// Variable to toggle if user is currently selecting an area.
private bool m_bZoomToRectSelect = false;
// Set of points defining the selected area.
private ImGearPoint[] igPointsZoomToRect;
// Color of selection box.
private Color m_SelectorColor = Color.White;

// Method to return appropriate height for a specific width 
// based upon the size of a scrollable view.
private int GetHeight(IImGearScrollableView igScrollableView, int Width)
{
    return Width * igScrollableView.ClientRectangle.Height / igScrollableView.ClientRectangle.Width;
}

private void menuZoomToRect_Click(object sender, EventArgs e)
{
    // Menu item used to toggle if Zoom to Rectangle is on or not.
    menuZoomToRect.Checked = !menuZoomToRect.Checked;
}

private void imGearPageView1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
    if (menuZoomToRect.Checked)
    {
        // Enter Zoom to Rectangle selection mode.
        m_bZoomToRectSelect = true;
        // Create a new pair of points to define the rectangle, 
        // setting the first point to the current position.
        igPointsZoomToRect = new ImGearPoint[2];
        igPointsZoomToRect[0].X = e.X;
        igPointsZoomToRect[0].Y = e.Y;
        // Register method to draw the selection rectangle.
        imGearPageView.RegisterAfterDraw(
            new ImGearPageView.AfterDraw(DrawSelector));
    }
}

private void imGearPageView1_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
{
    if (m_bZoomToRectSelect)
    {
        // Leave Zoom to Rectangle selection mode.
        imGearPageView.RegisterAfterDraw(null);
        m_bZoomToRectSelect = false;
        // Record the second point of the zoom rectangle,
        // normalizing it to the view's aspect ratio.
        igPointsZoomToRect[1].X = e.X;
        igPointsZoomToRect[1].Y = igPointsZoomToRect[0].Y +
            GetHeight(imGearPageView, Math.Abs(igPointsZoomToRect[1].X - igPointsZoomToRect[0].X) + 1) - 1;
        // Create a rectangle based upon the 2 points.
        ImGearRectangle igRectangle = new ImGearRectangle(igPointsZoomToRect[0], igPointsZoomToRect[1]);
        // Cancel the zoom if it would be for a 0x0 or 1x1 rectangle.
        if (igRectangle.Width <= 1 || igRectangle.Height <= 1)
            return;
        // Zoom to the selected rectangle
        imGearPageView.Display.ZoomToRectangle(imGearPageView, igRectangle);
        imGearPageView.Invalidate();
        // Disable Zoom to Rectangle.
        menuZoomToRect.Checked = false;
    }
}

private void imGearPageView1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
    if (m_bZoomToRectSelect)
    {
        // Record the second point of the zoom rectangle,
        // normalizing it to the view's aspect ratio.
        igPointsZoomToRect[1].X = e.X;
        igPointsZoomToRect[1].Y = igPointsZoomToRect[0].Y +
            GetHeight(imGearPageView, Math.Abs(igPointsZoomToRect[1].X - igPointsZoomToRect[0].X) + 1) - 1;
        // Cause a redraw which will update the zoom selection rectangle.
        imGearPageView.Invalidate();
    }
}

private void DrawSelector(System.Drawing.Graphics gr)
{
    if (m_bZoomToRectSelect)
    {
        // Create a new pen to draw dotted lines.
        Pen pen = new Pen(m_SelectorColor);
        pen.DashStyle = DashStyle.Dot;
        // Define the currently selected zoom rectangle.
        ImGearRectangle igRectangleZoom = new ImGearRectangle(igPointsZoomToRect[0], igPointsZoomToRect[1]);
        // Draw the selection box.
        gr.DrawRectangle(pen, igRectangleZoom.Left, igRectangleZoom.Top,
            igRectangleZoom.Width, igRectangleZoom.Height);
    }
}

'Variable to toggle if user is currently selecting an area.
Private m_bZoomToRectSelect As Boolean = False
'Set of points defining the selected area.
Private igPointsZoomToRect() As ImGearPoint
'Color of selection box.
Private m_SelectorColor As Color = Color.White

