ReadThumbnail(String,CodecsThumbnailOptions,Int32) Method

Creates a thumbnail from the specified image file.

Syntax

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public RasterImage ReadThumbnail( 
   string fileName,
   CodecsThumbnailOptions options,
   int pageNumber
)

'Declaration
 
Public Overloads Function ReadThumbnail( _
   ByVal fileName As String, _
   ByVal options As CodecsThumbnailOptions, _
   ByVal pageNumber As Integer _
) As RasterImage

'Usage
 
Dim instance As RasterCodecs
Dim fileName As String
Dim options As CodecsThumbnailOptions
Dim pageNumber As Integer
Dim value As RasterImage
 
value = instance.ReadThumbnail(fileName, options, pageNumber)

public RasterImage ReadThumbnail( 
   string fileName,
   CodecsThumbnailOptions options,
   int pageNumber
)

 function Leadtools.Codecs.RasterCodecs.ReadThumbnail(String,CodecsThumbnailOptions,Int32)( 
   fileName ,
   options ,
   pageNumber 
)

public:
RasterImage^ ReadThumbnail( 
   String^ fileName,
   CodecsThumbnailOptions options,
   int pageNumber
)

Parameters

fileName: A System.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 Leadtools.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(String,Int32).

Example

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

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

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";
}

RasterCodecsExamples.prototype.ReadThumbnailExample = function () {
   Tools.SetLicense();
   with (Leadtools) {
      with (Leadtools.Codecs) {
         var codecs = new RasterCodecs();

         var srcFileName = "Assets\\Image1.cmp";
         var thumbnail;
         var loadFile;
         // Create a thumbnail with default options 
         var options = new CodecsThumbnailOptions();
         options.loadStamp = false;
         return Tools.AppInstallFolder().getFileAsync(srcFileName).then(function (loadFileX) {
            loadFile = loadFileX;
            return codecs.readThumbnailAsync(LeadStreamFactory.create(loadFile), options, 1)
         })
         .then(function (thumb) {
            thumbnail = thumb;

            console.info("Thumbnail with default option:");
            console.info("  Size: ", thumbnail.width, " by ", thumbnail.Height, "pixels. Bits/Pixel: ", thumbnail.bitsPerPixel);
            thumbnail.close();

            // Create a thumbnail with some options
            options.loadStamp = false;
            options.width = 40;
            options.height = 80;
            options.forceSize = true;
            options.maintainAspectRatio = false;
            options.backColor = RasterColorHelper.fromKnownColor(RasterKnownColor.lightBlue);
            options.bitsPerPixel = 8;
            return codecs.readThumbnailAsync(LeadStreamFactory.create(loadFile), options, 1)
         })
         .then(function (thumb2) {
            thumbnail = thumb2;

            console.info("Thumbnail with set option (size: ", options.width, " by ", options.height, ", Bits/Pixel: ", options.bitsPerPixel, ", ForeSize: ", options.forceSize);
            console.info("  Size: ", thumbnail.width, " by ", thumbnail.height, " pixels. Bits/Pixel: ", thumbnail.bitsPerPixel);
            thumbnail.close();

            codecs.close();
         });
      }
   }
}

[TestMethod]
public async Task ReadThumbnailExample()
{
   RasterCodecs codecs = new RasterCodecs();
   string srcFileName = @"Assets\Image1.cmp";

   // Create a thumbnail with default options 
   CodecsThumbnailOptions options = new CodecsThumbnailOptions();
   options.LoadStamp = false;
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName);
   RasterImage thumbnail = await codecs.ReadThumbnailAsync(LeadStreamFactory.Create(loadFile), 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 = RasterColorHelper.FromKnownColor(RasterKnownColor.LightBlue);
   options.BitsPerPixel = 8;
   thumbnail = await codecs.ReadThumbnailAsync(LeadStreamFactory.Create(loadFile), 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();

   codecs.Dispose();
}

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();
}

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(&H00, &H00, &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: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RasterCodecs Class
RasterCodecs Members
Overload List
Thumbnail Browser