From b12c5b9ea072d1f3158b6e9979a0a1ae96eb448e Mon Sep 17 00:00:00 2001
From: Jonathan Kew <jkew@mozilla.com>
Date: Sun, 9 Aug 2020 07:23:42 +0000
Subject: [PATCH] Bug 1657892 - Cache variation axes in the UnscaledFontMac to
 accelerate font instantiations. r=lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D86475
---
 gfx/2d/ScaledFontMac.cpp  | 29 ++++++++++++++++-------------
 gfx/2d/UnscaledFontMac.h  | 11 ++++++++++-
 gfx/thebes/gfxMacFont.cpp |  2 +-
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/gfx/2d/ScaledFontMac.cpp b/gfx/2d/ScaledFontMac.cpp
index 5948a9e31ca6..920275baf4cb 100644
--- a/gfx/2d/ScaledFontMac.cpp
+++ b/gfx/2d/ScaledFontMac.cpp
@@ -493,7 +493,7 @@ ScaledFontMac::InstanceData::InstanceData(
 }
 
 static CFDictionaryRef CreateVariationDictionaryOrNull(
-    CGFontRef aCGFont, uint32_t aVariationCount,
+    CGFontRef aCGFont, CFArrayRef& aAxesCache, uint32_t aVariationCount,
     const FontVariation* aVariations) {
   // Avoid calling potentially buggy variation APIs on pre-Sierra macOS
   // versions (see bug 1331683)
@@ -501,14 +501,16 @@ static CFDictionaryRef CreateVariationDictionaryOrNull(
     return nullptr;
   }
 
-  AutoRelease<CTFontRef> ctFont(
-      CTFontCreateWithGraphicsFont(aCGFont, 0, nullptr, nullptr));
-  AutoRelease<CFArrayRef> axes(CTFontCopyVariationAxes(ctFont));
-  if (!axes) {
-    return nullptr;
+  if (!aAxesCache) {
+    AutoRelease<CTFontRef> ctFont(
+        CTFontCreateWithGraphicsFont(aCGFont, 0, nullptr, nullptr));
+    aAxesCache = CTFontCopyVariationAxes(ctFont);
+    if (!aAxesCache) {
+      return nullptr;
+    }
   }
 
-  CFIndex axisCount = CFArrayGetCount(axes);
+  CFIndex axisCount = CFArrayGetCount(aAxesCache);
   AutoRelease<CFMutableDictionaryRef> dict(CFDictionaryCreateMutable(
       kCFAllocatorDefault, axisCount, &kCFTypeDictionaryKeyCallBacks,
       &kCFTypeDictionaryValueCallBacks));
@@ -520,7 +522,7 @@ static CFDictionaryRef CreateVariationDictionaryOrNull(
   for (CFIndex i = 0; i < axisCount; ++i) {
     // We sanity-check the axis info found in the CTFont, and bail out
     // (returning null) if it doesn't have the expected types.
-    CFTypeRef axisInfo = CFArrayGetValueAtIndex(axes, i);
+    CFTypeRef axisInfo = CFArrayGetValueAtIndex(aAxesCache, i);
     if (CFDictionaryGetTypeID() != CFGetTypeID(axisInfo)) {
       return nullptr;
     }
@@ -592,14 +594,15 @@ static CFDictionaryRef CreateVariationDictionaryOrNull(
   return dict.forget();
 }
 
+/* static */
 CGFontRef UnscaledFontMac::CreateCGFontWithVariations(
-    CGFontRef aFont, uint32_t aVariationCount,
+    CGFontRef aFont, CFArrayRef& aAxesCache, uint32_t aVariationCount,
     const FontVariation* aVariations) {
   MOZ_ASSERT(aVariationCount > 0);
   MOZ_ASSERT(aVariations);
 
-  AutoRelease<CFDictionaryRef> varDict(
-      CreateVariationDictionaryOrNull(aFont, aVariationCount, aVariations));
+  AutoRelease<CFDictionaryRef> varDict(CreateVariationDictionaryOrNull(
+      aFont, aAxesCache, aVariationCount, aVariations));
   if (!varDict) {
     return nullptr;
   }
@@ -622,8 +625,8 @@ already_AddRefed<ScaledFont> UnscaledFontMac::CreateScaledFont(
 
   CGFontRef fontRef = mFont;
   if (aNumVariations > 0) {
-    CGFontRef varFont =
-        CreateCGFontWithVariations(mFont, aNumVariations, aVariations);
+    CGFontRef varFont = CreateCGFontWithVariations(mFont, mAxesCache,
+                                                   aNumVariations, aVariations);
     if (varFont) {
       fontRef = varFont;
     }
diff --git a/gfx/2d/UnscaledFontMac.h b/gfx/2d/UnscaledFontMac.h
index d4884a24fcad..86b62f14b15e 100644
--- a/gfx/2d/UnscaledFontMac.h
+++ b/gfx/2d/UnscaledFontMac.h
@@ -26,7 +26,12 @@ class UnscaledFontMac final : public UnscaledFont {
       : mFont(aFont), mIsDataFont(aIsDataFont) {
     CFRetain(mFont);
   }
-  virtual ~UnscaledFontMac() { CFRelease(mFont); }
+  virtual ~UnscaledFontMac() {
+    if (mAxesCache) {
+      CFRelease(mAxesCache);
+    }
+    CFRelease(mFont);
+  }
 
   FontType GetType() const override { return FontType::MAC; }
 
@@ -47,16 +52,20 @@ class UnscaledFontMac final : public UnscaledFont {
       const FontVariation* aVariations, uint32_t aNumVariations) override;
 
   static CGFontRef CreateCGFontWithVariations(CGFontRef aFont,
+                                              CFArrayRef& aAxesCache,
                                               uint32_t aVariationCount,
                                               const FontVariation* aVariations);
 
   bool GetFontDescriptor(FontDescriptorOutput aCb, void* aBaton) override;
 
+  CFArrayRef& AxesCache() { return mAxesCache; }
+
   static already_AddRefed<UnscaledFont> CreateFromFontDescriptor(
       const uint8_t* aData, uint32_t aDataLength, uint32_t aIndex);
 
  private:
   CGFontRef mFont;
+  CFArrayRef mAxesCache = nullptr;  // Cached array of variation axis details
   bool mIsDataFont;
 };
 
diff --git a/gfx/thebes/gfxMacFont.cpp b/gfx/thebes/gfxMacFont.cpp
index 329a75da323b..0e8ff1cf6d5a 100644
--- a/gfx/thebes/gfxMacFont.cpp
+++ b/gfx/thebes/gfxMacFont.cpp
@@ -102,7 +102,7 @@ gfxMacFont::gfxMacFont(const RefPtr<UnscaledFontMac>& aUnscaledFont,
     }
 
     mCGFont = UnscaledFontMac::CreateCGFontWithVariations(
-        baseFont, vars.Length(), vars.Elements());
+        baseFont, aUnscaledFont->AxesCache(), vars.Length(), vars.Elements());
     if (!mCGFont) {
       ::CFRetain(baseFont);
       mCGFont = baseFont;