Unify glyph metrics to use the same Skia API

third_party/WebKit/Source/platform/fonts/skia/SkiaTextMetrics.cpp

Index: third_party/WebKit/Source/platform/fonts/skia/SkiaTextMetrics.cpp
diff --git a/third_party/WebKit/Source/platform/fonts/skia/SkiaTextMetrics.cpp b/third_party/WebKit/Source/platform/fonts/skia/SkiaTextMetrics.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..05e92c252823f69f8e7659a66ea51207e071b696
--- /dev/null
+++ b/third_party/WebKit/Source/platform/fonts/skia/SkiaTextMetrics.cpp
@@ -0,0 +1,88 @@
+// Copyright 2016 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 "SkiaTextMetrics.h"
+
+#include "wtf/MathExtras.h"
+
+#include <SkPath.h>
+
+namespace blink {
+
+static hb_position_t SkiaScalarToHarfBuzzPosition(SkScalar value)
+{
+    // We treat HarfBuzz hb_position_t as 16.16 fixed-point.
+    static const int kHbPosition1 = 1 << 16;
+    return clampTo<int>(value * kHbPosition1);
+}
+
+SkiaTextMetrics::SkiaTextMetrics(const SkPaint* paint)
+    : m_paint(paint)
+{
+    CHECK(m_paint->getTextEncoding() == SkPaint::kGlyphID_TextEncoding);
+}
+
+void SkiaTextMetrics::getGlyphWidthAndExtentsForHarfBuzz(hb_codepoint_t codepoint, hb_position_t* width, hb_glyph_extents_t* extents)
+{
+    DCHECK_LE(codepoint, 0xFFFFu);
+
+    SkScalar skWidth;
+    SkRect skBounds;
+    uint16_t glyph = codepoint;
+
+    m_paint->getTextWidths(&glyph, sizeof(glyph), &skWidth, &skBounds);
+    if (width) {
+        if (!m_paint->isSubpixelText())
+            skWidth = SkScalarRoundToInt(skWidth);
+        *width = SkiaScalarToHarfBuzzPosition(skWidth);
+    }
+    if (extents) {
+        if (!m_paint->isSubpixelText()) {
+            // Use roundOut() rather than round() to avoid rendering glyphs
+            // outside the visual overflow rect. crbug.com/452914.
+            SkIRect ir;
+            skBounds.roundOut(&ir);
+            skBounds.set(ir);
+        }
+        // Invert y-axis because Skia is y-grows-down but we set up HarfBuzz to be y-grows-up.
+        extents->x_bearing = SkiaScalarToHarfBuzzPosition(skBounds.fLeft);
+        extents->y_bearing = SkiaScalarToHarfBuzzPosition(-skBounds.fTop);
+        extents->width = SkiaScalarToHarfBuzzPosition(skBounds.width());
+        extents->height = SkiaScalarToHarfBuzzPosition(-skBounds.height());
+    }
+}
+
+void SkiaTextMetrics::getSkiaBoundsForGlyph(Glyph glyph, SkRect *bounds)
+{
+#if OS(MACOSX)
+    // TODO(drott): Remove this once we have better metrics bounds
+    // on Mac, https://bugs.chromium.org/p/skia/issues/detail?id=5328
+    SkPath path;
+    m_paint->getTextPath(&glyph, sizeof(glyph), 0, 0, &path);
+    *bounds = path.getBounds();
+#else
+    m_paint->getTextWidths(&glyph, sizeof(glyph), nullptr, bounds);
+#endif
+
+    if (!m_paint->isSubpixelText()) {
+        SkIRect ir;
+        bounds->roundOut(&ir);
+        bounds->set(ir);
+    }
+
+}
+
+float SkiaTextMetrics::getSkiaWidthForGlyph(Glyph glyph)
+{
+    SkScalar skWidth;
+    m_paint->getTextWidths(&glyph, sizeof(glyph), &skWidth, nullptr);
+
+    if (!m_paint->isSubpixelText())
+        skWidth = SkScalarRoundToInt(skWidth);
+
+    return SkScalarToFloat(skWidth);
+}
+
+
+} // namespace blink