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RasterImage Serialization

Deriving from RasterImage and Serialization

Introduction

The RasterImage interface and the RasterImage class implement the ISerializable interface and thus support standard .NET serialization.

Serialization is the process of converting the state of an object into a form that can be persisted or transported. The complement of serialization is deserialization, which converts a stream into an object. Together, these processes allow data to be easily stored and transferred.

You can easily save and restore the image data of a RasterImage object by saving/loading the image back into one of the numerous file image formats supported by LEADTOOLS. However, by doing so, you lose any data that is not supported by the image file format. For example, the region data you currently have in the image is not supported by any file image format. The metadata (tags, markers and comments) are supported by some formats but not all.

Serialization solves these problems by saving everything in the image and later deserializing back into its original state. Moreover, when you derive your own class from RasterImage, you can extend the serialization mechanism to support saving/restoring your own data inside the image.

The RasterImage supports both binary and XML serialization.

Binary Serialization

You can use binary serialization to share the RasterImage object between different applications by serializing it to the Clipboard. You can serialize the RasterImage to a stream, to a disk, to memory, over the network, and so forth. Remoting uses binary serialization to pass objects "by value" from one computer or application domain to another.

Binary serialization is the most efficient way to serialize a RasterImage object both in speed of serialization/deserialization as well using less space for the object data.

Examples of binary serialization:

Imports System.IO 
Imports System.Runtime.Serialization.Formatters.Binary 
Imports Leadtools 
Imports Leadtools.Codecs 
             
Private Sub BinarySerializationTest() 
    Dim codecs As RasterCodecs = New RasterCodecs() 
                 
    ' Load an image 
    Dim image1 As RasterImage = codecs.Load("C:\LEADTOOLS21\Resources\Images\Image1.cmp") 
                 
    ' Use the binary formatter 
    Dim formatter As BinaryFormatter = New BinaryFormatter() 
                 
    ' Serialize this image into a memory stream 
    Dim ms As MemoryStream = New MemoryStream() 
    formatter.Serialize(ms, image1) 
                 
    ' We are done with the image 
    image1.Dispose() 
                 
    ' Move back to the beginning of the stream 
    ms.Position = 0 
                 
    ' De-serialize the image back 
    Dim image2 As RasterImage = CType(If(TypeOf formatter.Deserialize(ms) Is RasterImage, formatter.Deserialize(ms), Nothing), RasterImage) 
                 
    ' re-save the image 
    codecs.Save(image2, "C:\LEADTOOLS21\Resources\Images\Image1_Serialized.bmp", RasterImageFormat.Bmp, 24) 
                 
    ' Clean up 
    image2.Dispose() 
    ms.Close() 
                 
    codecs.Dispose() 
End Sub

using System.IO; 
using System.Runtime.Serialization.Formatters.Binary; 
using Leadtools; 
using Leadtools.Codecs; 
             
private void BinarySerializationTest() 
{ 
    RasterCodecs codecs = new RasterCodecs(); 
                 
    // Load an image 
    RasterImage image1 = codecs.Load(@"C:\LEADTOOLS21\Resources\Images\Image1.cmp"); 
                 
    // Use the binary formatter 
    BinaryFormatter formatter = new BinaryFormatter(); 
                 
    // Serialize this image into a memory stream 
    MemoryStream ms = new MemoryStream(); 
    formatter.Serialize(ms, image1); 
                 
    // We are done with the image 
    image1.Dispose(); 
                 
    // Move back to the beginning of the stream 
    ms.Position = 0; 
                 
    // De-serialize the image back 
    RasterImage image2 = formatter.Deserialize(ms) as RasterImage; 
                 
    // re-save the image 
    codecs.Save(image2, @"C:\LEADTOOLS21\Resources\Images\Image1_Serialized.bmp", RasterImageFormat.Bmp, 24); 
                 
    // Clean up 
    image2.Dispose(); 
    ms.Close(); 
                 
    codecs.Dispose(); 
}

XML serialization

You can also use serialize a RasterImage object to XML. Since XML is an open standard, XML serialization is an attractive choice for sharing a RasterImage object across the Web.