'Function to return appropriate height for a specific width 
' based upon the size of a scrollable view.
Private Function GetHeight(ByVal igScrollableView As IImGearScrollableView, ByVal Width As Integer) As Integer
    GetHeight = Width * igScrollableView.ClientRectangle.Height / igScrollableView.ClientRectangle.Width
End Function


Private Sub menuZoomtoRect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
                Handles menuZoomtoRect.Click
    menuZoomtoRect.Checked = Not menuZoomtoRect.Checked
End Sub

Private Sub ImGearPageView1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) _
                Handles ImGearPageView1.MouseDown
    If (menuZoomtoRect.Checked) Then
        'Enter Zoom to Rectangle selection mode.
        m_bZoomToRectSelect = True
        'Create a new pair of points to define the rectangle, 
        ' setting the first point to the current position.
        ReDim igPointsZoomToRect(2)
        igPointsZoomToRect(0).X = e.X
        igPointsZoomToRect(0).Y = e.Y
        'Register function to draw the selection rectangle.
        ImGearPageView1.RegisterAfterDraw( _
            New ImGearPageView.AfterDraw(AddressOf DrawSelector))
    End If
End Sub

Private Sub ImGearPageView1_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) _
                Handles ImGearPageView1.MouseUp
    If (m_bZoomToRectSelect) Then
        'Leave Zoom to Rectangle selection mode.
        ImGearPageView1.RegisterAfterDraw(Nothing)
        m_bZoomToRectSelect = False
        'Record the second point of the zoom rectangle,
        ' normalizing it to the view's aspect ratio.
        igPointsZoomToRect(1).X = e.X
        igPointsZoomToRect(1).Y = igPointsZoomToRect(0).Y + _
            GetHeight(ImGearPageView1, Math.Abs(igPointsZoomToRect(1).X - igPointsZoomToRect(0).X) + 1) - 1
        'Create a rectangle based upon the 2 points.
        Dim igRectangle As ImGearRectangle = New ImGearRectangle(igPointsZoomToRect(0), igPointsZoomToRect(1))
        'Cancel the zoom if it would be for a 0x0 or 1x1 rectangle.
        If (igRectangle.Width <= 1 Or igRectangle.Height <= 1) Then
            Return
        End If
        'Zoom to the selected rectangle
        ImGearPageView1.Display.ZoomToRectangle(ImGearPageView1, igRectangle)
        ImGearPageView1.Invalidate()
        'Disable Zoom to Rectangle.
        menuZoomtoRect.Checked = False
    End If
End Sub

Private Sub ImGearPageView1_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) _
                Handles ImGearPageView1.MouseMove
    If (m_bZoomToRectSelect) Then
        'Record the second point of the zoom rectangle,
        ' normalizing it to the view's aspect ratio.
        igPointsZoomToRect(1).X = e.X
        igPointsZoomToRect(1).Y = igPointsZoomToRect(0).Y + _
            GetHeight(ImGearPageView1, Math.Abs(igPointsZoomToRect(1).X - igPointsZoomToRect(0).X) + 1) - 1
        'Cause a redraw which will update the zoom selection rectangle.
        ImGearPageView1.Invalidate()
    End If
End Sub

Private Sub DrawSelector(ByVal gr As System.Drawing.Graphics)
    If (m_bZoomToRectSelect) Then
        'Create a new pen to draw dotted lines.
        Dim pen As Pen = New Pen(m_SelectorColor)
        Pen.DashStyle = DashStyle.Dot
        'Define the currently selected zoom rectangle.
        Dim igRectangleZoom As ImGearRectangle = New ImGearRectangle(igPointsZoomToRect(0), igPointsZoomToRect(1))
        'Draw the selection box.
        gr.DrawRectangle(pen, igRectangleZoom.Left, igRectangleZoom.Top, igRectangleZoom.Width, igRectangleZoom.Height)
    End If
End Sub