mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QDebug>
#include <QDesktopWidget>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
    
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    
    void InitWidget();
    void resetGrid(QWidget *widget,double factorx,double factory);

private:
    Ui::MainWindow *ui;

    double factorx;//横向缩放比例
    double factory;//纵向缩放比例
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"


#define INIT_SREEN_WID 1920.0   //初始化环境分辨率
#define INIT_SREEN_HEI 1080.0

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setFixedSize(1280, 800);
    QFont font;
    font.setFamily(QString::fromLocal8Bit("楷体"));
    font.setPixelSize(90);
    font.setBold(true);
    ui->label->setFont( font );
    InitWidget();
    QFont ft = ui->label->font();
    int fontsize = ft.pixelSize();
    font.setPixelSize( fontsize * factory );
    ui->label->setFont( font );

    QObjectList q(ui->centralWidget->children());

    for (int i = 0; i < q.length(); i++)
    {
        QObject* o = q.at(i);
        if (o->inherits("QPushButton"))
        {
            QPushButton* b = qobject_cast<QPushButton*>(o);
            resetGrid(b, factory, factory);
        }
        else if ( o->inherits("QLineEdit") )
        {
            QLineEdit* b = qobject_cast<QLineEdit*>(o);
            resetGrid(b, factory, factory);
        }
        else if ( o->inherits("QComboBox") )
        {
            QComboBox* b = qobject_cast<QComboBox*>(o);
            resetGrid(b, factory, factory);
        }
        else if ( o->inherits("QLabel") )
        {
            QLabel* b = qobject_cast<QLabel*>(o);
            resetGrid(b, factory, factory);
        }
    }

    qDebug() << "@@@:" << (double)ui->pushButton->width()/(double)ui->pushButton->height();
    qDebug() << "###:" << (double)1280.0/(double)800.0;
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::InitWidget()
{
    int currentScreenWid = QApplication::desktop()->width();
    int currentScreenHei = QApplication::desktop()->height();
    qDebug() << currentScreenWid << "*" << currentScreenHei;
    double ScreenWid = INIT_SREEN_WID;
    double ScreenHei = INIT_SREEN_HEI;
    factorx = (double)currentScreenWid/ScreenWid;
    factory = (double)currentScreenHei/ScreenHei;
    qDebug() << "factorx:" << factorx << "factory" << factory;
    resetGrid(this, factory, factory);
}

void MainWindow::resetGrid(QWidget *widget,double factorx,double factory)
{
    int widgetX = widget->x();
    int widgetY = widget->y();
    int widgetWid = widget->width();
    int widgetHei = widget->height();
    int nWidgetX = (int)(widgetX*factorx);
    int nWidgetY = (int)(widgetY*factory);
    int nWidgetWid = (int)(widgetWid*factorx);
    int nWidgetHei = (int)(widgetHei*factory);
    widget->setGeometry(nWidgetX,nWidgetY,nWidgetWid,nWidgetHei);
    widget->setFixedSize(nWidgetWid, nWidgetHei);
}

main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    w.move ((QApplication::desktop()->width() - w.width())/2,(QApplication::desktop()->height() - w.height())/2);

    return a.exec();
}