每一个声明Q_OBJECT的类都具有QMetaObject对象
Q_OBJECT宏源代码：
#define Q_OBJECT \
public: \
QT_WARNING_PUSH \
Q_OBJECT_NO_OVERRIDE_WARNING \
static const QMetaObject staticMetaObject; \
virtual const QMetaObject *metaObject() const; \
virtual void *qt_metacast(const char *); \
virtual int qt_metacall(QMetaObject::Call, int, void **); \
QT_TR_FUNCTIONS \
private: \
Q_OBJECT_NO_ATTRIBUTES_WARNING \
Q_DECL_HIDDEN_STATIC_METACALL static void qt_static_metacall(QObject *, QMetaObject::Call, int, void **); \
QT_WARNING_POP \
struct QPrivateSignal {}; \
QT_ANNOTATE_CLASS(qt_qobject, "")
每一个声明Q_OBJECT类的对象都具有同一静态成员staticMetaObject，staticMetaObject用于存储类的基础信息，比如类属性、类信息。
例如类XTest的QMetaObject staticMetaObject
XTest::staticMetaObject中包含类信息"author", "Sabrina Schweinsteiger"，类属性autoStartup，槽函数、信号、其它函数
XTest.h
#pragma once
#include <qobject.h>
#include <QFlags>
class XTest : public QObject
{
Q_OBJECT
Q_CLASSINFO("author", "Sabrina Schweinsteiger")
Q_PROPERTY(bool autoStartup READ autoStartup WRITE setAutoStartup NOTIFY sigAutoStartup)
public:
XTest(QObject* p = nullptr) {}
~XTest() {}
public:
enum Priority
{
High,
Low,
VeryHigh,
VeryLow
};
Q_ENUM(Priority)
enum PriorityFlag
{
High1,
Low1,
VeryHigh1,
VeryLow1
};
Q_FLAG(PriorityFlag)
Q_DECLARE_FLAGS(Alignment, PriorityFlag)
Q_FLAG(Alignment)
public:
bool autoStartup() { return m_autoStartup; }
void setAutoStartup(bool b) { m_autoStartup = b; emit sigAutoStartup(); }
public slots:
void slot1(double* p1) {}
Q_INVOKABLE void slot2(int* p2) {}
Q_REVISION(1) void slot3(char* p3) {}
Q_INVOKABLE void slot4(int p2, double) {}
signals:
void sig1(void * p4);
void sigAutoStartup();
private:
Q_REVISION(1) bool m_autoStartup = false;
};
XTest.cpp:
#include "XTest.h"
qt生成的moc文件moc_XTest.cpp:
/****************************************************************************
** Meta object code from reading C++ file 'XTest.h'
**
** Created by: The Qt Meta Object Compiler version 67 (Qt 5.15.2)
**
** WARNING! All changes made in this file will be lost!
*****************************************************************************/
#include <memory>
#include "../../../XTest.h"
#include <QtCore/qbytearray.h>
#include <QtCore/qmetatype.h>
#if !defined(Q_MOC_OUTPUT_REVISION)
#error "The header file 'XTest.h' doesn't include <QObject>."
#elif Q_MOC_OUTPUT_REVISION != 67
#error "This file was generated using the moc from 5.15.2. It"
#error "cannot be used with the include files from this version of Qt."
#error "(The moc has changed too much.)"
#endif
QT_BEGIN_MOC_NAMESPACE
QT_WARNING_PUSH
QT_WARNING_DISABLE_DEPRECATED
struct qt_meta_stringdata_XTest_t {
QByteArrayData data[29];
char stringdata0[212];
};
#define QT_MOC_LITERAL(idx, ofs, len) \
Q_STATIC_BYTE_ARRAY_DATA_HEADER_INITIALIZER_WITH_OFFSET(len, \
qptrdiff(offsetof(qt_meta_stringdata_XTest_t, stringdata0) + ofs \
- idx * sizeof(QByteArrayData)) \
)
static const qt_meta_stringdata_XTest_t qt_meta_stringdata_XTest = {
{
QT_MOC_LITERAL(0, 0, 5), // "XTest"
QT_MOC_LITERAL(1, 6, 6), // "author"
QT_MOC_LITERAL(2, 13, 22), // "Sabrina Schweinsteiger"
QT_MOC_LITERAL(3, 36, 4), // "sig1"
QT_MOC_LITERAL(4, 41, 0), // ""
QT_MOC_LITERAL(5, 42, 2), // "p4"
QT_MOC_LITERAL(6, 45, 14), // "sigAutoStartup"
QT_MOC_LITERAL(7, 60, 5), // "slot1"
