DataGridView Print/Print Preview Solution - Part II

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Printing;

namespace GridPrintPreviewLib
{
    /// <summary>
    /// Control to manage margins setting with preview
    /// </summary>
    public partial class GLMarginSettings : UserControl
    {
        // Maring and Size are stored in display unit
        private Margins m_PageMargins = new Margins(0, 0 , 0, 0);
        private PaperSize m_PageSize = new PaperSize();
        // Unit used for show margin to user
        private PrinterUnit m_UnitForShow = PrinterUnit.Display;
        // Flag to check if page is in landscape
        private bool m_Landscape = false;

        public GLMarginSettings()
        {
            InitializeComponent();
        }

        /// <summary>
        /// PageSize in display unit
        /// </summary>
        public PaperSize PageSize
        {
            get
            {
                return m_PageSize;
            }
            set
            {
                m_PageSize = value;
                RefreshPreview();
            }
        }

        /// <summary>
        /// Margins in display unit
        /// </summary>
        public Margins PageMargins
        {
            get
            {
                return m_PageMargins;
            }
            set
            {
                m_PageMargins = value;
                RefreshPreview();
                RefreshUnit();
            }
        }

        /// <summary>
        /// Unit used for show values to user
        /// </summary>
        public PrinterUnit ShowUnit
        {
            get
            {
                return m_UnitForShow;
            }
            set
            {
                m_UnitForShow = value;
                RefreshUnit();
            }
        }

        /// <summary>
        /// Get/Set if page in is landscape
        /// </summary>
        public bool Landscape
        {
            get
            {
                return m_Landscape;
            }
            set
            {
                m_Landscape = value;
                RefreshPreview();
            }
        }

        /// <summary>
        /// Refresh image of the page with margin
        /// </summary>
        private void RefreshPreview()
        {
            if(m_PageSize.Width == 0 || m_PageSize.Height == 0)
            {
                return;
            }
            if (pbPage.Image == null)
            {
                Bitmap bitmap = new Bitmap(pbPage.Width, pbPage.Height);
                pbPage.Image = bitmap;
            }
            using (Graphics g = Graphics.FromImage(pbPage.Image))
            {
                float pageWidth = (!m_Landscape) ? m_PageSize.Width : m_PageSize.Height;
                float pageHeight = (!m_Landscape) ? m_PageSize.Height : m_PageSize.Width;
                float scaleX = pbPage.Width / pageWidth;
                float scaleY = pbPage.Height / pageHeight;
                float scale = Math.Min(scaleX, scaleY);
                SizeF scalePageSize = new SizeF(pageWidth * scale, pageHeight * scale);
                float x = (pbPage.Width - scalePageSize.Width) / 2;
                float y = (pbPage.Height - scalePageSize.Height) / 2;
                g.FillRectangle(Brushes.Gray, 0, 0, pbPage.Width, pbPage.Height);
                g.FillRectangle(Brushes.White, x, y, scalePageSize.Width, scalePageSize.Height);
                Pen p = new Pen(Color.Black, 1);
                p.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash;
                float mleft = m_PageMargins.Left * scaleX + x;
                g.DrawLine(p, mleft, 0, mleft, pbPage.Height);
                float mright = x + scalePageSize.Width - (m_PageMargins.Right * scaleX);
                g.DrawLine(p, mright, 0, mright, pbPage.Height);
                float mtop = m_PageMargins.Top * scaleY + y;
                g.DrawLine(p, 0, mtop, pbPage.Width, mtop);
                float mbottom = y + scalePageSize.Height - (m_PageMargins.Bottom * scaleY);
                g.DrawLine(p, 0, mbottom, pbPage.Width, mbottom);
            }
            this.pbPage.Refresh();
        }

        /// <summary>
        /// Refresh unit shown to user
        /// </summary>
        private void RefreshUnit()
        {
            Margins m = TransformHelper.Convert(m_PageMargins, PrinterUnit.Display, m_UnitForShow);
            nudLeft.Value = m.Left;
            nudTop.Value = m.Top;
            nudRight.Value = m.Right;
            nudBottom.Value = m.Bottom;
        }

        /// <summary>
        /// Handle numeric up down change
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void nud_ValueChanged(object sender, EventArgs e)
        {
            Margins m = new Margins((int)nudLeft.Value, (int)nudRight.Value, (int)nudTop.Value, (int)nudBottom.Value);
            m_PageMargins = TransformHelper.Convert(m, m_UnitForShow, PrinterUnit.Display);
            this.RefreshPreview();
        }
    }
}