However, since XML is a text format, XML serialization is not recommended to be used with a RasterImage object. The speed of serialization/deserialization is a lot slower than binary serialization and XML serialization uses a lot more space for the object data.

Serialization Example (Using the Windows Clipboard) The following example shows you how to copy and paste a RasterImage object to the Windows clipboard using serialization. This example assumes that you have added the code to a Form and call the method created in the example from the constructor or another method on the form.

Imports System 
Imports System.Windows.Forms 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.WinForms 
             
Private panel1 As Panel 
Private loadButton As Button 
Private clearButton As Button 
Private copyButton As Button 
Private pasteButton As Button 
Private rasterImageViewer1 As RasterImageViewer 
Private codecs1 As RasterCodecs 
             
Private Sub ClipboardTest() 
   ' Add the controls to the form 
   ' 1. RasterImageViewer control 
   ' 2. Load button to load an image into the viewer 
   ' 3. Clear button to reset the viewer's image. 
   ' 3. Copy button to copy the image to the clipboard 
   ' 4. Paste button to paste the image from the clipboard to the viewer 
             
   ' Create the controls 
             
   Me.SuspendLayout() 
             
   loadButton = New Button 
             
   panel1 = New Panel 
   panel1.Dock = DockStyle.Left 
   panel1.Width = loadButton.Width 
   Me.Controls.Add(panel1) 
             
   loadButton.Text = "Load" 
   loadButton.Location = New Point(0, 0) 
   panel1.Controls.Add(loadButton) 
   loadButton.BringToFront() 
   AddHandler loadButton.Click, AddressOf loadButton_Click 
             
   clearButton = New Button 
   clearButton.Text = "Clear" 
   clearButton.Location = New Point(0, loadButton.Bottom) 
   panel1.Controls.Add(clearButton) 
   clearButton.BringToFront() 
   AddHandler clearButton.Click, AddressOf clearButton_Click 
             
   copyButton = New Button 
   copyButton.Text = "Copy" 
   copyButton.Location = New Point(0, clearButton.Bottom) 
   panel1.Controls.Add(copyButton) 
   copyButton.BringToFront() 
   AddHandler copyButton.Click, AddressOf copyButton_Click 
             
   pasteButton = New Button 
   pasteButton.Text = "Paste" 
   pasteButton.Location = New Point(0, copyButton.Bottom) 
   panel1.Controls.Add(pasteButton) 
   pasteButton.BringToFront() 
   AddHandler pasteButton.Click, AddressOf pasteButton_Click 
             
   rasterImageViewer1 = New RasterImageViewer 
   rasterImageViewer1.Dock = DockStyle.Fill 
   Controls.Add(rasterImageViewer1) 
   rasterImageViewer1.BringToFront() 
             
   Me.ResumeLayout() 
             
   ' Initialize the codecs object 
   codecs1 = New RasterCodecs 
             
   ' Update our user interface 
   UpdateMyUserInterface() 
End Sub 
             
Private Sub UpdateMyUserInterface() 
   ' Update the buttons depending on the application state 
             
   ' The Clear button is enabled if we have an image 
   clearButton.Enabled = (Not rasterImageViewer1.Image Is Nothing) 
             
   ' The Copy button is enabled if we have an image 
   copyButton.Enabled = (Not rasterImageViewer1.Image Is Nothing) 
             
   ' The paste button is enabled if we have a valid clipboard format 
   Dim data As IDataObject = Clipboard.GetDataObject() 
   pasteButton.Enabled = data.GetDataPresent(GetType(RasterImage)) 
End Sub 
             
Private Sub loadButton_Click(ByVal sender As Object, ByVal e As EventArgs) 
   ' Load a new image into the viewer 
   Dim dlg As New OpenFileDialog 
   dlg.Filter = "All Files|*.*" 
   If (dlg.ShowDialog(Me) = DialogResult.OK) Then 
      Try 
         rasterImageViewer1.Image = codecs1.Load(dlg.FileName) 
      Catch ex As Exception 
         MessageBox.Show(Me, ex.Message) 
      Finally 
      ' Update the user interface 
      UpdateMyUserInterface() 
      End Try 
   End If 
End Sub 
             
