Qt5学习笔记（控件）

上面的程序仅仅可以显示一个　大概　的界面，对其进行单击等操作，界面仅有一些简单的反应，对应的程序不能得知界面有什么改变（是否进行单击选择，文本框中是否有文字输入）

下面对程序进行完善。

T05Controls.pro

 HEADERS += \
     MyWidget.h

 SOURCES += \
     MyWidget.cpp

 QT += widgets gui

 CONFIG += C++

MyWidget.h

 #ifndef MYWIDGET_H
 #define MYWIDGET_H

 #include <QWidget>
 #include <QTextEdit>
 class MyWidget : public QWidget
 {
     Q_OBJECT
 public:
     explicit MyWidget(QWidget *parent = nullptr);

     QTextEdit* _edit; //保存到成员变量里面

 signals:

 public slots:
     void slotComboBoxIndexChanged(const QString&); //槽 函数
 };

 #endif // MYWIDGET_H

MyWidget.cpp

 #include "MyWidget.h"
 #include <QApplication>
 #include <QLabel>  //display ststic text, or image
 #include <QPushButton>
 #include <QLineEdit>  //single line

 #include <QComboBox>
 #include <QCheckBox>
 #include <QRadioButton>
 #include <QTextEdit> //multi lines, rich text
 #include <QTextBrowser>  //readonly textedit
 #include <QGroupBox>
 #include <QSlider>   //模拟方式显示数值
 #include <QSpinBox>  //数字
 #include <QDateEdit>
 #include <QTimeEdit>
 #include <QDateTimeEdit>
 #include <QTabWidget> //不介绍，不算控件

 #include <QCompleter>
 #include <QVBoxLayout>
 #include <QDebug>
 #include <QHBoxLayout>
 #include <QLCDNumber>
 MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
 {
     QVBoxLayout* lay = new QVBoxLayout(this);  //this ,MyWidget,不用写this->setLayout();
     QLabel* label;
     QComboBox* combo;
     QPushButton* button;
     QRadioButton* radio;
     QTextEdit* edit;
     QGroupBox* group;

     lay->addWidget(label = new QLabel("<font color = red>Label</font>")); //支持html,静态文本

     lay->addWidget(button = new QPushButton("Button"));
     button->setStyleSheet("QPushButton {font:bold 16px; color:green}");

     lay->addWidget(radio = new QRadioButton("Radio"));
     radio->setStyleSheet("QRadioButton {font:bold 16px; color:blue}");
     connect(radio, &QRadioButton::clicked,[](bool v){
         qDebug() << v;
     });

     lay->addWidget(new QCheckBox("check box"));

     lay->addWidget(combo = new QComboBox());
     combo->addItem("Select item1");
     combo->addItem("Select item2");
     combo->addItem("nizhipeng");
     combo->addItem("jackson");
     combo->setEditable(true); //下拉框可编辑
     connect(combo, SIGNAL(currentIndexChanged(QString)), this, SLOT(slotComboBoxIndexChanged(QString)));

     combo->setCompleter(new QCompleter(QStringList() << "nizhipeng" << "jackson" ));

     lay->addWidget(edit = new QTextEdit);
     edit->setText("<table border=1><tr><th>head1</th><th>head2</th></tr>"
                   "<tr><td>value1</td><td>value2</td></tr>"
                   "<tr><td>value3</td><td>value4</td></tr>"
                   "</table><br>"
                   "<img src=../doge.jpg></img>");
     _edit = edit;
     connect(edit, &QTextEdit::textChanged, [&](){
        //(QTextEdit*) edit = this->sender();
        qDebug() << _edit->toPlainText();
     });
     //edit->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded); 不写也有滚动条
     //edit->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);//将水平滚动条取消

     lay->addWidget(group = new QGroupBox("Some items"));//lay->addWidget(group = new QGroupBox);
     QHBoxLayout* hBoxlay;
     group->setLayout(hBoxlay = new QHBoxLayout);
     hBoxlay->addWidget(new QPushButton("aaa"));
     hBoxlay->addWidget(new QPushButton("aaa"));

     QSlider* slider;
     QSpinBox* spinBox;

     lay->addWidget(slider = new QSlider(Qt::Horizontal));
     slider->setMaximum();
     slider->setMinimum();
     //slider->value();

     lay->addWidget(spinBox = new QSpinBox);
     spinBox->setMaximum();
     spinBox->setMinimum();

     connect(slider,SIGNAL(valueChanged(int)), spinBox, SLOT(setValue(int)));//互相影响
     connect(spinBox,SIGNAL(valueChanged(int)), slider, SLOT(setValue(int)));

     lay->addWidget(new QDateTimeEdit);

