qpainter.cpp

奇趣公司比较新的qt/emd版本

/*!
    Restores the current painter state (pops a saved state off the
    stack).

    \sa save()
*/

void QPainter::restore()
{
#ifdef QT_DEBUG_DRAW
    if (qt_show_painter_debug_output)
        printf("QPainter::restore()\n");
#endif
    Q_D(QPainter);
    if (d->states.size()<=1) {
        qWarning("QPainter::restore: Unbalanced save/restore");
        return;
    } else if (!isActive()) {
        qWarning("QPainter::restore: Painter not active");
        return;
    }

    QPainterState *tmp = d->state;
    d->states.pop_back();
    d->state = d->states.back();
    d->txinv = false;

    // trigger clip update if the clip path/region has changed since
    // last save
    if (!d->state->clipInfo.isEmpty()
        && (tmp->changeFlags & (QPaintEngine::DirtyClipRegion | QPaintEngine::DirtyClipPath))) {
        // reuse the tmp state to avoid any extra allocs...
        tmp->dirtyFlags = QPaintEngine::DirtyClipPath;
        tmp->clipOperation = Qt::NoClip;
        tmp->clipPath = QPainterPath();
        d->engine->updateState(*tmp);
        // replay the list of clip states,
        for (int i=0; i<d->state->clipInfo.size(); ++i) {
            const QPainterClipInfo &info = d->state->clipInfo.at(i);
            tmp->matrix.setMatrix(info.matrix.m11(), info.matrix.m12(), info.matrix.m13(),
                                  info.matrix.m21(), info.matrix.m22(), info.matrix.m23(),
                                  info.matrix.dx() - d->redirection_offset.x(),
                                  info.matrix.dy() - d->redirection_offset.y(), info.matrix.m33());
            tmp->clipOperation = info.operation;
            if (info.clipType == QPainterClipInfo::RegionClip) {
                tmp->dirtyFlags = QPaintEngine::DirtyClipRegion | QPaintEngine::DirtyTransform;
                tmp->clipRegion = info.region;
            } else { // clipType == QPainterClipInfo::PathClip
                tmp->dirtyFlags = QPaintEngine::DirtyClipPath | QPaintEngine::DirtyTransform;
                tmp->clipPath = info.path;
            }
            d->engine->updateState(*tmp);
        }


        //Since we've updated the clip region anyway, pretend that the clip path hasn't changed:
        d->state->dirtyFlags &= ~(QPaintEngine::DirtyClipPath | QPaintEngine::DirtyClipRegion);
        tmp->changeFlags &= ~(QPaintEngine::DirtyClipPath | QPaintEngine::DirtyClipRegion);
        tmp->changeFlags |= QPaintEngine::DirtyTransform;
    }

    d->updateState(d->state);
    delete tmp;
}


/*!

    \fn bool QPainter::begin(QPaintDevice *device)

    Begins painting the paint \a device and returns true if
    successful; otherwise returns false.

    Notice that all painter settings (setPen(), setBrush() etc.) are reset
    to default values when begin() is called.

    The errors that can occur are serious problems, such as these:

    \code
        painter->begin(0); // impossible - paint device cannot be 0

        QPixmap image(0, 0);
        painter->begin(&image); // impossible - image.isNull() == true;

        painter->begin(myWidget);
        painter2->begin(myWidget); // impossible - only one painter at a time
    \endcode

    Note that most of the time, you can use one of the constructors
    instead of begin(), and that end() is automatically done at
    destruction.

    \warning A paint device can only be painted by one painter at a
    time.

    \sa end(), QPainter()
*/

bool QPainter::begin(QPaintDevice *pd)
{
    Q_ASSERT(pd);

    Q_D(QPainter);
    if (d->engine) {
        qWarning("QPainter::begin: Painter already active");
        return false;
    }

    // Ensure fresh painter state
    if (d->emptyState && !d->state->dirtyFlags)
        d->emptyState = false;
    else
        d->state->init(d->state->painter);

    d->original_device = pd;
    QPaintDevice *rpd = redirected(pd, &d->redirection_offset);

    if (rpd) {
        pd = rpd;
    }

#ifdef QT_DEBUG_DRAW
    if (qt_show_painter_debug_output)
        printf("QPainter::begin(), device=%p, type=%d\n", pd, pd->devType());
#endif


    d->state->bgOrigin = QPointF();

    d->device = pd;
    if (pd->devType() == QInternal::Pixmap)
        static_cast<QPixmap *>(pd)->detach();
    else if (pd->devType() == QInternal::Image)
        static_cast<QImage *>(pd)->detach();

    d->engine = pd->paintEngine();

    if (!d->engine) {
        qWarning("QPainter::begin: Paint device returned engine == 0, type: %d", pd->devType());
        return true;
    }
    switch (pd->devType()) {
        case QInternal::Widget:
        {
            const QWidget *widget = static_cast<const QWidget *>(pd);
            Q_ASSERT(widget);

            if(!d->engine->hasFeature(QPaintEngine::PaintOutsidePaintEvent)
               && !widget->testAttribute(Qt::WA_PaintOutsidePaintEvent)
               && !widget->testAttribute(Qt::WA_WState_InPaintEvent)) {
                qWarning("QPainter::begin: Widget painting can only begin as a "
                         "result of a paintEvent");
                return false;
            }
            break;
        }
        case QInternal::Pixmap:
        {
            const QPixmap *pm = static_cast<const QPixmap *>(pd);
            Q_ASSERT(pm);
            if (pm->isNull()) {
                qWarning("QPainter::begin: Cannot paint on a null pixmap");
                return false;
            }

            if (pm->depth() == 1) {
                d->state->pen = QPen(Qt::color1);
                d->state->brush = QBrush(Qt::color0);
            }
            break;
        }
        case QInternal::Image:
        {
            const QImage *img = static_cast<const QImage *>(pd);
            Q_ASSERT(img);
            if (img->isNull()) {
                qWarning("QPainter::begin: Cannot paint on a null image");
                return false;
            }
            if (img->depth() == 1) {
                d->state->pen = QPen(Qt::color1);
                d->state->brush = QBrush(Qt::color0);
            }
            break;
        }
        default:
            break;
    }
    if (d->state->ww == 0) // For compat with 3.x painter defaults
        d->state->ww = d->state->wh = d->state->vw = d->state->vh = 1024;

