//
// PDFNet Copyright (c) 2001-2008 by PDFTron Systems Inc. All Rights Reserved.
//

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;

using pdftron;
using pdftron.Common;
using pdftron.Filters;
using pdftron.SDF;
using pdftron.PDF;

namespace JBIG2Test
{
	/// <summary>
	/// This sample project illustrates how to recompress bi-tonal images in an 
	/// existing PDF document using JBIG2 compression. The sample is not intended 
	/// to be a generic PDF optimization tool.
	/// 
	/// You can download a sample scanned document using the following link:
	///   http://www.pdftron.com/net/samplecode/data/US061222892.pdf
	///
	/// Also a sample page compressed using CCITT Fax compression is located under 
	/// 'PDFNet/Samples/TestFiles' folder.
	/// </summary>
	public class JBIG2TestDlg : System.Windows.Forms.Form
	{
		private System.Windows.Forms.Button button1;
		private System.Windows.Forms.Button button2;
		private System.Windows.Forms.Label label1;
		private System.Windows.Forms.Button button3;
		private System.Windows.Forms.CheckBox lossy;
		/// <summary>
		/// Required designer variable.
		/// </summary>
		private System.ComponentModel.Container components = null;

		public JBIG2TestDlg()
		{
			//
			// Required for Windows Form Designer support
			//
			InitializeComponent();

			ObjSet hint_set = new ObjSet();
			_JBIG2_hint = hint_set.CreateArray();
            _JBIG2_hint.PushBackName("JBIG2");
			_JBIG2_hint.PushBackName("Lossless");
		}

		Obj _JBIG2_hint;

		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				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.button1 = new System.Windows.Forms.Button();
			this.button2 = new System.Windows.Forms.Button();
			this.label1 = new System.Windows.Forms.Label();
			this.button3 = new System.Windows.Forms.Button();
			this.lossy = new System.Windows.Forms.CheckBox();
			this.SuspendLayout();
			// 
			// button1
			// 
			this.button1.Location = new System.Drawing.Point(160, 104);
			this.button1.Name = "button1";
			this.button1.Size = new System.Drawing.Size(184, 40);
			this.button1.TabIndex = 0;
			this.button1.Text = "Load PDF";
			this.button1.Click += new System.EventHandler(this.button1_Click);
			// 
			// button2
			// 
			this.button2.Location = new System.Drawing.Point(160, 160);
			this.button2.Name = "button2";
			this.button2.Size = new System.Drawing.Size(184, 40);
			this.button2.TabIndex = 1;
			this.button2.Text = "Save using JBIG2";
			this.button2.Click += new System.EventHandler(this.button2_Click);
			// 
			// label1
			// 
			this.label1.Location = new System.Drawing.Point(32, 16);
			this.label1.Name = "label1";
			this.label1.Size = new System.Drawing.Size(304, 64);
			this.label1.TabIndex = 2;
			this.label1.Text = "This sample project illustrates how to recompress bi-tonal images in an existing " +
				"PDF document using JBIG2 compression. The sample is not intended to be a generic" +
				" PDF optimization tool.";
			// 
			// button3
			// 
			this.button3.Location = new System.Drawing.Point(160, 216);
			this.button3.Name = "button3";
			this.button3.Size = new System.Drawing.Size(184, 40);
			this.button3.TabIndex = 3;
			this.button3.Text = "Quit";
			this.button3.Click += new System.EventHandler(this.button3_Click);
			// 
			// lossy
			// 
			this.lossy.Location = new System.Drawing.Point(24, 160);
			this.lossy.Name = "lossy";
			this.lossy.Size = new System.Drawing.Size(120, 32);
			this.lossy.TabIndex = 4;
			this.lossy.Text = "Lossy Compression";
			// 
			// JBIG2TestDlg
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(6, 15);
			this.ClientSize = new System.Drawing.Size(384, 284);
			this.Controls.Add(this.lossy);
			this.Controls.Add(this.button3);
			this.Controls.Add(this.label1);
			this.Controls.Add(this.button2);
			this.Controls.Add(this.button1);
			this.Name = "JBIG2TestDlg";
			this.Text = "JBIG2 Test";
			this.ResumeLayout(false);

		}
		#endregion

		// On exit, finish using PDFNet 
		private void button3_Click(object sender, System.EventArgs e)
		{
			Application.Exit();
		}

		private PDFDoc doc = null; 

		// On Load ... 
		private void button1_Click(object sender, System.EventArgs e)
		{
			OpenFileDialog dlg=new OpenFileDialog();
			dlg.Filter="PDF (*.pdf)|*.pdf|All files (*.*)|*.*";
			
			if(dlg.ShowDialog()==DialogResult.OK)
			{
				if (doc != null) 
				{
					doc.Close();
				}
				doc = new PDFDoc(dlg.FileName);
				doc.InitSecurityHandler();
			}
		}

