q3scrollview.cpp

奇趣公司比较新的qt/emd版本

    labels as child widgets. When the view is scrolled the viewport()
    is moved; its children move with it as child widgets normally do.

    \target allviews
    \section1 Details Relevant for All Views

    Normally you will use the first or third method if you want any
    child widgets in the view.

    Note that the widget you see in the scrolled area is the
    viewport() widget, not the Q3ScrollView itself. So to turn mouse
    tracking on, for example, use viewport()->setMouseTracking(true).

    To enable drag-and-drop, you would setAcceptDrops(true) on the
    Q3ScrollView (because drag-and-drop events propagate to the
    parent). But to work out the logical position in the view, you
    would need to map the drop co-ordinate from being relative to the
    Q3ScrollView to being relative to the contents; use the function
    viewportToContents() for this.

    To handle mouse events on the scrolling area, subclass scrollview
    as you would subclass other widgets, but rather than
    reimplementing mousePressEvent(), reimplement
    contentsMousePressEvent() instead. The contents specific event
    handlers provide translated events in the coordinate system of the
    scrollview. If you reimplement mousePressEvent(), you'll get
    called only when part of the Q3ScrollView is clicked: and the only
    such part is the "corner" (if you don't set a cornerWidget()) and
    the frame; everything else is covered up by the viewport, clipper
    or scroll bars.

    When you construct a Q3ScrollView, some of the window flags apply
    to the viewport() instead of being sent to the QWidget constructor
    for the Q3ScrollView.

    \list

    \i An image-manipulation widget would use \c
    WNoAutoErase|WStaticContents because the widget draws all pixels
    itself, and when its size increases, it only needs a paint event
    for the new part because the old part remains unchanged.

    \i A scrolling game widget in which the background scrolls as the
    characters move might use \c WNoAutoErase (in addition to \c
    WStaticContents) so that the window system background does not
    flash in and out during scrolling.

    \i A word processing widget might use \c WNoAutoErase and repaint
    itself line by line to get a less-flickery resizing. If the widget
    is in a mode in which no text justification can take place, it
    might use \c WStaticContents too, so that it would only get a
    repaint for the newly visible parts.

    \endlist

    Child widgets may be moved using addChild() or moveChild(). Use
    childX() and childY() to get the position of a child widget.

    A widget may be placed in the corner between the vertical and
    horizontal scroll bars with setCornerWidget(). You can get access
    to the scroll bars using horizontalScrollBar() and
    verticalScrollBar(), and to the viewport with viewport(). The
    scroll view can be scrolled using scrollBy(), ensureVisible(),
    setContentsPos() or center().

    The visible area is given by visibleWidth() and visibleHeight(),
    and the contents area by contentsWidth() and contentsHeight(). The
    contents may be repainted using one of the repaintContents() or
    updateContents() functions.

    Coordinate conversion is provided by contentsToViewport() and
    viewportToContents().

    The contentsMoving() signal is emitted just before the contents
    are moved to a new position.

    \warning Q3ScrollView currently does not erase the background when
    resized, i.e. you must always clear the background manually in
    scrollview subclasses. This will change in a future version of Qt
    and we recommend specifying the \c WNoAutoErase flag explicitly.
*/


/*!
    \enum Q3ScrollView::ResizePolicy

    This enum type is used to control a Q3ScrollView's reaction to
    resize events.

    \value Default  the Q3ScrollView selects one of the other settings
    automatically when it has to. In this version of Qt, Q3ScrollView
    changes to \c Manual if you resize the contents with
    resizeContents() and to \c AutoOne if a child is added.

    \value Manual  the contents stays the size set by resizeContents().

    \value AutoOne  if there is only one child widget the contents stays
    the size of that widget. Otherwise the behavior is undefined.

    \value AutoOneFit if there is only one child widget the contents stays
    the size of that widget's sizeHint(). If the scrollview is resized
    larger than the child's sizeHint(), the child will be resized to
    fit. If there is more than one child, the behavior is undefined.

*/
//####  The widget will be resized to its sizeHint() when a LayoutHint event
//#### is received

/*!
    Constructs a Q3ScrollView called \a name with parent \a parent and
    widget flags \a f.