Private Sub clearButton_Click(ByVal sender As Object, ByVal e As EventArgs) 
   ' Delete the image in the viewer 
   rasterImageViewer1.Image = Nothing 
             
   ' Update the user interface 
   UpdateMyUserInterface() 
End Sub 
             
Private Sub copyButton_Click(ByVal sender As Object, ByVal e As EventArgs) 
   ' Copy the image in the viewer into the clipboard 
   Clipboard.SetDataObject(rasterImageViewer1.Image, True) 
             
   ' Update the user interface 
   UpdateMyUserInterface() 
End Sub 
             
Private Sub pasteButton_Click(ByVal sender As Object, ByVal e As EventArgs) 
   ' Paste the image from the clipboard into the viewer 
   Dim data As IDataObject = Clipboard.GetDataObject() 
   rasterImageViewer1.Image = CType(data.GetData(GetType(RasterImage)), RasterImage) 
             
   ' Update the user interface 
   UpdateMyUserInterface() 
End Sub

using System; 
using System.Windows.Forms; 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.WinForms; 
             
private Panel panel1; 
private Button loadButton; 
private Button clearButton; 
private Button copyButton; 
private Button pasteButton; 
private RasterImageViewer rasterImageViewer1; 
private RasterCodecs codecs1; 
             
private void ClipboardTest() 
{ 
   // Add the controls to the form 
   // 1. RasterImageViewer control 
   // 2. Load button to load an image into the viewer 
   // 3. Clear button to reset the viewer's image. 
   // 3. Copy button to copy the image to the clipboard 
   // 4. Paste button to paste the image from the clipboard to the viewer 
             
   // Create the controls 
             
   this.SuspendLayout(); 
             
   loadButton = new Button(); 
             
   panel1 = new Panel(); 
   panel1.Dock = DockStyle.Left; 
   panel1.Width = loadButton.Width; 
   this.Controls.Add(panel1); 
             
   loadButton.Text = "Load"; 
   loadButton.Location = new Point(0, 0); 
   panel1.Controls.Add(loadButton); 
   loadButton.BringToFront(); 
   loadButton.Click += new EventHandler(loadButton_Click); 
             
   clearButton = new Button(); 
   clearButton.Text = "Clear"; 
   clearButton.Location = new Point(0, loadButton.Bottom); 
   panel1.Controls.Add(clearButton); 
   clearButton.BringToFront(); 
   clearButton.Click += new EventHandler(clearButton_Click); 
             
   copyButton = new Button(); 
   copyButton.Text = "Copy"; 
   copyButton.Location = new Point(0, clearButton.Bottom); 
   panel1.Controls.Add(copyButton); 
   copyButton.BringToFront(); 
   copyButton.Click += new EventHandler(copyButton_Click); 
             
   pasteButton = new Button(); 
   pasteButton.Text = "Paste"; 
   pasteButton.Location = new Point(0, copyButton.Bottom); 
   panel1.Controls.Add(pasteButton); 
   pasteButton.BringToFront(); 
   pasteButton.Click += new EventHandler(pasteButton_Click); 
             
   rasterImageViewer1 = new RasterImageViewer(); 
   rasterImageViewer1.Dock = DockStyle.Fill; 
   Controls.Add(rasterImageViewer1); 
   rasterImageViewer1.BringToFront(); 
             
   this.ResumeLayout(); 
             
   // Initialize the codecs object 
   codecs1 = new RasterCodecs(); 
             
   // Update our user interface 
   UpdateMyUserInterface(); 
} 
             
private void UpdateMyUserInterface() 
{ 
   // Update the buttons depending on the application state 
             
   // The Clear button is enabled if we have an image 
   clearButton.Enabled = rasterImageViewer1.Image != null; 
             
   // The Copy button is enabled if we have an image 
   copyButton.Enabled = rasterImageViewer1.Image != null; 
             