		// On Save...
		private void button2_Click(object sender, System.EventArgs e)
		{
			SaveFileDialog dlg=new SaveFileDialog();
			dlg.Filter="PDF (*.pdf)|*.pdf|All files (*.*)|*.*";

			if(dlg.ShowDialog()==DialogResult.OK)
			{
				if (doc != null)
				{	
					Recompress();
					doc.Save(dlg.FileName, SDFDoc.SaveOptions.e_remove_unused);
					doc.Close();
					doc = null;
				}
			}
		}

		byte[] _img_buf = null;

		private void Recompress() 
		{
			if (lossy.Checked) 
			{
				_JBIG2_hint.GetAt(1).SetName("Lossy");
			}
			else 
			{
				_JBIG2_hint.GetAt(1).SetName("Lossless");
			}

			SDFDoc cos_doc = doc.GetSDFDoc();
			int num_objs = cos_doc.XRefSize();

			for (int i=1; i<num_objs; ++i) 
			{
				Obj obj = cos_doc.GetObj(i);

				if (obj!=null && !obj.IsFree()&& obj.IsStream()) 
				{
					// Process only images
					DictIterator itr = obj.Find("Subtype");
					if (!itr.HasNext() || itr.Value().GetName() != "Image") 
						continue; 

					pdftron.PDF.Image input_image = new pdftron.PDF.Image(obj);
					pdftron.PDF.Image new_image = null;

					// Process only gray-scale images
					if (input_image.GetComponentNum() != 1) 
						continue; 
					
					int bpc = input_image.GetBitsPerComponent();
					if (bpc == 1) // Recompress 1 BPC images
					{
						// Skip images that are already compressed using JBIG2
						itr = obj.Find("Filter");
						if (!itr.HasNext() && itr.Value().IsName() && 
							itr.Value().GetName() == "JBIG2Decode") 
							continue; 

						FilterReader reader = new FilterReader(obj.GetDecodedStream());
						new_image = pdftron.PDF.Image.Create(
							cos_doc, 
							reader, 							
							input_image.GetImageWidth(), 
							input_image.GetImageHeight(), 
							1, 
							ColorSpace.CreateDeviceGray(),
							_JBIG2_hint  // A hint to image encoder to use JBIG2 compression
							);
					}
					else if (bpc == 8)
					{
						// Some black and white images are stored as 8 bits per pixel
						// grayscale images. In this case convert the image to 1 BPC 
						// image and then compress using JBIG2.
						int width = input_image.GetImageWidth();
						int height = input_image.GetImageHeight();
						int bytes_per_row = (width + 7)/8;
						int img_buf_size = width * height;

						if (_img_buf == null || _img_buf.Length<img_buf_size)
						{
							_img_buf = new byte[img_buf_size * 2];
						}

						FilterReader reader = new FilterReader(obj.GetDecodedStream());
						byte acc;
						int in_pos = 0;
						int out_pos = 0;
						int pad = width%8;

						reader.Read(_img_buf);

						for (int y=0; y<height; ++y) 
						{
							acc = 0;
							for (int x=0; x<width; ++x) 
							{
								acc <<= 1;								
								if (_img_buf[in_pos++] > 128)
								{
									acc |= 0x01;
								}

								if (x!=0 && (x%8)==0) 
								{
									_img_buf[out_pos] = acc;
									++out_pos;
								}
							}

							if (pad!=0) 
							{
								acc <<= (8 - pad);
							}

							_img_buf[out_pos] = acc;
							++out_pos;
						}

						new_image = pdftron.PDF.Image.Create(
							cos_doc, 
							_img_buf, 
							width, height, 1, ColorSpace.CreateDeviceGray(),
							_JBIG2_hint  // A hint to image encoder to use JBIG2 compression
							);
					}

					Obj new_img_obj = new_image.GetSDFObj();

					// Copy any important entries from the image dictionary
					itr = obj.Find("Decode");
					if (itr.HasNext()) new_img_obj.Put("Decode", itr.Value());

					itr = obj.Find("ImageMask");
					if (itr.HasNext()) new_img_obj.Put("ImageMask", itr.Value());

					itr = obj.Find("Mask");
					if (itr.HasNext()) new_img_obj.Put("Mask", itr.Value());

					cos_doc.Swap(i, new_image.GetSDFObj().GetObjNum());
				}
			}
		}

		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main() 
		{
			// Initialize PDFNet before calling any other PDFNet function.
			PDFNet.Initialize();
			PDFNet.SetResourcesPath("../../../../../resources");
			Application.Run(new JBIG2TestDlg());
			PDFNet.Terminate();
		}
	}
}