    The widget flags \c WStaticContents, \c WNoAutoErase and \c
    WPaintClever are propagated to the viewport() widget. The other
    widget flags are propagated to the parent constructor as usual.
*/

Q3ScrollView::Q3ScrollView(QWidget *parent, const char *name, Qt::WindowFlags f) :
    Q3Frame(parent, name, f & (~WStaticContents) & (~WNoAutoErase) & (~WResizeNoErase))
{
    WindowFlags flags = WResizeNoErase | (f&WPaintClever) | (f&WRepaintNoErase) | (f&WStaticContents);
    d = new Q3ScrollViewData(this, flags);

#ifndef QT_NO_DRAGANDDROP
    connect(&d->autoscroll_timer, SIGNAL(timeout()),
             this, SLOT(doDragAutoScroll()));
#endif

    connect(d->hbar, SIGNAL(valueChanged(int)),
        this, SLOT(hslide(int)));
    connect(d->vbar, SIGNAL(valueChanged(int)),
        this, SLOT(vslide(int)));

    connect(d->hbar, SIGNAL(sliderPressed()), this, SLOT(hbarIsPressed()));
    connect(d->hbar, SIGNAL(sliderReleased()), this, SLOT(hbarIsReleased()));
    connect(d->vbar, SIGNAL(sliderPressed()), this, SLOT(vbarIsPressed()));
    connect(d->vbar, SIGNAL(sliderReleased()), this, SLOT(vbarIsReleased()));


    d->viewport->installEventFilter(this);

    connect(&d->scrollbar_timer, SIGNAL(timeout()),
             this, SLOT(updateScrollBars()));

    setFrameStyle(Q3Frame::StyledPanel | Q3Frame::Sunken);
    setLineWidth(style()->pixelMetric(QStyle::PM_DefaultFrameWidth));
    setSizePolicy(QSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding));
}


/*!
    Destroys the Q3ScrollView. Any children added with addChild() will
    be deleted.
*/
Q3ScrollView::~Q3ScrollView()
{
    // Be careful not to get all those useless events...
    if (d->clipped_viewport)
        d->clipped_viewport->removeEventFilter(this);
    else
        d->viewport->removeEventFilter(this);

    // order is important
    // ~QWidget may cause a WM_ERASEBKGND on Windows
    delete d->vbar;
    d->vbar = 0;
    delete d->hbar;
    d->hbar = 0;
    delete d->viewport;
    d->viewport = 0;
    delete d;
    d = 0;
}

/*!
    \fn void Q3ScrollView::horizontalSliderPressed()

    This signal is emitted whenever the user presses the horizontal slider.
*/
/*!
    \fn void Q3ScrollView::horizontalSliderReleased()

    This signal is emitted whenever the user releases the horizontal slider.
*/
/*!
    \fn void Q3ScrollView::verticalSliderPressed()

    This signal is emitted whenever the user presses the vertical slider.
*/
/*!
    \fn void Q3ScrollView::verticalSliderReleased()

    This signal is emitted whenever the user releases the vertical slider.
*/
void Q3ScrollView::hbarIsPressed()
{
    d->hbarPressed = true;
    emit(horizontalSliderPressed());
}

void Q3ScrollView::hbarIsReleased()
{
    d->hbarPressed = false;
    emit(horizontalSliderReleased());
}

/*!
    Returns true if horizontal slider is pressed by user; otherwise returns false.
*/
bool Q3ScrollView::isHorizontalSliderPressed()
{
    return d->hbarPressed;
}

void Q3ScrollView::vbarIsPressed()
{
    d->vbarPressed = true;
    emit(verticalSliderPressed());
}

void Q3ScrollView::vbarIsReleased()
{
    d->vbarPressed = false;
    emit(verticalSliderReleased());
}

/*!
    Returns true if vertical slider is pressed by user; otherwise returns false.
*/
bool Q3ScrollView::isVerticalSliderPressed()
{
    return d->vbarPressed;
}

/*!
    \reimp
*/
void Q3ScrollView::styleChange(QStyle& old)
{
    QWidget::styleChange(old);
    updateScrollBars();
    d->cachedSizeHint = QSize();
}

/*!
    \reimp
*/
void Q3ScrollView::fontChange(const QFont &old)
{
    QWidget::fontChange(old);
    updateScrollBars();
    d->cachedSizeHint = QSize();
}

void Q3ScrollView::hslide(int pos)
{
    if (!d->signal_choke) {
        moveContents(-pos, -d->contentsY());
        QApplication::syncX();
    }
}

void Q3ScrollView::vslide(int pos)
{
    if (!d->signal_choke) {
        moveContents(-d->contentsX(), -pos);
        QApplication::syncX();
    }
}

/*!
    Called when the horizontal scroll bar geometry changes. This is
    provided as a protected function so that subclasses can do
    interesting things such as providing extra buttons in some of the
    space normally used by the scroll bars.

    The default implementation simply gives all the space to \a hbar.
    The new geometry is given by \a x, \a y, \a w and \a h.

    \sa setVBarGeometry()
*/
void Q3ScrollView::setHBarGeometry(QScrollBar& hbar,
    int x, int y, int w, int h)
{
    hbar.setGeometry(x, y, w, h);
}

/*!
    Called when the vertical scroll bar geometry changes. This is
    provided as a protected function so that subclasses can do
    interesting things such as providing extra buttons in some of the
    space normally used by the scroll bars.

    The default implementation simply gives all the space to \a vbar.
    The new geometry is given by \a x, \a y, \a w and \a h.

