Call FT_Set_Default_Properties when available.

FreeType 2.7.0 added the ability to read some global properties from
environment variables to configure an FT_Library. However, this did
not apply to FT_New_Library. After 2.7.1 FT_Set_Default_Properties was
added so that users of FT_New_Library can also repect these properties.

This also removes SK_FONTHOST_FREETYPE_USE_NORMAL_LCD_FILTER and
associated code since there are no users of this flag, the behavior it
guards is now more or less in upstream FreeType, and the pattern in the
code it guards is now in use for calling FT_Set_Default_Properties.

BUG=skia:6165

Change-Id: I9fca86cc8b1bb9709c0b980330cf974455be3b57
Reviewed-on: https://skia-review.googlesource.com/9109
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

diff --git a/src/ports/SkFontHost_FreeType.cpp b/src/ports/SkFontHost_FreeType.cpp
index 1feea4d..c7bc07a 100644 (file)
--- a/src/ports/SkFontHost_FreeType.cpp
+++ b/src/ports/SkFontHost_FreeType.cpp
@@ -71,7 +71,6 @@
 
 //#define ENABLE_GLYPH_SPEW     // for tracing calls
 //#define DUMP_STRIKE_CREATION
-//#define SK_FONTHOST_FREETYPE_USE_NORMAL_LCD_FILTER
 //#define SK_FONTHOST_FREETYPE_RUNTIME_VERSION
 //#define SK_GAMMA_APPLY_TO_A8
 
@@ -107,58 +106,51 @@ public:
         }
         FT_Add_Default_Modules(fLibrary);
 
+        // When using dlsym
+        // *(void**)(&procPtr) = dlsym(self, "proc");
+        // is non-standard, but safe for POSIX. Cannot write
+        // *reinterpret_cast<void**>(&procPtr) = dlsym(self, "proc");
+        // because clang has not implemented DR573. See http://clang.llvm.org/cxx_dr_status.html .
+
+        FT_Int major, minor, patch;
+        FT_Library_Version(fLibrary, &major, &minor, &patch);
+
 #if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02070100
         fGetVarDesignCoordinates = FT_Get_Var_Design_Coordinates;
 #elif SK_FREETYPE_MINIMUM_RUNTIME_VERSION & SK_FREETYPE_DLOPEN
-        FT_Int major, minor, patch;
-        FT_Library_Version(fLibrary, &major, &minor, &patch);
-        if (major > 2 || ((major == 2 && minor > 7) || (major == 2 && minor == 7 && patch >= 1))) {
+        if (major > 2 || ((major == 2 && minor > 7) || (major == 2 && minor == 7 && patch >= 0))) {
             //The FreeType library is already loaded, so symbols are available in process.
             void* self = dlopen(nullptr, RTLD_LAZY);
             if (self) {
-                // The following cast is non-standard, but safe for POSIX.
-                // Cannot write this with reinterpret_cast, because clang has not implemented DR573.
-                // See http://clang.llvm.org/cxx_dr_status.html .
-                //*reinterpret_cast<void**>(&fGetVarDesignCoordinates) =
-                //        dlsym(self, "FT_Get_Var_Design_Coordinates");
                 *(void**)(&fGetVarDesignCoordinates) = dlsym(self, "FT_Get_Var_Design_Coordinates");
                 dlclose(self);
             }
         }
 #endif
 
-        // Setup LCD filtering. This reduces color fringes for LCD smoothed glyphs.
-        // Default { 0x10, 0x40, 0x70, 0x40, 0x10 } adds up to 0x110, simulating ink spread.
-        // SetLcdFilter must be called before SetLcdFilterWeights.
-        if (FT_Library_SetLcdFilter(fLibrary, FT_LCD_FILTER_DEFAULT) == 0) {
-            fIsLCDSupported = true;
-            fLCDExtra = 2; //Using a filter adds one full pixel to each side.
-
-#ifdef SK_FONTHOST_FREETYPE_USE_NORMAL_LCD_FILTER
-            // Adds to 0x110 simulating ink spread, but provides better results than default.
-            static unsigned char gGaussianLikeHeavyWeights[] = { 0x1A, 0x43, 0x56, 0x43, 0x1A, };
-
-#  if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02040000
-            FT_Library_SetLcdFilterWeights(fLibrary, gGaussianLikeHeavyWeights);
-#  elif SK_FREETYPE_MINIMUM_RUNTIME_VERSION & SK_FREETYPE_DLOPEN
+#if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02070200
+        FT_Set_Default_Properties(fLibrary);
+#elif SK_FREETYPE_MINIMUM_RUNTIME_VERSION & SK_FREETYPE_DLOPEN
+        if (major > 2 || ((major == 2 && minor > 7) || (major == 2 && minor == 7 && patch >= 1))) {
             //The FreeType library is already loaded, so symbols are available in process.
             void* self = dlopen(nullptr, RTLD_LAZY);
             if (self) {
-                FT_Library_SetLcdFilterWeightsProc setLcdFilterWeights;
-                // The following cast is non-standard, but safe for POSIX.
-                // Cannot write this with reinterpret_cast, because clang has not implemented DR573.
-                // See http://clang.llvm.org/cxx_dr_status.html .
-                //*reinterpret_cast<void**>(&setLcdFilterWeights) =
-                //        dlsym(self, "FT_Library_SetLcdFilterWeights");
-                *(void**)(&setLcdFilterWeights) = dlsym(self, "FT_Library_SetLcdFilterWeights");
+                FT_Set_Default_PropertiesProc setDefaultProperties;
+                *(void**)(&setDefaultProperties) = dlsym(self, "FT_Set_Default_Properties");
                 dlclose(self);
 
-                if (setLcdFilterWeights) {
-                    setLcdFilterWeights(fLibrary, gGaussianLikeHeavyWeights);
+                if (setDefaultProperties) {
+                    setDefaultProperties(fLibrary);
                 }
             }
-#  endif
+        }
 #endif
+
+        // Setup LCD filtering. This reduces color fringes for LCD smoothed glyphs.
+        // The default has changed over time, so this doesn't mean the same thing to all users.
+        if (FT_Library_SetLcdFilter(fLibrary, FT_LCD_FILTER_DEFAULT) == 0) {
+            fIsLCDSupported = true;
+            fLCDExtra = 2; //Using a filter adds one full pixel to each side.
         }
     }
     ~FreeTypeLibrary() {
@@ -192,6 +184,10 @@ private:
     // Android >= Gingerbread (good)
     // RHEL >= 7 (6 has 2.3.11, EOL Nov 2020, Phase 3 May 2017)
     using FT_Library_SetLcdFilterWeightsProc = FT_Error (*)(FT_Library, unsigned char*);
+
+    // FreeType added the ability to read global properties in 2.7.0. After 2.7.1 a means for users
+    // of FT_New_Library to request these global properties to be read was added.
+    using FT_Set_Default_PropertiesProc = void (*)(FT_Library);
 };
 
 struct SkFaceRec;