    // Slip a painter state into the engine before we do any other operations
    d->engine->state = d->state;

    d->engine->setPaintDevice(pd);

    bool begun = d->engine->begin(pd);
    if (!begun) {
        qWarning("QPainter::begin(): Returned false");
        end();
        return false;
    } else {
        d->engine->setActive(begun);
    }

    // Copy painter properties from original paint device,
    // required for QPixmap::grabWidget()
    if (d->original_device->devType() == QInternal::Widget) {
        QWidget *widget = static_cast<QWidget *>(d->original_device);
        initFrom(widget);
    } else {
        d->state->layoutDirection = QApplication::layoutDirection();
        // make sure we have a font compatible with the paintdevice
        d->state->deviceFont = d->state->font = QFont(d->state->deviceFont, d->device);
    }

    QRect systemRect = d->engine->systemRect();
    if (!systemRect.isEmpty()) {
        d->state->ww = d->state->vw = systemRect.width();
        d->state->wh = d->state->vh = systemRect.height();
    } else {
        d->state->ww = d->state->vw = pd->metric(QPaintDevice::PdmWidth);
        d->state->wh = d->state->vh = pd->metric(QPaintDevice::PdmHeight);
    }

    d->redirection_offset += d->engine->coordinateOffset();

    Q_ASSERT(d->engine->isActive());

    if (!d->redirection_offset.isNull())
        d->updateMatrix();

    Q_ASSERT(d->engine->isActive());
    d->state->renderHints = QPainter::TextAntialiasing;
    ++d->device->painters;

    d->state->emulationSpecifier = 0;

    return true;
}

/*!
    Ends painting. Any resources used while painting are released. You
    don't normally need to call this since it is called by the
    destructor.

    Returns true if the painter is no longer active; otherwise returns false.

    \sa begin(), isActive()
*/

bool QPainter::end()
{
#ifdef QT_DEBUG_DRAW
    if (qt_show_painter_debug_output)
        printf("QPainter::end()\n");
#endif

    if (!isActive()) {
        qWarning("QPainter::end: Painter not active, aborted");
        return false;
    }

    Q_D(QPainter);
    if (d->states.size()>1) {
        qWarning("QPainter::end: Painter ended with %d saved states",
                 d->states.size());
    }

    bool ended = true;

    d->fillrect_func = 0;

    if (d->engine->isActive()) {
        ended = d->engine->end();
        d->updateState(0);

        --d->device->painters;
        if (d->device->painters == 0) {
            d->engine->setPaintDevice(0);
            d->engine->setActive(false);
        }
    }

    if (d->engine->autoDestruct()) {
        delete d->engine;
    }

    d->engine = 0;

    d->device = 0;
    return ended;
}


/*!
    Returns the paint engine that the painter is currently operating
    on if the painter is active; otherwise 0.

    \sa isActive()
*/
QPaintEngine *QPainter::paintEngine() const
{
    Q_D(const QPainter);
    return d->engine;
}


/*!
    Returns the font metrics for the painter if the painter is
    active. Otherwise, the return value is undefined.

    \sa font(), isActive(), {QPainter#Settings}{Settings}
*/

QFontMetrics QPainter::fontMetrics() const
{
    Q_D(const QPainter);
    return QFontMetrics(d->state->font);
}


/*!
    Returns the font info for the painter if the painter is
    active. Otherwise, the return value is undefined.

    \sa font(), isActive(), {QPainter#Settings}{Settings}
*/

QFontInfo QPainter::fontInfo() const
{
    Q_D(const QPainter);
    return QFontInfo(d->state->font);
}

/*!
    \since 4.2

    Returns the opacity of the painter. The default value is
    1.
*/

qreal QPainter::opacity() const
{
    Q_D(const QPainter);
    return d->state->opacity;
}

/*!
    \since 4.2

    Sets the opacity of the painter to \a opacity. The value should
    be in the range 0.0 to 1.0, where 0.0 is fully transparent and
    1.0 is fully opaque.

    Opacity set on the painter will apply to all drawing operations
    individually.
*/

void QPainter::setOpacity(qreal opacity)
{
    Q_D(QPainter);
    d->state->opacity = qMin(qreal(1), qMax(qreal(0), opacity));
    d->state->dirtyFlags |= QPaintEngine::DirtyOpacity;
}


/*!
    Returns the currently set brush origin.

    \sa setBrushOrigin(), {QPainter#Settings}{Settings}
*/

QPoint QPainter::brushOrigin() const
{
    Q_D(const QPainter);
    return QPointF(d->state->bgOrigin).toPoint();
}

/*!
    \fn void QPainter::setBrushOrigin(const QPointF &position)

    Sets the brush origin to \a position.

    The brush origin specifies the (0, 0) coordinate of the painter's
    brush. This setting only applies to pattern brushes and pixmap
    brushes.