Create PDF content groups using PDF objects in C# and VB.NET

A content group (represented by the PdfContentGroup class) is a group of PdfContentElements that can be jointly transformed and/or clipped without affecting the rest of the content.

The following example shows how to create content groups and how transformation and clipping applied to a content group do not affect the content outside that group.

PDF content groups created with GemBox.Pdf C#/VB.NET library
Screenshot of PDF content groups created with GemBox.Pdf library
using GemBox.Pdf;
using GemBox.Pdf.Content;

class Program
{
    static void Main()
    {
        // If using Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        using (var document = new PdfDocument())
        {
            var page = document.Pages.Add();

            // Add a rectangle with a green fill whose bottom-left corner is at location (100, 450) from the bottom-left corner of the page.
            var path = page.Content.Elements.AddPath();
            path.AddRectangle(100, 450, 200, 100);
            var format = path.Format;
            format.Fill.IsApplied = true;
            format.Fill.Color = PdfColors.Green;

            // Add an outer group whose bottom-left corner is at the same location as the page's bottom-left corner.
            var outerGroup = page.Content.Elements.AddGroup();
            // Add an inner group whose bottom-left corner is at location (100, 250) from the bottom-left corner of the outer group/page.
            var innerGroup = outerGroup.Elements.AddGroup();
            innerGroup.Transform = PdfMatrix.CreateTranslation(100, 250);

            // Add a rectangle that clips its content and the content of all elements that come after it in the same group.
            // The bottom-left corner of the clipping rectangle is at location (50, -150) from the bottom-left corner of the inner group.
            // The clipping rectangle is also stroked to show that it goes over the first and the last rectangle from the main content group, but it doesn't clip them because they are in the main content group.
            var clippingPath = innerGroup.Elements.AddPath();
            clippingPath.AddRectangle(50, -150, 100, 400);
            format = clippingPath.Format;
            format.Clip.IsApplied = true;
            format.Stroke.IsApplied = true;
            format.Stroke.Width = 2;
            format.Stroke.DashPattern = PdfLineDashPatterns.Dash;

            // Add a rectangle with a red fill that gets clipped by the previous rectangle, thus making it a square.
            // The bottom-left corner is at the same location as the inner group's bottom-left corner.
            var clippedPath = innerGroup.Elements.AddPath();
            clippedPath.AddRectangle(0, 0, 200, 100);
            format = clippedPath.Format;
            format.Fill.IsApplied = true;
            format.Fill.Color = PdfColors.Red;

            // Add the same rectangle as the first one and move it down by 400 points.
            path = page.Content.Elements.AddClone(path);
            path.Subpaths.Transform(PdfMatrix.CreateTranslation(0, -400));

            document.Save("ContentGroups.%OutputFileType%");
        }
    }
}
Imports GemBox.Pdf
Imports GemBox.Pdf.Content

Module Program

    Sub Main()

        ' If using Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        Using document = New PdfDocument()

            Dim page = document.Pages.Add()

            ' Add a rectangle with a green fill whose bottom-left corner is at location (100, 450) from the bottom-left corner of the page.
            Dim path = page.Content.Elements.AddPath()
            path.AddRectangle(100, 450, 200, 100)
            Dim format = path.Format
            format.Fill.IsApplied = True
            format.Fill.Color = PdfColors.Green

            ' Add an outer group whose bottom-left corner is at the same location as the page's bottom-left corner.
            Dim outerGroup = page.Content.Elements.AddGroup()
            ' Add an inner group whose bottom-left corner is at location (100, 250) from the bottom-left corner of the outer group/page.
            Dim innerGroup = outerGroup.Elements.AddGroup()
            innerGroup.Transform = PdfMatrix.CreateTranslation(100, 250)

            ' Add a rectangle that clips its content and the content of all elements that come after it in the same group.
            ' The bottom-left corner of the clipping rectangle is at location (50, -150) from the bottom-left corner of the inner group.
            ' The clipping rectangle is also stroked to show that it goes over the first and the last rectangle from the main content group, but it doesn't clip them because they are in the main content group.
            Dim clippingPath = innerGroup.Elements.AddPath()
            clippingPath.AddRectangle(50, -150, 100, 400)
            format = clippingPath.Format
            format.Clip.IsApplied = True
            format.Stroke.IsApplied = True
            format.Stroke.Width = 2
            format.Stroke.DashPattern = PdfLineDashPatterns.Dash

            ' Add a rectangle with a red fill that gets clipped by the previous rectangle, thus making it a square.
            ' The bottom-left corner is at the same location as the inner group's bottom-left corner.
            Dim clippedPath = innerGroup.Elements.AddPath()
            clippedPath.AddRectangle(0, 0, 200, 100)
            format = clippedPath.Format
            format.Fill.IsApplied = True
            format.Fill.Color = PdfColors.Red

            ' Add the same rectangle as the first one and move it down by 400 points.
            path = page.Content.Elements.AddClone(path)
            path.Subpaths.Transform(PdfMatrix.CreateTranslation(0, -400))

            document.Save("ContentGroups.%OutputFileType%")
        End Using
    End Sub
End Module

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