.NET TWAIN image scanner

using System;
using System.Text;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;

using GdiPlusLib;

namespace TwainGui
{

public class PicForm : System.Windows.Forms.Form
	{
	private System.ComponentModel.Container components = null;
	private System.Windows.Forms.MenuItem menuItemClose;
	private System.Windows.Forms.MenuItem menuItemInfo;
	private System.Windows.Forms.MenuItem menuMainFilePic;
	private System.Windows.Forms.MenuItem menuItemSaveAs;
	private System.Windows.Forms.MainMenu picformMenu;
	private System.Windows.Forms.MenuItem menuItemSepPic;

	public PicForm( IntPtr dibhandp )
		{
		InitializeComponent();

		SetStyle( ControlStyles.DoubleBuffer, false );
		SetStyle( ControlStyles.AllPaintingInWmPaint, true );
		SetStyle( ControlStyles.Opaque, true );
		SetStyle( ControlStyles.ResizeRedraw, true );
		SetStyle( ControlStyles.UserPaint, true );

		bmprect = new Rectangle( 0, 0, 0, 0 );
		dibhand = dibhandp;
		bmpptr = GlobalLock( dibhand );
		pixptr = GetPixelInfo( bmpptr );
		
		this.AutoScrollMinSize = new System.Drawing.Size( bmprect.Width, bmprect.Height );
		}

	protected override void Dispose( bool disposing )
		{
		if( disposing )
			{
			if( dibhand != IntPtr.Zero )
				{
				GlobalFree( dibhand );
				dibhand = IntPtr.Zero;
				}
				
			if(components != null)
				{
				components.Dispose();
				}
			}

		base.Dispose( disposing );
		}

		#region Windows Form Designer generated code
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{
			this.menuItemSepPic = new System.Windows.Forms.MenuItem();
			this.menuItemSaveAs = new System.Windows.Forms.MenuItem();
			this.menuItemInfo = new System.Windows.Forms.MenuItem();
			this.menuItemClose = new System.Windows.Forms.MenuItem();
			this.picformMenu = new System.Windows.Forms.MainMenu();
			this.menuMainFilePic = new System.Windows.Forms.MenuItem();
			// 
			// menuItemSepPic
			// 
			this.menuItemSepPic.Index = 3;
			this.menuItemSepPic.MergeOrder = 4;
			this.menuItemSepPic.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
			this.menuItemSepPic.Text = "-";
			// 
			// menuItemSaveAs
			// 
			this.menuItemSaveAs.Index = 1;
			this.menuItemSaveAs.MergeOrder = 2;
			this.menuItemSaveAs.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
			this.menuItemSaveAs.Text = "&Save As...";
			this.menuItemSaveAs.Click += new System.EventHandler(this.menuItemSaveAs_Click);
			// 
			// menuItemInfo
			// 
			this.menuItemInfo.Index = 0;
			this.menuItemInfo.MergeOrder = 1;
			this.menuItemInfo.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
			this.menuItemInfo.Text = "&Info...";
			this.menuItemInfo.Click += new System.EventHandler(this.menuItemInfo_Click);
			// 
			// menuItemClose
			// 
			this.menuItemClose.Index = 2;
			this.menuItemClose.MergeOrder = 3;
			this.menuItemClose.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
			this.menuItemClose.Text = "&Close";
			this.menuItemClose.Click += new System.EventHandler(this.menuItemClose_Click);
			// 
			// picformMenu
			// 
			this.picformMenu.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
																						this.menuMainFilePic});
			// 
			// menuMainFilePic
			// 
			this.menuMainFilePic.Index = 0;
			this.menuMainFilePic.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
																							this.menuItemInfo,
																							this.menuItemSaveAs,
																							this.menuItemClose,
																							this.menuItemSepPic});
			this.menuMainFilePic.MergeType = System.Windows.Forms.MenuMerge.MergeItems;
			this.menuMainFilePic.Text = "&File";
			// 
			// PicForm
			// 
			this.AutoScale = false;
			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
			this.AutoScroll = true;
			this.AutoScrollMinSize = new System.Drawing.Size(256, 256);
			this.BackColor = System.Drawing.Color.Black;
			this.ClientSize = new System.Drawing.Size(464, 221);
			this.Menu = this.picformMenu;
			this.MinimumSize = new System.Drawing.Size(80, 80);
			this.Name = "PicForm";
			this.Opacity = 0;
			this.ShowInTaskbar = false;
			this.Text = "PicForm";

