declarative/graphicsitems/qdeclarativetextlayout.cpp

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#include "qdeclarativetextlayout_p.h"
#include <private/qstatictext_p.h>
#include <private/qfontengine_p.h>
#include <private/qtextengine_p.h>
#include <private/qpainter_p.h>
#include <private/qpaintengineex_p.h>

QT_BEGIN_NAMESPACE

class QDeclarativeTextLayoutPrivate
{
public:
    QDeclarativeTextLayoutPrivate()
    : cached(false) {}

    QPointF position;

    bool cached;
    QVector<QStaticTextItem> items;
    QVector<QFixedPoint> positions;
    QVector<glyph_t> glyphs;
    QVector<QChar> chars;
};

namespace {
class DrawTextItemRecorder: public QPaintEngine
{
    public:
        DrawTextItemRecorder(bool untransformedCoordinates, bool useBackendOptimizations)
            : m_inertText(0), m_dirtyPen(false), m_useBackendOptimizations(useBackendOptimizations),
              m_untransformedCoordinates(untransformedCoordinates), m_currentColor(Qt::black)
            {
            }

        virtual void updateState(const QPaintEngineState &newState)
        {
            if (newState.state() & QPaintEngine::DirtyPen
                && newState.pen().color() != m_currentColor) {
                m_dirtyPen = true;
                m_currentColor = newState.pen().color();
            }
        }

        virtual void drawTextItem(const QPointF &position, const QTextItem &textItem)
        {
            int glyphOffset = m_inertText->glyphs.size(); // Store offset into glyph pool
            int positionOffset = m_inertText->glyphs.size(); // Offset into position pool
            int charOffset = m_inertText->chars.size();

            const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);

            bool needFreshCurrentItem = true;
            if (!m_inertText->items.isEmpty()) {
                QStaticTextItem &last = m_inertText->items[m_inertText->items.count() - 1];

                if (last.fontEngine() == ti.fontEngine && last.font == ti.font() &&
                    (!m_dirtyPen || last.color == state->pen().color())) {
                    needFreshCurrentItem = false;

                    last.numChars += ti.num_chars;

                }
            }

            if (needFreshCurrentItem) {
                QStaticTextItem currentItem;

                currentItem.setFontEngine(ti.fontEngine);
                currentItem.font = ti.font();
                currentItem.charOffset = charOffset;
                currentItem.numChars = ti.num_chars;
                currentItem.numGlyphs = 0;
                currentItem.glyphOffset = glyphOffset;
                currentItem.positionOffset = positionOffset;
                currentItem.useBackendOptimizations = m_useBackendOptimizations;
                if (m_dirtyPen)
                    currentItem.color = m_currentColor;

                m_inertText->items.append(currentItem);
            }

            QStaticTextItem &currentItem = m_inertText->items.last();

            QTransform matrix = m_untransformedCoordinates ? QTransform() : state->transform();
            matrix.translate(position.x(), position.y());

            QVarLengthArray<glyph_t> glyphs;
            QVarLengthArray<QFixedPoint> positions;
            ti.fontEngine->getGlyphPositions(ti.glyphs, matrix, ti.flags, glyphs, positions);

            int size = glyphs.size();
            Q_ASSERT(size == positions.size());
            currentItem.numGlyphs += size;

            m_inertText->glyphs.resize(m_inertText->glyphs.size() + size);
            m_inertText->positions.resize(m_inertText->glyphs.size());
            m_inertText->chars.resize(m_inertText->chars.size() + ti.num_chars);

            glyph_t *glyphsDestination = m_inertText->glyphs.data() + glyphOffset;
            qMemCopy(glyphsDestination, glyphs.constData(), sizeof(glyph_t) * size);

            QFixedPoint *positionsDestination = m_inertText->positions.data() + positionOffset;
            qMemCopy(positionsDestination, positions.constData(), sizeof(QFixedPoint) * size);