   // The paste button is enabled if we have a valid clipboard format 
   IDataObject data = Clipboard.GetDataObject(); 
   pasteButton.Enabled = data.GetDataPresent(typeof(RasterImage)); 
} 
             
private void loadButton_Click(object sender, EventArgs e) 
{ 
   // Load a new image into the viewer 
   OpenFileDialog dlg = new OpenFileDialog(); 
   dlg.Filter = "All Files|*.*"; 
   if(dlg.ShowDialog(this) == DialogResult.OK) 
   { 
      try 
      { 
         rasterImageViewer1.Image = codecs1.Load(dlg.FileName); 
      } 
      catch(Exception ex) 
      { 
         MessageBox.Show(this, ex.Message); 
      } 
      finally 
      { 
         // Update the user interface 
         UpdateMyUserInterface(); 
      } 
   } 
} 
             
private void clearButton_Click(object sender, EventArgs e) 
{ 
   // Delete the image in the viewer 
   rasterImageViewer1.Image = null; 
             
   // Update the user interface 
   UpdateMyUserInterface(); 
} 
             
private void copyButton_Click(object sender, EventArgs e) 
{ 
   // Copy the image in the viewer into the clipboard 
   Clipboard.SetDataObject(rasterImageViewer1.Image, true); 
             
   // Update the user interface 
   UpdateMyUserInterface(); 
} 
             
private void pasteButton_Click(object sender, EventArgs e) 
{ 
   // Paste the image from the clipboard into the viewer 
   IDataObject data = Clipboard.GetDataObject(); 
   rasterImageViewer1.Image = data.GetData(typeof(RasterImage)) as RasterImage; 
             
   // Update the user interface 
   UpdateMyUserInterface(); 
}

Deriving from RasterImage and Serialization

The RasterImage class can be derived from to add user-defined functionality. Derived classes might need to add new class member variables to the class that define this new functionality. The author must add support for serializing these new class member variables in order to participate in the serialization process.

The following example shows MyRasterImage, a class that derives from RasterImage adding two new properties.

Imports System.IO 
Imports System.Runtime.Serialization 
Imports System.Runtime.Serialization.Formatters.Binary 
Imports Leadtools 
Imports Leadtools.Codecs 
             
Public Class MyRasterImage 
   Inherits RasterImage 
   ' Our new members 
   ' We are going to do the serialization ourselves 
   Private _myIntegerData As Integer 
   Private _myStringData As String 
             
   ' Accessors 
   Public Property MyIntegerData() As Integer 
      Get 
          Return _myIntegerData 
      End Get 
      Set(ByVal Value As Integer) 
         _myIntegerData = Value 
      End Set 
   End Property 
             
   Public Property MyStringData() As String 
      Get 
         Return _myStringData 
      End Get 
      Set(ByVal Value As String) 
         _myStringData = Value 
      End Set 
   End Property 
             
   ' Constructor 
   Public Sub New(ByVal src As RasterImage) 
      MyBase.New(src) 
             
      _myIntegerData = 0 
      _myStringData = String.Empty 
   End Sub 
             
   ' Serialization code 
   Protected Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext) 
      MyBase.New(info, context) 
             
      ' Load our data 
      _myIntegerData = info.GetInt32("MyIntegerData") 
      _myStringData = info.GetString("MyStringData") 
   End Sub 
             
   Public Overrides Sub GetObjectData(ByVal info As SerializationInfo, ByVal context As StreamingContext) 
      ' Always call the base method 
      MyBase.GetObjectData(info, context) 
             
      ' Save our data 
      info.AddValue("MyIntegerData", _myIntegerData) 
      info.AddValue("MyStringData", _myStringData) 
   End Sub 
End Class 
             
Private Sub MyRasterImageTest() 
   ' Load an image 
   Dim codecs As New RasterCodecs 
             
   Dim img As RasterImage = codecs.Load("C:\LEADTOOLS21\Resources\Images\Image1.cmp") 
             
   ' create a new MyRasterImage instance out of this image 
   Dim myImage As MyRasterImage = New MyRasterImage(img) 
             
