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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_FONT_HEIGHT_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_FONT_HEIGHT_H_
#include "third_party/blink/renderer/platform/fonts/font_baseline.h"
#include "third_party/blink/renderer/platform/geometry/layout_unit.h"
namespace blink {
// Represents line-progression metrics for line boxes and inline boxes.
// Computed for inline boxes, then the metrics of inline boxes are united to
// compute metrics for line boxes.
// https://drafts.csswg.org/css2/visudet.html#line-height
struct PLATFORM_EXPORT FontHeight {
FontHeight() = default;
FontHeight(LayoutUnit ascent, LayoutUnit descent)
: ascent(ascent), descent(descent) {}
// "Empty" is for when zero is a valid non-empty value.
static FontHeight Empty() {
return FontHeight(LayoutUnit::Min(), LayoutUnit::Min());
}
bool IsEmpty() const {
return ascent == LayoutUnit::Min() && descent == LayoutUnit::Min();
}
LayoutUnit LineHeight() const { return ascent + descent; }
bool operator==(const FontHeight& other) const {
return ascent == other.ascent && descent == other.descent;
}
bool operator!=(const FontHeight& other) const { return !operator==(other); }
// True if `other`'s ascent and descent are both equal to or less than `this`.
bool Contains(const FontHeight& other) const {
return other.ascent <= ascent && other.descent <= descent;
}
// Add the leading space. `leading_space.ascent` will be added into ascent and
// `leading_space.descent` will be added to descent.
// https://drafts.csswg.org/css2/visudet.html#leading
void AddLeading(const FontHeight& leading_space);
// Move the metrics by the specified amount, in line progression direction.
void Move(LayoutUnit);
// Unite a metrics for an inline box to a metrics for a line box.
void Unite(const FontHeight&);
void operator+=(const FontHeight&);
// Ascent and descent of glyphs, or synthesized for replaced elements.
// Then united to compute 'text-top' and 'text-bottom' of line boxes.
LayoutUnit ascent;
LayoutUnit descent;
};
PLATFORM_EXPORT std::ostream& operator<<(std::ostream&, const FontHeight&);
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_FONT_HEIGHT_H_
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