76.QT槽的机制

Posted 2020-10-27 喵小喵~

• 按钮点击获取文本框输入

   1 void Dialog::on_pushButton_clicked()
   2 {
   3     //获取文本输入
   4     QString vstr = ui->lineEdit->text();
   5 
   6     //判断是否转换成功
   7     bool isok;
   8     //转换
   9     int value = vstr.toInt(&isok);
  10     double area = value*value*PI;
  11     QString tempstr;
  12     ui->lineEdit_2->setText(tempstr.setNum(area));
  13 }

   

• 文本框内容改变执行的操作

  void Dialog::on_lineEdit_textChanged(const QString &arg1)
  {
      this->on_pushButton_clicked();
  }

   

手动实现QT的界面

• dialog.h添加按钮,文本框,标签等头文件

  1 #include <QDialog>
  2 #include <QPushButton>
  3 #include <QLineEdit>
  4 #include <QLabel>

   

• 在dialog.h类中添加按钮,文本框,标签的指针,并添加按钮的触发函数

   1 private:
   2     Ui::Dialog *ui;
   3     //图形控件
   4     QLabel *label1,*label2;
   5     QLineEdit *edit1,*edit2;
   6     QPushButton *button;
   7 
   8 //触发机制
   9 private slots:
  10     void showit();

   

• 在dialog.cpp中初始化,并创建布局
• 创建布局头文件

  1 #include "QGridLayout"//布局

   

• 初始化

   1 //加上this显示在当前窗口
   2     button = new QPushButton(this);
   3     button->setText(tr("计算"));
   4     //button->show();
   5     button->resize(100,100);
   6 
   7     edit1 = new QLineEdit(this);
   8 
   9     edit2 = new QLineEdit(this);
  10 
  11     label1 = new QLabel(this);
  12 
  13     label1->setText("输入半径:");
  14 
  15     label2 = new QLabel(this);
  16 
  17     label2->setText("输出面积:");

   

• 创建布局

  1  //网格布局
  2     QGridLayout *mylayout = new QGridLayout(this);
  3     mylayout->addWidget(label1,0,0);
  4     mylayout->addWidget(label2,1,0);
  5     mylayout->addWidget(edit1,0,1);
  6     mylayout->addWidget(edit2,1,1);
  7     mylayout->addWidget(button,2,0);

   

• 关联按钮的函数或者文本框变化的函数

  1  //clicked触发         关联
  2     connect(button,SIGNAL(clicked(bool)),this,SLOT(showit()));
  3     connect(edit1,SIGNAL(textChanged(QString)),this,SLOT(showit()));

   

• 按钮点击函数实现

   1 void Dialog::showit()
   2 {
   3     //获取文本输入
   4     QString vstr = edit1->text();
   5 
   6     //判断是否转换成功
   7     bool isok;
   8     //转换
   9     int value = vstr.toInt(&isok);
  10     double area = value*value*PI;
  11     QString tempstr;
  12     edit2->setText(tempstr.setNum(area));
  13 }

   

---

完整代码:

• dialog.h

   1 #ifndef DIALOG_H
   2 #define DIALOG_H
   3 
   4 #include <QDialog>
   5 #include <QPushButton>
   6 #include <QLineEdit>
   7 #include <QLabel>
   8 
   9 namespace Ui {
  10 class Dialog;
  11 }
  12 
  13 class Dialog : public QDialog
  14 {
  15     Q_OBJECT
  16 
  17 public:
  18     explicit Dialog(QWidget *parent = 0);
  19     ~Dialog();
  20 
  21 private:
  22     Ui::Dialog *ui;
  23     //图形控件
  24     QLabel *label1,*label2;
  25     QLineEdit *edit1,*edit2;
  26     QPushButton *button;
  27 
  28 //触发机制
  29 private slots:
  30     void showit();
  31 };
  32 
  33 #endif // DIALOG_H

   

• dialog.cpp

   1 #include "dialog.h"
   2 #include "ui_dialog.h"
   3 #include "QGridLayout"//布局
   4 #define PI 3.14159
   5 
   6 Dialog::Dialog(QWidget *parent) :
   7     QDialog(parent),
   8     ui(new Ui::Dialog)
   9 {
  10     //加上this显示在当前窗口
  11     button = new QPushButton(this);
  12     button->setText(tr("计算"));
  13     //button->show();
  14     button->resize(100,100);
  15 
  16     edit1 = new QLineEdit(this);
  17 
  18     edit2 = new QLineEdit(this);
  19 
  20     label1 = new QLabel(this);
  21 
  22     label1->setText("输入半径:");
  23 
  24     label2 = new QLabel(this);
  25 
  26     label2->setText("输出面积:");
  27 
  28     //网格布局
  29     QGridLayout *mylayout = new QGridLayout(this);
  30     mylayout->addWidget(label1,0,0);
  31     mylayout->addWidget(label2,1,0);
  32     mylayout->addWidget(edit1,0,1);
  33     mylayout->addWidget(edit2,1,1);
  34     mylayout->addWidget(button,2,0);
  35 
  36     //clicked触发         关联
  37     connect(button,SIGNAL(clicked(bool)),this,SLOT(showit()));
  38     connect(edit1,SIGNAL(textChanged(QString)),this,SLOT(showit()));
  39     ui->setupUi(this);
  40 }
  41 
  42 Dialog::~Dialog()
  43 {
  44     delete ui;
  45 }
  46 
  47 void Dialog::showit()
  48 {
  49     //获取文本输入
  50     QString vstr = edit1->text();
  51 
  52     //判断是否转换成功
  53     bool isok;
  54     //转换
  55     int value = vstr.toInt(&isok);
  56     double area = value*value*PI;
  57     QString tempstr;
  58     edit2->setText(tempstr.setNum(area));
  59 }

   

• main.cpp

   1 #include "dialog.h"
   2 #include <QApplication>
   3 
   4 int main(int argc, char *argv[])
   5 {
   6     QApplication a(argc, argv);
   7     Dialog w;
   8     w.show();
   9 
  10     return a.exec();
  11 }