Bug 1662331 - Part 1: Use the sheetCount from printPreview directly r=emalysz

Differential Revision: https://phabricator.services.mozilla.com/D95332

toolkit/components/printing/content/print.js

@@ -641,12 +641,12 @@ var PrintEventHandler = {
         .add(elapsed);
     }
 
-    // This resolves with a PrintPreviewSuccessInfo dictionary.  That also has
-    // a `sheetCount` property available which we should use (bug 1662331).
-    let totalPageCount, hasSelection;
+    let totalPageCount, sheetCount, hasSelection;
     try {
+      // This resolves with a PrintPreviewSuccessInfo dictionary.
       ({
         totalPageCount,
+        sheetCount,
         hasSelection,
       } = await previewBrowser.frameLoader.printPreview(settings, sourceWinId));
     } catch (e) {
@@ -654,18 +654,12 @@ var PrintEventHandler = {
       throw e;
     }
 
-    // Send the page count and show the preview.
-    let numPages = totalPageCount;
-    // Adjust number of pages if the user specifies the pages they want printed
-    if (settings.printRange == Ci.nsIPrintSettings.kRangeSpecifiedPageRange) {
-      numPages = settings.endPageRange - settings.startPageRange + 1;
-    }
     // Update the settings print options on whether there is a selection.
     settings.isPrintSelectionRBEnabled = hasSelection;
 
     document.dispatchEvent(
       new CustomEvent("page-count", {
-        detail: { numPages, totalPages: totalPageCount },
+        detail: { numPages: sheetCount, totalPages: totalPageCount },
       })
     );
 

toolkit/components/printing/tests/browser_sheet_count.js

@@ -91,3 +91,31 @@ add_task(async function testSheetCount() {
     await helper.closeDialog();
   });
 });
+
+add_task(async function testSheetCountPageRange() {
+  await PrintHelper.withTestPage(async helper => {
+    await helper.startPrint();
+    await helper.waitForPreview(() =>
+      helper.dispatchSettingsChange({
+        shrinkToFit: false,
+        scaling: 2,
+      })
+    );
+
+    let sheetCount = helper.get("sheet-count");
+    let sheets = getSheetCount(sheetCount);
+    ok(sheets >= 3, "There are at least 3 pages");
+
+    // Set page range to 2-3, sheet count should be 2.
+    await helper.waitForPreview(() =>
+      helper.dispatchSettingsChange({
+        printRange: helper.settings.kRangeSpecifiedPageRange,
+        startPageRange: 2,
+        endPageRange: 3,
+      })
+    );
+
+    sheets = getSheetCount(sheetCount);
+    is(sheets, 2, "There are now only 2 pages shown");
+  });
+});