(DO NOT LAND, EXPERIMENTAL) os/2

third_party/WebKit/Source/platform/fonts/opentype/OpenTypeOS2Table.cpp

Index: third_party/WebKit/Source/platform/fonts/opentype/OpenTypeOS2Table.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeOS2Table.cpp b/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeOS2Table.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..6a9bcbd90ac42f4595cf615cd2b5dd164d6d55e3
--- /dev/null
+++ b/third_party/WebKit/Source/platform/fonts/opentype/OpenTypeOS2Table.cpp
@@ -0,0 +1,83 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "platform/fonts/opentype/OpenTypeOS2Table.h"
+
+#include "SkTypeface.h"
+#include "platform/fonts/opentype/OpenTypeTypes.h"
+
+namespace blink {
+namespace OpenType {
+
+#pragma pack(1)
+
+// https://www.microsoft.com/typography/otspec/os2.htm
+
+enum class FontSelectionFlag1 : uint8_t {
+    USE_TYPO_METRICS = 1 << 7,
+};
+
+inline bool operator&(FontSelectionFlag1 lhs, FontSelectionFlag1 rhs)
+{
+    return static_cast<uint8_t>(lhs) & static_cast<uint8_t>(rhs);
+}
+
+struct OS2TableV3 {
+    OpenType::UInt16 version;
+    OpenType::Int16 xAvgCharWidth;
+    OpenType::UInt16 usWeightClass;
+    OpenType::UInt16 usWidthClass;
+    OpenType::UInt16 fsType;
+    OpenType::Int16 ySubscriptXSize;
+    OpenType::Int16 ySubscriptYSize;
+    OpenType::Int16 ySubscriptXOffset;
+    OpenType::Int16 ySubscriptYOffset;
+    OpenType::Int16 ySuperscriptXSize;
+    OpenType::Int16 ySuperscriptYSize;
+    OpenType::Int16 ySuperscriptXOffset;
+    OpenType::Int16 ySuperscriptYOffset;
+    OpenType::Int16 yStrikeoutSize;
+    OpenType::Int16 yStrikeoutPosition;
+    OpenType::Int16 sFamilyClass;
+    uint8_t panose[10];
+    OpenType::UInt32 ulUnicodeRange[4];
+    int8_t achVendID[4];
+    uint8_t fsSelection0;
+    FontSelectionFlag1 fsSelection1;
+    OpenType::UInt16 usFirstCharIndex;
+    OpenType::UInt16 usLastCharIndex;
+    OpenType::Int16 sTypoAscender;
+    OpenType::Int16 sTypoDescender;
+    OpenType::Int16 sTypoLineGap;
+    OpenType::UInt16 usWinAscent;
+    OpenType::UInt16 usWinDescent;
+    OpenType::UInt32 ulCodePageRange[2];
+    OpenType::Int16 sxHeight;
+    OpenType::Int16 sCapHeight;
+    OpenType::UInt16 usDefaultChar;
+    OpenType::UInt16 usBreakChar;
+    OpenType::UInt16 usMaxContext;
+
+    OS2Table() { }
+};
+
+#pragma pack()
+
+} // namespace OpenType
+
+bool getAscentDescentFromOS2Table(SkTypeface* face, short& ascentInUnits, short& descentInUnits)
+{
+    static const uint32_t os2Tag = SkSetFourByteTag('O', 'S', '/', '2');
+    OpenType::OS2TableV3 os2Table;
+    if (face->getTableData(os2Tag, 0, sizeof(os2Table), &os2Table) != sizeof(os2Table))
+        return false;
+    if (!(os2Table.fsSelection1 & OpenType::FontSelectionFlag1::USE_TYPO_METRICS))
+        return false;
+    ascentInUnits = os2Table.sTypoAscender;
+    descentInUnits = os2Table.sTypoDescender;
+    return true;
+}
+
+} // namespace blink