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** Public License version 3.0 as published by the Free Software Foundation
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#include "qdesktopwidget.h"
#include "private/qapplication_p.h"
#include "private/qgraphicssystem_p.h"
#include <QWidget>
#include "private/qwidget_p.h"
#include "private/qdesktopwidget_qpa_p.h"
QT_BEGIN_NAMESPACE

QT_USE_NAMESPACE

void QDesktopWidgetPrivate::updateScreenList()
{
    Q_Q(QDesktopWidget);

    QList<QPlatformScreen *> screenList = QApplicationPrivate::platformIntegration()->screens();
    int targetLength = screenList.length();
    int currentLength = screens.length();

    // Add or remove screen widgets as necessary
    if(currentLength > targetLength) {
        QDesktopScreenWidget *screen;
        while (currentLength-- > targetLength) {
            screen = screens.takeLast();
            delete screen;
        }
    }
    else if (currentLength < targetLength) {
        QDesktopScreenWidget *screen;
        while (currentLength < targetLength) {
            screen = new QDesktopScreenWidget(currentLength++);
            screens.append(screen);
        }
    }

    QRegion virtualGeometry;

    // update the geometry of each screen widget
    for (int i = 0; i < screens.length(); i++) {
        QRect screenGeometry = screenList.at(i)->geometry();
        screens.at(i)->setGeometry(screenGeometry);
        virtualGeometry += screenGeometry;
    }

    q->setGeometry(virtualGeometry.boundingRect());
}

QDesktopWidget::QDesktopWidget()
    : QWidget(*new QDesktopWidgetPrivate, 0, Qt::Desktop)
{
    Q_D(QDesktopWidget);
    setObjectName(QLatin1String("desktop"));
    d->updateScreenList();
}

QDesktopWidget::~QDesktopWidget()
{
}

bool QDesktopWidget::isVirtualDesktop() const
{
    return QApplicationPrivate::platformIntegration()->isVirtualDesktop();
}

int QDesktopWidget::primaryScreen() const
{
    return 0;
}

int QDesktopWidget::numScreens() const
{
    QPlatformIntegration *pi = QApplicationPrivate::platformIntegration();
    return qMax(pi->screens().size(), 1);
}

QWidget *QDesktopWidget::screen(int screen)
{
    Q_D(QDesktopWidget);
    if (screen < 0 || screen >= d->screens.length())
        return d->screens.at(0);
    return d->screens.at(screen);
}

const QRect QDesktopWidget::availableGeometry(int screenNo) const
{
    QPlatformIntegration *pi = QApplicationPrivate::platformIntegration();
    QList<QPlatformScreen *> screens = pi->screens();
    if (screenNo == -1)
        screenNo = 0;
    if (screenNo < 0 || screenNo >= screens.size())
        return QRect();
    else
        return screens[screenNo]->availableGeometry();
}

const QRect QDesktopWidget::screenGeometry(int screenNo) const
{
    QPlatformIntegration *pi = QApplicationPrivate::platformIntegration();
    QList<QPlatformScreen *> screens = pi->screens();
    if (screenNo == -1)
        screenNo = 0;
    if (screenNo < 0 || screenNo >= screens.size())
        return QRect();
    else
        return screens[screenNo]->geometry();
}

int QDesktopWidget::screenNumber(const QWidget *w) const
{
    if (!w)
        return 0;

    QRect frame = w->frameGeometry();
    if (!w->isWindow())
        frame.moveTopLeft(w->mapToGlobal(QPoint(0, 0)));
    const QPoint midpoint = (frame.topLeft() + frame.bottomRight()) / 2;
    return screenNumber(midpoint);
}

int QDesktopWidget::screenNumber(const QPoint &p) const
{
    QPlatformIntegration *pi = QApplicationPrivate::platformIntegration();
    QList<QPlatformScreen *> screens = pi->screens();

    for (int i = 0; i < screens.size(); ++i)
        if (screens[i]->geometry().contains(p))
            return i;

    return primaryScreen(); //even better would be closest screen
}

void QDesktopWidget::resizeEvent(QResizeEvent *)
{
}

QT_END_NAMESPACE