addWatermarkRender

(Pro version only. Requires RxCore version 37.14 or newer.)

The addWatermarkRender method adds a temporary (render-only) watermark to the active document viewer.
This watermark is not embedded into the PDF and will not appear in exported or printed documents.

NB! this can not be removed using the removeWatermarkFromAllPages method.

Use this for dynamic, session-based, or user-specific watermarks such as timestamps, usernames, or “For internal use only” labels.

Example

async function applyWatermark() {
  const text = document.getElementById("wmText").value;
  const settings = {
    fontUrl: document.getElementById("wmFontUrl").value,   // Optional custom font URL (.ttf)
    fontName: document.getElementById("wmFontName").value, // Custom font name
    fontSize: parseInt(document.getElementById("wmFontSize").value, 10),
    color: document.getElementById("wmColor").value,       // e.g., "#FF0000"
    rotation: parseInt(document.getElementById("wmRotation").value, 10),
    opacity: parseInt(document.getElementById("wmOpacity").value, 10),
    scale: parseFloat(document.getElementById("wmScale").value),
    position: document.getElementById("wmPosition").value, // "Center", "TopLeft", etc.
    useRelativeScale: true,
    offsetX: 0,
    offsetY: 0,
    fontStyle: "normal"
  };

  const viewerCore = viewerFrame?.contentWindow?.RxCore;
  if (viewerCore && typeof viewerCore.addWatermarkRender === "function") {
    await viewerCore.addWatermarkRender(text, settings);
    console.log("✅ Watermark applied through iframe viewer.");
  } else {
    console.error("❌ RxCore.addWatermarkRender not available inside iframe.");
  }
}

Syntax

await viewerCore.addWatermarkRender(text, settings);

Parameters

Parameter	Type	Description
text	string	The watermark text to display.
settings	object (optional)	Configuration for appearance and positioning.

Supported Settings

In addition to the standard watermark options, the following extra fields are supported:

Property	Type	Description
fontUrl	string	URL to a custom font file (e.g., .ttf).
fontName	string	Name of the custom font (used with fontUrl).
fontSize	number	Font size in points.
color	string	Font color as a hex string (e.g., "#FF0000").
rotation	number	Rotation angle in degrees.
opacity	number	Opacity level (0–100).
scale	number	Scale factor.
position	string	"Center", "TopLeft", etc.
useRelativeScale	boolean	If true, scales relative to page size.
offsetX / offsetY	number	Manual X/Y offsets.
fontStyle	string	"normal", "italic", or "bold".