

        ''======四角画像を変形表示させる位置を指定する=======
        ''元の画像の左上の位置を(ulx, uly)にする
        ''元の画像の右上の位置を(urx, ury)にする
        ''元の画像の左下の位置を(llx, lly)にする
        Dim destinationPoints() As Point
        destinationPoints = New Point() {New Point(ulx, uly),
            New Point(urx, ury),
            New Point(llx, lly)}


        'canvasを変形して傾いた画像をg3(canvas3)へ描画する
        g3.DrawImage(canvas, destinationPoints)
        'Graphicsオブジェクトのリソースを解放する
        g.Dispose()
        g3.Dispose()

        'PictureBox1に表示する
        PictureBox2.Image = canvas 'gで大きなtotalPlotを切り取った画像canvasをPictureBox2へ書き込む
        PictureBox3.Image = canvas3 'g3で作っグラフィックcanvas3をPictureBox3へ書き込む
    End Sub

    Private Sub HScrollBar1_ValueChanged(sender As Object, e As EventArgs) Handles HScrollBar1.ValueChanged
        'maximum=1200 minimum=0
        Dim slideVal As Integer = HScrollBar1.Value
        plotSlider(slideVal)
        TextBox1.Text = CStr(slideVal)

    End Sub

    '元グラフを作成する
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        totalPlot = New Bitmap(PictureBox1.Width * 3, PictureBox1.Height)
        tg = Graphics.FromImage(totalPlot)
        Dim i As Integer

        For i = 1 To PictureBox1.Width * 3
                Dim px As Integer = i
                Dim py As Integer = Math.Sin(Math.PI / 30 * i) * 100 * (i / 1200) + 100
                tg.FillEllipse(Brushes.Red, px, py, 4, 4)

        Next i

        PictureBox1.Image = totalPlot

    End Sub


    Private Sub PictureBox3_MouseClick(sender As Object, e As MouseEventArgs) Handles PictureBox3.MouseClick
        '画面座標でマウスポインタの位置を取得する
        Dim sp As System.Drawing.Point = System.Windows.Forms.Cursor.Position
        '画面座標をクライアント座標に変換する
        Dim cp As System.Drawing.Point = Me.PointToClient(sp)
        'X座標を取得する
        Dim x As Integer = cp.X
        'Y座標を取得する
        Dim y As Integer = cp.Y
        If RadioButton1.Checked = True Then
            ulx = x - PictureBox3.Left
            TextBox2.Text = x - PictureBox2.Left
            uly = y - PictureBox3.Top
            TextBox3.Text = y - PictureBox2.Top
        End If
        If RadioButton2.Checked = True Then
            urx = x - PictureBox3.Left
            TextBox4.Text = x - PictureBox2.Left
            ury = y - PictureBox3.Top
            TextBox5.Text = y - PictureBox2.Top
        End If
        If RadioButton3.Checked = True Then
            llx = x - PictureBox3.Left
            TextBox6.Text = x - PictureBox2.Left
            lly = y - PictureBox3.Top
            TextBox7.Text = y - PictureBox2.Top
        End If
    End Sub
End Class