Leadtools.Codecs Send comments on this topic. | Back to Introduction - All Topics | Help Version 16.5.9.25
LoadInformation Event
See Also  Example
Leadtools.Codecs Namespace > RasterCodecs Class : LoadInformation Event



Occurs during loading of a file for which LEADTOOLS cannot recognize the format.

Syntax

Visual Basic (Declaration) 
Public Event LoadInformation() As EventHandler(Of CodecsLoadInformationEventArgs)
Visual Basic (Usage)Copy Code
Dim instance As RasterCodecs
Dim handler As EventHandler(Of CodecsLoadInformationEventArgs)
 
AddHandler instance.LoadInformation, handler
C# 
public event EventHandler<CodecsLoadInformationEventArgs> LoadInformation()
C++/CLI 
public:
event EventHandler<CodecsLoadInformationEventArgs>^ LoadInformation();

Example

This example demonstrates saving and loading raw/headerless image files.

Visual BasicCopy Code
Private Structure RawData
   Public Width As Integer ' Width of image
   Public Height As Integer ' Height of image
   Public BitsPerPixel As Integer ' Bits per pixel of image--if palettized, a gray palette is generated
   Public ViewPerspective As RasterViewPerspective ' View perspective of raw data (TopLeft, BottomLeft, etc)
   Public Order As RasterByteOrder ' Rgb or Bgr
   Public XResolution As Integer ' Horizontal resolution in DPI
   Public YResolution As Integer ' Vertical resolution in DPI
   Public Offset As Integer ' Offset into file where raw data begins
   Public Padding As Boolean ' true if each line of data is padded to four bytes
   Public ReverseBits As Boolean ' true if the bits of each byte are reversed
End Structure
Private myRawData As RawData

Private Sub codecs_LoadInformation(ByVal sender As Object, ByVal e As CodecsLoadInformationEventArgs)
   ' Set the information
   e.Format = RasterImageFormat.Raw
   e.Width = myRawData.Width
   e.Height = myRawData.Height
   e.BitsPerPixel = myRawData.BitsPerPixel
   e.XResolution = myRawData.XResolution
   e.YResolution = myRawData.YResolution
   e.Offset = myRawData.Offset

   If myRawData.Padding Then
      e.Pad4 = True
   End If

   e.Order = myRawData.Order

   If myRawData.ReverseBits Then
      e.LeastSignificantBitFirst = True
   End If

   e.ViewPerspective = myRawData.ViewPerspective

   ' If image is palettized create a grayscale palette
   If e.BitsPerPixel <= 8 Then
      Dim colors As Integer = 1 << e.BitsPerPixel
      Dim palette As RasterColor() = New RasterColor(colors - 1) {}
      Dim i As Integer = 0
      Do While i < palette.Length
         Dim val As Byte = CByte((i * 255) / (colors - 1))
         palette(i) = New RasterColor(val, val, val)
         i += 1
      Loop

      e.SetPalette(palette)
   End If
End Sub


Public Sub LoadInformationExample()
   RasterCodecs.Startup()
   Dim codecs As RasterCodecs = New RasterCodecs()

   ' First, load a JPEG or CMP file
   Dim srcFilename As String = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"
   Dim rawFileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.raw"
   Dim image As RasterImage = codecs.Load(srcFilename)

   ' Save this image as RAW data

   ' Set RAW options
   codecs.Options.Raw.Save.Pad4 = True
   codecs.Options.Raw.Save.ReverseBits = True
   codecs.Options.Save.OptimizedPalette = True

   codecs.Save(image, rawFileName, RasterImageFormat.Raw, 0)

   ' Save information about this image so we can use it to load the RAW file
   myRawData = New RawData()
   myRawData.Width = image.Width
   myRawData.Height = image.Height
   myRawData.BitsPerPixel = image.BitsPerPixel
   myRawData.ViewPerspective = image.ViewPerspective
   myRawData.Order = image.Order
   myRawData.XResolution = image.XResolution
   myRawData.YResolution = image.YResolution
   myRawData.Offset = 0
   myRawData.Padding = True
   myRawData.ReverseBits = True

   ' We dont need the image anymore
   image.Dispose()

   ' Now load this RAW image back

   ' First subscribe to the LoadInformation event so we can set the image information
   AddHandler codecs.LoadInformation, AddressOf codecs_LoadInformation

   ' Load the image
   image = codecs.Load(rawFileName)

   ' Unsubscribe from the event
   RemoveHandler codecs.LoadInformation, AddressOf codecs_LoadInformation

   ' save it as bmp for testing
   codecs.Save(image, LeadtoolsExamples.Common.ImagesPath.Path + "Image1_raw.bmp", RasterImageFormat.Bmp, 0)

