Working with Layers
Layers, also known as Option Content refers to sections of content in a PDF document that can be selectively viewed or hidden by document authors or consumers. This capability is useful in items such as CAD drawings, layered artwork, maps, and multi-language documents.
Essential PDF provides support to create, add and merge the layers into PDF document.
Adding Layers in a PDF document
Essential PDF allows the users to create a layer in a PDF page using PdfPageLayer class. The below code snippet illustrates how to add the multiple layers in a new PDF document.
//Create PDF document.
PdfDocument document = new PdfDocument();
PdfPage page = document.Pages.Add();
//Add the first layer.
PdfPageLayer layer = page.Layers.Add("Layer1");
PdfGraphics graphics = layer.Graphics;
graphics.TranslateTransform(100, 60);
//Draw arc.
PdfPen pen = new PdfPen(System.Drawing.Color.Red, 50);
RectangleF bounds = new RectangleF(0, 0, 50, 50);
graphics.DrawArc(pen, bounds, 360, 360);
//Add another layer on the page.
PdfPageLayer layer2 = page.Layers.Add("Layer2");
graphics = layer2.Graphics;
graphics.TranslateTransform(100, 180);
//Draw ellipse.
graphics.DrawEllipse(pen, bounds);
//Save the document.
document.Save("Sample.pdf");
//Close the document
document.Close(true);'Create PDF document.
Dim document As New PdfDocument()
Dim page As PdfPage = document.Pages.Add()
'Add the first layer.
Dim layer As PdfPageLayer = page.Layers.Add("Layer1")
Dim graphics As PdfGraphics = layer.Graphics
graphics.TranslateTransform(100, 60)
'Draw arc.
Dim pen As New PdfPen(System.Drawing.Color.Red, 50)
Dim bounds As New RectangleF(0, 0, 50, 50)
graphics.DrawArc(pen, bounds, 360, 360)
'Add another layer on the page.
Dim layer2 As PdfPageLayer = page.Layers.Add("Layer2")
graphics = layer2.Graphics
graphics.TranslateTransform(100, 180)
'Draw ellipse.
graphics.DrawEllipse(pen, bounds)
'Save the document.
document.Save("Sample.pdf")
'Close the document
document.Close(True)The below code illustrates how to add the multiple layers in an existing PDF document.
//Load the existing PDF document.
PdfLoadedDocument loadedDocument = new PdfLoadedDocument(fileName);
PdfLoadedPage loadedPage = loadedDocument.Pages[0] as PdfLoadedPage;
//Add the first layer.
PdfPageLayer layer = loadedPage.Layers.Add("Layer1");
PdfGraphics graphics = layer.Graphics;
graphics.TranslateTransform(100, 60);
//Draw arc.
PdfPen pen = new PdfPen(System.Drawing.Color.Gray, 50);
RectangleF bounds = new RectangleF(0, 0, 50, 50);
graphics.DrawArc(pen, bounds, 360, 360);
//Add another layer on the page.
PdfPageLayer layer2 = loadedPage.Layers.Add("Layer2");
graphics = layer2.Graphics;
graphics.TranslateTransform(100, 180);
//Draw ellipse.
graphics.DrawEllipse(pen, bounds);
//Save the document.
loadedDocument.Save("Output.pdf");
//Close the document
loadedDocument.Close(true);'Load the existing PDF document.
Dim loadedDocument As New PdfLoadedDocument(fileName)
Dim loadedPage As PdfLoadedPage = TryCast(loadedDocument.Pages(0), PdfLoadedPage)
'Add the first layer.
Dim layer As PdfPageLayer = loadedPage.Layers.Add("Layer1")
Dim graphics As PdfGraphics = layer.Graphics
graphics.TranslateTransform(100, 60)
'Draw arc.
Dim pen As New PdfPen(System.Drawing.Color.Gray, 50)
Dim bounds As New RectangleF(0, 0, 50, 50)
graphics.DrawArc(pen, bounds, 360, 360)
'Add another layer on the page.
