Resolution Property

Visual Basic
C#
Objective-C
Java
C++

public int Resolution {get; set;}

'Declaration
 
Public Property Resolution As Integer

'Usage
 
Dim instance As PDFDocument
Dim value As Integer
 
instance.Resolution = value
 
value = instance.Resolution

public:
property int Resolution {
   int get();
   void set (    int value);
}

Property Value

A System.Int32 that specifies the resolution in dots per inch of this PDF document. The default value is the value of the static (Shared in Visual Basic) PDFDocument.DefaultResolution property.

A value of 0 means "Use current screen resolution", usually, 96. High resolution values will render the document with greater details at the expense of using more system resources. Typical resolution values are 72, 96, 150, 200, 300 and 600.

PDF documents do not have a resolution. Instead, all locations and sizes are stored in PDF units which equivalant to 1/72 of an inch. To convert a PDF unit to a physical value such as pixels, you must provide an external value for the resolution.

Physical values such as pixels are typically needed when a PDF document is rendered to the screen. To convert from logical to physical units, a resolution must be provided. Resolution is the value of dots (pixels) per inch to use when converting logical to physical values. For a example, if a PDF document has a page width and height of 612 by 792 units and the resolution value set in Resolution is 150, then:

The size of the page in inches is 8.5" by 11" - Obtained by dividing 612 and 792 by 72
The size of the page in pixels is 1275 by 1650 - Obtained by multiplying 8.5" and 11" by 150, the current resolution

The PDFDocumentPage.ConvertPoint and PDFDocumentPage.ConvertRect uses the value of Resolution when converting to and from pixels. Also, the GetPageImage method will also use this resolution when calculating the page size in pixels.

You can change the Resolution value at any time based on your need. For example, a PDF viewer may set Resolution to a low value, for example, 96, and calls GetPageImage to render the PDF page on the screen when the image is zoomed out and not alot of details will be viewed. When the user zooms in into the page, a higher quality with finer details is required, the viewer then can obtain a new version of the image with a higher resolution by setting a new value into Resolution, such as 200, and calling GetPageImage again.

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 PDFDocumentResolutionExample()
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "LEAD.pdf")
   Dim outFileName1 As String = Path.Combine(LEAD_VARS.ImagesDir, "PageAt150.png")
   Dim outFileName2 As String = Path.Combine(LEAD_VARS.ImagesDir, "PageAt300.png")

   ' Create a PDF document for file
   Using document As New PDFDocument(pdfFileName)

      ' Get the first page in the document
      Dim page As PDFDocumentPage = document.Pages(0)

      Using codecs As New RasterCodecs()
         ' Use a resolution of 150
         document.Resolution = 150
         Console.WriteLine("Page size in pixels at {0} is {1} by {2}", document.Resolution, page.WidthPixels, page.HeightPixels)

         ' Save this page at this resolution
         Using image As RasterImage = document.GetPageImage(codecs, 1)
            codecs.Save(image, outFileName1, RasterImageFormat.Png, 32)
         End Using

         ' Use a resolution of 300, the new size should be twice as much as the previous one
         document.Resolution = 300
         Console.WriteLine("Page size in pixels at {0} is {1} by {2}", document.Resolution, page.WidthPixels, page.HeightPixels)

         ' Save this page at this resolution
         Using image As RasterImage = document.GetPageImage(codecs, 1)
            codecs.Save(image, outFileName2, RasterImageFormat.Png, 32)
         End Using
      End Using

      ' Open both PNG files and notice that PageAt300.png has more details that PageAt150.png
   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 PDFDocumentResolutionExample()
{
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, @"LEAD.pdf");
   string outFileName1 = Path.Combine(LEAD_VARS.ImagesDir, @"PageAt150.png");
   string outFileName2 = Path.Combine(LEAD_VARS.ImagesDir, @"PageAt300.png");

   // Create a PDF document for file
   using(PDFDocument document = new PDFDocument(pdfFileName))
   {
      // Get the first page in the document
      PDFDocumentPage page = document.Pages[0];

      using(RasterCodecs codecs = new RasterCodecs())
      {
         // Use a resolution of 150
         document.Resolution = 150;
         Console.WriteLine("Page size in pixels at {0} is {1} by {2}", document.Resolution, page.WidthPixels, page.HeightPixels);

         // Save this page at this resolution
         using(RasterImage image = document.GetPageImage(codecs, 1))
         {
            codecs.Save(image, outFileName1, RasterImageFormat.Png, 32);
         }

         // Use a resolution of 300, the new size should be twice as much as the previous one
         document.Resolution = 300;
         Console.WriteLine("Page size in pixels at {0} is {1} by {2}", document.Resolution, page.WidthPixels, page.HeightPixels);

         // Save this page at this resolution
         using(RasterImage image = document.GetPageImage(codecs, 1))
         {
            codecs.Save(image, outFileName2, RasterImageFormat.Png, 32);
         }
      }

      // Open both PNG files and notice that PageAt300.png has more details that PageAt150.png
   }
}

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

Target Platforms

Reference

PDFDocument Class
PDFDocument Members