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ReadThumbnail(string,CodecsThumbnailOptions,int) Method

Summary

Creates a thumbnail from the specified image file.

Syntax
C#
VB
Objective-C
C++
public RasterImage ReadThumbnail( 
   string fileName, 
   CodecsThumbnailOptions options, 
   int pageNumber 
) 
Public Overloads Function ReadThumbnail( _ 
   ByVal fileName As String, _ 
   ByVal options As CodecsThumbnailOptions, _ 
   ByVal pageNumber As Integer _ 
) As RasterImage 
- (nullable LTRasterImage *)readThumbnailFromFile:(NSString *)file  
                                          options:(LTCodecsThumbnailOptions *)thumbnailOptions  
                                       pageNumber:(NSInteger)pageNumber  
                                            error:(NSError **)error 
public: 
RasterImage^ ReadThumbnail(  
   String^ fileName, 
   CodecsThumbnailOptions options, 
   int pageNumber 
)  

Parameters

fileName
A String containing the name of the file from which the thumbnail image will be created.

options
Options for creating the thumbnail image.

pageNumber
1-based index of the page from which the thumbnail image should be created.

Return Value

The RasterImage object that this method creates.

Remarks

This method will always return a thumbnail image. Depending on the options passed, this method might read the stamp stored inside EXIF, CMP, JFIF and FlashPix files and return that. To read the file stamp only, use ReadStamp.

Example

This example will read a thumbnail from a CMP file

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
using LeadtoolsExamples.Common; 
 
public void ReadThumbnailExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
 
   // Create a thumbnail with default options 
   CodecsThumbnailOptions options = CodecsThumbnailOptions.Default; 
   options.LoadStamp = false; 
   RasterImage thumbnail = codecs.ReadThumbnail(srcFileName, options, 1); 
 
   Console.WriteLine("Thumbnail with default option:"); 
   Console.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel); 
   thumbnail.Dispose(); 
 
   // Create a thumbnail with some options 
   options.LoadStamp = false; 
   options.Width = 40; 
   options.Height = 80; 
   options.ForceSize = true; 
   options.MaintainAspectRatio = false; 
   options.BackColor = RasterColor.FromKnownColor(RasterKnownColor.LightBlue); 
   options.BitsPerPixel = 8; 
   thumbnail = codecs.ReadThumbnail(srcFileName, options, 1); 
 
   Console.WriteLine("Thumbnail with set option (size: {0} by {1}, Bits/Pixel: {2}, ForeSize: {3}", 
      options.Width, options.Height, options.BitsPerPixel, options.ForceSize); 
   Console.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel); 
   thumbnail.Dispose(); 
 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Sub ReadThumbnailExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
 
   Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp") 
 
   ' Create a thumbnail with default options 
   Dim options As CodecsThumbnailOptions = CodecsThumbnailOptions.Default 
   options.LoadStamp = False 
   Dim thumbnail As RasterImage = codecs.ReadThumbnail(srcFileName, options, 1) 
 
   Console.WriteLine("Thumbnail with default option:") 
   Console.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel) 
   thumbnail.Dispose() 
 
   ' Create a thumbnail with some options 
   options.LoadStamp = False 
   options.Width = 40 
   options.Height = 80 
   options.ForceSize = True 
   options.MaintainAspectRatio = False 
   options.BackColor = RasterColor.FromKnownColor(RasterKnownColor.LightBlue) 
   options.BitsPerPixel = 8 
   thumbnail = codecs.ReadThumbnail(srcFileName, options, 1) 
 
   Console.WriteLine("Thumbnail with set option (size: {0} by {1}, Bits/Pixel: {2}, ForeSize: {3}", options.Width, options.Height, options.BitsPerPixel, options.ForceSize) 
   Console.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel) 
   thumbnail.Dispose() 
 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 
c#[Silverlight C# Example] 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Examples; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Windows.Media; 
 
public void ReadThumbnailExample(Stream inStreamCmp) 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   // Create a thumbnail with default options 
   CodecsThumbnailOptions options = CodecsThumbnailOptions.Default; 
   options.LoadStamp = false; 
   RasterImage thumbnail = codecs.ReadThumbnail(inStreamCmp, options, 1); 
 
   Debug.WriteLine("Thumbnail with default option:"); 
   Debug.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel); 
   thumbnail.Dispose(); 
 
   // Create a thumbnail with some options 
   options.LoadStamp = false; 
   options.Width = 40; 
   options.Height = 80; 
   options.ForceSize = true; 
   options.MaintainAspectRatio = false; 
   options.BackColor = new RasterColor(0x00, 0x00, 0x7F); 
   options.BitsPerPixel = 8; 
   thumbnail = codecs.ReadThumbnail(inStreamCmp, options, 1); 
 
   Debug.WriteLine("Thumbnail with set option (size: {0} by {1}, Bits/Pixel: {2}, ForeSize: {3}", 
      options.Width, options.Height, options.BitsPerPixel, options.ForceSize); 
   Debug.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel); 
   thumbnail.Dispose(); 
} 
vb[Silverlight VB Example] 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Windows.Media 
 
Public Sub ReadThumbnailExample(ByVal inStreamCmp As Stream) 
   Dim codecs As RasterCodecs = New RasterCodecs() 
 
   ' Create a thumbnail with default options 
   Dim options As CodecsThumbnailOptions = CodecsThumbnailOptions.Default 
   options.LoadStamp = False 
   Dim thumbnail As RasterImage = codecs.ReadThumbnail(inStreamCmp, options, 1) 
 
   Debug.WriteLine("Thumbnail with default option:") 
   Debug.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel) 
   thumbnail.Dispose() 
 
   ' Create a thumbnail with some options 
   options.LoadStamp = False 
   options.Width = 40 
   options.Height = 80 
   options.ForceSize = True 
   options.MaintainAspectRatio = False 
   options.BackColor = New RasterColor(&H0, &H0, &H7F) 
   options.BitsPerPixel = 8 
   thumbnail = codecs.ReadThumbnail(inStreamCmp, options, 1) 
 
   Debug.WriteLine("Thumbnail with set option (size: {0} by {1}, Bits/Pixel: {2}, ForeSize: {3}", options.Width, options.Height, options.BitsPerPixel, options.ForceSize) 
   Debug.WriteLine("  Size: {0} by {1} pixels. Bits/Pixel: {2}", thumbnail.Width, thumbnail.Height, thumbnail.BitsPerPixel) 
   thumbnail.Dispose() 
End Sub 

Requirements

Target Platforms

Help Version 20.0.2019.3.11
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Leadtools.Codecs Assembly