Qt初学者指南

╰半夏微凉° 2022-04-16 04:17 421阅读 0赞

# 基本概念 #

1.  信号和槽

QObject::connect( &quit, SIGNAL(clicked()), &a, SLOT(quit()) );

在两个Qt对象（直接或间接继承QObject对象的对象）中建立了一种单向的连接。每一个Qt对象都有signals（发送消息）和slots（接收消息）。所有窗口部件都是Qt对象。它们继承QWidget，而QWidget继承QObject。  
这里quit的clicked()**信号**和a的quit()**槽**连接起来了，所以当这个按钮被按下的时候，这个程序就退出了。

# 学习资料 #

## QT教程第三章 ##

//#include "ex_ch1.h"
    //#include <QtWidgets/QApplication>
    #include <qpushbutton.h>
    #include <qfont.h>
    #include <qboxlayout.h>
    #include<qapplication.h>
    
    
    int main(int argc, char *argv[])
    {
    	QApplication a(argc, argv);
    	//ex_ch1 w;
    	//w.show();
    	QWidget window;
    	window.resize(200,120);
    	QVBoxLayout layout;
    	QPushButton quit("Quit",&window);
    	quit.setFont(QFont("Times",18,QFont::Bold));
    	QObject::connect(&quit,SIGNAL(clicked()),&a,SLOT(quit()));
    	layout.addWidget(&quit);
    	window.setLayout(&layout);
    	window.show();
    	return a.exec();
    }

### 效果： ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N0eTk0NQ_size_16_color_FFFFFF_t_70]

# Qt 第四章使用窗口插件 #

#include<qapplication.h>
    #include<qpushbutton.h>
    #include<qfont.h>
    
    class MyWidget: public QWidget
    {
    public:
    	MyWidget(QWidget *parent=0, const char *name=0);
    };
    
    
    MyWidget::MyWidget(QWidget *parent, const char *name)
    {
    	setMinimumSize(200, 120);
    	setMaximumSize(400, 1200);
    	QPushButton *quit = new QPushButton("Quit", this);
    	//QPushButton *quit = new QPushButton(QIcon("Quit"), this, "quit");
    	quit->setGeometry(62, 40, 75, 30);
    	quit->setFont(QFont("Times", 18, QFont::Bold));
    	QPushButton *ui = new QPushButton("UI", this);
    	ui->setGeometry(100, 100, 100, 100);
    	ui->setFont(QFont("Times", 20, QFont::Bold));
    	connect(quit, SIGNAL(clicked()), quit, SLOT(quit()));
    }
    
    int main(int argc, char *argv[])
    {
    	QApplication a(argc, argv);
    	//ex_ch4 w;
    	//w.show();
    	MyWidget w;
    	w.setGeometry(100, 100, 200, 120);
    	w.show();
    	return a.exec();
    }

### 展示 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N0eTk0NQ_size_16_color_FFFFFF_t_70 1]

# 第五章：组装积木 #

#include <qapplication.h>
    #include <qpushbutton.h>
    #include <qslider.h>
    #include <qlcdnumber.h>
    #include <qfont.h>
    
    #include <QVBoxLayout>
    
    int main( int argc, char **argv )
    {
        QApplication a( argc, argv );
    
        QWidget window;
        
        QPushButton *quit = new QPushButton( "Quit", &window );
        quit->setFont( QFont( "Times", 18, QFont::Bold ) );
    
        QObject::connect( quit, SIGNAL(clicked()), qApp, SLOT(quit()) );
    
        QLCDNumber *lcd  = new QLCDNumber( 2, &window );
    
        QSlider * slider = new QSlider( Qt::Horizontal, &window );
        slider->setRange( 0, 99 );
        slider->setValue( 0 );
    
        QObject::connect( slider, SIGNAL(valueChanged(int)), lcd, SLOT(display(int)) );
        
        QVBoxLayout layout;
        layout.addWidget(quit);
        layout.addWidget(lcd);
        layout.addWidget(slider);
        
        window.setLayout(&layout);
        window.show();
        
        return a.exec();
    }

# 第六章 组装丰富的积木 #

#include<qapplication.h>
    #include<qpushbutton.h>
    #include<qslider.h>
    #include<qlcdnumber.h>
    #include<qfont.h>
    #include<qboxlayout.h>
    #include<qgridlayout.h>
    
    class LCDRange:public QWidget
    {
    public:
    	LCDRange(QWidget *parent=0, Qt::WindowFlags f=0);
    };
    
    LCDRange::LCDRange(QWidget *parent, Qt::WindowFlags f):QWidget(parent, f)
    {
    	QLCDNumber *lcd = new QLCDNumber(2);
    	QSlider *slider = new QSlider(Qt::Horizontal);
    	slider->setRange(0, 99);
    	slider->setValue(0);
    	connect(slider, SIGNAL(valueChanged(int)), lcd, SLOT(display(int)));
    
