Bug 1298484. Use cleartype and convert to grayscale AA for skia windows fonts if cleartype is disabled system wide. r=lsalzman

gfx/2d/2D.h

@@ -672,6 +672,7 @@ public:
   typedef void (*FontDescriptorOutput)(const uint8_t *aData, uint32_t aLength, Float aFontSize, void *aBaton);
 
   virtual FontType GetType() const = 0;
+  virtual AntialiasMode GetDefaultAAMode() { return AntialiasMode::DEFAULT; }
 
   /** This allows getting a path that describes the outline of a set of glyphs.
    * A target is passed in so that the guarantee is made the returned path

gfx/2d/DrawTargetSkia.cpp

@@ -1183,12 +1183,8 @@ ShouldUseCGToFillGlyphs(const GlyphRenderingOptions* aOptions, const Pattern& aP
 
 #endif
 
-void
-DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
-                           const GlyphBuffer &aBuffer,
-                           const Pattern &aPattern,
-                           const DrawOptions &aOptions,
-                           const GlyphRenderingOptions *aRenderingOptions)
+static bool
+CanDrawFont(ScaledFont* aFont)
 {
   switch (aFont->GetType()) {
   case FontType::SKIA:
@@ -1197,8 +1193,20 @@ DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
   case FontType::MAC:
   case FontType::GDI:
   case FontType::DWRITE:
-    break;
+    return true;
   default:
+    return false;
+  }
+}
+
+void
+DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
+                           const GlyphBuffer &aBuffer,
+                           const Pattern &aPattern,
+                           const DrawOptions &aOptions,
+                           const GlyphRenderingOptions *aRenderingOptions)
+{
+  if (!CanDrawFont(aFont)) {
     return;
   }
 
@@ -1219,11 +1227,18 @@ DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
   }
 
   AutoPaintSetup paint(mCanvas.get(), aOptions, aPattern);
+  AntialiasMode aaMode = aFont->GetDefaultAAMode();
+  if (aOptions.mAntialiasMode != AntialiasMode::DEFAULT) {
+    aaMode = aOptions.mAntialiasMode;
+  }
+  bool aaEnabled = aaMode != AntialiasMode::NONE;
+
+  paint.mPaint.setAntiAlias(aaEnabled);
   paint.mPaint.setTypeface(typeface);
   paint.mPaint.setTextSize(SkFloatToScalar(skiaFont->mSize));
   paint.mPaint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
 
-  bool shouldLCDRenderText = ShouldLCDRenderText(aFont->GetType(), aOptions.mAntialiasMode);
+  bool shouldLCDRenderText = ShouldLCDRenderText(aFont->GetType(), aaMode);
   paint.mPaint.setLCDRenderText(shouldLCDRenderText);
 
   bool useSubpixelText = true;
@@ -1237,7 +1252,7 @@ DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
     useSubpixelText = false;
     break;
   case FontType::MAC:
-    if (aOptions.mAntialiasMode == AntialiasMode::GRAY) {
+    if (aaMode == AntialiasMode::GRAY) {
       // Normally, Skia enables LCD FontSmoothing which creates thicker fonts
       // and also enables subpixel AA. CoreGraphics without font smoothing
       // explicitly creates thinner fonts and grayscale AA.
@@ -1257,14 +1272,15 @@ DrawTargetSkia::FillGlyphs(ScaledFont *aFont,
     }
     break;
   case FontType::GDI:
+  {
     if (!shouldLCDRenderText) {
-      // If we have non LCD GDI text, Cairo currently always uses cleartype fonts and
-      // converts them to grayscale. Force Skia to do the same, otherwise we use
-      // GDI fonts with the ANTIALIASED_QUALITY which is generally bolder than
-      // Cleartype fonts.
+      // If we have non LCD GDI text, render the fonts as cleartype and convert them
+      // to grayscale. This seems to be what Chrome and IE are doing on Windows 7.
+      // This also applies if cleartype is disabled system wide.
       paint.mPaint.setFlags(paint.mPaint.getFlags() | SkPaint::kGenA8FromLCD_Flag);
     }
     break;
+  }
   default:
     break;
   }

