转载：Qt应用程序采用双屏显示的一些想法

 转载地址：https://www.cnblogs.com/ppffs/p/3186221.html

最近由于项目需要，采用Qt开发的程序要能够支持双屏显示，在网上调研了以下，发现网页http://www.ics.com/blog/whats-new-qt-5-qscreen-class#.Ud9mY4csnXB中对于Qt的多屏幕管理有一定论述，指出采用QScreen可以获取窗口的相关信息，代码如下：

#include <QGuiApplication>
#include <QScreen>
#include <QDebug>

/*
  Example of using Qt 5 QScreen class.
*/

// Helper function to return display orientation as a string.
QString Orientation(Qt::ScreenOrientation orientation)
{
    switch (orientation) {
        case Qt::PrimaryOrientation           : return "Primary";
        case Qt::LandscapeOrientation         : return "Landscape";
        case Qt::PortraitOrientation          : return "Portrait";
        case Qt::InvertedLandscapeOrientation : return "Inverted landscape";
        case Qt::InvertedPortraitOrientation  : return "Inverted portrait";
        default                               : return "Unknown";
    }
}

int main(int argc, char *argv)
{
    QGuiApplication a(argc, &argv);

    qDebug() << "Number of screens:" << QGuiApplication::screens().size();

    qDebug() << "Primary screen:" << QGuiApplication::primaryScreen()->name();

    foreach (QScreen *screen, QGuiApplication::screens()) {
        qDebug() << "Information for screen:" << screen->name();
        qDebug() << "  Available geometry:" << screen->availableGeometry().x() << screen->availableGeometry().y() << screen->availableGeometry().width() << "x" << screen->availableGeometry().height();
        qDebug() << "  Available size:" << screen->availableSize().width() << "x" << screen->availableSize().height();
        qDebug() << "  Available virtual geometry:" << screen->availableVirtualGeometry().x() << screen->availableVirtualGeometry().y() << screen->availableVirtualGeometry().width() << "x" << screen->availableVirtualGeometry().height();
        qDebug() << "  Available virtual size:" << screen->availableVirtualSize().width() << "x" << screen->availableVirtualSize().height();
        qDebug() << "  Depth:" << screen->depth() << "bits";
        qDebug() << "  Geometry:" << screen->geometry().x() << screen->geometry().y() << screen->geometry().width() << "x" << screen->geometry().height();
        qDebug() << "  Logical DPI:" << screen->logicalDotsPerInch();
        qDebug() << "  Logical DPI X:" << screen->logicalDotsPerInchX();
        qDebug() << "  Logical DPI Y:" << screen->logicalDotsPerInchY();
        qDebug() << "  Orientation:" << Orientation(screen->orientation());
        qDebug() << "  Physical DPI:" << screen->physicalDotsPerInch();
        qDebug() << "  Physical DPI X:" << screen->physicalDotsPerInchX();
        qDebug() << "  Physical DPI Y:" << screen->physicalDotsPerInchY();
        qDebug() << "  Physical size:" << screen->physicalSize().width() << "x" << screen->physicalSize().height() << "mm";
        qDebug() << "  Primary orientation:" << Orientation(screen->primaryOrientation());
        qDebug() << "  Refresh rate:" << screen->refreshRate() << "Hz";
        qDebug() << "  Size:" << screen->size().width() << "x" << screen->size().height();
        qDebug() << "  Virtual geometry:" << screen->virtualGeometry().x() << screen->virtualGeometry().y() << screen->virtualGeometry().width() << "x" << screen->virtualGeometry().height();
        qDebug() << "  Virtual size:" << screen->virtualSize().width() << "x" << screen->virtualSize().height();
    }
}

     于是，有了建立基于Qt的双屏显示程序的思路：建立两个QMainWindow，然后分别通过函数setGeometry分别指定两个QMainWindow为显示器一和显示器二的位置，这样总体的效果就是这个程序能够实现双屏的功能。同时需要注意，在定义QMainWindow的对象时，需要使用堆内存的方法，不能采用栈内存，在网页http://www.qtcentre.org/archive/index.php/t-16439.html中对此有过论述。