            QChar *charsDestination = m_inertText->chars.data() + charOffset;
            qMemCopy(charsDestination, ti.chars, sizeof(QChar) * ti.num_chars);

        }

        virtual void drawPolygon(const QPointF *, int , PolygonDrawMode )
        {
            /* intentionally empty */
        }

        virtual bool begin(QPaintDevice *)  { return true; }
        virtual bool end() { return true; }
        virtual void drawPixmap(const QRectF &, const QPixmap &, const QRectF &) {}
        virtual Type type() const
        {
            return User;
        }

        void begin(QDeclarativeTextLayoutPrivate *t) {
            m_inertText = t;
            m_dirtyPen = false;
        }

    private:
        QDeclarativeTextLayoutPrivate *m_inertText;

        bool m_dirtyPen;
        bool m_useBackendOptimizations;
        bool m_untransformedCoordinates;
        QColor m_currentColor;
};

class DrawTextItemDevice: public QPaintDevice
{
    public:
        DrawTextItemDevice(bool untransformedCoordinates, bool useBackendOptimizations)
        {
            m_paintEngine = new DrawTextItemRecorder(untransformedCoordinates,
                    useBackendOptimizations);
        }

        ~DrawTextItemDevice()
        {
            delete m_paintEngine;
        }

        void begin(QDeclarativeTextLayoutPrivate *t) {
            m_paintEngine->begin(t);
        }

        int metric(PaintDeviceMetric m) const
        {
            int val;
            switch (m) {
            case PdmWidth:
            case PdmHeight:
            case PdmWidthMM:
            case PdmHeightMM:
                val = 0;
                break;
            case PdmDpiX:
            case PdmPhysicalDpiX:
                val = qt_defaultDpiX();
                break;
            case PdmDpiY:
            case PdmPhysicalDpiY:
                val = qt_defaultDpiY();
                break;
            case PdmNumColors:
                val = 16777216;
                break;
            case PdmDepth:
                val = 24;
                break;
            default:
                val = 0;
                qWarning("DrawTextItemDevice::metric: Invalid metric command");
            }
            return val;
        }

        virtual QPaintEngine *paintEngine() const
        {
            return m_paintEngine;
        }

    private:
        DrawTextItemRecorder *m_paintEngine;
};

struct InertTextPainter {
    InertTextPainter()
    : device(true, true), painter(&device)
    {
        painter.setPen(QPen(QColor())); // explicitly invalid color.
    }

    DrawTextItemDevice device;
    QPainter painter;
};
}

Q_GLOBAL_STATIC(InertTextPainter, inertTextPainter);

/*!
\class QDeclarativeTextLayout
\brief The QDeclarativeTextLayout class is a version of QStaticText that works with QTextLayouts.
\internal

This class is basically a copy of the QStaticText code, but it is adapted to source its text from
QTextLayout.

It is also considerably faster to create a QDeclarativeTextLayout than a QStaticText because it uses
a single, shared QPainter instance.  QStaticText by comparison creates a new QPainter per instance.
As a consequence this means that QDeclarativeTextLayout is not re-enterant.  Adding a lock around
the shared painter solves this, and only introduces a minor performance penalty, but is unnecessary
for QDeclarativeTextLayout's current use (QDeclarativeText is already tied to the GUI thread).
*/

QDeclarativeTextLayout::QDeclarativeTextLayout()
: d(0)
{
}

QDeclarativeTextLayout::QDeclarativeTextLayout(const QString &text)
: QTextLayout(text), d(0)
{
}

