blob: 8d7a67a4f972c051a3c8eb4ec72e7b4fd8a599de [file] [log] [blame]
// Copyright 2014 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 "third_party/blink/renderer/core/layout/text_decoration_offset_base.h"
#include <algorithm>
#include "third_party/blink/renderer/core/paint/decoration_info.h"
#include "third_party/blink/renderer/platform/fonts/font_metrics.h"
#include "third_party/blink/renderer/platform/fonts/font_vertical_position_type.h"
namespace blink {
int TextDecorationOffsetBase::ComputeUnderlineOffsetForRoman(
const FontMetrics& font_metrics,
float text_decoration_thickness) const {
// Compute the gap between the font and the underline. Use at least one
// pixel gap, if underline is thick then use a bigger gap.
int gap = 0;
// Underline position of zero means draw underline on Baseline Position,
// in Blink we need at least 1-pixel gap to adding following check.
// Positive underline Position means underline should be drawn above baseline
// and negative value means drawing below baseline, negating the value as in
// Blink downward Y-increases.
if (font_metrics.UnderlinePosition())
gap = -font_metrics.UnderlinePosition();
gap = std::max<int>(1, ceilf(text_decoration_thickness / 2.f));
// Position underline near the alphabetic baseline.
return font_metrics.Ascent() + gap;
int TextDecorationOffsetBase::ComputeUnderlineOffset(
ResolvedUnderlinePosition underline_position,
const FontMetrics& font_metrics,
float text_decoration_thickness) const {
switch (underline_position) {
case ResolvedUnderlinePosition::kRoman:
return ComputeUnderlineOffsetForRoman(font_metrics,
case ResolvedUnderlinePosition::kUnder:
// Position underline at the under edge of the lowest element's
// content box.
return ComputeUnderlineOffsetForUnder(
} // namespace blink