JUCE/modules/juce_graphics/detail/juce_JustifiedText.h

/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

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  ==============================================================================
*/

namespace juce::detail
{

template <size_t StartingAt, typename Tuple, size_t... Is>
constexpr auto partiallyUnpackImpl (Tuple&& tuple, std::index_sequence<Is...>)
{
    return std::tie (std::get<StartingAt + Is> (tuple)...);
}

template <size_t StartingAt, size_t NumElems, typename Tuple>
constexpr auto partiallyUnpack (Tuple&& tuple)
{
    return partiallyUnpackImpl<StartingAt> (std::forward<Tuple> (tuple), std::make_index_sequence<NumElems>{});
}

class JustifiedText
{
private:
    enum class DrawType
    {
        normal,
        ellipsis
    };

public:
    JustifiedText (const SimpleShapedText& t, const ShapedTextOptions& options);

    template <typename Callable, typename... RangedValues>
    void accessTogetherWith (Callable&& callback, RangedValues&&... rangedValues) const
    {
        std::optional<int64> lastLine;
        Point<float> anchor {};

        for (const auto item : makeIntersectingRangedValues (&shapedText.getLineNumbers(),
                                                             &shapedText.getResolvedFonts(),
                                                             &lineAnchors,
                                                             &rangesToDraw,
                                                             &whitespaceStretch,
                                                             (&rangedValues)...))
        {
            const auto& [range, line, font, lineAnchor, drawType, stretch] = partiallyUnpack<0, 6> (item);
            const auto& rest = partiallyUnpack<6, std::tuple_size_v<decltype (item)> - 6> (item);

            if (std::exchange (lastLine, line) != line)
                anchor = lineAnchor;

            const auto glyphs = [this, r = range, dt = drawType]() -> Span<const ShapedGlyph>
            {
                if (dt == DrawType::ellipsis)
                    return ellipsis->getGlyphs();

                return shapedText.getGlyphs (r);
            }();

            std::vector<Point<float>> positions (glyphs.size());

            std::transform (glyphs.begin(),
                            glyphs.end(),
                            positions.begin(),
                            [&anchor, &s = stretch] (auto& glyph)
                            {
                                auto result = anchor + glyph.offset;

                                anchor += glyph.advance;

                                if (glyph.whitespace)
                                    anchor.addXY (s, 0.0f);

                                return result;
                            });

            const auto callbackFont =
                drawType == DrawType::ellipsis ? ellipsis->getResolvedFonts().front().value : font;
            const auto callbackParameters =
                std::tuple_cat (std::tie (glyphs, positions, callbackFont, range, line), rest);

            const auto invokeNullChecked = [&] (auto&... params)
            { NullCheckedInvocation::invoke (callback, params...); };

            std::apply (invokeNullChecked, callbackParameters);
        }
    }

    /* The callback receives (Span<const ShapedGlyph> glyphs,
                              Span<Point<float>> positions,
                              Font font,
                              Range<int64> glyphRange,
                              int64 lineNumber) // So far this has been indexed from 0 per SimpleShapedText
                                                // object, but maybe we'll find we want global text level
                                                // line numbers, so only assume they are increasing by one
    */
    template <typename Callable>
    void access (Callable&& callback) const;

    /*  This is how much cumulative widths glyphs take up in each line. Whether the trailing
        whitespace is included depends on the ShapedTextOptions::getWhitespaceShouldFitInLine()
        setting.
    */
    auto& getMinimumRequiredWidthForLines() const { return minimumRequiredWidthsForLine; }

private:
    const SimpleShapedText& shapedText;
    detail::RangedValues<Point<float>> lineAnchors;
    std::optional<SimpleShapedText> ellipsis;
    detail::RangedValues<DrawType> rangesToDraw;
    detail::RangedValues<float> whitespaceStretch;
    std::vector<float> minimumRequiredWidthsForLine;
};

} // namespace juce::detail