     QLCDNumber* lcd;
     lay->addWidget(lcd = new QLCDNumber());
     lcd->display();
     //lcd->setMode(QLCDNumber::Hex); //16进制
     lcd->setSegmentStyle(QLCDNumber::Flat);//数字更清晰

 }

 //槽函数
 void MyWidget::slotComboBoxIndexChanged(const QString &str)
 {
     qDebug() << "slotComboBoxIndexChanged" << str;
 }

 int main(int argc, char** argv)
 {
     QApplication app(argc, argv);

     MyWidget w;
     w.show();

     return app.exec();
 }

下面详细的介绍以上完整的程序：

     QLabel* label;
     lay->addWidget(label = new QLabel("<font color = red>Label</font>")); //支持html,静态文本

 QPushButton* button;
 lay->addWidget(button = new QPushButton("Button"));
 button->setStyleSheet("QPushButton {font:bold 16px; color:green}");

如果不需要特殊设置颜色，只需要写成　lay->addWidget(　new QPushButton("Button")　);

 QRadioButton* radio;
 lay->addWidget(radio = new QRadioButton("Radio"));
 radio->setStyleSheet("QRadioButton {font:bold 16px; color:blue}");//设置颜色
 connect(radio, &QRadioButton::clicked,[](bool v){
         qDebug() << v;
 });

选择返回true,不选择返回false。

lay->addWidget(new QCheckBox("check box"));

仅仅显示

     QComboBox* combo;
     lay->addWidget(combo = new QComboBox());
     combo->addItem("Select item1");
     combo->addItem("Select item2");
     combo->addItem("nizhipeng");
     combo->addItem("jackson");
     combo->setEditable(true); //下拉框可编辑
     connect(combo, SIGNAL(currentIndexChanged(QString)), this,SLOT(slotComboBoxIndexChanged(QString)));

     combo->setCompleter(new QCompleter(QStringList() << "nizhipeng" << "jackson" ));//补全提示

设置下拉框中内容，获得改变后的值，设置补全提示。

其中槽函数为：

 //槽函数
 void MyWidget::slotComboBoxIndexChanged(const QString &str)
 {
     qDebug() << "slotComboBoxIndexChanged" << str;
 }

输出为 "slotComboBoxIndexChanged" << str;与上图一致。

根据下拉框中选择的内容，返回对应的内容。

     QTextEdit* edit;
     lay->addWidget(edit = new QTextEdit);
     edit->setText("<table border=1><tr><th>head1</th><th>head2</th></tr>"
                   "<tr><td>value1</td><td>value2</td></tr>"
                   "<tr><td>value3</td><td>value4</td></tr>"
                   "</table><br>"
                   "<img src=../doge.jpg></img>");
     _edit = edit;
     connect(edit, &QTextEdit::textChanged, [&](){
        //(QTextEdit*) edit = this->sender();
        qDebug() << _edit->toPlainText();
     });

可以输入的文本框。

     QGroupBox* group;
     lay->addWidget(group = new QGroupBox("Some items"));//lay->addWidget(group = new QGroupBox);
     QHBoxLayout* hBoxlay;
     group->setLayout(hBoxlay = new QHBoxLayout);
     hBoxlay->addWidget(new QPushButton("aaa"));
     hBoxlay->addWidget(new QPushButton("aaa"));

     QSlider* slider;
     QSpinBox* spinBox;

     lay->addWidget(slider = new QSlider(Qt::Horizontal));
     slider->setMaximum();
     slider->setMinimum();
     //slider->value();

     lay->addWidget(spinBox = new QSpinBox);
     spinBox->setMaximum();
     spinBox->setMinimum();

     connect(slider,SIGNAL(valueChanged(int)), spinBox, SLOT(setValue(int)));//互相影响
     connect(spinBox,SIGNAL(valueChanged(int)), slider, SLOT(setValue(int)));

上下的值互相对应，一个改变另一个也改变。

lay->addWidget(new QDateTimeEdit);

     QLCDNumber* lcd;
     lay->addWidget(lcd = new QLCDNumber());
     lcd->display();
     //lcd->setMode(QLCDNumber::Hex); //16进制
     lcd->setSegmentStyle(QLCDNumber::Flat);//数字更清晰