qgraphicsview.cpp

奇趣公司比较新的qt/emd版本

    view will not allow interaction, and any mouse or key events are ignored
    (i.e., it will act as a read-only view).
*/
bool QGraphicsView::isInteractive() const
{
    Q_D(const QGraphicsView);
    return d->sceneInteractionAllowed;
}
void QGraphicsView::setInteractive(bool allowed)
{
    Q_D(QGraphicsView);
    d->sceneInteractionAllowed = allowed;
}

/*!
    Returns a pointer to the scene that is currently visualized in the
    view. If no scene is currently visualized, 0 is returned.

    \sa setScene()
*/
QGraphicsScene *QGraphicsView::scene() const
{
    Q_D(const QGraphicsView);
    return d->scene;
}

/*!
    Sets the current scene to \a scene. If \a scene is already being
    viewed, this function does nothing.

    When a scene is set on a view, the QGraphicsScene::changed() signal
    is automatically connected to this view's updateScene() slot, and the
    view's scroll bars are adjusted to fit the size of the scene.
*/
void QGraphicsView::setScene(QGraphicsScene *scene)
{
    Q_D(QGraphicsView);
    if (d->scene == scene)
        return;

    if (d->scene) {
        disconnect(d->scene, SIGNAL(changed(QList<QRectF>)),
                   this, SLOT(updateScene(QList<QRectF>)));
        disconnect(d->scene, SIGNAL(sceneRectChanged(QRectF)),
                   this, SLOT(updateSceneRect(QRectF)));
        d->scene->d_func()->views.removeAll(this);
    }

    if ((d->scene = scene)) {
        connect(d->scene, SIGNAL(changed(QList<QRectF>)),
                this, SLOT(updateScene(QList<QRectF>)));
        connect(d->scene, SIGNAL(sceneRectChanged(QRectF)),
                this, SLOT(updateSceneRect(QRectF)));
        d->scene->d_func()->views << this;
        d->recalculateContentSize();
        d->lastCenterPoint = sceneRect().center();
        d->keepLastCenterPoint = true;
    } else {
        viewport()->update();
        d->recalculateContentSize();
    }
}

/*!
    \property QGraphicsView::sceneRect
    \brief the area of the scene visualized by this view.

    The scene rect defines the extent of the scene, and in the view's case,
    this means the area of the scene that you can navigate using the scroll
    bars.

    If unset, or if a null QRectF is set, this property has the same value as
    QGraphicsScene::sceneRect, and it changes with
    QGraphicsScene::sceneRect. Otherwise, the view's scene rect is unaffected
    by the scene.

    Note that although the scene supports a virtually unlimited size, the
    range of the scroll bars will never exceed the range of an integer
    (INT_MIN, INT_MAX). When the scene is larger than the scroll bars' values,
    you can choose to use translate() to navigate the scene instead.

    \sa QGraphicsScene::sceneRect
*/
QRectF QGraphicsView::sceneRect() const
{
    Q_D(const QGraphicsView);
    if (d->hasSceneRect)
        return d->sceneRect;
    if (d->scene)
        return d->scene->sceneRect();
    return QRectF();
}
void QGraphicsView::setSceneRect(const QRectF &rect)
{
    Q_D(QGraphicsView);
    d->hasSceneRect = !rect.isNull();
    d->sceneRect = rect;
    d->recalculateContentSize();
}

/*!
    Returns the current transformation matrix for the view. If no current
    transformation is set, the identity matrix is returned.

    \sa setMatrix(), rotate(), scale(), shear(), translate()
*/
QMatrix QGraphicsView::matrix() const
{
    Q_D(const QGraphicsView);
    return d->matrix.toAffine();
}

/*!
    Sets the view's current transformation matrix to \a matrix.

    If \a combine is true, then \a matrix is combined with the current matrix;
    otherwise, \a matrix \e replaces the current matrix. \a combine is false
    by default.

    The transformation matrix tranforms the scene into view coordinates. Using
    the default transformation, provided by the identity matrix, one pixel in
    the view represents one unit in the scene (e.g., a 10x10 rectangular item
    is drawn using 10x10 pixels in the view). If a 2x2 scaling matrix is
    applied, the scene will be drawn in 1:2 (e.g., a 10x10 rectangular item is
    then drawn using 20x20 pixels in the view).