Dim layer2 As PdfPageLayer = loadedPage.Layers.Add("Layer2")
graphics = layer2.Graphics
graphics.TranslateTransform(100, 180)
'Draw ellipse.
graphics.DrawEllipse(pen, bounds)
'Save the document.
loadedDocument.Save("Output.pdf")
'Close the document
loadedDocument.Close(True)Adding annotation to layer
Essential PDF allows the users to add annotation to layers in the PDF document. Refer to the following code snippet.
//Create new PDF document
PdfDocument document = new PdfDocument();
//Add page
PdfPage page = document.Pages.Add();
//Add the layer
PdfLayer layer = document.Layers.Add("Layer");
//Create graphics for layer
PdfGraphics graphics = layer.CreateGraphics(page);
//Draw ellipse
graphics.DrawEllipse(PdfPens.Red, new RectangleF(50, 50, 40, 40));
//Create square annotation
PdfSquareAnnotation annotation = new PdfSquareAnnotation(new RectangleF(200, 260, 50, 50), "Square annotation");
annotation.Color = new PdfColor(Color. Red);
//Set layer to annotation
annotation.Layer = layer;
//Add annotation to the created page
page.Annotations.Add(annotation);
//Save the document
document.Save("Output.pdf");
//Close the document
document.Close(true);'Create new PDF document
Dim document As New PdfDocument()
'Add page
Dim page As PdfPage = document.Pages.Add()
'Add the layer
Dim Layer As PdfLayer = document.Layers.Add("Layer")
'Create graphics for layer
Dim graphics As PdfGraphics = Layer.CreateGraphics(page)
'Draw ellipse
graphics.DrawEllipse(PdfPens.Red, New RectangleF(50, 50, 40, 40))
'Create square annotation
Dim annotation As New PdfSquareAnnotation(New RectangleF(200, 260, 50, 50), "Square annotation")
annotation.Color = New PdfColor(Color.Red)
'Set layer to annotation
annotation.Layer = Layer
'Add annotation to the created page
page.Annotations.Add(annotation)
'Save the document
document.Save("Output.pdf")
'Close the document
document.Close(True)The following code illustrates how to add annotation to the layers in an existing PDF document.
//Load the existing PDF document
PdfLoadedDocument loadedDocument = new PdfLoadedDocument("Input.pdf");
//Gets the first page from the document
PdfLoadedPage loadedPage = loadedDocument.Pages[0] as PdfLoadedPage;
//Add the layer
PdfLayer Layer = loadedDocument.Layers.Add("Layer");
//Create graphics for layer
PdfGraphics graphics = Layer.CreateGraphics(loadedPage);
//Draw ellipse
graphics.DrawEllipse(PdfPens.Red, new RectangleF(50, 50, 40, 40));
//Create square annotation
PdfSquareAnnotation annotation = new PdfSquareAnnotation(new RectangleF(200, 260, 50, 50), "Square annotation");
annotation.Color = new PdfColor(Color.Red);
//Set layer to annotation
annotation.Layer = Layer;
//Add annotation to the created page
loadedPage.Annotations.Add(annotation);
//Save the document
loadedDocument.Save("Output.pdf");
//Close the document
loadedDocument.Close(true);'Load the existing PDF document
Dim loadedDocument As New PdfLoadedDocument("Input.pdf")
'Gets the first page from the document
Dim loadedPage As PdfLoadedPage = TryCast(loadedDocument.Pages(0), PdfLoadedPage)
'Add the layer
Dim Layer As PdfLayer = loadedDocument.Layers.Add("Layer")
'Create graphics for layer
Dim graphics As PdfGraphics = Layer.CreateGraphics(loadedPage)
'Draw ellipse
graphics.DrawEllipse(PdfPens.Red, New RectangleF(50, 50, 40, 40))
'Create square annotation
Dim annotation As New PdfSquareAnnotation(New RectangleF(200, 260, 50, 50), "Square annotation")
annotation.Color = New PdfColor(Color.Red)
'Set layer to annotation
annotation.Layer = Layer
'Add annotation to the created page
loadedPage.Annotations.Add(annotation)
'Save the document
loadedDocument.Save("Output.pdf")
'Close the document
loadedDocument.Close(True)Removing layers from an existing PDF document
You can remove the layers from layer collection, represented by the PdfPageLayerCollection of the loaded page. This is illustrated in the following code sample.