   ' Clean up
   image.Dispose()
   codecs.Dispose()
   RasterCodecs.Shutdown()
End Sub
C#Copy Code
private struct RawData 
{ 
   public int Width;                               // Width of image 
   public int Height;                              // Height of image 
   public int BitsPerPixel;                        // Bits per pixel of image--if palettized, a gray palette is generated 
   public RasterViewPerspective ViewPerspective;   // View perspective of raw data (TopLeft, BottomLeft, etc) 
   public RasterByteOrder Order;                   // Rgb or Bgr 
   public int XResolution;                         // Horizontal resolution in DPI 
   public int YResolution;                         // Vertical resolution in DPI 
   public int Offset;                              // Offset into file where raw data begins 
   public bool Padding;                            // true if each line of data is padded to four bytes 
   public bool ReverseBits;                        // true if the bits of each byte are reversed  
} 
private RawData myRawData; 
 
private void codecs_LoadInformation(object sender, CodecsLoadInformationEventArgs e) 
{ 
   // Set the information 
   e.Format = RasterImageFormat.Raw; 
   e.Width = myRawData.Width; 
   e.Height = myRawData.Height; 
   e.BitsPerPixel = myRawData.BitsPerPixel; 
   e.XResolution = myRawData.XResolution; 
   e.YResolution = myRawData.YResolution; 
   e.Offset = myRawData.Offset; 
 
   if(myRawData.Padding) 
      e.Pad4 = true; 
 
   e.Order = myRawData.Order; 
 
   if(myRawData.ReverseBits) 
      e.LeastSignificantBitFirst = true; 
 
   e.ViewPerspective = myRawData.ViewPerspective; 
 
   // If image is palettized create a grayscale palette 
   if(e.BitsPerPixel <= 8) 
   { 
      int colors = 1 << e.BitsPerPixel; 
      RasterColor[] palette = new RasterColor[colors]; 
      for(int i = 0; i < palette.Length; i++) 
      { 
         byte val = (byte)((i * 255) / (colors - 1)); 
         palette[i] = new RasterColor(val, val, val); 
      } 
 
      e.SetPalette(palette); 
   } 
} 
 
 
public void LoadInformationExample() 
{ 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
 
   // First, load a JPEG or CMP file 
   string srcFilename = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.cmp"; 
   string rawFileName = LeadtoolsExamples.Common.ImagesPath.Path + "Image1.raw"; 
   RasterImage image = codecs.Load(srcFilename); 
 
   // Save this image as RAW data 
 
   // Set RAW options 
   codecs.Options.Raw.Save.Pad4 = true; 
   codecs.Options.Raw.Save.ReverseBits = true; 
   codecs.Options.Save.OptimizedPalette = true; 
 
   codecs.Save(image, rawFileName, RasterImageFormat.Raw, 0); 
 
   // Save information about this image so we can use it to load the RAW file 
   myRawData = new RawData(); 
   myRawData.Width = image.Width; 
   myRawData.Height = image.Height; 
   myRawData.BitsPerPixel = image.BitsPerPixel; 
   myRawData.ViewPerspective = image.ViewPerspective; 
   myRawData.Order = image.Order; 
   myRawData.XResolution = image.XResolution; 
   myRawData.YResolution = image.YResolution; 
   myRawData.Offset = 0; 
   myRawData.Padding = true; 
   myRawData.ReverseBits = true; 
 
   // We dont need the image anymore 
   image.Dispose(); 
 
   // Now load this RAW image back 
 
   // First subscribe to the LoadInformation event so we can set the image information 
   codecs.LoadInformation += new EventHandler<CodecsLoadInformationEventArgs>(codecs_LoadInformation); 
 
   // Load the image 
   image = codecs.Load(rawFileName); 
 
   // Unsubscribe from the event 
   codecs.LoadInformation -= new EventHandler<CodecsLoadInformationEventArgs>(codecs_LoadInformation); 
 
   // save it as bmp for testing 
   codecs.Save(image,  LeadtoolsExamples.Common.ImagesPath.Path + "Image1_raw.bmp", RasterImageFormat.Bmp, 0); 
 
   // Clean up 
   image.Dispose(); 
   codecs.Dispose(); 
   RasterCodecs.Shutdown(); 
}

Remarks

The LoadInformation event will occur when LEADTOOLS cannot recognize the image file format during a call to GetInformation. This event can be used for loading raw FAX data (CCITT Group 3 or Group 4), raw run-length-encoded data (4-bit or 8-bit), raw Bitfield compressed data, raw PackBits compressed data or raw uncompressed data.

To load a raw fax file, you must subscribe to this event first. When the toolkit fails to recognize the image file format, it will fire this event. If you know the size of the fax image, then set the values in the CodecsLoadInformationEventArgs.Width and CodecsLoadInformationEventArgs.Height properties of the CodecsLoadInformationEventArgs passed as the event data. To automatically detect the width and height of the fax file, set CodecsLoadInformationEventArgs.Width and CodecsLoadInformationEventArgs.Height to -1.

To load raw uncompressed data, you must subscribe to this event first. When the toolkit fails to recognize the image file format, it will fire this event. Set the CodecsLoadInformationEventArgs.Format property to RasterImageFormat.Raw. Valid values must also be set for the following properties:

If each line of RAW data is padded so that the number of bytes is a multiple of 4 (as is the case with raw Windows BMP data), set CodecsLoadInformationEventArgs.Pad4 to true. Include an orientation in the CodecsLoadInformationEventArgs.ViewPerspective to load with the proper orientation. For example, raw Windows BMP data is stored with a RasterViewPerspective.BottomLeft orientation. If the orientation is unknown, then set it to RasterViewPerspective.BottomLeft. If the raw data is 8 bits per pixel or less, then the image is palettized and a palette must be generated. If this is the case, pass in a valid palette with 1 >gt; bits/pixel number of entries to the CodecsLoadInformationEventArgs.SetPalette method.

Set the correct color order in the CodecsLoadInformationEventArgs.Order property. For example, if the order of the data is BGR, then set this value to RasterByteOrder.Bgr.

For more information, refer to CodecsLoadInformationEventArgs.

Requirements

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

See Also