qscrollarea.cpp

Go to the documentation of this file.

/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qscrollarea.h"
#include "private/qscrollarea_p.h"

#ifndef QT_NO_SCROLLAREA

#include "qscrollbar.h"
#include "qlayout.h"
#include "qstyle.h"
#include "qapplication.h"
#include "qvariant.h"
#include "qdebug.h"
#include "private/qlayoutengine_p.h"

QT_BEGIN_NAMESPACE

QScrollArea::QScrollArea(QWidget *parent)
    : QAbstractScrollArea(*new QScrollAreaPrivate,parent)
{
    Q_D(QScrollArea);
    d->viewport->setBackgroundRole(QPalette::NoRole);
    d->vbar->setSingleStep(20);
    d->hbar->setSingleStep(20);
    d->layoutChildren();
}

QScrollArea::QScrollArea(QScrollAreaPrivate &dd, QWidget *parent)
    : QAbstractScrollArea(dd, parent)
{
    Q_D(QScrollArea);
    d->viewport->setBackgroundRole(QPalette::NoRole);
    d->vbar->setSingleStep(20);
    d->hbar->setSingleStep(20);
    d->layoutChildren();
}

QScrollArea::~QScrollArea()
{
}

void QScrollAreaPrivate::updateWidgetPosition()
{
    Q_Q(QScrollArea);
    Qt::LayoutDirection dir = q->layoutDirection();
    QRect scrolled = QStyle::visualRect(dir, viewport->rect(), QRect(QPoint(-hbar->value(), -vbar->value()), widget->size()));
    QRect aligned = QStyle::alignedRect(dir, alignment, widget->size(), viewport->rect());
    widget->move(widget->width() < viewport->width() ? aligned.x() : scrolled.x(),
                 widget->height() < viewport->height() ? aligned.y() : scrolled.y());
}

void QScrollAreaPrivate::updateScrollBars()
{
    Q_Q(QScrollArea);
    if (!widget)
        return;
    QSize p = viewport->size();
    QSize m = q->maximumViewportSize();

    QSize min = qSmartMinSize(widget);
    QSize max = qSmartMaxSize(widget);

    if (resizable) {
        if ((widget->layout() ? widget->layout()->hasHeightForWidth() : widget->sizePolicy().hasHeightForWidth())) {
            QSize p_hfw = p.expandedTo(min).boundedTo(max);
            int h = widget->heightForWidth( p_hfw.width() );
            min = QSize(p_hfw.width(), qMax(p_hfw.height(), h));
        }
    }

    if ((resizable && m.expandedTo(min) == m && m.boundedTo(max) == m)
        || (!resizable && m.expandedTo(widget->size()) == m))
        p = m; // no scroll bars needed

    if (resizable)
        widget->resize(p.expandedTo(min).boundedTo(max));
    QSize v = widget->size();

    hbar->setRange(0, v.width() - p.width());
    hbar->setPageStep(p.width());
    vbar->setRange(0, v.height() - p.height());
    vbar->setPageStep(p.height());
    updateWidgetPosition();

}

QWidget *QScrollArea::widget() const
{
    Q_D(const QScrollArea);
    return d->widget;
}

void QScrollArea::setWidget(QWidget *widget)
{
    Q_D(QScrollArea);
    if (widget == d->widget || !widget)
        return;

    delete d->widget;
    d->widget = 0;
    d->hbar->setValue(0);
    d->vbar->setValue(0);
    if (widget->parentWidget() != d->viewport)
        widget->setParent(d->viewport);
    if (!widget->testAttribute(Qt::WA_Resized))
        widget->resize(widget->sizeHint());
    d->widget = widget;
    d->widget->setAutoFillBackground(true);
    widget->installEventFilter(this);
    d->widgetSize = QSize();
    d->updateScrollBars();
    d->widget->show();

}

QWidget *QScrollArea::takeWidget()
{
    Q_D(QScrollArea);
    QWidget *w = d->widget;
    d->widget = 0;
    if (w)
        w->setParent(0);
    return w;
}

bool QScrollArea::event(QEvent *e)
{
    Q_D(QScrollArea);
    if (e->type() == QEvent::StyleChange || e->type() == QEvent::LayoutRequest) {
        d->updateScrollBars();
    }
#ifdef QT_KEYPAD_NAVIGATION
    else if (QApplication::keypadNavigationEnabled()) {
        if (e->type() == QEvent::Show)
            QApplication::instance()->installEventFilter(this);
        else if (e->type() == QEvent::Hide)
            QApplication::instance()->removeEventFilter(this);
    }
#endif
    return QAbstractScrollArea::event(e);
}


bool QScrollArea::eventFilter(QObject *o, QEvent *e)
{
    Q_D(QScrollArea);
#ifdef QT_KEYPAD_NAVIGATION
    if (d->widget && o != d->widget && e->type() == QEvent::FocusIn
            && QApplication::keypadNavigationEnabled()) {
        if (o->isWidgetType())
            ensureWidgetVisible(static_cast<QWidget *>(o));
    }
#endif
    if (o == d->widget && e->type() == QEvent::Resize)
        d->updateScrollBars();

    return false;
}

void QScrollArea::resizeEvent(QResizeEvent *)
{
    Q_D(QScrollArea);
    d->updateScrollBars();

