Bug 1400411 - text-layers: fallback if SVG fonts or tofu is found. r=jrmuizel

MozReview-Commit-ID: 9vUK5r5sKWB

--HG--
extra : rebase_source : 5e4c026cf6c802554772a99064898fde3b414ea8

gfx/thebes/gfxFont.cpp

@@ -40,6 +40,7 @@
 #include "gfxMathTable.h"
 #include "gfxSVGGlyphs.h"
 #include "gfx2DGlue.h"
+#include "TextDrawTarget.h"
 
 #include "GreekCasing.h"
 
@@ -1922,6 +1923,10 @@ gfxFont::DrawGlyphs(const gfxShapedText      *aShapedText,
                     double advance = details->mAdvance;
 
                     if (glyphData->IsMissing()) {
+                        if (auto* textDrawer = aRunParams.context->GetTextDrawer()) {
+                            textDrawer->FoundUnsupportedFeature();
+                            return false;
+                        }
                         // Default-ignorable chars will have zero advance width;
                         // we don't have to draw the hexbox for them.
                         if (aRunParams.drawMode != DrawMode::GLYPH_PATH &&
@@ -2061,7 +2066,14 @@ gfxFont::Draw(const gfxTextRun *aTextRun, uint32_t aStart, uint32_t aEnd,
         return;
     }
 
+    auto* textDrawer = aRunParams.context->GetTextDrawer();
     fontParams.haveSVGGlyphs = GetFontEntry()->TryGetSVGData(this);
+
+    if (fontParams.haveSVGGlyphs && textDrawer) {
+        textDrawer->FoundUnsupportedFeature();
+        return;
+    }
+
     fontParams.haveColorGlyphs = GetFontEntry()->TryGetColorGlyphs();
     fontParams.contextPaint = aRunParams.runContextPaint;
     fontParams.isVerticalFont =

layout/generic/TextDrawTarget.h

@@ -92,7 +92,7 @@ public:
   };
 
   explicit TextDrawTarget()
-  : mCurrentlyDrawing(Phase::eSelection)
+  : mCurrentlyDrawing(Phase::eSelection), mHasUnsupportedFeatures(false)
   {
     mCurrentTarget = gfx::Factory::CreateDrawTarget(gfx::BackendType::SKIA, IntSize(1, 1), gfx::SurfaceFormat::B8G8R8A8);
     SetSelectionIndex(0);
@@ -104,6 +104,7 @@ public:
 
   // Change the phase of text we're drawing.
   void StartDrawing(Phase aPhase) { mCurrentlyDrawing = aPhase; }
+  void FoundUnsupportedFeature() { mHasUnsupportedFeatures = true; }
 
   void SetSelectionIndex(size_t i) {
     // i should only be accessed if i-1 has already been
@@ -257,6 +258,10 @@ public:
   bool
   CanSerializeFonts()
   {
+    if (mHasUnsupportedFeatures) {
+      return false;
+    }
+
     for (const SelectedTextRunFragment& part : GetParts()) {
       for (const TextRunFragment& frag : part.text) {
         if (!frag.font->CanSerialize()) {
@@ -385,6 +390,9 @@ private:
   // A dummy to handle parts of the DrawTarget impl we don't care for
   RefPtr<DrawTarget> mCurrentTarget;
 
+  // Whether Tofu or SVG fonts were encountered
+  bool mHasUnsupportedFeatures;
+
   // The rest of this is dummy implementations of DrawTarget's API
 public:
   DrawTargetType GetType() const override {