Adding a text watermark in Node with Needle

In this guide, we'll walk you through the process of adding text watermarks to your PDF files, using PDFShift's API.

Adding a watermark to your PDF can be done by adding the watermark object to your query. Adding a text allows you to customize its content and PDFShift's API provides a few properties to help you customize the visual aspect, such as the font size, color, and position.

const needle = require('needle');
const fs = require('fs');

// You can get an API key at https://pdfshift.io
api_key = 'sk_xxxxxxxxxxxx'

params = {
    source: 'https://www.example.com',
    watermark: {
        text: 'PROTECTED DOCUMENT',
        offset_x: 'center',
        offset_top: 'top'
    }
}

needle.post(
    'https://api.pdfshift.io/v3/convert/pdf',
    params,
    {
        username: 'api',
        password: apiKey,
        json: params,
    },
    function(err, resp) {
        if (err) throw err;

        // Write the response body to a local file
        fs.writeFileSync('result.pdf', resp.body, 'binary');

        console.log('The PDF document was generated and saved to result.pdf');
    }
)

You can customize the text watermark by applying the following properties:

• font_size: The size of the text. An integer value in pixels. Defaults to 16.
• font_family : The font family to be used. Defaults to Helvetica.
• font_color : The color of the text. A hexadecimal color value. Defaults to '000000'.
• font_opacity : The opacity of the text. A float value between 0 and 100. Defaults to 100.
• font_bold: A boolean to set the text as bold. Defaults to false.
• font_italic: A boolean to set the text as italic. Defaults to false.

You can also customize the position of the text watermark by applying the following properties:

• offset_x: The horizontal position of the text. Can be 'left', 'center', 'right', or a specific value in pixels. Defaults to 'center'.
• offset_y: The vertical position of the text. Can be 'top', 'middle', 'bottom', or a specific value in pixels. Defaults to 'center'.

For the offset positions, we accept a value in integer which will be translated to pixels, but you can also pass a unit such as 'px', 'in', 'cm', 'mm', 'pt'.

For example:

params = {
    "source": "https://www.example.com",
    "watermark": {
        "text": "PROTECTED DOCUMENT",
        "offset_x": "5cm",
        "offset_top": "15mm"
    }
}