    	QVBoxLayout* layout = new QVBoxLayout;
    	layout->addWidget(lcd);
    	layout->addWidget(slider);
    	setLayout(layout);
    }
    
    
    class MyWidget:public QWidget
    {
    public:
    	MyWidget(QWidget *parent=0, Qt::WindowFlags f=0);
    };
    
    MyWidget::MyWidget(QWidget *parent, Qt::WindowFlags f):QWidget(parent, f)
    {
    	QVBoxLayout *layout = new QVBoxLayout;
    	QPushButton *quit = new QPushButton("Quit");
    	quit->setFont(QFont("Times", 18, QFont::Bold));
    	connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
    	QGridLayout *grid = new QGridLayout;
    	for (int r = 0; r < 4; r++)
    	{
    		for (int c = 0; c < 5; c++)
    		{
    			grid->addWidget(new LCDRange(this), r, c);
    		}
    	}
    	layout->addWidget(quit);
    	layout->addLayout(grid);
    	setLayout(layout);
    }
    
    
    int main(int argc, char **argv)
    {
    	QApplication a(argc, argv);
    	MyWidget w;
    	w.resize(600, 100);
    	w.show();
    	return a.exec();
    }

### 展示 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N0eTk0NQ_size_16_color_FFFFFF_t_70 2]

# 第七章：一个事物领导另一个 #

**main.cpp**

//#include "ex_ch6.h"
    //#include <QtWidgets/QApplication>
    
    #include<qapplication.h>
    #include<qpushbutton.h>
    #include<qslider.h>
    #include<qlcdnumber.h>
    #include<qfont.h>
    #include<qboxlayout.h>
    #include<qgridlayout.h>
    #include<lcdrange.h>
    
    
    class MyWidget:public QWidget
    {
    public:
    	MyWidget(QWidget *parent=0, Qt::WindowFlags f=0);
    };
    
    MyWidget::MyWidget(QWidget *parent, Qt::WindowFlags f):QWidget(parent, f)
    {
    	QVBoxLayout *layout = new QVBoxLayout;
    	QPushButton *quit = new QPushButton("Quit");
    	quit->setFont(QFont("Times", 18, QFont::Bold));
    	connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));
    	QGridLayout *grid = new QGridLayout;
    	LCDRange *previous = 0;
    	for (int r = 0; r < 4; r++)
    	{
    		for (int c = 0; c < 5; c++)
    		{
    			LCDRange *lr = new LCDRange(this);
    			grid->addWidget(lr, r, c);
    			if (previous)
    			{
    				connect(lr, SIGNAL(valueChanged(int)), previous, SLOT(setValue(int)));
    			}
    			previous = lr;
    		}
    	}
    	layout->addWidget(quit);
    	layout->addLayout(grid);
    	setLayout(layout);
    }
    
    
    int main(int argc, char **argv)
    {
    	QApplication a(argc, argv);
    	MyWidget w;
    	w.resize(600, 100);
    	w.show();
    	return a.exec();
    }

**lcdrange.h**

#ifndef LCDRANGE_H
    #define LCDRANGE_H
    
    #include<qboxlayout.h>
    #include<qwidget.h>
    #include<qslider.h>
    #include<qlcdnumber.h>
    
    class QSlider;
    
    class LCDRange:public QWidget
    {
    	Q_OBJECT
    public:
    	LCDRange(QWidget *parent=0, Qt::WindowFlags=0);
    	int value() const;
    
    public slots:
    	void setValue(int);
    
    signals:
    	void valueChanged(int);
    
    private:
    	QSlider *slider;
    
    };
    
    #endif

**lcdrange.cpp**

#include "lcdrange.h"
    
    
    LCDRange::LCDRange(QWidget *parent, Qt::WindowFlags f):QWidget(parent, f)
    {
    	QLCDNumber *lcd = new QLCDNumber(2);
    	QSlider *slider = new QSlider(Qt::Horizontal);
    	slider->setRange(0, 99);
    	slider->setValue(0);
    	connect(slider, SIGNAL(valueChanged(int)), lcd, SLOT(display(int)));
    	QVBoxLayout *layout = new QVBoxLayout;
    	layout->addWidget(lcd);
    	layout->addWidget(slider);
    	setLayout(layout);
    }
    
    int LCDRange::value() const
    {
    	return slider->value();
    }
    
    void LCDRange::setValue(int value)
    {
    	slider->setValue(value);
    }

### 效果 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N0eTk0NQ_size_16_color_FFFFFF_t_70 3]

# 第八章：准备战斗 #

# 几个需要注意的问题 #

1.  在qt5.x中`#include <qvbox.h>`变成了`#include <qboxlayout.h>`

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