QT designer for QT learning

1. Create a project directory
   mkdir Calculator2

2. Enter the project directory , Launch Designer
   1） perform “designer” You can enter the designer
   2） In the new form interface, select “Dialog Without Buttons”// You can also select other parent windows

3. Finish the interface design in the designer
   1） from "Widget Box" Select control required , Drag and drop above the parent window
   LineEdit(3 individual )
   Label(1 individual )
   PushButton(1 individual )
   2） Set the properties of the parent window and each control
   –》 The parent window
   objectname( Object name )：CalculatorDialog
   notes ： In the future, the parent window object name will generate the same class name
   font( typeface ): Point size (20)
   windowTitle( Window title ): Calculator
   –》 Left operand
   objectname：m_editX
   alignment: level (AlignRight)
   –》 Right operands
   objectname：m_editY
   alignment: level (AlignRight)
   –》 Show results
   objectname：m_editZ
   alignment: level (AlignRight)
   readOnly： Check √
   –》 plus
   objectname：m_label
   text:"+"
   –》 Equal sign
   objectname：m_button
   enabled： Uncheck √ // Ban
   text:"="
   3） Resize and position
   –》 Method 1： The mouse to drag and drop
   –》 Method 2： keyboard ,ctrl/shift+ Direction key
   –》 Method 3： Set up geometry, Location (x,y)/ size ( Width , Height )
   –》 Method 4： Set the layout // recommend
   4） forms -> preview
   5） preservation (ctrl+s)
   Specify a filename ：CalculatorDialog.ui
   6） sign out , Finally, we get CalculatorDialog.ui file

4. take ".ui"(xml) transformation ".h"(C++) notes ： This step is not necessary , To understand the principle
   uic CalculatorDialog.ui -o ui_CalculatorDialog.h

   ui_CalculatorDialog.h The contents of the document :

   class Ui_CalculatorDialog{
         
   public:
      Graphical control declaration ;
     void setupUi(){
         // Interface initialization }
   };
   namespace Ui{
         
     class CalculatorDialog:public Ui_CalculatorDialog{
         
     };
   }
   Ui::CalculatorDialog<= Equivalent =>Ui_CalculatorDialog
   

   Use ui_CalculatorDialog.h Method ：
   Method 1： Inherit // Reference resources CalculatorDialog2
   class XX:public Ui::CalculatorDialog{
   // Inherit the code related to the interface and use it directly
   };
   Method 2： Combine // Reference resources CalculatorDialog2_2
   class XX{
   Constructors ():ui(new Ui::CalculatorDialog){}
   // adopt "ui->" Access and interface related code
   // visit 　ui In the pointer setupUi Also use ui->
   // Add destructors to this class
   Ui::CalculatorDialog* ui;
   };

5. code 、 structure 、 Testing and running
   Inheritance method ：
    
   CalculatorDialog.h

   #ifndef __CALCULATORDIALOG_H
   #define __CALCULATORDIALOG_H
   // Method 1 : Inherit 
   #include "ui_CalculatorDialog.h"
   
   // Inherit the parent window class , The current class is also the parent window 
   class CalculatorDialog
       :public QDialog,public Ui::CalculatorDialog{
         
       Q_OBJECT //moc
   public:
       // Constructors 
       CalculatorDialog(void);
   public slots:// Custom slot function 
       // The reset button is the slot function in the normal state 
       void enableButton(void);
       // Slot function for calculating and displaying results 
       void clickButton(void);
   };
   
   #endif//__CALCULATORDIALOG_H
   

   CalculatorDialog.cpp

   #include "CalculatorDialog.h"
   // Constructors 
   CalculatorDialog::CalculatorDialog(void){
         
       // Interface initialization 
       setupUi(this);
       // Set up the digital verifier : You can only enter content in digital form 
       m_editX->setValidator(
               new QDoubleValidator(this));
       m_editY->setValidator(
               new QDoubleValidator(this));
   
