First day of QT study

( One )Qt relevant

1. Can be in bash Direct execution
   1）assistant(Qt assistant )//Qt Help book
   2）qmake(Qt Builder )
   3）designer(Qt The designer )// Graphical editing tools
   4）uic(Qt Interface converter )// take ui File grab and replace with c++ Code
   5）moc(Qt Metaobject compiler )// take qt Syntax extensions revert to standard C++
   6）rcc(Qt Resource compiler )// Compile resources such as pictures into C++ Code
   7）qtcreator(Qt Creator )//Qt The inheritance development environment of (IDE)

2. Qt Help manual use (assistant)
   1） First read the first sentence , Understand the functions of this class , If you don't understand , Sure “more” link , Jump to specify the location .
   2） Move on to the header file 、 Build options (QT+=widgets)、 Inheritance relationships
   3）Properties( Member variables )
   4）Public Functions( Public member functions )
   5）Reimplemented Public Functions( Reimplemented public virtual functions )
   6）Public Slots( Slot function )//Qt Grammar extension
   7）Signals( The signal )//Qt Grammar extension
   8）Static Public Members( Static public members )
   9）Reimplemented Protected Functions( Protected virtual functions )
   10）Detailed Description( Detailed instructions )

( Two ) The first program

1. Create a project directory
   mkdir Hello
   notes ： Every Qt Programs should be placed in separate directories
2. Enter the project directory , Write source code (cpp)
   cd Hello
   vi main.cpp
3. perform “qmake -project”, Generate platform independent project files (Hello.pro)
   notes ： You need to add qmake Build options
   QT += widgets // Load in the future widgets Modules correspond to header files and library files
4. perform “qmake”, According to the previous engineering document , Generate compilation links Makefile
5. perform “make”, according to Makefile Complete compilation and linking
6. test run “./Hello”
   notes ： If the code has syntax errors , After modifying the code , Re execution "make" that will do , front 3、4 There is no need to repeat .

   #include <QApplication>
   #include <QLabel>
   int main(int argc,char** argv){
         
       // establish Qt Applications 
       QApplication app(argc,argv);
       
       // Create a label control ( Components \ parts \ artifacts ) 
       QLabel label("Hello Qt!");
       // Show labels 
       label.show();
   
       // Let the application enter the event loop 
       return app.exec();
   }
   

( 3、 ... and )Qt character string

1. Common codes
   1）linux System default ：utf-8
   2）windows System default ：gbk/gb2312/gb18030
   3）Qt Of QSring String default ：unicode(utf-16)

2. Code conversion class (QTextCodec)
   // establish GBK Coding object
   QTextCodec *codec = QTextCodec::codecForName(“GBK”);
   // take GBK Convert Chinese string to unicode code
   QString string = codec->toUnicode(“GBK Chinese string ”);
    
   notes ： If the structure QString String object , If there is no explicit transcoding , It's using utf-8 Of " Constant string " The default is to call fromUtf8 Automatically convert it to Qt For internal use unicode code . Of course , If not utf-8 String , It will also call by default fromUtf8, It's just a mess .

( Four ) The parent window ( Container window )

1. The parent window can be used to manage the entire interface , When creating a control, you can specify to dock on the parent window , If no parent window is specified, it floats outside to form a separate form .

2. Common parent window classes
   1）QWidget // Graphic control base class
   2）QMainWindow // main window (QWidget Subclass )
   3）QDialog // Dialog box (QWidget Subclass )

3. QWidget Two common member functions in class
   1） Resize the parent window or control
   void resize(int w,int h);
   2） Adjust the position of the parent window or control
   void move(int x,int y);

   #include <QApplication>
   #include <QLabel>
   #include <QPushButton>
   #include <QWidget>
   #include <QDialog>
   #include <QMainWindow>
   #include <QFont>// typeface 
   int main(int argc,char** argv){
         
       QApplication app(argc,argv);
       // Create a parent window object 
       //QWidget parent;
       //QDialog parent;
       QMainWindow parent;
       // Set the font size of the parent window 
       QFont font;
       font.setPointSize(20);
       parent.setFont(font);
       // Set the size and position of the parent window 
       parent.resize(480,320);
       parent.move(200,100);
       
       // establish label And dock on the parent window 
       QLabel label(" I'm the label ",&parent);
       label.move(50,50);
       label.resize(150,50);
       // establish button And dock on the parent window 
       QPushButton button(" I'm the button ",&parent);
       button.move(50,200);
       button.resize(150,50);
       // Dynamically create button And dock on the parent window 
       // When the parent window is destroyed , The dynamic objects docked above will be automatically 
       //delete, There is no need to perform... Manually detele.
       QPushButton* button2 = 
           new QPushButton(" Me too ",&parent);
       button2->move(300,200);
       button2->resize(150,50);
   
       // Show parent window , The controls docked above will also be displayed together 
       parent.show();
       
       return app.exec();
   }