browser_viewport_changed_meta.js

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/* Any copyright is dedicated to the Public Domain.

   http://creativecommons.org/publicdomain/zero/1.0/ */

"use strict";

// Test that resolution is as expected when the viewport tag is changed.

// The page content is a 400 x 400 div in a 200 x 200 viewport. Initially,

// the viewport width is set to 800 at initial-scale 1, but then the tag

// content is changed. This triggers various rescale operations that will

// change the resolution of the page after reflow.

// Chrome handles many of these cases differently. The Chrome results are

// included as TODOs, but labelled as "res_chrome" to indicate that the

// goal is not necessarily to match an agreed-upon standard, but to

// achieve web compatability through changing either Firefox or Chrome

// behavior.

info("--- Starting viewport test output ---");

const WIDTH = 200;

const HEIGHT = 200;

const INITIAL_CONTENT = "width=800, initial-scale=1";

const INITIAL_RES_TARGET = 1.0;

const TESTS = [

  // This checks that when the replaced content matches the original content,

  // we get the same values as the original values.

  { content: INITIAL_CONTENT, res_target: INITIAL_RES_TARGET },

  // Section 1: Check the case of a viewport shrinking with the display width

  // staying the same. In this case, the shrink will fit the max of the 400px

  // content width and the viewport width into the 200px display area.

  { content: "width=200", res_target: 0.5 }, // fitting 400px content

  { content: "width=400", res_target: 0.5 }, // fitting 400px content/viewport

  { content: "width=500", res_target: 0.4 }, // fitting 500px viewport

  // Section 2: Same as Section 1, but adds user-scalable=no. The expected

  // results are similar to Section 1, but we ignore the content size and only

  // adjust resolution to make the viewport fit into the display area.

  { content: "width=200, user-scalable=no", res_target: 1.0 },

  { content: "width=400, user-scalable=no", res_target: 0.5 },

  { content: "width=500, user-scalable=no", res_target: 0.4 },

  // Section 3: Same as Section 1, but adds initial-scale=1. Initial-scale

  // prevents content shrink in Firefox, so the viewport is scaled based on its

  // changing size relative to the display area. In this case, the resolution

  // is increased to maintain the proportional amount of the previously visible

  // content. With the initial conditions, the display area was showing 1/4 of

  // the content at 0.25x resolution. As the viewport width is shrunk, the

  // resolution will increase to ensure that only 1/4 of the content is visible.

  // Essentially, the new viewport width times the resolution will equal 800px,

  // the original viewport width times resolution.

//

  // Chrome treats the initial-scale=1 as inviolable and sets resolution to 1.0.

  { content: "width=200, initial-scale=1", res_target: 4.0, res_chrome: 1.0 },

  { content: "width=400, initial-scale=1", res_target: 2.0, res_chrome: 1.0 },

  { content: "width=500, initial-scale=1", res_target: 1.6, res_chrome: 1.0 },

  // Section 4: Same as Section 3, but adds user-scalable=no. The combination

  // of this and initial-scale=1 prevents the scaling-up of the resolution to

  // keep the proportional amount of the previously visible content.

  { content: "width=200, initial-scale=1, user-scalable=no", res_target: 1.0 },

  { content: "width=400, initial-scale=1, user-scalable=no", res_target: 1.0 },

  { content: "width=500, initial-scale=1, user-scalable=no", res_target: 1.0 },

];

const TEST_URL = `data:text/html;charset=utf-8,

  <html>

    <head><meta name="viewport" content="${INITIAL_CONTENT}"></head>

    <body style="margin:0">

      <div id="box" style="width:400px;height:400px;background-color:green">Initial</div>

    </body>

  </html>`;

addRDMTask(TEST_URL, async function ({ ui, manager }) {

  await setViewportSize(ui, manager, WIDTH, HEIGHT);

  await setTouchAndMetaViewportSupport(ui, true);

  // Check initial resolution value.

  const initial_resolution = await spawnViewportTask(ui, {}, () => {

    return content.windowUtils.getResolution();

});

is(

    initial_resolution.toFixed(2),

    INITIAL_RES_TARGET.toFixed(2),

    `Initial resolution is as expected.`

);

  for (const test of TESTS) {

    const { content: content, res_target, res_chrome } = test;

    await spawnViewportTask(ui, { content }, args => {

      const box = content.document.getElementById("box");

      box.textContent = args.content;

      const meta = content.document.getElementsByTagName("meta")[0];

      info(`Changing meta viewport content to "${args.content}".`);

      meta.content = args.content;

});

    await promiseContentReflow(ui);

    const resolution = await spawnViewportTask(ui, {}, () => {

      return content.windowUtils.getResolution();

});

is(

      resolution.toFixed(2),

      res_target.toFixed(2),

      `Replaced meta viewport content "${content}" resolution is as expected.`

);

    if (typeof res_chrome !== "undefined") {

      todo_is(

        resolution.toFixed(2),

        res_chrome.toFixed(2),

        `Replaced meta viewport content "${content}" resolution matches Chrome resolution.`

);

    info("Reload and wait for document to be loaded to prepare for next test.");

    await reloadBrowser();

});