From 2619698a2eb7363940d1e6a2d71a9ce7b366d3f5 Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Wed, 9 May 2018 17:52:17 +0200
Subject: Font fallback should detect emoji range for color emoji font.

---
 gfx/thebes/gfxWindowsPlatform.cpp | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

(limited to 'gfx/thebes/gfxWindowsPlatform.cpp')

diff --git a/gfx/thebes/gfxWindowsPlatform.cpp b/gfx/thebes/gfxWindowsPlatform.cpp
index af4d932a9..c68f622c6 100755
--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -13,6 +13,7 @@
 #include "gfxWindowsSurface.h"
 
 #include "nsUnicharUtils.h"
+#include "nsUnicodeProperties.h"
 
 #include "mozilla/Preferences.h"
 #include "mozilla/Services.h"
@@ -81,6 +82,7 @@ using namespace mozilla::gfx;
 using namespace mozilla::layers;
 using namespace mozilla::widget;
 using namespace mozilla::image;
+using namespace mozilla::unicode;
 
 IDWriteRenderingParams* GetDwriteRenderingParams(bool aGDI)
 {
@@ -669,9 +671,15 @@ gfxWindowsPlatform::GetCommonFallbackFonts(uint32_t aCh, uint32_t aNextCh,
                                            Script aRunScript,
                                            nsTArray<const char*>& aFontList)
 {
-    if (aNextCh == 0xfe0fu) {
-        aFontList.AppendElement(kFontSegoeUIEmoji);
-        aFontList.AppendElement(kFontTwemojiMozilla);
+    EmojiPresentation emoji = GetEmojiPresentation(aCh);
+    if (emoji != EmojiPresentation::TextOnly) {
+        if (aNextCh == kVariationSelector16 ||
+           (aNextCh != kVariationSelector15 &&
+            emoji == EmojiPresentation::EmojiDefault)) {
+            // if char is followed by VS16, try for a color emoji glyph
+            // XXX: For Win8+ native, aFontList.AppendElement(kFontSegoeUIEmoji);
+            aFontList.AppendElement(kFontTwemojiMozilla);
+        }
     }
 
     // Arial is used as the default fallback for system fallback
@@ -680,17 +688,7 @@ gfxWindowsPlatform::GetCommonFallbackFonts(uint32_t aCh, uint32_t aNextCh,
     if (!IS_IN_BMP(aCh)) {
         uint32_t p = aCh >> 16;
         if (p == 1) { // SMP plane
-            if (aNextCh == 0xfe0eu) {
-                aFontList.AppendElement(kFontSegoeUISymbol);
-                aFontList.AppendElement(kFontSegoeUIEmoji);
-                aFontList.AppendElement(kFontTwemojiMozilla);
-            } else {
-                if (aNextCh != 0xfe0fu) {
-                    aFontList.AppendElement(kFontSegoeUIEmoji);
-                    aFontList.AppendElement(kFontTwemojiMozilla);
-                }
-                aFontList.AppendElement(kFontSegoeUISymbol);
-            }
+            aFontList.AppendElement(kFontSegoeUISymbol);
             aFontList.AppendElement(kFontEbrima);
             aFontList.AppendElement(kFontNirmalaUI);
             aFontList.AppendElement(kFontCambriaMath);
-- 
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