gfx/2d/HelpersWinFonts.h

@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+namespace mozilla {
+namespace gfx {
+
+// Cleartype can be dynamically enabled/disabled, so we have to check it
+// everytime we want to render some text.
+static BYTE
+GetSystemTextQuality()
+{
+  BOOL font_smoothing;
+  UINT smoothing_type;
+
+  if (!SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &font_smoothing, 0)) {
+    return DEFAULT_QUALITY;
+  }
+
+  if (font_smoothing) {
+      if (!SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE,
+                                0, &smoothing_type, 0)) {
+        return DEFAULT_QUALITY;
+      }
+
+      if (smoothing_type == FE_FONTSMOOTHINGCLEARTYPE) {
+        return CLEARTYPE_QUALITY;
+      }
+
+      return ANTIALIASED_QUALITY;
+  }
+
+  return DEFAULT_QUALITY;
+}
+
+static AntialiasMode
+GetSystemDefaultAAMode()
+{
+  AntialiasMode defaultMode = AntialiasMode::SUBPIXEL;
+
+  switch (GetSystemTextQuality()) {
+  case CLEARTYPE_QUALITY:
+    defaultMode = AntialiasMode::SUBPIXEL;
+    break;
+  case ANTIALIASED_QUALITY:
+    defaultMode = AntialiasMode::GRAY;
+    break;
+  case DEFAULT_QUALITY:
+    defaultMode = AntialiasMode::NONE;
+    break;
+  }
+
+  return defaultMode;
+}
+
+} // namespace gfx
+} // namespace mozilla

gfx/2d/ScaledFontDWrite.cpp

@@ -22,35 +22,11 @@ using namespace std;
 #include "cairo-win32.h"
 #endif
 
+#include "HelpersWinFonts.h"
+
 namespace mozilla {
 namespace gfx {
 
-static BYTE
-GetSystemTextQuality()
-{
-  BOOL font_smoothing;
-  UINT smoothing_type;
-
-  if (!SystemParametersInfo(SPI_GETFONTSMOOTHING, 0, &font_smoothing, 0)) {
-    return DEFAULT_QUALITY;
-  }
-
-  if (font_smoothing) {
-      if (!SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE,
-                                0, &smoothing_type, 0)) {
-        return DEFAULT_QUALITY;
-      }
-
-      if (smoothing_type == FE_FONTSMOOTHINGCLEARTYPE) {
-        return CLEARTYPE_QUALITY;
-      }
-
-      return ANTIALIASED_QUALITY;
-  }
-
-  return DEFAULT_QUALITY;
-}
-
 #define GASP_TAG 0x70736167
 #define GASP_DOGRAY 0x2
 
@@ -315,19 +291,7 @@ ScaledFontDWrite::GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton
 AntialiasMode
 ScaledFontDWrite::GetDefaultAAMode()
 {
-  AntialiasMode defaultMode = AntialiasMode::SUBPIXEL;
-
-  switch (GetSystemTextQuality()) {
-  case CLEARTYPE_QUALITY:
-    defaultMode = AntialiasMode::SUBPIXEL;
-    break;
-  case ANTIALIASED_QUALITY:
-    defaultMode = AntialiasMode::GRAY;
-    break;
-  case DEFAULT_QUALITY:
-    defaultMode = AntialiasMode::NONE;
-    break;
-  }
+  AntialiasMode defaultMode = GetSystemDefaultAAMode();
 
   if (defaultMode == AntialiasMode::GRAY) {
     if (!DoGrayscale(mFontFace, mSize)) {

gfx/2d/ScaledFontDWrite.h

@@ -44,7 +44,7 @@ public:
 
   virtual bool GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton);
 
-  virtual AntialiasMode GetDefaultAAMode();
+  virtual AntialiasMode GetDefaultAAMode() override;
 
 #ifdef USE_SKIA
   virtual SkTypeface* GetSkTypeface();

gfx/2d/ScaledFontWin.cpp

@@ -18,6 +18,8 @@
 #include "cairo-win32.h"
 #endif
 
+#include "HelpersWinFonts.h"
+
 namespace mozilla {
 namespace gfx {
 
@@ -86,6 +88,12 @@ ScaledFontWin::GetFontDescriptor(FontDescriptorOutput aCb, void* aBaton)
   return true;
 }
 
+AntialiasMode
+ScaledFontWin::GetDefaultAAMode()
+{
+  return GetSystemDefaultAAMode();
+}
+
 #ifdef USE_SKIA
 SkTypeface* ScaledFontWin::GetSkTypeface()
 {

gfx/2d/ScaledFontWin.h

@@ -22,6 +22,7 @@ public:
   bool GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton) override;
 
   virtual bool GetFontDescriptor(FontDescriptorOutput aCb, void* aBaton) override;
+  virtual AntialiasMode GetDefaultAAMode() override;
 
 #ifdef USE_SKIA
   virtual SkTypeface* GetSkTypeface();