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** Copyright (C) 2017 The Qt Company Ltd.
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** This file is part of the Qt Quick Controls 2 module of the Qt Toolkit.
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or later as published by the Free
** Software Foundation and appearing in the file LICENSE.GPL included in
** the packaging of this file. Please review the following information to
** ensure the GNU General Public License version 2.0 requirements will be
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****************************************************************************/

#include "qquickninepatchimage_p.h"

#include <QtCore/qfileinfo.h>
#include <QtQuick/qsggeometry.h>
#include <QtQuick/qsgtexturematerial.h>
#include <QtQuick/private/qsgnode_p.h>
#include <QtQuick/private/qquickimage_p_p.h>

QT_BEGIN_NAMESPACE

struct QQuickNinePatchData
{
    QVector<qreal> coordsForSize(qreal count) const;

    inline bool isNull() const { return data.isEmpty(); }
    inline int count() const { return data.size(); }
    inline qreal at(int index) const { return data.at(index); }
    inline qreal size() const { return data.last(); }

    void fill(const QVector<qreal> &coords, qreal count);
    void clear();

private:
    bool inverted = false;
    QVector<qreal> data;
};

QVector<qreal> QQuickNinePatchData::coordsForSize(qreal size) const
{
    // n = number of stretchable sections
    // We have to compensate when adding 0 and/or
    // the source image width to the divs vector.
    const int l = data.size();
    const int n = (inverted ? l - 1 : l) / 2;
    const qreal stretch = (size - data.last()) / n;

    QVector<qreal> coords;
    coords.reserve(l);
    coords.append(0);

    bool stretched = !inverted;
    for (int i = 1; i < l; ++i) {
        qreal advance = data[i] - data[i - 1];
        if (stretched)
            advance += stretch;
        coords.append(coords.last() + advance);

        stretched = !stretched;
    }

    return coords;
}

void QQuickNinePatchData::fill(const QVector<qreal> &coords, qreal size)
{
    data.clear();
    inverted = coords.isEmpty() || coords.first() != 0;

    // Reserve an extra item in case we need to add the image width/height
    if (inverted) {
        data.reserve(coords.size() + 2);
        data.append(0);
    } else {
        data.reserve(coords.size() + 1);
    }

    data += coords;
    data.append(size);
}

void QQuickNinePatchData::clear()
{
    data.clear();
}

class QQuickNinePatchNode : public QSGGeometryNode
{
public:
    QQuickNinePatchNode();
    ~QQuickNinePatchNode();

    void initialize(QSGTexture *texture, const QSizeF &targetSize, const QSize &sourceSize,
                    const QQuickNinePatchData &xDivs, const QQuickNinePatchData &yDivs, qreal dpr);

private:
    QSGGeometry m_geometry;
    QSGTextureMaterial m_material;
};

QQuickNinePatchNode::QQuickNinePatchNode()
    : m_geometry(QSGGeometry::defaultAttributes_TexturedPoint2D(), 4)
{
    m_geometry.setDrawingMode(QSGGeometry::DrawTriangles);
    setGeometry(&m_geometry);
    setMaterial(&m_material);
}

QQuickNinePatchNode::~QQuickNinePatchNode()
{
    delete m_material.texture();
}

void QQuickNinePatchNode::initialize(QSGTexture *texture, const QSizeF &targetSize, const QSize &sourceSize,
                                     const QQuickNinePatchData &xDivs, const QQuickNinePatchData &yDivs, qreal dpr)
{
    delete m_material.texture();
    m_material.setTexture(texture);

    const int xlen = xDivs.count();
    const int ylen = yDivs.count();

    if (xlen > 0 && ylen > 0) {
        const int quads = (xlen - 1) * (ylen - 1);
        static const int verticesPerQuad = 6;
        m_geometry.allocate(xlen * ylen, verticesPerQuad * quads);

        QSGGeometry::TexturedPoint2D *vertices = m_geometry.vertexDataAsTexturedPoint2D();
        QVector<qreal> xCoords = xDivs.coordsForSize(targetSize.width());
        QVector<qreal> yCoords = yDivs.coordsForSize(targetSize.height());

        for (int y = 0; y < ylen; ++y) {
            for (int x = 0; x < xlen; ++x, ++vertices)
                vertices->set(xCoords[x] / dpr, yCoords[y] / dpr,
                              xDivs.at(x) / sourceSize.width(),
                              yDivs.at(y) / sourceSize.height());
        }

        quint16 *indices = m_geometry.indexDataAsUShort();
        int n = quads;
        for (int q = 0; n--; ++q) {
            if ((q + 1) % xlen == 0) // next row
                ++q;
            // Bottom-left half quad triangle
            indices[0] = q;
            indices[1] = q + xlen;
            indices[2] = q + xlen + 1;

