ladybird/Userland/Libraries/LibGfx/TextLayout.h

119 lines
3.4 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/ByteString.h>
#include <AK/CharacterTypes.h>
#include <AK/Forward.h>
#include <AK/Utf32View.h>
#include <AK/Utf8View.h>
#include <AK/Vector.h>
#include <LibGfx/Font/Font.h>
#include <LibGfx/FontCascadeList.h>
#include <LibGfx/Forward.h>
#include <LibGfx/Rect.h>
namespace Gfx {
inline bool should_paint_as_space(u32 code_point)
{
return is_ascii_space(code_point) || code_point == 0xa0;
}
enum class IncludeLeftBearing {
Yes,
No
};
struct DrawGlyph {
FloatPoint position;
u32 code_point;
NonnullRefPtr<Font const> font;
void translate_by(FloatPoint const& delta)
{
position.translate_by(delta);
}
};
struct DrawEmoji {
FloatPoint position;
Gfx::Bitmap const* emoji;
NonnullRefPtr<Font const> font;
void translate_by(FloatPoint const& delta)
{
position.translate_by(delta);
}
};
using DrawGlyphOrEmoji = Variant<DrawGlyph, DrawEmoji>;
class GlyphRun : public RefCounted<GlyphRun> {
public:
GlyphRun() = default;
GlyphRun(Vector<Gfx::DrawGlyphOrEmoji>&& glyphs)
: m_glyphs(move(glyphs))
{
}
[[nodiscard]] Vector<Gfx::DrawGlyphOrEmoji> const& glyphs() const { return m_glyphs; }
[[nodiscard]] bool is_empty() const { return m_glyphs.is_empty(); }
void append(Gfx::DrawGlyphOrEmoji glyph) { m_glyphs.append(glyph); }
private:
Vector<Gfx::DrawGlyphOrEmoji> m_glyphs;
};
Variant<DrawGlyph, DrawEmoji> prepare_draw_glyph_or_emoji(FloatPoint point, Utf8CodePointIterator& it, Font const& font);
template<typename Callback>
void for_each_glyph_position(FloatPoint baseline_start, Utf8View string, FontCascadeList const& font_list, Callback callback, IncludeLeftBearing include_left_bearing = IncludeLeftBearing::No, Optional<float&> width = {})
{
auto const& space_glyph_font = font_list.font_for_code_point(' ');
float space_width = space_glyph_font.glyph_width(' ');
u32 last_code_point = 0;
auto point = baseline_start;
for (auto code_point_iterator = string.begin(); code_point_iterator != string.end(); ++code_point_iterator) {
auto it = code_point_iterator; // The callback function will advance the iterator, so create a copy for this lookup.
auto code_point = *code_point_iterator;
RefPtr<Gfx::Font const> font = font_list.font_for_code_point(code_point);
point.set_y(baseline_start.y() - font->pixel_metrics().ascent);
if (should_paint_as_space(code_point)) {
point.translate_by(space_width, 0);
last_code_point = code_point;
continue;
}
auto kerning = font->glyphs_horizontal_kerning(last_code_point, code_point);
if (kerning != 0.0f)
point.translate_by(kerning, 0);
auto glyph_width = font->glyph_or_emoji_width(it);
auto glyph_or_emoji = prepare_draw_glyph_or_emoji(point, code_point_iterator, *font);
if (include_left_bearing == IncludeLeftBearing::Yes) {
if (glyph_or_emoji.has<DrawGlyph>())
glyph_or_emoji.get<DrawGlyph>().position += FloatPoint(font->glyph_left_bearing(code_point), 0);
}
callback(glyph_or_emoji);
point.translate_by(glyph_width, 0);
last_code_point = code_point;
}
if (width.has_value())
*width = point.x();
}
}