QT6 源码杂记

菜鸡一个，随便写写，勿喷。好记性不如烂笔头。

了解qt，第一个绕不过的坎便是qt的元对象系统 QMetaObject。

 1 class Object : public QObject
 2 {
 3     Q_OBJECT
 4         Q_PROPERTY(int age READ age  WRITE setAge NOTIFY ageChanged)
 5         Q_PROPERTY(int score READ score  WRITE setScore NOTIFY scoreChanged)
 6         Q_CLASSINFO("Author", "Scorpio")
 7         Q_CLASSINFO("Version", "2.0")
 8         Q_CLASSINFO("Department", "wk")
 9         Q_ENUMS(Level)
10 protected:
11     static const MyStruct sStruct;
12     QString m_name;
13     QString m_level;
14     int m_age;
15     int m_score;
16 public:
17     enum Level
18     {
19         Basic,
20         Middle,
21         Advanced
22     };
23 public:
24     Q_INVOKABLE explicit Object(QString name, QObject* parent = 0) :QObject(parent)
25     {
26         m_name = name;
27         setObjectName(m_name);
28         connect(this, &Object::ageChanged, this, &Object::onAgeChanged);
29         //connect(this, &Object::ageChanged, this, &Object::onScoreChanged);
30         connect(this, &Object::scoreChanged, this, &Object::onScoreChanged);
31     }
32 
33     int age()const
34     {
35         return m_age;
36     }
37 
38     Q_INVOKABLE void setAge(const int& age)
39     {
40         m_age = age;
41         emit ageChanged(m_age);
42     }
43 
44     Q_INVOKABLE int score()const
45     {
46         return m_score;
47     }
48 
49     Q_INVOKABLE void setScore(const int& score)
50     {
51         m_score = score;
52         emit scoreChanged(m_score);
53     }
54 signals:
55     void ageChanged(int age);
56     void scoreChanged(int score);
57 public slots:
58 
59     void onAgeChanged(int age)
60     {
61         //QObjectPrivate* p = static_cast (&(*d_ptr));
62         //p->receiverList(SIGNAL(ageChanged));
63         //d_ptr->
64         qDebug() << "age changed:" << age;
65     }
66     void onScoreChanged(int score)
67     {
68         qDebug() << "score changed:" << score;
69     }
70 };

View Code

通常继承qt的类，都会继承于QObject. 在类里添加一句 Q_OBJECT宏。如下所示，是qt信号槽的关键。

 1 #define Q_OBJECT \
 2 public: \
 3     QT_WARNING_PUSH \
 4     Q_OBJECT_NO_OVERRIDE_WARNING \
 5     static const QMetaObject staticMetaObject; \
 6     virtual const QMetaObject *metaObject() const; \
 7     virtual void *qt_metacast(const char *); \
 8     virtual int qt_metacall(QMetaObject::Call, int, void **); \
 9     QT_TR_FUNCTIONS \
10 private: \
11     Q_OBJECT_NO_ATTRIBUTES_WARNING \
12     Q_DECL_HIDDEN_STATIC_METACALL static void qt_static_metacall(QObject *, QMetaObject::Call, int, void **); \
13     QT_WARNING_POP \
14     struct QPrivateSignal {}; \
15     QT_ANNOTATE_CLASS(qt_qobject, "")

要想编译qt相关类，少不了moc工具。可以理解为qt的预编译工具，moc工具会解析具有Q_OBJECT宏的类，生成对应的moc_xx.cpp文件，该文件会随着项目一起编译。

