Issue #1610 Part 3: Bypass GDI table loading for embedded fonts.

This is required for DirectWrite because otherwise the font is seen as having no emoji entries
due to the fact that GDI data isn't populated (It isn't loaded through the GDI system like
system fontsand GDI as a result doesn't know anything about the font, and will likely use
random data from the last-loaded font instead).

1 files changed, 19 insertions, 21 deletions

diff --git a/gfx/thebes/gfxDWriteFontList.cpp b/gfx/thebes/gfxDWriteFontList.cpp
index 8d0ae818b..df704cab8 100644
--- a/gfx/thebes/gfxDWriteFontList.cpp
+++ b/gfx/thebes/gfxDWriteFontList.cpp
@@ -384,6 +384,7 @@ gfxDWriteFontEntry::CopyFontTable(uint32_t aTableTag,
                                   FallibleTArray<uint8_t> &aBuffer)
 {
     gfxDWriteFontList *pFontList = gfxDWriteFontList::PlatformFontList();
+    const uint32_t tagBE = NativeEndian::swapToBigEndian(aTableTag);
 
     // Don't use GDI table loading for symbol fonts or for
     // italic fonts in Arabic-script system locales because of
@@ -394,27 +395,22 @@ gfxDWriteFontEntry::CopyFontTable(uint32_t aTableTag,
         !mFont->IsSymbolFont())
     {
         LOGFONTW logfont = { 0 };
-        if (!InitLogFont(mFont, &logfont))
-            return NS_ERROR_FAILURE;
-
-        AutoDC dc;
-        AutoSelectFont font(dc.GetDC(), &logfont);
-        if (font.IsValid()) {
-            uint32_t tableSize =
-                ::GetFontData(dc.GetDC(),
-                              NativeEndian::swapToBigEndian(aTableTag), 0,
-                              nullptr, 0);
-            if (tableSize != GDI_ERROR) {
-                if (aBuffer.SetLength(tableSize)) {
-                    ::GetFontData(dc.GetDC(),
-                                  NativeEndian::swapToBigEndian(aTableTag), 0,
-                                  aBuffer.Elements(), aBuffer.Length());
-                    return NS_OK;
+        if (InitLogFont(mFont, &logfont)) {
+            AutoDC dc;
+            AutoSelectFont font(dc.GetDC(), &logfont);
+            if (font.IsValid()) {
+                uint32_t tableSize =
+                    ::GetFontData(dc.GetDC(), tagBE, 0, nullptr, 0);
+                if (tableSize != GDI_ERROR) {
+                    if (aBuffer.SetLength(tableSize)) {
+                        ::GetFontData(dc.GetDC(), tagBE, 0,
+                                      aBuffer.Elements(), aBuffer.Length());
+                        return NS_OK;
+                    }
+                    return NS_ERROR_OUT_OF_MEMORY;
                 }
-                return NS_ERROR_OUT_OF_MEMORY;
             }
         }
-        return NS_ERROR_FAILURE;
     }
 
     nsRefPtr<IDWriteFontFace> fontFace;
@@ -428,8 +424,7 @@ gfxDWriteFontEntry::CopyFontTable(uint32_t aTableTag,
     void *tableContext = nullptr;
     BOOL exists;
     HRESULT hr =
-        fontFace->TryGetFontTable(NativeEndian::swapToBigEndian(aTableTag),
-                                  (const void**)&tableData, &len,
+        fontFace->TryGetFontTable(tagBE, (const void**)&tableData, &len,
                                   &tableContext, &exists);
     if (FAILED(hr) || !exists) {
         return NS_ERROR_FAILURE;
@@ -646,7 +641,10 @@ gfxDWriteFontEntry::InitLogFont(IDWriteFont *aFont, LOGFONTW *aLogFont)
     IDWriteGdiInterop *gdi = 
         gfxDWriteFontList::PlatformFontList()->GetGDIInterop();
     hr = gdi->ConvertFontToLOGFONT(aFont, aLogFont, &isInSystemCollection);
-    return (FAILED(hr) ? false : true);
+    // If the font is not in the system collection, GDI will be unable to
+    // select it and load its tables, so we return false here to indicate
+    // failure, and let CopyFontTable fall back to DWrite native methods.
+    return (SUCCEEDED(hr) && isInSystemCollection);
 }
 
 bool