Qt-Qt之QDesktopWidget的使用说明(屏幕个数、屏幕分辩率、屏幕PDI、设置屏幕分辩率)

 相关资料：

https://download.csdn.net/download/zhujianqiangqq/86539703 CSDN代码包下载
https://blog.csdn.net/Superman___007/article/details/109450184
https://blog.csdn.net/chenyijun/article/details/104749632/

实例代码：

.pro

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

LIBS += -luser32
LIBS += -lgdi32

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

main.cpp

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

mainwindow.h

// 相关资料：
// https://blog.csdn.net/Superman___007/article/details/109450184
// https://blog.csdn.net/chenyijun/article/details/104749632/

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <Windows.h>//这个一定要添加，不然会报"No Target Architecture" 错误
#include <WinUser.h>
#include <wingdi.h>

#include <QMainWindow>
// 桌面对象引入
#include <QDesktopWidget>
#include <QDebug>
#include <QApplication>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_pushButton_4_clicked();

    void on_pushButton_3_clicked();

    void on_pushButton_2_clicked();

    void on_pushButton_clicked();

    void on_pushButton_5_clicked();

    void on_pushButton_7_clicked();

    void on_pushButton_6_clicked();

    void on_pushButton_8_clicked();

private:
    int GetTaskbarInfo();
    void GetTaskbarInfo(int &width, int &height, int &pos);
    Ui::MainWindow *ui;
    // 桌面对象
    QDesktopWidget *m_pDeskdop;

};
#endif // MAINWINDOW_H

mainwindow.cpp

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

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    // 设置标题
    setWindowTitle(QStringLiteral("Qt之QDesktopWidget的使用说明(屏幕个数、屏幕分辩率、屏幕PDI、设置屏幕分辩率)"));
    // 设置界面大小
    resize(600, 300);
    // 为了测试，先把界面放在左100，顶200位置上。
    move(100, 200);
    // 桌面操作作
    m_pDeskdop = QApplication::desktop();
    move((m_pDeskdop->width() - this->width())/2, (m_pDeskdop->height() - this->height())/2);
}

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

void MainWindow::on_pushButton_4_clicked()
{
    ui->textEdit->append(QString::number(m_pDeskdop->screenCount()));
}

void MainWindow::on_pushButton_3_clicked()
{
    ui->textEdit->append(QString::number(m_pDeskdop->numScreens()));
}

void MainWindow::on_pushButton_2_clicked()
{
    ui->textEdit->append(QString::number(m_pDeskdop->screenNumber()));
}

void MainWindow::on_pushButton_clicked()
{
    ui->textEdit->append(QString::number(m_pDeskdop->primaryScreen()));
}

void MainWindow::on_pushButton_5_clicked()
{
    ui->textEdit->append(QString::number(m_pDeskdop->screen()->width()));
    ui->textEdit->append(QString::number(m_pDeskdop->screen()->height()));
}

int MainWindow::GetTaskbarInfo()
{
    QRect deskRect = m_pDeskdop->availableGeometry();
    QRect screenRect = m_pDeskdop->screenGeometry();

    int nLocation = 1;
    if (deskRect.bottom() != screenRect.bottom()) //任务栏在下
    {
        nLocation = 1;
    }
    else if (deskRect.top() != screenRect.top()) //任务栏在上
    {
        nLocation = 2;
    }
    else if (deskRect.left() != screenRect.left()) //任务栏在左
    {
        nLocation = 3;
    }
    else if (deskRect.right() != screenRect.right()) //任务栏在右
    {
        nLocation = 4;
    }
    else    //任务栏处于自动隐藏状态
    {
        nLocation = 5;
    }

    return nLocation;
}

void MainWindow::GetTaskbarInfo(int &width, int &height, int &pos)
{
    // 得到被定义的系统数据或者系统配置信息
    int wx = GetSystemMetrics(SM_CXSCREEN);// 主显示器屏幕的宽度，以像素为单位。 这是通过调用GetDeviceCaps获得的相同值
    int wy = GetSystemMetrics(SM_CYSCREEN);// 主显示器屏幕的高度，以像素为单位。

