QT5笔记：17. QComboBox和QPlainTextEdit

• 例子

  #include "widget.h"
  #include "ui_widget.h"
  
  #include <QTextBlock>
  
  Widget::Widget(QWidget *parent)
      : QWidget(parent)
      , ui(new Ui::Widget)
  {
      ui->setupUi(this);
  }
  
  Widget::~Widget()
  {
      delete ui;
  }
  
  /**
   * @brief Widget::on_btnInit_clicked
   * @note 为ComboBox设置item，并为item设置图标
   */
  void Widget::on_btnInit_clicked()
  {
      QIcon icon(":/images/images/aim.ico");//获取资源文件中的图标
      ui->comboBox_2->clear();
      for (int i = 0; i < 20; i ++) {
          ui->comboBox_2->addItem(icon,QString::asprintf("item %d",i));//添加项
      }
  }
  
  void Widget::on_btnClear_clicked()
  {
      ui->comboBox_2->clear();
  }
  
  /**
   * @brief Widget::on_pushButton_3_clicked
   * @note 设置有用户数据的内容，类似于为每一项设置一个Tag
   */
  void Widget::on_pushButton_3_clicked()
  {
      QIcon icon(":/images/images/UNIT.ICO");
      ui->comboBox->clear();
      QMap<QString,int> map;
      map.insert("北京",10);
      map.insert("上海",20);
      map.insert("天津",30);
      foreach(auto str ,map.keys()){
          ui->comboBox->addItem(icon, str, map.value(str));
      }
  }
  
  void Widget::on_checkBox_clicked(bool checked)
  {
      ui->comboBox_2->setEditable(checked);
  }
  
  void Widget::on_comboBox_2_currentIndexChanged(const QString &arg1)
  {
      if(!arg1.isEmpty())ui->plainTextEdit->appendPlainText(arg1);
  }
  
  void Widget::on_comboBox_currentIndexChanged(const QString &arg1)
  {
      if(!arg1.isEmpty())
      {
          QString data = ui->comboBox->currentData().toString();
          if(!arg1.isEmpty())ui->plainTextEdit->appendPlainText(arg1+":"+data);
      }
  }
  
  void Widget::on_checkBox_2_clicked(bool checked)
  {
      ui->plainTextEdit->setReadOnly(checked);
  }
  
  void Widget::on_pushButton_5_clicked()
  {
      ui->plainTextEdit->clear();
  }
  
  /**
   * @brief Widget::on_pushButton_4_clicked
   * @note 将文本框中的内容设置为ComboBox的选择项
   */
  void Widget::on_pushButton_4_clicked()
  {
      QIcon icon(":/images/images/aim.ico");//设置图标
      ui->comboBox_2->clear();
      QTextDocument *doc = ui->plainTextEdit->document();//获取文本框的内容对象
      int blockCount = doc->blockCount();//获取文本框中的块数量（按照回车分块）
      for (int i = 0;i < blockCount; i ++) {
          QTextBlock text = doc->findBlockByNumber(i);//获取块对象
          ui->comboBox_2->addItem(icon, text.text());//将块的文本添加为ComboBox的选择项
      }
  }
  

• 界面