    Example:

    \code
        QGraphicsScene scene;
        scene.addText("GraphicsView rotated clockwise");

        QGraphicsView view(&scene);
        view.rotate(90); // the text is rendered with a 90 degree clockwise rotation
        view.show();
    \endcode

    To simplify interation with items using a transformed view, QGraphicsView
    provides mapTo... and mapFrom... functions that can translate between
    scene and view coordinates. For example, you can call mapToScene() to map
    a view coordinate to a floating point scene coordinate, or mapFromScene()
    to map from floating point scene coordinates to view coordinates.

    \sa matrix(), rotate(), scale(), shear(), translate()
*/
void QGraphicsView::setMatrix(const QMatrix &matrix, bool combine)
{
    setTransform(QTransform(matrix), combine);
}

/*!
    Resets the view transformation matrix to the identity matrix.
*/
void QGraphicsView::resetMatrix()
{
    resetTransform();
}

/*!
    Rotates the current view transformation \a angle degrees clockwise.

    \sa setMatrix(), matrix(), scale(), shear(), translate()
*/
void QGraphicsView::rotate(qreal angle)
{
    Q_D(QGraphicsView);
    QTransform matrix = d->matrix;
    matrix.rotate(angle);
    setTransform(matrix);
}

/*!
    Scales the current view transformation by (\a sx, \a sy).

    \sa setMatrix(), matrix(), rotate(), shear(), translate()
*/
void QGraphicsView::scale(qreal sx, qreal sy)
{
    Q_D(QGraphicsView);
    QTransform matrix = d->matrix;
    matrix.scale(sx, sy);
    setTransform(matrix);
}

/*!
    Shears the current view transformation by (\a sh, \a sv).

    \sa setMatrix(), matrix(), rotate(), scale(), translate()
*/
void QGraphicsView::shear(qreal sh, qreal sv)
{
    Q_D(QGraphicsView);
    QTransform matrix = d->matrix;
    matrix.shear(sh, sv);
    setTransform(matrix);
}

/*!
    Translates the current view transformation by (\a dx, \a dy).

    \sa setMatrix(), matrix(), rotate(), shear()
*/
void QGraphicsView::translate(qreal dx, qreal dy)
{
    Q_D(QGraphicsView);
    QTransform matrix = d->matrix;
    matrix.translate(dx, dy);
    setTransform(matrix);
}

/*!
    Scrolls the contents of the viewport to ensure that the scene
    coordinate \a pos, is centered in the view.

    Because \a pos is a floating point coordinate, and the scroll bars operate
    on integer coordinates, the centering is only an approximation.

    \note If the item is close to or outside the border, it will be visible
    in the view, but not centered.

    \sa ensureVisible()
*/
void QGraphicsView::centerOn(const QPointF &pos)
{
    Q_D(QGraphicsView);
    qreal width = viewport()->width();
    qreal height = viewport()->height();
    QPointF viewPoint = d->matrix.map(pos);
    QPointF oldCenterPoint = pos;

    if (!d->leftIndent) {
        if (isRightToLeft()) {
            qint64 horizontal = 0;
            horizontal += horizontalScrollBar()->minimum();
            horizontal += horizontalScrollBar()->maximum();
            horizontal -= int(viewPoint.x() - width / 2.0);
            horizontalScrollBar()->setValue(horizontal);
        } else {
            horizontalScrollBar()->setValue(int(viewPoint.x() - width / 2.0));
        }
    }
    if (!d->topIndent)
        verticalScrollBar()->setValue(int(viewPoint.y() - height / 2.0));
    d->lastCenterPoint = oldCenterPoint;
}

/*!
    \fn QGraphicsView::centerOn(qreal x, qreal y)
    \overload

    This function is provided for convenience. It's equivalent to calling
    centerOn(QPointF(\a x, \a y)).
*/

/*!
    \overload

    Scrolls the contents of the viewport to ensure that \a item
    is centered in the view.

    \sa ensureVisible()
*/
void QGraphicsView::centerOn(const QGraphicsItem *item)
{
    centerOn(item->sceneBoundingRect().center());
}

/*!
    Scrolls the contents of the viewport so that the scene rectangle \a rect
    is visible, with margins specified in pixels by \a xmargin and \a
    ymargin. If the specified rect cannot be reached, the contents are
    scrolled to the nearest valid position. The default value for both margins
    is 50 pixels.

