LoadInformation Event

Summary

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

Syntax

C++

Java

public event EventHandler<CodecsLoadInformationEventArgs> LoadInformation

Public Event LoadInformation As EventHandler(Of CodecsLoadInformationEventArgs)

synchronized public void addLoadInformationListener(CodecsLoadInformationListener listener) 
synchronized public void removeLoadInformationListener(CodecsLoadInformationListener listener)

public: 
event EventHandler<CodecsLoadInformationEventArgs^>^ LoadInformation

Event Data

The event handler receives an argument of type CodecsLoadInformationEventArgs containing data related to this event. The following CodecsLoadInformationEventArgs properties provide information specific to this event.

Property	Description
BitsPerPixel	Gets or sets the bits per pixel of the image data in the file.
Format	Gets the image file format.
Height	Gets or sets the image height in pixels.
LeastSignificantBitFirst	Gets or sets a value specifying whether the image data was saved with least significant bit first or last.
MotorolaOrder	Gets or sets a value that determines whether image data is in Motorola byte order.
Offset	Gets or sets the position of the first byte of image data.
Order	Gets or sets the byte order for the load process.
Pad4	Gets or sets a value indicating whether the image data was saved padded to 4-byte boundary.
PhotoInterpolation	Gets or sets the photometric interpolation for the load process.
PlanarConfiguration	Gets or sets the planar configuration.
Reverse	Gets or sets a value that determines whether each line is reversed (mirrored).
Signed	Gets or sets a value that determines whether the image data is signed.
Stream	Gets the stream used by the load process.
StripSize	Gets or sets the size of the data strip before it is decompressed.
ViewPerspective	Gets or sets the view perspective for the load process.
WhiteOnBlack	Gets or sets a value that determines if the image is black-on-white or white on black.
Width	Gets or sets the image width in pixels.
XResolution	Gets or sets the horizontal resolution for rendering the image, specified in dots per inch.
YResolution	Gets or sets the vertical resolution for rendering the image, specified in dots per inch.

Remarks

The LoadInformation event will occur when LEADTOOLS cannot recognize the image file format during a call to GetInformation or GetInformationAsync. 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:

CodecsLoadInformationEventArgs.Width
CodecsLoadInformationEventArgs.Height
CodecsLoadInformationEventArgs.BitsPerPixel
CodecsLoadInformationEventArgs.Offset (byte location in file where raw data begins)

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 << bits/pixel (2 ^ BitsPerPixel) 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.

Example

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

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
 
 
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 codecs = new RasterCodecs(); 
 
	// First, load a JPEG or CMP file 
	string srcFilename = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
	string rawFileName = Path.Combine(LEAD_VARS.ImagesDir, "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, Path.Combine(LEAD_VARS.ImagesDir, "Image1_raw.bmp"), RasterImageFormat.Bmp, 0); 
 
	// Clean up 
	image.Dispose(); 
	codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterCodecs Class

RasterCodecs Members

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Help Version 21.0.2021.7.2

Leadtools.Codecs Assembly

Introduction

Getting Started

Namespaces

Leadtools.Codecs Namespace

Assemblies