       // Signal and slot function connection 
       // When the left and right operand text changes , Sending signal textChanged
       connect(m_editX,SIGNAL(textChanged(QString)),
               this,SLOT(enableButton(void)));
       connect(m_editY,SIGNAL(textChanged(QString)),
               this,SLOT(enableButton(void)));
       // When the button is clicked , Sending signal clicked()
       connect(m_button,SIGNAL(clicked(void)),
               this,SLOT(clickButton(void)));
   }
   // Custom slot function 
   // The reset button is the slot function in the normal state 
   void CalculatorDialog::enableButton(void){
         
       bool bXOk,bYOk;
       //text(): Get text content (QString)
       //toDouble(): take QString transformation double, Convert to 
       // The result of work is saved in parameters 
       m_editX->text().toDouble(&bXOk);
       m_editY->text().toDouble(&bYOk);
       // If both the left and right operands have entered valid data , Then the resume button 
       // In the normal available state , Otherwise, set the disabled state 
       m_button->setEnabled(bXOk && bYOk);
   }
   // Slot function for calculating and displaying results 
   void CalculatorDialog::clickButton(void){
         
       // The result of the calculation is 
       double res = m_editX->text().toDouble() 
                  + m_editY->text().toDouble();
       // Convert the result to a string 
       //number(): take double Convert to QString
       QString str = QString::number(res);
       // Show calculation results 
       m_editZ->setText(str);
   }
   

   main.cpp

   #include "CalculatorDialog.h"
   #include <QApplication>
   
   int main(int argc,char** argv){
         
       QApplication app(argc,argv);
       CalculatorDialog dialog;
       dialog.show();
       return app.exec();
   }
   

   Combination method ：( If you can combine, you won't inherit )
   CalculatorDialog.h Add destructors and private member sub object pointers

   #ifndef __CALCULATORDIALOG_H
   #define __CALCULATORDIALOG_H
   // Method 1 : Combine 
   #include "ui_CalculatorDialog.h"
   
   // Inherit the parent window class , The current class is also the parent window 
   class CalculatorDialog:public QDialog{
         
       Q_OBJECT //moc
   public:
       // Constructors 
       CalculatorDialog(void);
       // Destructor 
       ~CalculatorDialog(void);
   public slots:// Custom slot function 
       // The reset button is the slot function in the normal state 
       void enableButton(void);
       // Slot function for calculating and displaying results 
       void clickButton(void);
   private:
       // adopt "ui->" Access interface related code 
       Ui::CalculatorDialog* ui;
   };
   
   #endif//__CALCULATORDIALOG_H
   

   CalculatorDialog.cpp

   #include "CalculatorDialog.h"
   // Constructors 
   CalculatorDialog::CalculatorDialog(void)
       :ui(new Ui::CalculatorDialog){
         
       // Interface initialization 
       ui->setupUi(this);
       // Set up the digital verifier : You can only enter content in digital form 
       ui->m_editX->setValidator(
               new QDoubleValidator(this));
       ui->m_editY->setValidator(
               new QDoubleValidator(this));
   
       // Signal and slot function connection 
       // When the left and right operand text changes , Sending signal textChanged
       connect(ui->m_editX,SIGNAL(textChanged(QString)),
               this,SLOT(enableButton(void)));
       connect(ui->m_editY,SIGNAL(textChanged(QString)),
               this,SLOT(enableButton(void)));
       // When the button is clicked , Sending signal clicked()
       connect(ui->m_button,SIGNAL(clicked(void)),
               this,SLOT(clickButton(void)));
   }
   CalculatorDialog::~CalculatorDialog(void){
         
       delete ui;
   }
   // Custom slot function 
   // The reset button is the slot function in the normal state 
   void CalculatorDialog::enableButton(void){
         
       bool bXOk,bYOk;
       //text(): Get text content (QString)
       //toDouble(): take QString transformation double, Convert to 
       // The result of work is saved in parameters 
       ui->m_editX->text().toDouble(&bXOk);
       ui->m_editY->text().toDouble(&bYOk);
       // If both the left and right operands have entered valid data , Then the resume button 
       // In the normal available state , Otherwise, set the disabled state 
       ui->m_button->setEnabled(bXOk && bYOk);
   }
   // Slot function for calculating and displaying results 
   void CalculatorDialog::clickButton(void){
         
       // The result of the calculation is 
       double res = ui->m_editX->text().toDouble() 
                  + ui->m_editY->text().toDouble();
       // Convert the result to a string 
       //number(): take double Convert to QString
       QString str = QString::number(res);
       // Show calculation results 
       ui->m_editZ->setText(str);
   }
   

   main.cpp unchanged