Bug 1673713 - Part 2: Pages per sheet option behind a pref r=sfoster,fluent-reviewers,flod

This adds the pages per sheet option behind the print.pages_per_sheet.enabled
pref. Sizes of 2 and 6 aren't supported yet, so this is off by default.

Differential Revision: https://phabricator.services.mozilla.com/D95335

modules/libpref/init/StaticPrefList.yaml

@@ -9028,6 +9028,12 @@
   value: @IS_EARLY_BETA_OR_EARLIER@
   mirror: always
 
+# Whether the pages per sheet print setting is enabled.
+- name: print.pages_per_sheet.enabled
+  type: RelaxedAtomicBool
+  value: false
+  mirror: always
+
 # Whether we allow the print progress dialog to show up.
 - name: print.show_print_progress
   type: RelaxedAtomicBool

toolkit/components/printing/content/print.html

@@ -163,6 +163,16 @@
               <scale-input></scale-input>
             </section>
 
+            <section id="pages-per-sheet" class="section-block" hidden>
+              <label id="pages-per-sheet-label" class="block-label" data-l10n-id="printui-pages-per-sheet"></label>
+              <select is="setting-select" id="pages-per-sheet-picker" class="row" data-setting-name="numPagesPerSheet">
+                <option value="1">1</option>
+                <option value="4">4</option>
+                <option value="9">9</option>
+                <option value="16">16</option>
+              </select>
+            </section>
+
             <section id="margins" class="section-block">
               <label for="margins-select" class="block-label" data-l10n-id="printui-margins"></label>
               <div id="margins-select" is="margins-select" class="margins-select row"></div>

toolkit/components/printing/content/print.js

@@ -148,7 +148,7 @@ var PrintEventHandler = {
 
   // These settings do not have an associated pref value or flag, but
   // changing them requires us to update the print preview.
-  _nonFlaggedUpdatePreviewSettings: new Set(["pageRanges"]),
+  _nonFlaggedUpdatePreviewSettings: new Set(["pageRanges", "numPagesPerSheet"]),
 
   async init() {
     Services.telemetry.scalarAdd("printing.preview_opened_tm", 1);
@@ -1546,6 +1546,10 @@ class PrintUIForm extends PrintUIControlMixin(HTMLFormElement) {
       // Move the Print button to the end if this isn't Windows.
       this.printButton.parentElement.append(this.printButton);
     }
+    this.querySelector("#pages-per-sheet").hidden = !Services.prefs.getBoolPref(
+      "print.pages_per_sheet.enabled",
+      false
+    );
   }
 
   requestPrint() {

toolkit/components/printing/tests/browser_sheet_count.js

@@ -117,3 +117,73 @@ add_task(async function testSheetCountPageRange() {
     is(sheets, 2, "There are now only 2 pages shown");
   });
 });
+
+add_task(async function testPagesPerSheetCount() {
+  await PrintHelper.withTestPage(async helper => {
+    let mockPrinterName = "A real printer!";
+    helper.addMockPrinter(mockPrinterName);
+
+    await SpecialPowers.pushPrefEnv({
+      set: [
+        ["print.pages_per_sheet.enabled", true],
+        ["print_printer", mockPrinterName],
+      ],
+    });
+
+    await helper.startPrint();
+
+    await helper.waitForPreview(() =>
+      helper.dispatchSettingsChange({
+        shrinkToFit: false,
+        scaling: 2,
+      })
+    );
+
+    let sheetCount = helper.get("sheet-count");
+    let sheets = getSheetCount(sheetCount);
+
+    ok(sheets > 1, "There are multiple pages");
+
+    await helper.openMoreSettings();
+    let pagesPerSheet = helper.get("pages-per-sheet-picker");
+    ok(BrowserTestUtils.is_visible(pagesPerSheet), "Pages per sheet is shown");
+    pagesPerSheet.focus();
+    EventUtils.sendKey("space", helper.win);
+    for (let i = 0; i < 5; i++) {
+      EventUtils.sendKey("down", helper.win);
+      if (pagesPerSheet.value == 16) {
+        break;
+      }
+    }
+    await helper.waitForPreview(() => EventUtils.sendKey("return", helper.win));
+
+    sheets = getSheetCount(sheetCount);
+    is(sheets, 1, "There's only one sheet now");
+
+    await helper.waitForSettingsEvent(() =>
+      helper.dispatchSettingsChange({ numCopies: 5 })
+    );
+
+    sheets = getSheetCount(sheetCount);
+    is(sheets, 5, "Copies are handled with pages per sheet correctly");
+
+    await helper.closeDialog();
+  });
+});
+
+add_task(async function testPagesPerSheetPref() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.pages_per_sheet.enabled", false]],
+  });
+
+  await PrintHelper.withTestPage(async helper => {
+    await helper.startPrint();
+
+    ok(
+      BrowserTestUtils.is_hidden(helper.get("pages-per-sheet")),
+      "Pages per sheet is hidden"
+    );
+
+    await helper.closeDialog();
+  });
+});

toolkit/components/printing/tests/head.js

@@ -265,8 +265,10 @@ class PrintHelper {
     await BrowserTestUtils.waitForEvent(this.doc, "preview-updated");
   }
 
-  async waitForSettingsEvent() {
+  async waitForSettingsEvent(changeFn) {
-    await BrowserTestUtils.waitForEvent(this.doc, "print-settings");
+    let changed = BrowserTestUtils.waitForEvent(this.doc, "print-settings");
+    await changeFn?.();
+    await changed;
   }
 
   click(el, { scroll = true } = {}) {

toolkit/locales/en-US/toolkit/printing/printUI.ftl

@@ -87,6 +87,8 @@ printui-loading = Preparing Preview
 printui-preview-label =
     .aria-label = Print Preview
 
+printui-pages-per-sheet = Pages per sheet
+
 ## Paper sizes that may be supported by the Save to PDF destination:
 
 printui-paper-a5 = A5