            // Top-right half quad triangle
            indices[3] = q;
            indices[4] = q + xlen + 1;
            indices[5] = q + 1;

            indices += verticesPerQuad;
        }
    }

    markDirty(QSGNode::DirtyGeometry | QSGNode::DirtyMaterial);
}

class QQuickNinePatchImagePrivate : public QQuickImagePrivate
{
    Q_DECLARE_PUBLIC(QQuickNinePatchImage)

public:
    void updatePatches();
    void updatePaddings(const QSizeF &size, const QVector<qreal> &horizontal, const QVector<qreal> &vertical);
    void updateInsets(const QVector<qreal> &horizontal, const QVector<qreal> &vertical);

    bool resetNode = false;
    qreal topPadding = 0;
    qreal leftPadding = 0;
    qreal rightPadding = 0;
    qreal bottomPadding = 0;
    qreal topInset = 0;
    qreal leftInset = 0;
    qreal rightInset = 0;
    qreal bottomInset = 0;

    QImage ninePatch;
    QQuickNinePatchData xDivs;
    QQuickNinePatchData yDivs;
};

static QVector<qreal> readCoords(const QRgb *data, int from, int count, int offset, QRgb color)
{
    int p1 = -1;
    QVector<qreal> coords;
    for (int i = 0; i < count; ++i) {
        int p2 = from + i * offset;
        if (data[p2] == color) {
            // colored pixel
            if (p1 == -1)
                p1 = i;
        } else {
            // empty pixel
            if (p1 != -1) {
                coords << p1 << i;
                p1 = -1;
            }
        }
    }
    return coords;
}

void QQuickNinePatchImagePrivate::updatePatches()
{
    if (ninePatch.isNull())
        return;

    int w = ninePatch.width();
    int h = ninePatch.height();
    const QRgb *data = reinterpret_cast<const QRgb *>(ninePatch.constBits());

    const QRgb black = qRgb(0,0,0);
    const QRgb red = qRgb(255,0,0);

    xDivs.fill(readCoords(data, 1, w - 1, 1, black), w - 2); // top left -> top right
    yDivs.fill(readCoords(data, w, h - 1, w, black), h - 2); // top left -> bottom left

    QVector<qreal> hInsets = readCoords(data, (h - 1) * w + 1, w - 1, 1, red); // bottom left -> bottom right
    QVector<qreal> vInsets = readCoords(data, 2 * w - 1, h - 1, w, red); // top right -> bottom right
    updateInsets(hInsets, vInsets);

    const QSizeF sz(w - leftInset - rightInset, h - topInset - bottomInset);
    QVector<qreal> hPaddings = readCoords(data, (h - 1) * w + leftInset + 1, sz.width() - 2, 1, black); // bottom left -> bottom right
    QVector<qreal> vPaddings = readCoords(data, (2 + topInset) * w - 1, sz.height() - 2, w, black); // top right -> bottom right
    updatePaddings(sz, hPaddings, vPaddings);
}

void QQuickNinePatchImagePrivate::updatePaddings(const QSizeF &size, const QVector<qreal> &horizontal, const QVector<qreal> &vertical)
{
    Q_Q(QQuickNinePatchImage);
    qreal oldTopPadding = topPadding;
    qreal oldLeftPadding = leftPadding;
    qreal oldRightPadding = rightPadding;
    qreal oldBottomPadding = bottomPadding;

    if (horizontal.count() >= 2) {
        leftPadding = horizontal.first();
        rightPadding = size.width() - horizontal.last() - 2;
    } else {
        leftPadding = 0;
        rightPadding = 0;
    }

    if (vertical.count() >= 2) {
        topPadding = vertical.first();
        bottomPadding = size.height() - vertical.last() - 2;
    } else {
        topPadding = 0;
        bottomPadding = 0;
    }

    if (!qFuzzyCompare(oldTopPadding, topPadding))
        emit q->topPaddingChanged();
    if (!qFuzzyCompare(oldBottomPadding, bottomPadding))
        emit q->bottomPaddingChanged();
    if (!qFuzzyCompare(oldLeftPadding, leftPadding))
        emit q->leftPaddingChanged();
    if (!qFuzzyCompare(oldRightPadding, rightPadding))
        emit q->rightPaddingChanged();
}

void QQuickNinePatchImagePrivate::updateInsets(const QVector<qreal> &horizontal, const QVector<qreal> &vertical)
{
    Q_Q(QQuickNinePatchImage);
    qreal oldTopInset = topInset;
    qreal oldLeftInset = leftInset;
    qreal oldRightInset = rightInset;
    qreal oldBottomInset = bottomInset;

    if (horizontal.count() >= 2 && horizontal.first() == 0)
        leftInset = horizontal.at(1);
    else
        leftInset = 0;

    if (horizontal.count() == 2 && horizontal.first() > 0)
        rightInset = horizontal.last() - horizontal.first();
    else if (horizontal.count() == 4)
        rightInset = horizontal.last() - horizontal.at(2);
    else
        rightInset = 0;

