The Annotation editor in GcDocs PDF Viewer allows you to edit and review PDF documents. You can add or remove different types of annotations, comment or reply on comments and set or modify annotation properties like text, color, position, border, style etc. Along with the Annotation editor's toolbar, you can access all the annotations and various other options through the the main toolbar. It provides editing tools which allow you to quickly perform edit operations without the need of switching into full editing mode.  

The editing tools displayed in the below screenshots provide the annotation options along with 'Undo, Redo and Delete' and Redact options in the quick editing toolbars.

Text Tools

On clicking the Text tools button, the quick editing toolbar appears which displays various related text annotation tools like sticky note, free text, ink annotation etc.

Draw Tools

On clicking the Draw tools button, the quick editing toolbar appears which displays various draw annotation tools like square, circle, line annotation etc.

Attachments and Stamps

On clicking the Attachments and stamps button, the quick editing editor toolbar appears which displays various attachment and stamp tools like stamp annotation, file attachment , signature tool etc. Stamp annotation also supports rotation through Rotate property or the rotation handle attached to the annotation. For more information, see "Stamp Rotation".

Page Tools

On clicking the Page tools button, the quick editing editor toolbar appears which displays various page related options like adding a new blank document, inserting a blank page, deleting current page and perform undo or redo operations.

The Form tools button in the above toolbar provides various form field buttons. To know more, refer Form Editor.

You can also configure which tools should be displayed in the second toolbar by using the secondToolbarLayout property as shown below:

const secondToolbarLayout = viewer.secondToolbarLayout;
secondToolbarLayout["text-tools"] = ['edit-text', 'edit-free-text'];

The output of above code will look like below:

You can also customize the second toolbar by using the render handler for secondToolbar option:

var React = viewer.getType("React");
// Create custom toolbar controls:
var toolbarControls = [React.createElement("label", { style: { color: "white" } }, "Custom toolbar"),
React.createElement("button", { className: "gc-btn gc-btn--accent", onClick: () => { alert("Execute action."); }, title: "Action title" }, "Action")];
// Register custom second toolbar for key "custom-toolbar-key":
viewer.options.secondToolbar = {
    render: function (toolbarKey) {
        if (toolbarKey === "custom-toolbar-key")
            return toolbarControls;
        return null;
    }
};
// Show custom second toolbar:
viewer.showSecondToolbar("custom-toolbar-key");

The output of above code will look like below:

Alternatively, you can access all the available annotations through the Annotation editor's toolbar which opens on clicking the Annotation editor button in the side panel. The below image shows Annotation editor and its toolbar in GcDocs PDF Viewer with a PDF document containing a Text annotation.

The different toolbar buttons are described as below. To know more about different annotations, refer Annotation Types.

Name	Toolbar Icons	Description
Select		Select an annotation added on PDF
Signature Tool		Adds graphical signatures on the PDF
Sticky Note		Adds text or sticky notes on the PDF
Free Text Annotation		Adds a note that is always visible on the PDF
Ink Annotation		Draws free-hand scribble on the PDF
Square Annotation		Adds a rectangle shape on PDF
Circle Annotation		Adds a circle shape on the PDF
Line Annotation		Adds a straight line on the PDF
PolyLine Annotation		Adds closed or open shapes of multiple edges on the PDF
Polygon Annotation		Adds a polygon on the PDF
Stamp Annotation		Adds image on the PDF
File Attachment Annotation		Attaches a file to the document, which will be embedded in the PDF
Sound Annotation		Adds sound (.au, .aiff, or .wav format) imported from a file or recorded from the computer’s microphone
Link Annotation		Adds link on the PDF
Delete Annotation Button		Deletes the annotation
Redact Annotation		Marks region on PDF document to be redacted
Apply Redact Annotation		Applies redact to all regions marked for redact

Apart from the different types of annotations described above, GcDocs PDF Viewer also provides some general editing features while working with PDF documents. They are explained as below:

Toolbar Icons	Description
	Undo changes
	Redo changes
	Saves the modified document on client
	Creates a new blank document
	Inserts a blank page
	Deletes current page

You can also insert a blank page in a PDF document and set its size by using the newPage method. Alternatively, you can only set the size of an existing page using setPageSize method as shown below:

viewer.open("AcmeFinancialReport.pdf");
viewer.onAfterOpen.register(()=>
    {   
      //Add new page at second position and set its size
      viewer.newPage({height:400, pageIndex:1, width:300});
      //Set page size for the first page
      viewer.setPageSize(0, { width: 300, height: 500 });
    });

Property Panel of Annotation Editor

When you click the Annotation editor icon in the left vertical panel, the Property panel of the Annotation editor becomes visible. The Property panel displays the list of all the annotations page-wise in your document.

It also allows you to set or modify properties of any annotation in the document like its text, color, border location etc. For eg. The image below shows the properties of a square annotation in the Property panel.

Enable Annotation Editor in GcDocs PDF Viewer

The Annotation editor is displayed by default in GcDocs PDF Viewer, by enabling the AnnotationEditorPanel in the viewer using code:

<script>
    var viewer = new GcPdfViewer("#host", { supportApi: 'SupportApi/GcPdfViewer' });
    viewer.addDefaultPanels();
    viewer.addAnnotationEditorPanel();
    viewer.beforeUnloadConfirmation = true;
    viewer.open("Home/GetPdf");
</script>

To customize the annotation options in GcDocs PDF Viewer, add the following lines of code in the class file where you load the PDF in the Viewer:

public static GcPdfViewerSupportApiDemo.Models.PdfViewerOptions PdfViewerOptions
{
        get => new GcPdfViewerSupportApiDemo.Models.PdfViewerOptions(
        GcPdfViewerSupportApiDemo.Models.PdfViewerOptions.Options.AnnotationEditorPanel |
        GcPdfViewerSupportApiDemo.Models.PdfViewerOptions.Options.ActivateAnnotationEditor,
        annotationEditorTools: new string[] { "edit-select", "$split", "edit-text", "edit-free-text", "$split", "edit-erase", "$split", "edit-redact", "edit-redact-apply", "$split", "edit-undo", "edit-redo", "save" });
}

Review PDF document using Annotation editor

Follow the below steps to review a PDF document using the annotation editor in GcDocs PDF Viewer:

1. Configure the GcDocs PDF Viewer for editing PDF documents.
2. Run the application and open the PDF you want to review using the Open button.
3. Open the Annotation Editor using the second last icon on the left vertical toolbar.
4. Choose any annotation from the different annotations available in the toolbar at the top.
5. Use that annotation to mark a correction in your document.
6. Set annotation properties from the Property panel like color, border etc.
7. Add a Text annotation and type the final review text.
8. Close the Annotation editor and go back to View mode.

The annotations are successfully added annotations to the document. You can also view the list of all the annotations in the property panel of Annotation Editor. 

For more information, refer Annotation Editor in GcDocs PDF Viewer demos.