    \sa setHBarGeometry()
*/
void Q3ScrollView::setVBarGeometry(QScrollBar& vbar,
    int x, int y, int w, int h)
{
    vbar.setGeometry(x, y, w, h);
}


/*!
    Returns the viewport size for size (\a x, \a y).

    The viewport size depends on (\a x, \a y) (the size of the contents),
    the size of this widget and the modes of the horizontal and
    vertical scroll bars.

    This function permits widgets that can trade vertical and
    horizontal space for each other to control scroll bar appearance
    better. For example, a word processor or web browser can control
    the width of the right margin accurately, whether or not there
    needs to be a vertical scroll bar.
*/

QSize Q3ScrollView::viewportSize(int x, int y) const
{
    int fw = frameWidth();
    int lmarg = fw+d->l_marg;
    int rmarg = fw+d->r_marg;
    int tmarg = fw+d->t_marg;
    int bmarg = fw+d->b_marg;

    int w = width();
    int h = height();

    bool needh, needv;
    bool showh, showv;
    int hsbExt = horizontalScrollBar()->sizeHint().height();
    int vsbExt = verticalScrollBar()->sizeHint().width();

    if (d->policy != AutoOne || d->anyVisibleChildren()) {
        // Do we definitely need the scroll bar?
        needh = w-lmarg-rmarg < x;
        needv = h-tmarg-bmarg < y;

        // Do we intend to show the scroll bar?
        if (d->hMode == AlwaysOn)
            showh = true;
        else if (d->hMode == AlwaysOff)
            showh = false;
        else
            showh = needh;

        if (d->vMode == AlwaysOn)
            showv = true;
        else if (d->vMode == AlwaysOff)
            showv = false;
        else
            showv = needv;

        // Given other scroll bar will be shown, NOW do we need one?
        if (showh && h-vsbExt-tmarg-bmarg < y) {
            if (d->vMode == Auto)
                showv=true;
        }
        if (showv && w-hsbExt-lmarg-rmarg < x) {
            if (d->hMode == Auto)
                showh=true;
        }
    } else {
        // Scroll bars not needed, only show scroll bar that are always on.
        showh = d->hMode == AlwaysOn;
        showv = d->vMode == AlwaysOn;
    }

    return QSize(w-lmarg-rmarg - (showv ? vsbExt : 0),
                  h-tmarg-bmarg - (showh ? hsbExt : 0));
}


/*!
    Updates scroll bars: all possibilities are considered. You should
    never need to call this in your code.
*/
void Q3ScrollView::updateScrollBars()
{
    if(!horizontalScrollBar() && !verticalScrollBar())
        return;

    // I support this should use viewportSize()... but it needs
    // so many of the temporary variables from viewportSize.  hm.
    int fw = frameWidth();
    int lmarg = fw+d->l_marg;
    int rmarg = fw+d->r_marg;
    int tmarg = fw+d->t_marg;
    int bmarg = fw+d->b_marg;

    int w = width();
    int h = height();

    int portw, porth;

    bool needh;
    bool needv;
    bool showh;
    bool showv;
    bool showc = false;

    int hsbExt = horizontalScrollBar()->sizeHint().height();
    int vsbExt = verticalScrollBar()->sizeHint().width();

    QSize oldVisibleSize(visibleWidth(), visibleHeight());

    if (d->policy != AutoOne || d->anyVisibleChildren()) {
        // Do we definitely need the scroll bar?
        needh = w-lmarg-rmarg < d->contentsWidth();
        if (d->inresize)
            needh  = !horizontalScrollBar()->isHidden();
        needv = h-tmarg-bmarg < contentsHeight();

        // Do we intend to show the scroll bar?
        if (d->hMode == AlwaysOn)
            showh = true;
        else if (d->hMode == AlwaysOff)
            showh = false;
        else
            showh = needh;

        if (d->vMode == AlwaysOn)
            showv = true;
        else if (d->vMode == AlwaysOff)
            showv = false;
        else
            showv = needv;

#ifdef Q_WS_MAC
        bool mac_need_scroll = false;
        if(!parentWidget()) {
            mac_need_scroll = true;
        } else {
            QWidget *tlw = window();
            QPoint tlw_br = QPoint(tlw->width(), tlw->height()),
                    my_br = qt_mac_posInWindow(this) + QPoint(w, h);
            if(my_br.x() >= tlw_br.x() - 3 && my_br.y() >= tlw_br.y() - 3)
                mac_need_scroll = true;
        }
        if(mac_need_scroll) {
            WindowAttributes attr;
            GetWindowAttributes((WindowPtr)handle(), &attr);
            mac_need_scroll = (attr & kWindowResizableAttribute);
        }
        if(mac_need_scroll) {
            showc = true;
            if(d->vMode == Auto)
                showv = true;
            if(d->hMode == Auto)
                showh = true;
        }
#endif

        // Given other scroll bar will be shown, NOW do we need one?
        if (showh && h-vsbExt-tmarg-bmarg < contentsHeight()) {