    if (vertical.count() >= 2 && vertical.first() == 0)
        topInset = vertical.at(1);
    else
        topInset = 0;

    if (vertical.count() == 2 && vertical.first() > 0)
        bottomInset = vertical.last() - vertical.first();
    else if (vertical.count() == 4)
        bottomInset = vertical.last() - vertical.at(2);
    else
        bottomInset = 0;

    if (!qFuzzyCompare(oldTopInset, topInset))
        emit q->topInsetChanged();
    if (!qFuzzyCompare(oldBottomInset, bottomInset))
        emit q->bottomInsetChanged();
    if (!qFuzzyCompare(oldLeftInset, leftInset))
        emit q->leftInsetChanged();
    if (!qFuzzyCompare(oldRightInset, rightInset))
        emit q->rightInsetChanged();
}

QQuickNinePatchImage::QQuickNinePatchImage(QQuickItem *parent)
    : QQuickImage(*(new QQuickNinePatchImagePrivate), parent)
{
}

qreal QQuickNinePatchImage::topPadding() const
{
    Q_D(const QQuickNinePatchImage);
    return d->topPadding / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::leftPadding() const
{
    Q_D(const QQuickNinePatchImage);
    return d->leftPadding / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::rightPadding() const
{
    Q_D(const QQuickNinePatchImage);
    return d->rightPadding / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::bottomPadding() const
{
    Q_D(const QQuickNinePatchImage);
    return d->bottomPadding / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::topInset() const
{
    Q_D(const QQuickNinePatchImage);
    return d->topInset / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::leftInset() const
{
    Q_D(const QQuickNinePatchImage);
    return d->leftInset / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::rightInset() const
{
    Q_D(const QQuickNinePatchImage);
    return d->rightInset / d->devicePixelRatio;
}

qreal QQuickNinePatchImage::bottomInset() const
{
    Q_D(const QQuickNinePatchImage);
    return d->bottomInset / d->devicePixelRatio;
}

void QQuickNinePatchImage::pixmapChange()
{
    Q_D(QQuickNinePatchImage);
    if (QFileInfo(d->url.fileName()).completeSuffix().toLower() == QLatin1String("9.png")) {
        d->resetNode = d->ninePatch.isNull();
        d->ninePatch = d->pix.image();
        if (d->ninePatch.depth() != 32)
            d->ninePatch = d->ninePatch.convertToFormat(QImage::Format_ARGB32);

        int w = d->ninePatch.width();
        int h = d->ninePatch.height();
        d->pix.setImage(QImage(d->ninePatch.constBits() + 4 * (w + 1), w - 2, h - 2, d->ninePatch.bytesPerLine(), d->ninePatch.format()));

        d->updatePatches();
    } else {
        /*
            Only change resetNode when it's false; i.e. when no reset is pending.
            updatePaintNode() will take care of setting it to false if it's true.

            Consider the following changes in source:

                normal.png => press.9.png => normal.png => focus.png

            If the last two events happen quickly, pixmapChange() can be called
            twice with no call to updatePaintNode() inbetween. On the first call,
            resetNode will be true (because ninePatch is not null since it is still
            in the process of going from a 9-patch image to a regular image),
            and on the second call, resetNode would be false if we didn't have this check.
            This results in the oldNode never being deleted, and QQuickImage
            tries to static_cast a QQuickNinePatchImage to a QSGInternalImageNode.
        */
        if (!d->resetNode)
            d->resetNode = !d->ninePatch.isNull();
        d->ninePatch = QImage();
    }
    QQuickImage::pixmapChange();
}

QSGNode *QQuickNinePatchImage::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *data)
{
    Q_D(QQuickNinePatchImage);
    Q_UNUSED(data);

    if (d->resetNode) {
        delete oldNode;
        oldNode = nullptr;
        d->resetNode = false;
    }

    QSizeF sz = size();
    QImage image = d->pix.image();
    if (!sz.isValid() || image.isNull()) {
        delete oldNode;
        return nullptr;
    }

    if (d->ninePatch.isNull())
        return QQuickImage::updatePaintNode(oldNode, data);

    QQuickNinePatchNode *patchNode = static_cast<QQuickNinePatchNode *>(oldNode);
    if (!patchNode)
        patchNode = new QQuickNinePatchNode;

#ifdef QSG_RUNTIME_DESCRIPTION
    qsgnode_set_description(patchNode, QString::fromLatin1("QQuickNinePatchImage: '%1'").arg(d->url.toString()));
#endif

    QSGTexture *texture = window()->createTextureFromImage(image);
    patchNode->initialize(texture, sz * d->devicePixelRatio, image.size(), d->xDivs, d->yDivs, d->devicePixelRatio);
    return patchNode;
}

QT_END_NAMESPACE