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

// 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::getGlyphWidthForHarfBuzz(hb_codepoint_t codepoint,
                                               hb_position_t* width) {
  DCHECK_LE(codepoint, 0xFFFFu);
  CHECK(width);

  SkScalar skWidth;
  uint16_t glyph = codepoint;

  m_paint->getTextWidths(&glyph, sizeof(glyph), &skWidth, nullptr);
  if (!m_paint->isSubpixelText())
    skWidth = SkScalarRoundToInt(skWidth);
  *width = SkiaScalarToHarfBuzzPosition(skWidth);
}

void SkiaTextMetrics::getGlyphExtentsForHarfBuzz(hb_codepoint_t codepoint,
                                                 hb_glyph_extents_t* extents) {
  DCHECK_LE(codepoint, 0xFFFFu);
  CHECK(extents);

  SkRect skBounds;
  uint16_t glyph = codepoint;

  m_paint->getTextWidths(&glyph, sizeof(glyph), nullptr, &skBounds);
  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