  1 /****************************************************************************
  2 ** Meta object code from reading C++ file 'Object.h'
  3 **
  4 ** Created by: The Qt Meta Object Compiler version 68 (Qt 6.0.0)
  5 **
  6 ** WARNING! All changes made in this file will be lost!
  7 *****************************************************************************/
  8 
  9 #include 
 10 #include "../../../Object.h"
 11 #include 
 12 #include 
 13 #if !defined(Q_MOC_OUTPUT_REVISION)
 14 #error "The header file 'Object.h' doesn't include ."
 15 #elif Q_MOC_OUTPUT_REVISION != 68
 16 #error "This file was generated using the moc from 6.0.0. It"
 17 #error "cannot be used with the include files from this version of Qt."
 18 #error "(The moc has changed too much.)"
 19 #endif
 20 
 21 QT_BEGIN_MOC_NAMESPACE
 22 QT_WARNING_PUSH
 23 QT_WARNING_DISABLE_DEPRECATED
 24 struct qt_meta_stringdata_Object_t {
 25     const uint offsetsAndSize[44];
 26     char stringdata0[167];
 27 };
 28 #define QT_MOC_LITERAL(ofs, len) \
 29     uint(offsetof(qt_meta_stringdata_Object_t, stringdata0) + ofs), len 
 30 static const qt_meta_stringdata_Object_t qt_meta_stringdata_Object = {
 31     {
 32 QT_MOC_LITERAL(0, 6), // "Object"
 33 QT_MOC_LITERAL(7, 6), // "Author"
 34 QT_MOC_LITERAL(14, 7), // "Scorpio"
 35 QT_MOC_LITERAL(22, 7), // "Version"
 36 QT_MOC_LITERAL(30, 3), // "2.0"
 37 QT_MOC_LITERAL(34, 10), // "Department"
 38 QT_MOC_LITERAL(45, 2), // "wk"
 39 QT_MOC_LITERAL(48, 10), // "ageChanged"
 40 QT_MOC_LITERAL(59, 0), // ""
 41 QT_MOC_LITERAL(60, 3), // "age"
 42 QT_MOC_LITERAL(64, 12), // "scoreChanged"
 43 QT_MOC_LITERAL(77, 5), // "score"
 44 QT_MOC_LITERAL(83, 12), // "onAgeChanged"
 45 QT_MOC_LITERAL(96, 14), // "onScoreChanged"
 46 QT_MOC_LITERAL(111, 6), // "setAge"
 47 QT_MOC_LITERAL(118, 8), // "setScore"
 48 QT_MOC_LITERAL(127, 4), // "name"
 49 QT_MOC_LITERAL(132, 6), // "parent"
 50 QT_MOC_LITERAL(139, 5), // "Level"
 51 QT_MOC_LITERAL(145, 5), // "Basic"
 52 QT_MOC_LITERAL(151, 6), // "Middle"
 53 QT_MOC_LITERAL(158, 8) // "Advanced"
 54 
 55     },
 56     "Object\0Author\0Scorpio\0Version\0""2.0\0"
 57     "Department\0wk\0ageChanged\0\0age\0"
 58     "scoreChanged\0score\0onAgeChanged\0"
 59     "onScoreChanged\0setAge\0setScore\0name\0"
 60     "parent\0Level\0Basic\0Middle\0Advanced"
 61 };
 62 #undef QT_MOC_LITERAL
 63 
 64 static const uint qt_meta_data_Object[] = {
 65 
 66  // content:
 67        9,       // revision
 68        0,       // classname
 69        3,   14, // classinfo
 70        7,   20, // methods
 71        2,   89, // properties
 72        1,   99, // enums/sets
 73        2,  110, // constructors
 74        0,       // flags
 75        2,       // signalCount
 76 
 77  // classinfo: key, value
 78        1,    2,
 79        3,    4,
 80        5,    6,
 81 
 82  // signals: name, argc, parameters, tag, flags, initial metatype offsets
 83        7,    1,   62,    8, 0x06,    2 /* Public */,
 84       10,    1,   65,    8, 0x06,    4 /* Public */,
 85 
 86  // slots: name, argc, parameters, tag, flags, initial metatype offsets
 87       12,    1,   68,    8, 0x0a,    6 /* Public */,
 88       13,    1,   71,    8, 0x0a,    8 /* Public */,
 89 
 90  // methods: name, argc, parameters, tag, flags, initial metatype offsets
 91       14,    1,   74,    8, 0x02,   10 /* Public */,
 92       11,    0,   77,    8, 0x02,   12 /* Public */,
 93       15,    1,   78,    8, 0x02,   13 /* Public */,
 94 
 95  // signals: parameters
 96     QMetaType::Void, QMetaType::Int,    9,
 97     QMetaType::Void, QMetaType::Int,   11,
 98 
 99  // slots: parameters
100     QMetaType::Void, QMetaType::Int,    9,
101     QMetaType::Void, QMetaType::Int,   11,
102 
103  // methods: parameters
104     QMetaType::Void, QMetaType::Int,    9,
105     QMetaType::Int,
106     QMetaType::Void, QMetaType::Int,   11,
107 
108  // constructors: parameters
109     0x80000000 | 8, QMetaType::QString, QMetaType::QObjectStar,   16,   17,
110     0x80000000 | 8, QMetaType::QString,   16,
111 
112  // properties: name, type, flags
113        9, QMetaType::Int, 0x00015103, uint(0), 0,
114       11, QMetaType::Int, 0x00015103, uint(1), 0,
115 
116  // enums: name, alias, flags, count, data
117       18,   18, 0x0,    3,  104,
118 
119  // enum data: key, value
120       19, uint(Object::Basic),
121       20, uint(Object::Middle),
122       21, uint(Object::Advanced),
123 
124  // constructors: name, argc, parameters, tag, flags, initial metatype offsets
125        0,    2,   81,    8, 0x0e,   15 /* Public */,
126        0,    1,   86,    8, 0x2e,   17 /* Public | MethodCloned */,
127 
128        0        // eod
129 };
130 
131 void Object::qt_static_metacall(QObject *_o, QMetaObject::Call _c, int _id, void **_a)
132 {
133     if (_c == QMetaObject::CreateInstance) {
134         switch (_id) {
135         case 0: { Object *_r = new Object((*reinterpret_cast< QString(*)>(_a[1])),(*reinterpret_cast< QObject*(*)>(_a[2])));
136             if (_a[0]) *reinterpret_cast(_a[0]) = _r; } break;
137         case 1: { Object *_r = new Object((*reinterpret_cast< QString(*)>(_a[1])));
138             if (_a[0]) *reinterpret_cast(_a[0]) = _r; } break;
139         default: break;
140         }
141     } else if (_c == QMetaObject::InvokeMetaMethod) {
142         auto *_t = static_cast