//Load the existing PDF document
PdfLoadedDocument document = new PdfLoadedDocument("Input.pdf");
//Gets the first page from the document
PdfLoadedPage loadedPage = document.Pages[0] as PdfLoadedPage;
//Get the layer collection
PdfPageLayerCollection layers = loadedPage.Layers;
//Remove the layer
layers.RemoveAt(0);
//Save the document
document.Save("Output.pdf");
//Close the document
document.Close(true);'Load the existing PDF document
Dim document As PdfLoadedDocument = New PdfLoadedDocument("Input.pdf")
'Gets the first page from the document
Dim loadedPage As PdfLoadedPage = TryCast(document.Pages(0), PdfLoadedPage)
'Get the layer collection
Dim layers As PdfPageLayerCollection = loadedPage.Layers
'Remove the layer.
layers.RemoveAt(0)
'Save the document.
document.Save("Output.pdf")
'Close the document.
document.Close(True)Toggling the visibility of layers
The visibility of a layer can be mentioned while creating a new page layer.
The below code illustrates how to toggle the visibility of layers in new PDF document.
//Create the document
PdfDocument document = new PdfDocument();
//Create a page
PdfPage page = document.Pages.Add();
//Add the first layer and enable the visibility.
PdfPageLayer layer = page.Layers.Add("Layer1",true);
PdfGraphics graphics = layer.Graphics;
graphics.TranslateTransform(100, 60);
//Draw Arc.
PdfPen pen = new PdfPen(System.Drawing.Color.Red, 50);
RectangleF bounds = new RectangleF(0, 0, 50, 50);
graphics.DrawArc(pen, bounds, 360, 360);
//Add another layer on the page and disable the visibility.
PdfPageLayer layer2 = page.Layers.Add("Layer2",false);
graphics = layer2.Graphics;
graphics.TranslateTransform(100, 180);
//Draw ellipse.
graphics.DrawEllipse(pen, bounds);
//Save the document.
document.Save("Sample.pdf");
//close the document
document.Close(true);'Create the document
Dim document As New PdfDocument()
'Create a page
Dim page As PdfPage = document.Pages.Add()
'Add the first layer and enable the visibility.
Dim layer As PdfPageLayer = page.Layers.Add("Layer1", True)
Dim graphics As PdfGraphics = layer.Graphics
graphics.TranslateTransform(100, 60)
'Draw Arc.
Dim pen As New PdfPen(System.Drawing.Color.Red, 50)
Dim bounds As New RectangleF(0, 0, 50, 50)
graphics.DrawArc(pen, bounds, 360, 360)
'Add another layer on the page and disable the visibility.
Dim layer2 As PdfPageLayer = page.Layers.Add("Layer2", False)
graphics = layer2.Graphics
graphics.TranslateTransform(100, 180)
'Draw ellipse.
graphics.DrawEllipse(pen, bounds)
'Save the document.
document.Save("Sample.pdf")
'close the document
document.Close(True)The following code illustrates how to toggle the visibility of layers in an existing PDF document.
//Load the existing PDF document
PdfLoadedDocument document = new PdfLoadedDocument("Input.pdf");
//Gets the first layer from the layer collection
PdfLayer layer = document.Layers[0];
//Disable the visibility
layer.Visible = false;
//Save the document
document.Save("Output.pdf");
//Close the document
document.Close(true);'Load the existing PDF document
Dim document As PdfLoadedDocument = New PdfLoadedDocument("Input.pdf")
'Get the first layer from the layer collection
Dim layer As PdfLayer = document.Layers(0)
'Disable the visibility
layer.Visible = False
'Save the document
document.Save("Output.pdf")
'Close the document
document.Close(True)
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