GetThumbnail Method

Visual Basic
C#
Objective-C
Java
C++

public RasterImage GetThumbnail( 
   RasterCodecs codecs,
   int pageNumber,
   int thumbnailWidth,
   int thumbnailHeight
)

'Declaration
 
Public Function GetThumbnail( _
   ByVal codecs As RasterCodecs, _
   ByVal pageNumber As Integer, _
   ByVal thumbnailWidth As Integer, _
   ByVal thumbnailHeight As Integer _
) As RasterImage

'Usage
 
Dim instance As PDFDocument
Dim codecs As RasterCodecs
Dim pageNumber As Integer
Dim thumbnailWidth As Integer
Dim thumbnailHeight As Integer
Dim value As RasterImage
 
value = instance.GetThumbnail(codecs, pageNumber, thumbnailWidth, thumbnailHeight)

public:
RasterImage^ GetThumbnail( 
   RasterCodecs^ codecs,
   int pageNumber,
   int thumbnailWidth,
   int thumbnailHeight
)

Parameters

codecs: An optional Leadtools.Codecs.RasterCodecs to use when reading the page. If you pass a null reference (Nothing in Visual Basic), then this method will internall create a new Leadtools.Codecs.RasterCodecs object and dispose before it returns.
pageNumber: The 1-based page number. Must be greater than or equal to 1 and less than or equal to the total number of pages in the document (Pages.Count). You can use the special value of -1 to donate "last page in the document".
thumbnailWidth: The desired maximum width of the thumbnail image in pixels. Must be greater than 32.
thumbnailHeight: The desired maximum height of the thumbnail image in pixels. Must be greater than 32.

Return Value

A new Leadtools.RasterImage that is the thumbnail image.

If the page width and height is less than thumbnailWidth and thumbnailHeight, then this method returns an in the original size.

If the page width or height is greater than thumbnailWidth and thumbnailHeight, then this method will return the biggest thumbnail it can fit into the dimensions specified by thumbnailWidth and thumbnailHeight, keeping the original image aspect ratio.

The result image will always have 24 bits per pixel and a resolution of 96 by 96 regardless of the value of Resolution set in this PDFDocument and will never return a thumbnail bigger than the original page size in pixels.

This method uses Leadtools.RasterImage.CalculatePaintModeRectangle(System.Int32,System.Int32,Leadtools.LeadRect,Leadtools.RasterPaintSizeMode,Leadtools.RasterPaintAlignMode,Leadtools.RasterPaintAlignMode) to calculate the thumbnail size and then the RasterCodecs.Load resize method to load the thumbnail with RasterSizeFlags.Resample will be used as the flags parameter.

Since a Leadtools.Codecs.RasterCodecs object is required by this method, you can either pass one through the codecs parameter and the method will use this object to load the page. This is helpful if you need to change the default Leadtools.Codecs.RasterCodecs load options or subscribe to any of the events that will occur during loading. If none of that is required, you can simply pass null (Nothing in Visual Basic) for the codecs parameter and this method will internally create, use and dispose a temporary Leadtools.Codecs.RasterCodecs object.

To get a render of the full size of any page in a PDF document, use GetPageImage.

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

Copy Code

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Pdf
Imports Leadtools.WinForms

Public Sub PDFDocumentGetThumbnailExample(ByVal imageList As RasterImageList)
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "LEAD.pdf")
   ' Open the document
   Using document As New PDFDocument(pdfFileName)

      Using codecs As RasterCodecs = New RasterCodecs()
         ' For each page...
         For i As Integer = 1 To document.Pages.Count
            ' Get the thumbnail of the page
            Dim image As RasterImage = document.GetThumbnail(codecs, i, 128, 128)

            ' Add it to the image list
            Dim item As New RasterImageListItem(image, 1, "Page " + i.ToString())
            imageList.Items.Add(item)
         Next
      End Using
   End Using
End Sub

Public NotInheritable Class LEAD_VARS
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Pdf;
using Leadtools.WinForms;

public void PDFDocumentGetThumbnailExample(RasterImageList imageList)
{
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, @"LEAD.pdf");
   // Open the document
   using(PDFDocument document = new PDFDocument(pdfFileName))
   {
      using(RasterCodecs codecs = new RasterCodecs())
      {
         // For each page...
         for(int i = 1; i <= document.Pages.Count; i++)
         {
            // Get the thumbnail of the page
            RasterImage image = document.GetThumbnail(codecs, i, 128, 128);

            // Add it to the image list
            RasterImageListItem item = new RasterImageListItem(image, 1, "Page " + i.ToString());
            imageList.Items.Add(item);
         }
      }
   }
}

static class LEAD_VARS
{
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

Target Platforms

Reference

PDFDocument Class
PDFDocument Members