Add a watermark only when printing

You may want to add a watermark to a document only when printing. At the moment, this is only possible when using NutrientViewer.PrintMode.DOM by executing the drawing commands in renderPageCallback during printing. This can be achieved with a snippet like the following:

let printingPage = -1;
let instance = null;
let isPrinting = false;


NutrientViewer.load({
  renderPageCallback: (ctx, pageIndex, pageSize) => {
    if (!isPrinting) {
      return;
    }


    printingPage++;
    if (printingPage === instance.totalPageCount - 1) {
      // Finished printing. Reset.
      printingPage = -1;
      isPrinting = false;
    }


    // Render the watermark.
  }
}).then((_instance) => {
  instance = _instance;
});


function pspdfkitPrint() {
  isPrinting = true;
  instance.print(NutrientViewer.PrintMode.DOM);
}


function pspdfkitCancelPrint() {
  isPrinting = false;
  instance.abortPrinting();
}

Call pspdfkitPrint() to print.

It might be necessary to replace the built-in print toolbar button.

When pressing Command-P or Control-P, Nutrient will print using the default behavior and won’t invoke the pspdfkitPrint function. To override the keyboard shortcut behavior or disable keyboard shortcuts, you’ll need to register a custom event handler in instance.contentDocument.