qscrollview.cpp

qtopia-phone-2.2.0下公共的控件实现源代码。

  <li> \c Manual - the view stays the size set by resizeContents().

  <li> \c AutoOne - if there is only child widget, the view stays
  the size of that widget.  Otherwise, the behaviour is undefined.

  <li> \c AutoOneFit - if there is only one child widget the view stays
  the size of that widget's sizeHint(). If the scrollview is resized bigger
  than the child's sizeHint(), the child will be resized to fit.
  If there is more than one child, the behaviour is undefined.

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

/*!

  Constructs a QScrollView with a \a parent, a \a name and widget
  flags \a f.

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



QScrollView::QScrollView( QWidget *parent, const char *name, WFlags f ) :
    QFrame( parent, name, f & (~WNorthWestGravity) & (~WRepaintNoErase), FALSE )
{
    d = new QScrollViewData(this,WResizeNoErase |
	    (f&WPaintClever) | (f&WRepaintNoErase) | (f&WNorthWestGravity) );
#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) ) );
    d->viewport.installEventFilter( this );

    setFrameStyle( QFrame::StyledPanel | QFrame::Sunken );
    setLineWidth( style().defaultFrameWidth() );
    setSizePolicy( QSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding ) );

#ifdef QT_KEYPAD_MODE
    if( qt_modalEditingEnabled ) {
	installEventFilter(this);
    }
#endif
}


/*!
  Destructs the QScrollView.  Any children added with addChild()
  will be destructed.
*/

QScrollView::~QScrollView()
{
    // Be careful not to get all those useless events...
    if ( d->clipped_viewport )
	d->clipped_viewport->removeEventFilter( this );
    else
	d->viewport.removeEventFilter( this );
    QScrollViewData* d2 = d;
    d = 0;
    delete d2;
}


/*!
  \reimp
*/
void QScrollView::styleChange( QStyle& old )
{
    QWidget::styleChange( old );
    updateScrollBars();
}


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

void QScrollView::vslide( int pos )
{
    if ( !d->signal_choke ) {
	if ( testWState(WState_GlobalBrushOrigin) ) {
	    // Reduce flicker by moving line at a time.
	    if (pos < verticalScrollBar()->maxValue()) {
		int step = verticalScrollBar()->lineStep();
		pos = (pos + step/2) / step * step;
	    }
	}
	moveContents( -contentsX(), -pos );
	QApplication::syncX();
    }
}

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

  The default implementation simply gives all the space to \a hbar.

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

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

  The default implementation simply gives all the space to \a vbar.

  \sa setHBarGeometry()
*/
void QScrollView::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,y (the size of the contents), the
  size of this widget, 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 there needs to be a vertical
  scroll bar or not.
*/

QSize QScrollView::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 scrollbar?
	needh = w-lmarg-rmarg < x;
	needv = h-tmarg-bmarg < y;

	// Do we intend to show the scrollbar?
	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 scrollbar 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 {
	// Scrollbars not needed, only show scrollbar 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) );
}

/*
  The surrounding environment (or application, if there is no
  environment, may set this. Requires Qt >= 2.3.8.
*/
bool qt_left_hand_scrollbars = FALSE;

/*!
  Updates scrollbars - all possibilities considered.  You should never
  need to call this in your code.
*/
void QScrollView::updateScrollBars()
{
    // 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;

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

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

	// Do we intend to show the scrollbar?
	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 scrollbar will be shown, NOW do we need one?
	if ( showh && h-vsbExt-tmarg-bmarg < contentsHeight() ) {
	    needv=TRUE;
	    if (d->vMode == Auto)
		showv=TRUE;
	}
	if ( showv && w-hsbExt-lmarg-rmarg < contentsWidth() ) {
	    needh=TRUE;
	    if (d->hMode == Auto)
		showh=TRUE;
	}
    } else {
	// Scrollbars not needed, only show scrollbar that are always on.
	needh = needv = FALSE;
	showh = d->hMode == AlwaysOn;
	showv = d->vMode == AlwaysOn;
    }

    bool sc = d->signal_choke;
    d->signal_choke=TRUE;

    // Hide unneeded scrollbar, calculate viewport size
    if ( showh ) {
        porth=h-hsbExt-tmarg-bmarg;
    } else {
	if (!needh)
	    d->hbar.setValue(0);
	d->hbar.hide();
	porth=h-tmarg-bmarg;
    }
    if ( showv ) {
	portw=w-vsbExt-lmarg-rmarg;
    } else {
	if (!needv)
	    d->vbar.setValue(0);
	d->vbar.hide();
	portw=w-lmarg-rmarg;
    }

    // Configure scrollbars that we will show
	if ( needv ) {
	    d->vbar.setRange( 0, contentsHeight()-porth );
	    d->vbar.setSteps( QScrollView::d->vbar.lineStep(), porth );
	} else {
	    d->vbar.setRange( 0, 0 );
	}
	if ( needh ) {
	    d->hbar.setRange( 0, contentsWidth()-portw );
	    d->hbar.setSteps( QScrollView::d->hbar.lineStep(), portw );
	} else {
	    d->hbar.setRange( 0, 0 );
	}