    \sa centerOn()
*/
void QGraphicsView::ensureVisible(const QRectF &rect, int xmargin, int ymargin)
{
    Q_D(QGraphicsView);
    Q_UNUSED(xmargin);
    Q_UNUSED(ymargin);
    qreal width = viewport()->width();
    qreal height = viewport()->height();
    QRectF viewRect = d->matrix.mapRect(rect);

    qreal left = d->horizontalScroll();
    qreal right = left + width;
    qreal top = d->verticalScroll();
    qreal bottom = top + height;

    if (viewRect.left() <= left + xmargin) {
        // need to scroll from the left
        if (!d->leftIndent)
            horizontalScrollBar()->setValue(int(viewRect.left() - xmargin - 0.5));
    }
    if (viewRect.right() >= right - xmargin) {
        // need to scroll from the right
        if (!d->leftIndent)
            horizontalScrollBar()->setValue(int(viewRect.right() - width + xmargin + 0.5));
    }
    if (viewRect.top() <= top + ymargin) {
        // need to scroll from the top
        if (!d->topIndent)
            verticalScrollBar()->setValue(int(viewRect.top() - ymargin - 0.5));
    }
    if (viewRect.bottom() >= bottom - ymargin) {
        // need to scroll from the bottom
        if (!d->topIndent)
            verticalScrollBar()->setValue(int(viewRect.bottom() - height + ymargin + 0.5));
    }
}

/*!
    \fn QGraphicsView::ensureVisible(qreal x, qreal y, qreal w, qreal h,
    int xmargin, int ymargin)
    \overload

    This function is provided for convenience. It's equivalent to calling
    ensureVisible(QRectF(\a x, \a y, \a w, \a h), \a xmargin, \a ymargin).
*/

/*!
    \overload

    Scrolls the contents of the viewport so that the center of item \a item is
    visible, with margins specified in pixels by \a xmargin and \a ymargin. If
    the specified point cannot be reached, the contents are scrolled to the
    nearest valid position. The default value for both margins is 50 pixels.

    \sa centerOn()
*/
void QGraphicsView::ensureVisible(const QGraphicsItem *item, int xmargin, int ymargin)
{
    ensureVisible(item->sceneBoundingRect(), xmargin, ymargin);
}

/*!
    Scales the view matrix and scrolls the scroll bars to ensure that the
    scene rectangle \a rect fits inside the viewport. \a rect must be inside
    the scene rect; otherwise, fitInView() cannot guarantee that the whole
    rect is visible.

    This function keeps the view's rotation, translation, or shear. The view
    is scaled according to \a aspectRatioMode. \a rect will be centered in the
    view if it does not fit tightly.

    \sa setMatrix(), ensureVisible(), centerOn()
*/
void QGraphicsView::fitInView(const QRectF &rect, Qt::AspectRatioMode aspectRatioMode)
{
    Q_D(QGraphicsView);
    if (!d->scene || rect.isNull())
        return;

    // Reset the view scale to 1:1.
    QRectF unity = d->matrix.mapRect(QRectF(0, 0, 1, 1));
    scale(1 / unity.width(), 1 / unity.height());

    // Find the ideal x / y scaling ratio to fit \a rect in the view.
    int margin = 2;
    QRectF viewRect = viewport()->rect().adjusted(margin, margin, -margin, -margin);
    QRectF sceneRect = d->matrix.mapRect(rect);
    qreal xratio = viewRect.width() / sceneRect.width();
    qreal yratio = viewRect.height() / sceneRect.height();

    // Respect the aspect ratio mode.
    switch (aspectRatioMode) {
    case Qt::KeepAspectRatio:
        xratio = yratio = qMin(xratio, yratio);
        break;
    case Qt::KeepAspectRatioByExpanding:
        xratio = yratio = qMax(xratio, yratio);
        break;
    case Qt::IgnoreAspectRatio:
        break;
    }

    // Scale and center on the center of \a rect.
    scale(xratio, yratio);
    centerOn(rect.center());
}

/*!
    \fn void QGraphicsView::fitInView(qreal x, qreal y, qreal w, qreal h,
    Qt::AspectRatioMode aspectRatioMode = Qt::IgnoreAspectRatio)