[DirectWrite] Force fully aliased text for certain fonts at small sizes

Force the use of fully aliased text for certain common east asian fonts
at smaller font sizes to ensure that text is legible. This is only
required for fonts without an embedded bitmap at a the specific size and
the minimum size for enabling anti aliasing is set on a per font basis.

BUG=383090,383040
R=dglazkov@chromium.org, cpu@chromium.org

Review URL: https://codereview.chromium.org/339693002

git-svn-id: svn://svn.chromium.org/blink/trunk@176244 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/TestExpectations

@@ -1017,6 +1017,10 @@ crbug.com/374569 [ Win ] http/tests/navigation/beacon-cross-origin.html [ Pass F
 crbug.com/374572 svg/filters/feImage-target-reappend-to-document.svg [ Pass Failure ]
 crbug.com/374572 svg/dynamic-updates/SVGImageElement-svgdom-preserveAspectRatio-prop.html [ Pass ImageOnlyFailure ]
 
+Bug(eae) [ Win7 ] fast/text/justify-ideograph-vertical.html [ NeedsRebaseline ]
+Bug(eae) [ Win7 ] virtual/antialiasedtext/fast/text/international/wrap-CJK-001.html [ NeedsRebaseline ]
+Bug(eae) [ Win7 ] virtual/antialiasedtext/fast/text/justify-ideograph-vertical.html [ NeedsRebaseline ]
+
 crbug.com/371651 svg/custom/deep-dynamic-updates.svg [ Pass Failure ]
 crbug.com/371651 svg/custom/js-update-gradient.svg [ Pass Failure ]
 crbug.com/371651 svg/custom/js-update-pattern.svg [ Pass Failure ]

third_party/WebKit/Source/platform/fonts/win/FontCacheSkiaWin.cpp

@@ -225,6 +225,23 @@ FontPlatformData* FontCache::createFontPlatformData(const FontDescription& fontD
         fontDescription.orientation(),
         s_useSubpixelPositioning);
 
+    struct FamilyMinSize {
+        const wchar_t* family;
+        unsigned minSize;
+    };
+    const static FamilyMinSize minAntiAliasSizeForFont[] = {
+        { L"simsun", 16 },
+        { L"dotum", 12 }
+    };
+    size_t numFonts = WTF_ARRAY_LENGTH(minAntiAliasSizeForFont);
+    for (size_t i = 0; i < numFonts; i++) {
+        FamilyMinSize entry = minAntiAliasSizeForFont[i];
+        if (typefacesMatchesFamily(tf.get(), entry.family)) {
+            result->setMinSizeForAntiAlias(entry.minSize);
+            break;
+        }
+    }
+
     return result;
 }
 

third_party/WebKit/Source/platform/fonts/win/FontPlatformDataWin.cpp

@@ -62,6 +62,7 @@ void FontPlatformData::setupPaint(SkPaint* paint, GraphicsContext* context) cons
     if (ts <= kMaxSizeForEmbeddedBitmap)
         flags |= SkPaint::kEmbeddedBitmapText_Flag;
 
+    if (ts >= m_minSizeForAntiAlias) {
         if (m_useSubpixelPositioning)
             flags |= SkPaint::kSubpixelText_Flag;
 
@@ -77,6 +78,7 @@ void FontPlatformData::setupPaint(SkPaint* paint, GraphicsContext* context) cons
         }
         SkASSERT(!(textFlags & ~textFlagsMask));
         flags |= textFlags;
+    }
 
     paint->setFlags(flags);
 }