}


void QScrollArea::scrollContentsBy(int, int)
{
    Q_D(QScrollArea);
    if (!d->widget)
        return;
    d->updateWidgetPosition();
}


bool QScrollArea::widgetResizable() const
{
    Q_D(const QScrollArea);
    return d->resizable;
}

void QScrollArea::setWidgetResizable(bool resizable)
{
    Q_D(QScrollArea);
    d->resizable = resizable;
    updateGeometry();
    d->updateScrollBars();
}

QSize QScrollArea::sizeHint() const
{
    Q_D(const QScrollArea);
    int f = 2 * d->frameWidth;
    QSize sz(f, f);
    int h = fontMetrics().height();
    if (d->widget) {
        if (!d->widgetSize.isValid())
            d->widgetSize = d->resizable ? d->widget->sizeHint() : d->widget->size();
        sz += d->widgetSize;
    } else {
        sz += QSize(12 * h, 8 * h);
    }
    if (d->vbarpolicy == Qt::ScrollBarAlwaysOn)
        sz.setWidth(sz.width() + d->vbar->sizeHint().width());
    if (d->hbarpolicy == Qt::ScrollBarAlwaysOn)
        sz.setHeight(sz.height() + d->hbar->sizeHint().height());
    return sz.boundedTo(QSize(36 * h, 24 * h));
}



bool QScrollArea::focusNextPrevChild(bool next)
{
    if (QWidget::focusNextPrevChild(next)) {
        if (QWidget *fw = focusWidget())
            ensureWidgetVisible(fw);
        return true;
    }
    return false;
}

void QScrollArea::ensureVisible(int x, int y, int xmargin, int ymargin)
{
    Q_D(QScrollArea);

    int logicalX = QStyle::visualPos(layoutDirection(), d->viewport->rect(), QPoint(x, y)).x();

    if (logicalX - xmargin < d->hbar->value()) {
        d->hbar->setValue(qMax(0, logicalX - xmargin));
    } else if (logicalX > d->hbar->value() + d->viewport->width() - xmargin) {
        d->hbar->setValue(qMin(logicalX - d->viewport->width() + xmargin, d->hbar->maximum()));
    }

    if (y - ymargin < d->vbar->value()) {
        d->vbar->setValue(qMax(0, y - ymargin));
    } else if (y > d->vbar->value() + d->viewport->height() - ymargin) {
        d->vbar->setValue(qMin(y - d->viewport->height() + ymargin, d->vbar->maximum()));
    }
}

void QScrollArea::ensureWidgetVisible(QWidget *childWidget, int xmargin, int ymargin)
{
    Q_D(QScrollArea);

    if (!d->widget->isAncestorOf(childWidget))
        return;

    const QRect microFocus = childWidget->inputMethodQuery(Qt::ImMicroFocus).toRect();
    const QRect defaultMicroFocus =
        childWidget->QWidget::inputMethodQuery(Qt::ImMicroFocus).toRect();
    QRect focusRect = (microFocus != defaultMicroFocus)
        ? QRect(childWidget->mapTo(d->widget, microFocus.topLeft()), microFocus.size())
        : QRect(childWidget->mapTo(d->widget, QPoint(0,0)), childWidget->size());
    const QRect visibleRect(-d->widget->pos(), d->viewport->size());

    if (visibleRect.contains(focusRect))
        return;

    focusRect.adjust(-xmargin, -ymargin, xmargin, ymargin);

    if (focusRect.width() > visibleRect.width())
        d->hbar->setValue(focusRect.center().x() - d->viewport->width() / 2);
    else if (focusRect.right() > visibleRect.right())
        d->hbar->setValue(focusRect.right() - d->viewport->width());
    else if (focusRect.left() < visibleRect.left())
        d->hbar->setValue(focusRect.left());

    if (focusRect.height() > visibleRect.height())
        d->vbar->setValue(focusRect.center().y() - d->viewport->height() / 2);
    else if (focusRect.bottom() > visibleRect.bottom())
        d->vbar->setValue(focusRect.bottom() - d->viewport->height());
    else if (focusRect.top() < visibleRect.top())
        d->vbar->setValue(focusRect.top());
}


void QScrollArea::setAlignment(Qt::Alignment alignment)
{
    Q_D(QScrollArea);
    d->alignment = alignment;
    if (d->widget)
        d->updateWidgetPosition();
}

Qt::Alignment QScrollArea::alignment() const
{
    Q_D(const QScrollArea);
    return d->alignment;
}

QT_END_NAMESPACE

#endif // QT_NO_SCROLLAREA