获取Qt中的物理屏幕大小

Question

我在Qt工作,我需要帮助来获得屏幕的物理尺寸(显示器),

在Qt一个可以得到一个QDesktopWidget从QApplication,我的意思是:

QDesktopWidget *mydesk = QApplication::desktop();

在QDesktopwidget有一些方法来获取像素的分辨率和一些获得了大小milimethers:

mydesk-> widthMM(); mydesk->heightMM();

但是,这与物理尺寸不符,当我用尺子测量我的屏幕时,存在相当大的差异.

还可以获得DPI测量并计算屏幕大小:

mydesk->physicalDpiX(); mydesk->physicalDpiY();

double Winches = (double)mydesk.width() / (double)mydesk.physicalDpiX();
double Hinches = (double)mydesk.Height() / (double)mydesk.physicalDpiY();

在那里mydesk.width() ,并mydesk.height()给在像素尺寸(分辨率)

然而,测量也是错误的,非常接近mydesk.widthMM()和mydesk.heightMM()

我也有三分mydesk.logicalDpiX(),它也有类似的结果.

Answer 1

这是我(快速和肮脏)的例子.它似乎对我有用,我希望它对你有用.我假设你可以自己照顾main.cpp.我在MacBook Air 11.6上做了这个,并用OS X中包含的USA图标替换了一角钱的图片:

#ifndef WINDOW_H
#define WINDOW_H

#include <QtGui>

class Window : public QWidget
{
    Q_OBJECT

public:
    QWidget *canvas;
    QSlider *slider;
    QPixmap pixmap;

private:
    qreal zoom;
    qreal pixels;
    qreal px_width;
    qreal px_height;
    qreal mm_width;
    qreal mm_height;

public:
    Window();
    void paintEvent(QPaintEvent *);

public slots:
    void setZoom(int);
};

Window::Window()
{
    QHBoxLayout *layout = new QHBoxLayout;

    canvas = new QWidget;
    slider = new QSlider;
    slider->setMinimum(0);
    slider->setMaximum(100);
    slider->setValue(50);

    layout->addWidget(canvas);
    layout->addWidget(slider);

    this->setLayout(layout);

    if(!pixmap.load(":/resources/USA.gif"))
    {
        qDebug() << "Fatal error: Unable to load image";
        exit(1);
    }

    QObject::connect(slider, SIGNAL(valueChanged(int)), SLOT(setZoom(int)));
}

void Window::paintEvent(QPaintEvent *event)
{
    QPainter paint;
    paint.begin(this);
    paint.scale(zoom, zoom);
    paint.drawPixmap(0,0, pixmap);
    paint.end();
}

void Window::setZoom(int new_zoom)
{
    zoom = (qreal)(50+new_zoom) /50;
    pixels = pixmap.width() * zoom;

    QDesktopWidget desk;

    px_width = desk.width() / pixels;
    px_height = desk.height() / pixels;
    mm_width = px_width * 17.9;
    mm_height = px_height * 17.9;

    qDebug() << "Zoom: " << zoom;
    qDebug() << "desk.widthMM:" << desk.widthMM();
    qDebug() << "px_width: " << px_width;
    qDebug() << "px_height: " << px_height;
    qDebug() << "mm_width: " << mm_width;
    qDebug() << "mm_height: " << mm_height;

    this->repaint();
}

#include "moc_window.cpp"

#endif // WINDOW_H