QDeclarativeTextLayout::~QDeclarativeTextLayout()
{
    if (d) delete d;
}

void QDeclarativeTextLayout::beginLayout()
{
    if (d && d->cached) {
        d->cached = false;
        d->items.clear();
        d->positions.clear();
        d->glyphs.clear();
        d->chars.clear();
        d->position = QPointF();
    }
    QTextLayout::beginLayout();
}

void QDeclarativeTextLayout::clearLayout()
{
    if (d && d->cached) {
        d->cached = false;
        d->items.clear();
        d->positions.clear();
        d->glyphs.clear();
        d->chars.clear();
        d->position = QPointF();
    }
    QTextLayout::clearLayout();
}

void QDeclarativeTextLayout::prepare()
{
    if (!d || !d->cached) {

        if (!d)
            d = new QDeclarativeTextLayoutPrivate;

        InertTextPainter *itp = inertTextPainter();
        itp->device.begin(d);
        QTextLayout::draw(&itp->painter, QPointF(0, 0));

        glyph_t *glyphPool = d->glyphs.data();
        QFixedPoint *positionPool = d->positions.data();
        QChar *charPool = d->chars.data();

        int itemCount = d->items.count();
        for (int ii = 0; ii < itemCount; ++ii) {
            QStaticTextItem &item = d->items[ii];
            item.glyphs = glyphPool + item.glyphOffset;
            item.glyphPositions = positionPool + item.positionOffset;
            item.chars = charPool + item.charOffset;
        }

        d->cached = true;
    }
}

// Defined in qpainter.cpp
extern Q_GUI_EXPORT void qt_draw_decoration_for_glyphs(QPainter *painter, const glyph_t *glyphArray,
                                                       const QFixedPoint *positions, int glyphCount,
                                                       QFontEngine *fontEngine, const QFont &font,
                                                       const QTextCharFormat &charFormat);

void QDeclarativeTextLayout::draw(QPainter *painter, const QPointF &p)
{
    QPainterPrivate *priv = QPainterPrivate::get(painter);

    bool paintEngineSupportsTransformations = priv->extended &&
                                              (priv->extended->type() == QPaintEngine::OpenGL2 ||
                                               priv->extended->type() == QPaintEngine::OpenVG ||
                                               priv->extended->type() == QPaintEngine::OpenGL);

    if (!paintEngineSupportsTransformations || !priv->state->matrix.isAffine()) {
        QTextLayout::draw(painter, p);
        return;
    }

    prepare();

    int itemCount = d->items.count();

    if (p != d->position) {
        QFixed fx = QFixed::fromReal(p.x());
        QFixed fy = QFixed::fromReal(p.y());
        QFixed oldX = QFixed::fromReal(d->position.x());
        QFixed oldY = QFixed::fromReal(d->position.y());
        for (int item = 0; item < itemCount; ++item) {
            QStaticTextItem &textItem = d->items[item];

            for (int ii = 0; ii < textItem.numGlyphs; ++ii) {
                textItem.glyphPositions[ii].x += fx - oldX;
                textItem.glyphPositions[ii].y += fy - oldY;
            }
            textItem.userDataNeedsUpdate = true;
        }

        d->position = p;
    }

    QPen oldPen = priv->state->pen;
    QColor currentColor = oldPen.color();
    QColor defaultColor = currentColor;
    for (int ii = 0; ii < itemCount; ++ii) {
        QStaticTextItem &item = d->items[ii];
        if (item.color.isValid() && currentColor != item.color) {
            // up-edge of a <font color="">text</font> tag
            // we set the painter pen to the text item's specified color.
            painter->setPen(item.color);
            currentColor = item.color;
        } else if (!item.color.isValid() && currentColor != defaultColor) {
            // down-edge of a <font color="">text</font> tag
            // we reset the painter pen back to the default color.
            currentColor = defaultColor;
            painter->setPen(currentColor);
        }
        priv->extended->drawStaticTextItem(&item);

        qt_draw_decoration_for_glyphs(painter, item.glyphs, item.glyphPositions,
                                      item.numGlyphs, item.fontEngine(), painter->font(),
                                      QTextCharFormat());
    }
    if (currentColor != oldPen.color())
        painter->setPen(oldPen);
}

QT_END_NAMESPACE