How to compress a PDF using C# and VB.NET
The Syncfusion Essential PDF is a feature-rich and high-performance .NET PDF library used to create, read, and edit PDF documents programmatically without Adobe dependencies. This library also offers functionality to merge, split, stamp, forms, compress, and secure PDF files.
Using this library, you can optimize or reduce a PDF file size in C# and VB.NET using different techniques as follows:
- Shrinking all images.
- Optimizing fonts.
- Removing metadata.
- Optimizing incremental updates.
- Removing or flattening form fields.
- Removing or flattening annotation.
Steps to compress the PDF programmatically:
- Create a new C# Windows Forms application project.
- Install the Syncfusion.Pdf.WinForms NuGet package as a reference to your .NET standard applications from NuGet.org.
- Include the following namespaces in Form.cs file.
C#
using Syncfusion.Pdf; using Syncfusion.Pdf.Parsing;
VB.NET
Imports Syncfusion.Pdf Imports Syncfusion.Pdf.Parsing
- Use the following code snippet to compress the existing PDF document.
C#
// [C# Code]
//Loads an existing PDF document
PdfLoadedDocument loadedDocument = new PdfLoadedDocument(inputFile);
//Create a new PDF compression options
PdfCompressionOptions options = new PdfCompressionOptions();
//Compress image
options.CompressImages = true;
options.ImageQuality = 50;
//Compress the font data
options.OptimizeFont = true;
//Compress the page contents
options.OptimizePageContents = true;
//Remove the metadata information
options.RemoveMetadata = true;
//Set the options to loaded PDF document
loadedDocument.CompressionOptions = options;
//Restructure the document
loadedDocument.FileStructure.IncrementalUpdate = false;
//Remove form fields and its data
RemoveFormFields(loadedDocument, false);
//Remove annotation and its data
RemoveAnnotations(loadedDocument, false);
//Save the document
loadedDocument.Save("Sample.pdf");
//Close the document
loadedDocument.Close(true);
//This will open the PDF file so, the result will be seen in default PDF viewer
Process.Start("Sample.pdf");
//Remove form fields and its data
Private void RemoveFormFields(PdfLoadedDocument loadedDocument, bool value)
{
if (!value)
{
int totalFieldCount = loadedDocument.Form.Fields.Count;
for (int i = totalFieldCount-1; i >= 0; i--)
{
PdfField field = loadedDocument.Form.Fields[i] as PdfField;
if (field != null)
{
loadedDocument.Form.Fields.Remove(field);
}
}
}
}
//Remove the annotation and its data
private void RemoveAnnotations(PdfLoadedDocument loadedDocument, bool value)
{
if (!value)
{
PdfLoadedAnnotationCollection collection = null;
for (int j = 0; j < loadedDocument.Pages.Count; j++)
{
collection = loadedDocument.Pages[j].Annotations;
int totalAnnotationCount = collection.Count;
for (int i = totalAnnotationCount-1; i >=0 ; i--)
{
collection.RemoveAt(i);
}
}
}
}
VB.NET
' [VB Code]
'Loads an existing PDF document
Dim loadedDocument As New PdfLoadedDocument(inputFile)
'Create a new PDF compression options
Dim options As New PdfCompressionOptions()
'Compress image
options.CompressImages = True
options.ImageQuality = 50
'Compress the font data
options.OptimizeFont = True
'Compress the page contents
options.OptimizePageContents = True
'Remove the metadata information
options.RemoveMetadata = True
'Set the options to loaded PDF document
loadedDocument.CompressionOptions = options
'Restructure the document
loadedDocument.FileStructure.IncrementalUpdate = False
'Remove form fields and its data
RemoveFormFields(loadedDocument, False)
'Remove annotation and its data
RemoveAnnotations(loadedDocument, False)
'Save the document
loadedDocument.Save("Sample.pdf")
'Close the document
loadedDocument.Close(True)
'This will open the PDF file so, the result will be seen in default PDF viewer
Process.Start("Sample.pdf")
'Remove form fields and its data
Private Sub RemoveAnnotations(loadedDocument As PdfLoadedDocument, value As Boolean)
If Not value Then
Dim collection As PdfLoadedAnnotationCollection = Nothing
For j As Integer = 0 To loadedDocument.Pages.Count - 1
collection = loadedDocument.Pages(j).Annotations
Dim totalAnnotationCount As Integer = collection.Count
For i As Integer = totalAnnotationCount - 1 To 0 Step -1
collection.RemoveAt(i)
Next
Next
End If
End Sub
'Remove form fields and its data
Private Sub RemoveFormFields(loadedDocument As PdfLoadedDocument, value As Boolean)
If Not value Then
Dim totalFieldCount As Integer = loadedDocument.Form.Fields.Count
For i As Integer = totalFieldCount - 1 To 0 Step -1
Dim field As PdfField = TryCast(loadedDocument.Form.Fields(i), PdfField)
If field IsNot Nothing Then
loadedDocument.Form.Fields.Remove(field)
End If
Next
End If
End Sub
A complete work sample can be downloaded from OptimizePDFSample.Zip.
By executing the program, the original PDF document size is reduced, and you will get the optimized PDF.
Take a moment to peruse the documentation, where you will find other options like compressing images with image quality, optimizing embedded fonts, optimizing page contents, and removing metadata information with code examples.
An online sample link to compress existing PDF Click here to explore the rich set of Syncfusion Essential PDF features.
Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, include a license key in your projects. Refer to link to learn about generating and registering Syncfusion license key in your application to use the components without trail message.