   ' Set custom data 
   myImage.MyIntegerData = 10 
   myImage.MyStringData = "My string" 
   Dim msg As String = String.Format("Before serialization.  MyIntegerData = {0}, MyStringData = {1}", myImage.MyIntegerData, myImage.MyStringData) 
   MessageBox.Show(msg) 
             
   ' img is invalid now and should be disposed 
   img.Dispose() 
             
   ' Serialize myImage 
   Dim formatter As New BinaryFormatter 
   Dim ms As New MemoryStream 
   formatter.Serialize(ms, myImage) 
             
   ' dispose myImage 
   myImage.Dispose() 
   myImage = Nothing 
             
   ' Deserialize back from the stream 
   ms.Position = 0 
   myImage = DirectCast(formatter.Deserialize(ms), MyRasterImage) 
             
   msg = String.Format("After serialization.  MyIntegerData = {0}, MyStringData = {1}", myImage.MyIntegerData, myImage.MyStringData) 
   MessageBox.Show(msg) 
             
   ' Clean up 
   ms.Close() 
   myImage.Dispose() 
   codecs.Dispose() 
End Sub

using System.IO; 
using System.Runtime.Serialization; 
using System.Runtime.Serialization.Formatters.Binary; 
using Leadtools; 
using Leadtools.Codecs; 
             
[Serializable] 
public class MyRasterImage : RasterImage 
{ 
   // Our new members 
   // We are going to do the serialization ourselves 
   [NonSerialized] private int _myIntegerData; 
   [NonSerialized] private string _myStringData; 
             
   // Accessors 
   public int MyIntegerData 
   { 
      get 
      { 
         return _myIntegerData; 
      } 
      set 
      { 
         _myIntegerData = value; 
      } 
   } 
             
   public string MyStringData 
   { 
      get 
      { 
         return _myStringData; 
      } 
      set 
      { 
         _myStringData = value; 
      } 
   } 
             
   // Constructor 
   public MyRasterImage(RasterImage src) : 
   base(src) 
   { 
      _myIntegerData = 0; 
      _myStringData = string.Empty; 
   } 
             
   // Serialization code 
   protected MyRasterImage(SerializationInfo info, StreamingContext context) : 
   base(info, context) 
   { 
      // Load our data 
      _myIntegerData = info.GetInt32("MyIntegerData"); 
      _myStringData = info.GetString("MyStringData"); 
   } 
             
   public override void GetObjectData(SerializationInfo info, StreamingContext context) 
   { 
      // Always call the base method 
      base.GetObjectData(info, context); 
             
      // Save our data 
      info.AddValue("MyIntegerData", _myIntegerData); 
      info.AddValue("MyStringData", _myStringData); 
   } 
} 
             
private void MyRasterImageTest() 
{ 
   // Load an image 
   RasterCodecs codecs = new RasterCodecs(); 
             
   RasterImage img = codecs.Load(@"C:\LEADTOOLS21\Resources\Images\Image1.cmp"); 
             
   // create a new MyRasterImage instance out of this image 
   MyRasterImage myImage = new MyRasterImage(img); 
             
   // Set custom data 
   myImage.MyIntegerData = 10; 
   myImage.MyStringData = "My string"; 
   string msg = string.Format("Before serialization.  MyIntegerData = {0}, MyStringData = {1}", myImage.MyIntegerData, myImage.MyStringData); 
   MessageBox.Show(msg); 
             
   // img is invalid now and should be disposed 
   img.Dispose(); 
             
   // Serialize myImage 
   BinaryFormatter formatter = new BinaryFormatter(); 
   MemoryStream ms = new MemoryStream(); 
   formatter.Serialize(ms, myImage); 
             
   // dispose myImage 
   myImage.Dispose(); 
   myImage = null; 
             
   // Deserialize back from the stream 
   ms.Position = 0; 
   myImage = formatter.Deserialize(ms) as MyRasterImage; 
             
   msg = string.Format("After serialization.  MyIntegerData = {0}, MyStringData = {1}", myImage.MyIntegerData, myImage.MyStringData); 
   MessageBox.Show(msg); 
             
   // Clean up 
   ms.Close(); 
   myImage.Dispose(); 
   codecs.Dispose(); 
}