ladybird/Userland/Libraries/LibGfx/TextLayout.h

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/*
* 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>
#include <LibGfx/TextElision.h>
#include <LibGfx/TextWrapping.h>
namespace Gfx {
// FIXME: This currently isn't an ideal way of doing things; ideally, TextLayout
// would be doing the rendering by painting individual glyphs. However, this
// would regress our Unicode bidirectional text support. Therefore, fixing this
// requires:
// - Moving the bidirectional algorithm either here, or some place TextLayout
// can access;
// - Making TextLayout render the given text into something like a Vector<Line>
// where:
// using Line = Vector<DirectionalRun>;
// struct DirectionalRun {
// Utf32View glyphs;
// Vector<int> advance;
// TextDirection direction;
// };
// - Either;
// a) Making TextLayout output these Lines directly using a given Painter, or
// b) Taking the Lines from TextLayout and painting each glyph.
class TextLayout {
public:
TextLayout(Gfx::Font const& font, Utf8View const& text, FloatRect const& rect)
: m_font(font)
, m_font_metrics(font.pixel_metrics())
, m_text(text)
, m_rect(rect)
{
}
Vector<ByteString, 32> lines(TextElision elision, TextWrapping wrapping) const
{
return wrap_lines(elision, wrapping);
}
FloatRect bounding_rect(TextWrapping) const;
private:
Vector<ByteString, 32> wrap_lines(TextElision, TextWrapping) const;
ByteString elide_text_from_right(Utf8View) const;
Font const& m_font;
FontPixelMetrics m_font_metrics;
Utf8View m_text;
FloatRect m_rect;
};
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;
};
struct DrawEmoji {
FloatPoint position;
Gfx::Bitmap const* emoji;
NonnullRefPtr<Font const> font;
};
using DrawGlyphOrEmoji = Variant<DrawGlyph, DrawEmoji>;
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 = {})
{
float space_width = font_list.first().glyph_width(' ') + font_list.first().glyph_spacing();
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) + font->glyph_spacing();
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() - font_list.first().glyph_spacing();
}
}