qt缩放参考

#include "widget.h"#include <QApplication>#include <QObject>#include <QWidget>#include <QDesktopWidget>#include <QMessageBox>//#include <stdio.h>//#include <string>#include "windows.h"#pragma comment(lib,"User32.lib")#pragma execution_character_set("utf-8")int main(int argc, char *argv[]){    QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);//控制图片缩放质量    //QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);    //qreal  cx = QApplication::desktop()->width();    //QMessageBox::information(nullptr, QString::number(cx),QString::number(cx));    //qreal scale = cx / 1920;    //if(scale > 0.7) scale = 1.0;    //qputenv("QT_SCALE_FACTOR", QString::number(scale).toLatin1());    //qputenv("QT_SCALE_FACTOR", "1.0");    //qputenv("QT_ENABLE_HIGHDPI_SCALING", "1");    //QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);    //qputenv("QT_AUTO_SCREEN_SCALE_FACTOR", "1.0");    QApplication a(argc, argv);    DEVMODE devmode;    //memset(&devmode, 0, sizeof (devmode));    //devmode.dmSize = sizeof(DEVMODE);    //devmode.dmDriverExtra = 0;    BOOL  Isgetdisplay = EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &devmode);    QMessageBox::information(nullptr, "QString::number(devmode.dmPelsWidth)",QString::number(devmode.dmPelsWidth));    Widget w;    w.show();    return a.exec();}