Text and Image-based Watermarks – Gravity PDF Development

Introduction

A watermark is a semi-transparent element overlaid on each page of your PDF. Both text and image watermarks are supported, and you have full control over the transparency.

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Two unique HTML tags are used to output watermarks (one for text watermarks and one for images):

• <watermarktext content [ alpha ] />
• <watermarkimage src [ alpha ] [ size ] [ position ] />

Watermarks cannot be used when setting the PDF format to PDF/A-1b or PDF/X-1a.

Text Watermarks

<watermarktext content [ alpha ] />

Text watermarks can be enabled by including the following HTML in your PDF template:

<watermarktext content="PRIVATE" />

content : The text you want watermarked on the PDF. This is a required attribute. : If content is set to blank it will disable watermarking in the document from that page onwards. : The content attribute must have special characters encoded correctly. This includes the <, >, ', " and & symbols. To prevent unexpected behaviour use the PHP function htmlspecialchars.

<watermarktext content="<?php echo htmlspecialchars( '<CONFIDENTIAL>', ENT_QUOTES ); ?>" />

alpha : Controls the text transparency and should be a number between 0-1. This field is optional.

<watermarktext content="PRIVATE" alpha="0.3" />

Image Watermarks

<watermarkimage src [ alpha ] [ size ] [ position ] />

The image watermark only requires the src attribute. The alpha, size and position attributes are all optional.

src : The URL or path to the image. We recommend using the path as it has better support across a range of hosting environments.

alpha : Controls the image transparency and should be a number between 0-1

size : Controls the image size that your watermark should be displayed at. By default the image will display at its original size (depending on the PDF DPI settings) : Values: D – Display at original image size (default) P – Resize image to fit the full page F – Resize to fit the PDF print area, respecting page margins width,height – Two comma-separated numbers specifying the width and height of the image in millimetres

position : Specifies where the image should be positioned on the page : Values: P – Vertically and horizontally centred on the page F – Vertically and horizontally centred on the print area with respect to page margins width,height – Specify the x and y position (in millimetres) of where the image should be placed

<!-- Basic Image Watermark -->

<watermarkimage src="<?php echo PDF_PLUGIN_DIR; ?>resources/images/gravityformspdfextended.jpg" />

<pagebreak>

<!-- Image watermark with 50% transparency -->

<watermarkimage src="<?php echo PDF_PLUGIN_DIR; ?>resources/images/gravityformspdfextended.jpg" alpha="0.5" />

<pagebreak>

<!-- Image watermark resized to fit the full page -->

<watermarkimage src="<?php echo PDF_PLUGIN_DIR; ?>resources/images/gravityformspdfextended.jpg" size="P" />

<pagebreak>

<!-- Image watermark with default size positioned 10mm x 10mm from the top left corner -->

<watermarkimage src="<?php echo PDF_PLUGIN_DIR; ?>resources/images/gravityformspdfextended.jpg" position="10,10" />

<pagebreak>

<!-- Image watermark resized to 50x50mm image -->

<watermarkimage src="<?php echo PDF_PLUGIN_DIR; ?>resources/images/gravityformspdfextended.jpg" size="50,50" />

Example

We’ve put together a sample showing off the text and image watermark capabilities in Gravity PDF.