Migrate font fallback on Mac to Skia implementation

The gfx GetFontFallback(...) using Skia is using the same
API under the hood than font_fallback_mac.mm.
see: https://cs.chromium.org/chromium/src/third_party/skia/src/ports/SkFontHost_mac.cpp?l=3043

This CL is doing the migration to use GetSkiaFallbackTypeface(..) like
other platforms to have an more uniform results.

Skia Implementation also supported other corner cases like decomposition.
see: ui/gfx/font_fallback_skia_impl.cc

Bug: 1026735
Change-Id: If26ce32a0a826fea688dbbf25977ffb7590e31df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2075222Reviewed-by: Dominik Röttsches <drott@chromium.org>
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745591}

ui/gfx/BUILD.gn

@@ -344,7 +344,7 @@ jumbo_component("gfx") {
     ]
   }
 
-  if (is_android || is_fuchsia || is_win) {
+  if (is_android || is_fuchsia || is_win || is_mac) {
     sources += [
       "font_fallback_skia_impl.cc",
       "font_fallback_skia_impl.h",

ui/gfx/font_fallback_mac.mm

@@ -11,33 +11,12 @@
 #import "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
 #import "base/strings/sys_string_conversions.h"
+#include "base/trace_event/trace_event.h"
 #include "ui/gfx/font.h"
+#include "ui/gfx/font_fallback_skia_impl.h"
+#include "ui/gfx/platform_font.h"
 
 namespace gfx {
-namespace {
-
-// CTFontCreateForString() sometimes re-wraps its result in a new CTFontRef with
-// identical attributes. This wastes time shaping the text run and confounds
-// Skia's internal typeface cache.
-bool FontsEqual(CTFontRef lhs, CTFontRef rhs) {
-  if (lhs == rhs)
-    return true;
-
-  // Compare ATSFontRef typeface IDs. These are typedef uint32_t. Typically if
-  // RenderText decided to hunt for a fallback in the first place, this check
-  // fails and FontsEqual returns here.
-  if (CTFontGetPlatformFont(lhs, nil) != CTFontGetPlatformFont(rhs, nil))
-    return false;
-
-  // Comparing addresses of descriptors seems to be sufficient for other cases.
-  base::ScopedCFTypeRef<CTFontDescriptorRef> lhs_descriptor(
-      CTFontCopyFontDescriptor(lhs));
-  base::ScopedCFTypeRef<CTFontDescriptorRef> rhs_descriptor(
-      CTFontCopyFontDescriptor(rhs));
-  return lhs_descriptor.get() == rhs_descriptor.get();
-}
-
-}  // namespace
 
 std::vector<Font> GetFallbackFonts(const Font& font) {
   DCHECK(font.GetNativeFont());
@@ -76,15 +55,20 @@ bool GetFallbackFont(const Font& font,
                      const std::string& locale,
                      base::StringPiece16 text,
                      Font* result) {
-  base::ScopedCFTypeRef<CFStringRef> cf_string(CFStringCreateWithCharacters(
-      kCFAllocatorDefault, text.data(), text.length()));
-  CTFontRef ct_font = base::mac::NSToCFCast(font.GetNativeFont());
-  base::ScopedCFTypeRef<CTFontRef> ct_result(
-      CTFontCreateForString(ct_font, cf_string, {0, text.length()}));
-  if (FontsEqual(ct_font, ct_result))
+  TRACE_EVENT0("fonts", "gfx::GetFallbackFont");
+
+  sk_sp<SkTypeface> fallback_typeface =
+      GetSkiaFallbackTypeface(font, locale, text);
+
+  if (!fallback_typeface)
     return false;
 
-  *result = Font(base::mac::CFToNSCast(ct_result.get()));
+  // Fallback needs to keep the exact SkTypeface, as re-matching the font using
+  // family name and styling information loses access to the underlying platform
+  // font handles and is not guaranteed to result in the correct typeface, see
+  // https://crbug.com/1003829
+  *result = Font(PlatformFont::CreateFromSkTypeface(
+      std::move(fallback_typeface), font.GetFontSize(), base::nullopt));
   return true;
 }
 

ui/gfx/font_fallback_mac_unittest.cc

@@ -34,8 +34,6 @@ TEST(FontFallbackMacTest, GetFallbackFont) {
   const base::string16 emoji = base::UTF8ToUTF16("😋");
 
   gfx::Font fallback;
-  EXPECT_FALSE(
-      GetFallbackFont(arial, kDefaultApplicationLocale, ascii, &fallback));
   EXPECT_TRUE(
       GetFallbackFont(arial, kDefaultApplicationLocale, hebrew, &fallback));
   EXPECT_EQ("Lucida Grande", fallback.GetFontName());

ui/gfx/platform_font_mac.h

@@ -20,6 +20,10 @@ class PlatformFontMac : public PlatformFont {
   PlatformFontMac(const std::string& font_name,
                   int font_size);
 
+  PlatformFontMac(sk_sp<SkTypeface> typeface,
+                  int font_size_pixels,
+                  const base::Optional<FontRenderParams>& params);
+
   // Overridden from PlatformFont:
   Font DeriveFont(int size_delta,
                   int style,

ui/gfx/platform_font_mac.mm

@@ -181,6 +181,12 @@ NSFont* ValidateFont(NSFont* font) {
   return font ? font : [NSFont systemFontOfSize:[NSFont systemFontSize]];
 }
 
+std::string GetFamilyNameFromTypeface(sk_sp<SkTypeface> typeface) {
+  SkString family;
+  typeface->getFamilyName(&family);
+  return family.c_str();
+}
+
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -205,6 +211,16 @@ PlatformFontMac::PlatformFontMac(const std::string& font_name, int font_size)
                       Font::NORMAL,
                       Font::Weight::NORMAL) {}
 
+PlatformFontMac::PlatformFontMac(sk_sp<SkTypeface> typeface,
+                                 int font_size_pixels,
+                                 const base::Optional<FontRenderParams>& params)
+    : PlatformFontMac(
+          base::mac::CFToNSCast(SkTypeface_GetCTFontRef(typeface.get())),
+          GetFamilyNameFromTypeface(typeface),
+          font_size_pixels,
+          (typeface->isItalic() ? Font::ITALIC : Font::NORMAL),
+          FontWeightFromInt(typeface->fontStyle().weight())) {}
+
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformFontMac, PlatformFont implementation:
 
@@ -388,4 +404,12 @@ PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
   return new PlatformFontMac(font_name, font_size);
 }
 
+// static
+PlatformFont* PlatformFont::CreateFromSkTypeface(
+    sk_sp<SkTypeface> typeface,
+    int font_size_pixels,
+    const base::Optional<FontRenderParams>& params) {
+  return new PlatformFontMac(typeface, font_size_pixels, params);
+}
+
 }  // namespace gfx