    RECT rtWorkArea;
    // 函数查询或设置系统级参数
    SystemParametersInfo(SPI_GETWORKAREA, 0, &rtWorkArea, 0);// 工作区是指屏幕上不被系统任务条或应用程序桌面工具遮盖的部分
    //1.任务栏停靠在左边情况
    if (0 != rtWorkArea.left)
    {
        width = wx - rtWorkArea.right;
        height = wy;
        pos = 0;
        return;
    }
    //2.任务栏停靠在上边情况
    if(0!=rtWorkArea.top)
    {
        width = wx;
        height = wy - rtWorkArea.bottom;
        pos = 1;
        return;
    }
    //3.任务栏停靠在右边情况
    if(0==rtWorkArea.left && wx!=rtWorkArea.right)
    {
        width = wx - rtWorkArea.right;
        height = wy;
        pos = 2;
        return;
    }
    //4.任务栏停靠在下边情况
    if(0==rtWorkArea.top && wy!=rtWorkArea.bottom)
    {
        width = wx;
        height = wy - rtWorkArea.bottom;
        pos = 3;
        return;
    }
    //5.任务栏自动隐藏的情况，这样其宽高都是0
    if(0==rtWorkArea.left && 0==rtWorkArea.top
    && wx==rtWorkArea.right && wy==rtWorkArea.bottom)
    {
        width = 0;
        height =0;
        pos = 4;
        return;
    }
}

void MainWindow::on_pushButton_7_clicked()
{
    ui->textEdit->append(QString::number(GetTaskbarInfo()));
}

void MainWindow::on_pushButton_6_clicked()
{
    int w, h, pos;
    GetTaskbarInfo(w, h, pos);
    ui->textEdit->append(QStringLiteral("任务栏 宽：%1 高：%2 位置：%3").arg(w).arg(h).arg(pos));
}

void MainWindow::on_pushButton_8_clicked()
{
    int nScreenWidth = ::GetSystemMetrics(SM_CXSCREEN);
    int nScreenHeight = ::GetSystemMetrics(SM_CYSCREEN);

    HWND hwd = ::GetDesktopWindow();
    HDC hdc = ::GetDC(hwd);
    int width = GetDeviceCaps(hdc, DESKTOPHORZRES);
    int height = GetDeviceCaps(hdc, DESKTOPVERTRES);

    double dWidth = (double)width;
    double dScreenWidth = (double)nScreenWidth;
    double scale = dWidth / dScreenWidth;

    ui->textEdit->append(QStringLiteral("nScreenWidth：%1 nScreenHeight：%2 width：%3 height:%4 scale:%5")
                         .arg(nScreenWidth).arg(nScreenHeight)
                         .arg(width).arg(height)
                         .arg(scale));
}

mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>728</width>
    <height>374</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QHBoxLayout" name="horizontalLayout">
    <item>
     <layout class="QVBoxLayout" name="verticalLayout">
      <item>
       <widget class="QTextEdit" name="textEdit"/>
      </item>
      <item>
       <layout class="QHBoxLayout" name="horizontalLayout_2">
        <item>
         <widget class="QPushButton" name="pushButton_7">
          <property name="text">
           <string>获取系统的任务栏位置以及高度</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton_6">
          <property name="text">
           <string>获取系统任务栏位置宽高信息的方法</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton_8">
          <property name="text">
           <string>设备的物理分辩率</string>
          </property>
         </widget>
        </item>
       </layout>
      </item>
      <item>
       <layout class="QHBoxLayout" name="horizontalLayout_3">
        <item>
         <widget class="QPushButton" name="pushButton_4">
          <property name="text">
           <string>获得屏幕数量</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton_3">
          <property name="text">
           <string>获得屏幕数量2</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton_2">
          <property name="text">
           <string>屏幕编号</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton">
          <property name="text">
           <string>主屏幕编号</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton_5">
          <property name="text">
           <string>屏幕宽高</string>
          </property>
         </widget>
        </item>
       </layout>
      </item>
     </layout>
    </item>
   </layout>
  </widget>
 </widget>
 <resources/>
 <connections/>
</ui>

 

 

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