Bug 1473742 - Fix printing fonts loaded with JS API. r=jfkthame

Copy over non-rule font faces to the static clone document that is used
during printing.

MozReview-Commit-ID: 8ggNrCcVpEK

--HG--
extra : rebase_source : 27e270edd28c3ecf19a99f4df5398a89e6c53e6a

dom/base/nsDocument.cpp

@@ -9578,6 +9578,13 @@ nsIDocument::CreateStaticClone(nsIDocShell* aCloneContainer)
           }
         }
       }
+
+      // Font faces created with the JS API will not be reflected in the
+      // stylesheets and need to be copied over to the cloned document.
+      if (const FontFaceSet* set = GetFonts()) {
+        set->CopyNonRuleFacesTo(clonedDoc->Fonts());
+      }
+
     }
   }
   mCreatingStaticClone = false;

layout/base/tests/chrome/chrome.ini

@@ -13,6 +13,8 @@ support-files =
   printpreview_bug396024_helper.xul
   printpreview_bug482976_helper.xul
   printpreview_helper.xul
+  printpreview_font_api.html
+  printpreview_font_api_ref.html
   file_bug1018265.xul
 
 [test_bug396367-1.html]

layout/base/tests/chrome/printpreview_helper.xul

@@ -280,6 +280,32 @@ function runTest7() {
   exitprintpreview();
   ok(compareCanvases(), "Printing light DOM and shadow DOM should create same output");
 
+  requestAnimationFrame(function() { setTimeout(runTest8); } );
+}
+
+async function runTest8() {
+  // Test that fonts loaded with CSS and JS are printed the same.
+  const iframeElement = document.getElementsByTagName("iframe")[0];
+
+  // First, snapshot the page with font defined in CSS.
+  await new Promise((resolve) => {
+    iframeElement.addEventListener("load", resolve, { capture: true, once: true });
+    iframeElement.setAttribute("src", "printpreview_font_api_ref.html");
+  });
+  printpreview();
+  ctx1.drawWindow(window.frames[1], 0, 0, 400, 400, "rgb(255,255,255)");
+  exitprintpreview();
+
+  // Second, snapshot the page with font loaded in JS.
+  await new Promise((resolve) => {
+    iframeElement.addEventListener("message", resolve, { capture: true, once: true });
+    iframeElement.setAttribute("src", "printpreview_font_api.html");
+  });
+  printpreview();
+  ctx2.drawWindow(window.frames[1], 0, 0, 400, 400, "rgb(255,255,255)");
+  exitprintpreview();
+  ok(compareCanvases(), "Printing pages with fonts loaded from CSS and JS should be the same.");
+
   finish();
 }
 

layout/style/FontFaceSet.cpp

@@ -1936,6 +1936,17 @@ FontFaceSet::RefreshStandardFontLoadPrincipal()
   }
 }
 
+void
+FontFaceSet::CopyNonRuleFacesTo(FontFaceSet* aFontFaceSet) const
+{
+  for (const FontFaceRecord& rec : mNonRuleFaces) {
+    ErrorResult rv;
+    RefPtr<FontFace> f = rec.mFontFace;
+    aFontFaceSet->Add(*f, rv);
+    MOZ_ASSERT(!rv.Failed());
+  }
+}
+
 // -- FontFaceSet::UserFontSet ------------------------------------------------
 
 /* virtual */ bool

layout/style/FontFaceSet.h

@@ -177,6 +177,8 @@ public:
 
   void RefreshStandardFontLoadPrincipal();
 
+  void CopyNonRuleFacesTo(FontFaceSet* aFontFaceSet) const;
+
   nsIDocument* Document() const { return mDocument; }
 
   // -- Web IDL --------------------------------------------------------------