// Copyright (C) 2016 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qsvgfont_p.h"

#include "qpainter.h"

#include "qpen.h"

#include "qdebug.h"

QT_BEGIN_NAMESPACE

QSvgGlyph::QSvgGlyph(const QString &unicode, const QPainterPath &path, qreal horizAdvX)

    : m_unicode(unicode), m_path(path), m_horizAdvX(horizAdvX)

{

}

QSvgFont::QSvgFont(qreal horizAdvX)

    : m_horizAdvX(horizAdvX)

{

}

QString QSvgFont::familyName() const

{

    return m_familyName;

}

void QSvgFont::addGlyph(const QString &unicode, const QPainterPath &path, qreal horizAdvX)

{

    m_glyphs.emplaceBack(unicode, path, (horizAdvX == -1) ? m_horizAdvX : horizAdvX);

}

bool QSvgFont::addMissingGlyph(const QPainterPath &path, qreal horizAdvX)

{

    if (m_missingGlyph) {

        qWarning("The font already has a 'missing-glyph' element.");

        return false;

    }

    m_missingGlyph.reset(new QSvgGlyph(QChar(), path, (horizAdvX == -1) ? m_horizAdvX : horizAdvX));

    return true;

}

void QSvgFont::draw(QPainter *p, const QPointF &point, const QList<const QSvgGlyph *> &glyphs,

                    qreal pixelSize, Qt::Alignment alignment) const

{

    draw_helper(p, point, glyphs, pixelSize, alignment, nullptr);

}

QRectF QSvgFont::boundingRect(QPainter *p, const QPointF &point,

                              const QList<const QSvgGlyph *> &glyphs,

                              qreal pixelSize, Qt::Alignment alignment) const

{

    QRectF bounds;

    draw_helper(p, point, glyphs, pixelSize, alignment, &bounds);

    return bounds;

}

// text must not be empty

char32_t firstUcs4(QStringView text)

{

    if (text.size() > 1 && text.at(0).isHighSurrogate() && text.at(1).isLowSurrogate())

        return QChar::surrogateToUcs4(text.at(0), text.at(1));

    return text.first().unicode();

}

// returns a pointer to the first QSvgGlyph to be used in the text

// or nullptr if none can be found

const QSvgGlyph *QSvgFont::findFirstGlyphFor(QStringView text) const

{

    const auto possibleIndices = m_possibleGlyphIndicesForChar.value(firstUcs4(text));

    for (const qsizetype i : possibleIndices) {

        const QSvgGlyph &currentGlyph = m_glyphs.at(i);

        if (text.startsWith(currentGlyph.m_unicode)) {

            return &currentGlyph;

        }

    }

    for (; m_firstUnscannedGlyphIdx < m_glyphs.size(); ++m_firstUnscannedGlyphIdx) {

        const QSvgGlyph &currentGlyph = m_glyphs.at(m_firstUnscannedGlyphIdx);

        m_possibleGlyphIndicesForChar[firstUcs4(currentGlyph.m_unicode)].push_back(m_firstUnscannedGlyphIdx);

        if (text.startsWith(currentGlyph.m_unicode)) {

            ++m_firstUnscannedGlyphIdx;

            return &currentGlyph;

        }

    }

    return nullptr;

}

QList<const QSvgGlyph *> QSvgFont::toGlyphs(QStringView text) const

{

    QList<const QSvgGlyph *> glyphs;

    glyphs.reserve(text.length());

    while (text.length()) {

        const QSvgGlyph *foundGlyph = findFirstGlyphFor(text);

        if (foundGlyph) {

            glyphs.append(foundGlyph);

            text.slice(foundGlyph->m_unicode.length());

        } else {

            if (m_missingGlyph)

                glyphs.append(m_missingGlyph.get());

            if (text.size() > 1

                && text.at(0).isHighSurrogate() && text.at(1).isLowSurrogate()) {

                text.slice(2);

            } else {

                text.slice(1);

            }

        }

    }

    return glyphs;

}

void QSvgFont::draw_helper(QPainter *p, const QPointF &point,

                           const QList<const QSvgGlyph *> &glyphs, qreal pixelSize,

                           Qt::Alignment alignment, QRectF *boundingRect) const

{

    const bool isPainting = (boundingRect == nullptr);

    p->save();

    p->translate(point);

    p->scale(pixelSize / m_unitsPerEm, -pixelSize / m_unitsPerEm);

    // Calculate the text width to be used for alignment

    int textWidth = 0;

    for (const auto *glyph : glyphs)

        textWidth += static_cast<int>(glyph->m_horizAdvX);

    QPoint alignmentOffset(0, 0);

    if (alignment == Qt::AlignHCenter) {

        alignmentOffset.setX(-textWidth / 2);

    } else if (alignment == Qt::AlignRight) {

        alignmentOffset.setX(-textWidth);

    }

    p->translate(alignmentOffset);

    // since in SVG the embedded font ain't really a path

    // the outline has got to stay untransformed...

    qreal penWidth = p->pen().widthF();

    penWidth /= (pixelSize/m_unitsPerEm);

    QPen pen = p->pen();

    pen.setWidthF(penWidth);

    p->setPen(pen);

    for (const auto *glyph : glyphs) {

        if (isPainting)

            p->drawPath(glyph->m_path);

        if (boundingRect) {

            QPainterPathStroker stroker;

            stroker.setWidth(penWidth);

            stroker.setJoinStyle(p->pen().joinStyle());

            stroker.setMiterLimit(p->pen().miterLimit());

            QPainterPath stroke = stroker.createStroke(glyph->m_path);

            *boundingRect |= p->transform().map(stroke).boundingRect();

        }

        p->translate(glyph->m_horizAdvX, 0);

    }

    p->restore();

}

void QSvgFont::setFamilyName(const QString &name)

{

    m_familyName = name;

}

void QSvgFont::setUnitsPerEm(qreal upem)

{

    m_unitsPerEm = upem;

}

QT_END_NAMESPACE