    // Position the scrollbars, viewport, and corner widget.
    int bottom;
    int xoffset = ( qt_left_hand_scrollbars && ( showv || cornerWidget() ) ) ? vsbExt : 0;
    int xpos    =   qt_left_hand_scrollbars ? 0 : w-vsbExt;
    xpos    =  (style() == WindowsStyle) && qt_left_hand_scrollbars ? xpos + fw : xpos - fw;
    int ypos    = tmarg;
    ypos        = (style() == WindowsStyle) ? ypos +fw : 0;
    if ( showh ) {
	int right = ( showv || cornerWidget() ) ? w-vsbExt : w;
	if ( style() == WindowsStyle )
            setHBarGeometry(d->hbar, fw + xoffset , h-hsbExt-fw,
                            right-fw-fw, hsbExt );
	else
            setHBarGeometry(d->hbar, 0+  xoffset, h-hsbExt, right,
                            hsbExt );
	bottom=h-hsbExt;
    } else {
        bottom=h;
    }
    if ( showv ) {
	clipper()->setGeometry( lmarg + xoffset, tmarg,
                                w-vsbExt-lmarg-rmarg,
                                bottom-tmarg-bmarg );
	d->viewportResized( w-vsbExt-lmarg-rmarg, bottom-tmarg-bmarg );
	if ( style() == WindowsStyle )
	    changeFrameRect(QRect(xoffset, 0, w, h) );
	else
	    changeFrameRect(QRect(xoffset, 0, w-vsbExt, bottom));
	if (cornerWidget()) {
	    bottom = h-hsbExt;	// must reserve space for corner button
	    if ( style() == WindowsStyle )
                setVBarGeometry( d->vbar, xpos,
                                 ypos, vsbExt,
                                 bottom-fw-ypos );
	    else
                setVBarGeometry( d->vbar, xpos, ypos,
                                 vsbExt,
                                 bottom-ypos );
	}
	else {
	    if ( style() == WindowsStyle )
                setVBarGeometry( d->vbar, xpos,
                                 ypos, vsbExt,
                                 bottom-fw-ypos );
	    else
                setVBarGeometry( d->vbar, xpos, ypos,
                                 vsbExt, bottom-ypos );
	}
    } else {
	if ( style() == WindowsStyle )
	    changeFrameRect(QRect(0, 0, w, h));
	else
	    changeFrameRect(QRect(0, 0, w, bottom));
	clipper()->setGeometry( lmarg, tmarg,
				 w-lmarg-rmarg, bottom-tmarg-bmarg );
	d->viewportResized( w-lmarg-rmarg, bottom-tmarg-bmarg );
    }
    if ( d->corner ) {
	if ( style() == WindowsStyle )
            d->corner->setGeometry( xpos,
                                    h-hsbExt-fw,
                                    vsbExt,
                                    hsbExt );
	else
            d->corner->setGeometry( xpos,
                                    h-hsbExt,
                                    vsbExt,
                                    hsbExt );
    }

    d->signal_choke=sc;

    if ( contentsX()+visibleWidth() > contentsWidth() ) {
	int x=QMAX(0,contentsWidth()-visibleWidth());
	d->hbar.setValue(x);
	// Do it even if it is recursive
	moveContents( -x, -contentsY() );
    }
    if ( contentsY()+visibleHeight() > contentsHeight() ) {
	int y=QMAX(0,contentsHeight()-visibleHeight());
	d->vbar.setValue(y);
	// Do it even if it is recursive
	moveContents( -contentsX(), -y );
    }

    // Finally, show the scrollbars.
    if ( showh && !d->hbar.isVisible() )
	d->hbar.show();
    if ( showv && !d->vbar.isVisible() )
	d->vbar.show();
}


/*! \reimp
*/
void QScrollView::show()
{
    //     Ensures that scrollbars have the correct size when the
    //     widget is shown.
    if (isVisible()) return;
    QWidget::show();
    updateScrollBars();
    d->hideOrShowAll(this);
}

/*! \reimp
 */
void QScrollView::resize( int w, int h )
{
    //   Ensures that scrollbars have the correct size when the widget is
    //   resized.
    QWidget::resize( w, h );
}

/*! \reimp
*/
void QScrollView::resize( const QSize& s )
{
    //   Ensures that scrollbars have the correct size when the widget is
    //   resized.
    resize(s.width(),s.height());
}

/*! \reimp
*/
void QScrollView::resizeEvent( QResizeEvent* event )
{
    // Ensures that scrollbars have the correct size when the widget
    // is resized.
    bool u = isUpdatesEnabled();
    setUpdatesEnabled( FALSE );
    QFrame::resizeEvent( event );

    // do _not_ update the scrollbars when updates have been
    // disabled. This makes it possible for subclasses to implement
    // dynamic wrapping without a horizontal scrollbar showing up all
    // the time when making a window smaller.
    if ( u )
	updateScrollBars();
    d->hideOrShowAll(this);
    setUpdatesEnabled( u );
}


/*! \reimp
*/
void QScrollView::wheelEvent( QWheelEvent *e ){
    QWheelEvent ce( viewport()->mapFromGlobal( e->globalPos() ),
		    e->globalPos(), e->delta(), e->state());
    viewportWheelEvent(&ce);
    if ( !ce.isAccepted() ) {
	if (verticalScrollBar())
	    QApplication::sendEvent( verticalScrollBar(), e);
    }
}

/*!
  Returns the currently set mode for the vertical scrollbar.

  \sa setVScrollBarMode()
*/
QScrollView::ScrollBarMode QScrollView::vScrollBarMode() const
{
    return d->vMode;
}


/*! \enum QScrollView::ScrollBarMode

  This enum type describes the various modes of QScrollView's scroll
  bars.  The defined modes are: <ul>

   <li> \c Auto - QScrollView shows a scrollbar when the content is
   too tall to fit and not else.  This is the default.

   <li> \c AlwaysOff - QScrollView never shows a scrollbar.

   <li> \c AlwaysOn - QScrollView always shows a scrollbar.