terriajs/lib/Core/printWindow.js

Geospatial data visualization platform.

const when = require('terriajs-cesium/Source/ThirdParty/when');
const TerriaError = require('./TerriaError');

/**
 * Tells the web browser to print a given window, which my be an iframe window, and
 * returns a promise that resolves when printing is safely over so that, for example
 * the window can be removed.
 * @param {Window} windowToPrint The window to print.
 * @returns {Promise} A promise that resolves when printing is safely over. The prommise is rejected if
 *                    there is no indication that the browser's print
 */
function printWindow(windowToPrint) {
    const deferred = when.defer();
    let printInProgressCount = 0;

    const timeout = setTimeout(function() {
        deferred.reject(new TerriaError({
            title: 'Error printing',
            message: 'Printing did not start within 10 seconds. Maybe this web browser does not support printing?'
        }));
    }, 10000);

    function cancelTimeout() {
        clearTimeout(timeout);
    }

    function resolveIfZero() {
        if (printInProgressCount <= 0) {
            deferred.resolve();
        }
    }

    if (windowToPrint.matchMedia) {
        windowToPrint.matchMedia('print').addListener(function (evt) {
            cancelTimeout();
            if (evt.matches) {
                console.log('print media start');
                ++printInProgressCount;
            } else {
                console.log('print media end');
                --printInProgressCount;
                resolveIfZero();
            }
        });
    }

    windowToPrint.onbeforeprint = function () {
        cancelTimeout();
        console.log('onbeforeprint');
        ++printInProgressCount;
    };
    windowToPrint.onafterprint = function () {
        cancelTimeout();
        console.log('onafterprint');
        --printInProgressCount;
        resolveIfZero();
    };

    // First try printing with execCommand, because, in IE11, `printWindow.print()`
    // prints the entire page instead of just the embedded iframe (if the window
    // is an iframe, anyway).
    const result = windowToPrint.document.execCommand('print', true, null);
    if (!result) {
        windowToPrint.print();
    }

    return deferred.promise;
}

module.exports = printWindow;