Initial OpenType Font Variations Support

third_party/WebKit/Source/platform/fonts/FontCustomPlatformData.cpp

Index: third_party/WebKit/Source/platform/fonts/FontCustomPlatformData.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/FontCustomPlatformData.cpp b/third_party/WebKit/Source/platform/fonts/FontCustomPlatformData.cpp
index 67a56fe7176bc960e2cb2102fa6f6e1400038ffc..a11ff8e083f014514dca25a103add905ce13ed7b 100644
--- a/third_party/WebKit/Source/platform/fonts/FontCustomPlatformData.cpp
+++ b/third_party/WebKit/Source/platform/fonts/FontCustomPlatformData.cpp
@@ -37,6 +37,7 @@
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontPlatformData.h"
 #include "platform/fonts/WebFontDecoder.h"
+#include "platform/fonts/opentype/FontSettings.h"
 #include "third_party/skia/include/core/SkStream.h"
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "wtf/PtrUtil.h"
@@ -46,18 +47,54 @@ namespace blink {
 
 FontCustomPlatformData::FontCustomPlatformData(sk_sp<SkTypeface> typeface,
                                                size_t dataSize)
-    : m_typeface(typeface), m_dataSize(dataSize) {}
+    : m_baseTypeface(typeface), m_dataSize(dataSize) {}
 
 FontCustomPlatformData::~FontCustomPlatformData() {}
 
+SkFourByteTag atomicStringToFourByteTag(AtomicString tag) {
+  return SkSetFourByteTag(tag[0], tag[1], tag[2], tag[3]);

[eae, 2016/12/16 18:48:27]

DCHECK(tag.size() == 4);

actually, as the tags can be user supplied this should be a proper if-check if
we haven't validated that already. If we have then a dcheck is fine.

[drott, 2016/12/19 14:12:34]

Added the DCHECK. Generally the feature tags can only come in through
CSSPropertyParser, which has length-checks in
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/parse...

+}
+
 FontPlatformData FontCustomPlatformData::fontPlatformData(
     float size,
     bool bold,
     bool italic,
-    FontOrientation orientation) {
-  ASSERT(m_typeface);
-  return FontPlatformData(m_typeface, "", size, bold && !m_typeface->isBold(),
-                          italic && !m_typeface->isItalic(), orientation);
+    FontOrientation orientation,
+    FontVariationSettings* variationSettings) {
+  DCHECK(m_baseTypeface);
+
+  sk_sp<SkTypeface> returnTypeface = m_baseTypeface;
+
+  if (variationSettings && variationSettings->size() < UINT16_MAX) {

[eae, 2016/12/16 18:48:27]

I'm guessing the size < UINT16_MAX check is a security check for malicious
content? Regardless, please add a comment explaining the limit.

[drott, 2016/12/19 14:12:34]

Explained in new comment.

+    // TODO, crbug.com/674878 second duplicate value should supersede first.
+    RefPtr<SkFontMgr> fm = adoptRef(SkFontMgr::RefDefault());
+    Vector<SkFontMgr::FontParameters::Axis, 0> axes;
+    axes.reserveCapacity(variationSettings->size());
+    for (size_t i = 0; i < variationSettings->size(); ++i) {
+      SkFontMgr::FontParameters::Axis axis = {
+          atomicStringToFourByteTag(variationSettings->at(i).tag()),
+          SkFloatToScalar(variationSettings->at(i).value())};
+      axes.append(axis);
+    }
+
+    sk_sp<SkTypeface> skVariationFont(fm->createFromStream(
+        m_baseTypeface->openStream(nullptr)->duplicate(),
+        SkFontMgr::FontParameters().setAxes(axes.data(), axes.size())));
+
+    if (skVariationFont) {
+      returnTypeface = skVariationFont;
+    } else {
+      SkString familyName;
+      m_baseTypeface->getFamilyName(&familyName);
+      // TODO: Surface this as a console message?
+      LOG(ERROR) << "Unable for apply variation axis properties for font: "
+                 << familyName.c_str();
+    }
+  }
+
+  return FontPlatformData(returnTypeface, "", size,
+                          bold && !m_baseTypeface->isBold(),
+                          italic && !m_baseTypeface->isItalic(), orientation);
 }
 
 std::unique_ptr<FontCustomPlatformData> FontCustomPlatformData::create(