		}
		#endregion

	protected override void OnPaint( System.Windows.Forms.PaintEventArgs e )
		{
		Rectangle	cltrect = ClientRectangle;
		Rectangle	clprect = e.ClipRectangle;
		Point		scrol = AutoScrollPosition;

		Rectangle	realrect = clprect;
		realrect.X -= scrol.X;
		realrect.Y -= scrol.Y;

		SolidBrush brbg = new SolidBrush( Color.Black );
		if( realrect.Right > bmprect.Width )
			{
			Rectangle	bgri = clprect;
			int ovri = bmprect.Width - realrect.X;
			if( ovri > 0 )
				{
				bgri.X += ovri;
				bgri.Width -= ovri;
				}
			e.Graphics.FillRectangle( brbg, bgri );
			}

		if( realrect.Bottom > bmprect.Height )
			{
			Rectangle	bgbo = clprect;
			int ovbo = bmprect.Height - realrect.Y;
			if( ovbo > 0 )
				{
				bgbo.Y += ovbo;
				bgbo.Height -= ovbo;
				}
			e.Graphics.FillRectangle( brbg, bgbo );
			}

		realrect.Intersect( bmprect );
		if( ! realrect.IsEmpty )
			{
			int bot = bmprect.Height - realrect.Bottom;
			IntPtr hdc = e.Graphics.GetHdc();
			SetDIBitsToDevice( hdc, clprect.X, clprect.Y, realrect.Width, realrect.Height,
					realrect.X, bot, 0, bmprect.Height, pixptr, bmpptr, 0 );
			e.Graphics.ReleaseHdc(hdc);
			}
		}

	protected override void OnPaintBackground( System.Windows.Forms.PaintEventArgs e )
		{
		}

	protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
		{
		this.Menu.MenuItems.Clear();
		base.OnClosing( e );
		}



	private void menuItemClose_Click(object sender, System.EventArgs e)
		{
		Close();
		}

	private void menuItemInfo_Click( object sender, System.EventArgs e )
		{
		InfoForm iform = new InfoForm( bmi );
		iform.ShowDialog( this );
		}

	private void menuItemSaveAs_Click(object sender, System.EventArgs e)
		{
		Gdip.SaveDIBAs( this.Text, bmpptr, pixptr );
		}


	protected IntPtr GetPixelInfo( IntPtr bmpptr )
		{
		bmi = new BITMAPINFOHEADER();
		Marshal.PtrToStructure( bmpptr, bmi );

		bmprect.X = bmprect.Y = 0;
		bmprect.Width = bmi.biWidth;
		bmprect.Height = bmi.biHeight;

		if( bmi.biSizeImage == 0 )
			bmi.biSizeImage = ((((bmi.biWidth * bmi.biBitCount) + 31) & ~31) >> 3) * bmi.biHeight;

		int p = bmi.biClrUsed;
		if( (p == 0) && (bmi.biBitCount <= 8) )
			p = 1 << bmi.biBitCount;
		p = (p * 4) + bmi.biSize + (int) bmpptr;
		return (IntPtr) p;
		}

	BITMAPINFOHEADER	bmi;
	Rectangle			bmprect;
	IntPtr	dibhand;
	IntPtr	bmpptr;
	IntPtr	pixptr;
	
		[DllImport("gdi32.dll", ExactSpelling=true)]
	internal static extern int SetDIBitsToDevice( IntPtr hdc, int xdst, int ydst,
											int width, int height, int xsrc, int ysrc, int start, int lines,
											IntPtr bitsptr, IntPtr bmiptr, int color );

		[DllImport("kernel32.dll", ExactSpelling=true)]
	internal static extern IntPtr GlobalLock( IntPtr handle );
		[DllImport("kernel32.dll", ExactSpelling=true)]
	internal static extern IntPtr GlobalFree( IntPtr handle );

	[DllImport("kernel32.dll", CharSet=CharSet.Auto) ]
	public static extern void OutputDebugString( string outstr );



	} // class PicForm


	[StructLayout(LayoutKind.Sequential, Pack=2)]
internal class BITMAPINFOHEADER
	{
	public int      biSize;
	public int      biWidth;
	public int      biHeight;
	public short    biPlanes;
	public short    biBitCount;
	public int      biCompression;
	public int      biSizeImage;
	public int      biXPelsPerMeter;
	public int      biYPelsPerMeter;
	public int      biClrUsed;
	public int      biClrImportant;
	}

} // namespace TwainGui