QT_MOC_LITERAL(8, 66, 7), // "double*"
QT_MOC_LITERAL(9, 74, 2), // "p1"
QT_MOC_LITERAL(10, 77, 5), // "slot2"
QT_MOC_LITERAL(11, 83, 4), // "int*"
QT_MOC_LITERAL(12, 88, 2), // "p2"
QT_MOC_LITERAL(13, 91, 5), // "slot3"
QT_MOC_LITERAL(14, 97, 5), // "char*"
QT_MOC_LITERAL(15, 103, 2), // "p3"
QT_MOC_LITERAL(16, 106, 5), // "slot4"
QT_MOC_LITERAL(17, 112, 11), // "autoStartup"
QT_MOC_LITERAL(18, 124, 8), // "Priority"
QT_MOC_LITERAL(19, 133, 4), // "High"
QT_MOC_LITERAL(20, 138, 3), // "Low"
QT_MOC_LITERAL(21, 142, 8), // "VeryHigh"
QT_MOC_LITERAL(22, 151, 7), // "VeryLow"
QT_MOC_LITERAL(23, 159, 12), // "PriorityFlag"
QT_MOC_LITERAL(24, 172, 5), // "High1"
QT_MOC_LITERAL(25, 178, 4), // "Low1"
QT_MOC_LITERAL(26, 183, 9), // "VeryHigh1"
QT_MOC_LITERAL(27, 193, 8), // "VeryLow1"
QT_MOC_LITERAL(28, 202, 9) // "Alignment"
},
"XTest\0author\0Sabrina Schweinsteiger\0"
"sig1\0\0p4\0sigAutoStartup\0slot1\0double*\0"
"p1\0slot2\0int*\0p2\0slot3\0char*\0p3\0slot4\0"
"autoStartup\0Priority\0High\0Low\0VeryHigh\0"
"VeryLow\0PriorityFlag\0High1\0Low1\0"
"VeryHigh1\0VeryLow1\0Alignment"
};
#undef QT_MOC_LITERAL
static const uint qt_meta_data_XTest[] = {
// content:
8, // revision
0, // classname
1, 14, // classinfo
6, 16, // methods
1, 70, // properties
3, 74, // enums/sets
0, 0, // constructors
0, // flags
2, // signalCount
// classinfo: key, value
1, 2,
// signals: name, argc, parameters, tag, flags
3, 1, 52, 4, 0x06 /* Public */,
6, 0, 55, 4, 0x06 /* Public */,
// slots: name, argc, parameters, tag, flags
7, 1, 56, 4, 0x0a /* Public */,
10, 1, 59, 4, 0x0a /* Public */,
13, 1, 62, 4, 0x8a /* Public | MethodRevisioned */,
16, 2, 65, 4, 0x0a /* Public */,
// signals: revision
0,
0,
// slots: revision
0,
0,
1,
0,
// signals: parameters
QMetaType::Void, QMetaType::VoidStar, 5,
QMetaType::Void,
// slots: parameters
QMetaType::Void, 0x80000000 | 8, 9,
QMetaType::Void, 0x80000000 | 11, 12,
QMetaType::Void, 0x80000000 | 14, 15,
QMetaType::Void, QMetaType::Int, QMetaType::Double, 12, 4,
// properties: name, type, flags
17, QMetaType::Bool, 0x00495103,
// properties: notify_signal_id
1,
// enums: name, alias, flags, count, data
18, 18, 0x0, 4, 89,
23, 23, 0x1, 4, 97,
28, 23, 0x1, 4, 105,
// enum data: key, value
19, uint(XTest::High),
20, uint(XTest::Low),
21, uint(XTest::VeryHigh),
22, uint(XTest::VeryLow),
24, uint(XTest::High1),
25, uint(XTest::Low1),
26, uint(XTest::VeryHigh1),
27, uint(XTest::VeryLow1),
24, uint(XTest::High1),
25, uint(XTest::Low1),
26, uint(XTest::VeryHigh1),
27, uint(XTest::VeryLow1),
0 // eod
};
void XTest::qt_static_metacall(QObject *_o, QMetaObject::Call _c, int _id, void **_a)
{
if (_c == QMetaObject::InvokeMetaMethod) {
auto *_t = static_cast<XTest *>(_o);
Q_UNUSED(_t)
switch (_id) {
case 0: _t->sig1((*reinterpret_cast< void*(*)>(_a[1]))); break;
case 1: _t->sigAutoStartup(); break;
case 2: _t->slot1((*reinterpret_cast< double*(*)>(_a[1]))); break;
case 3: _t->slot2((*reinterpret_cast< int*(*)>(_a[1]))); break;
case 4: _t->slot3((*reinterpret_cast< char*(*)>(_a[1]))); break;
case 5: _t->slot4((*reinterpret_cast< int(*)>(_a[1])),(*reinterpret_cast< double(*)>(_a[2]))); break;
default: ;
}
} else if (_c == QMetaObject::IndexOfMethod) {
int *result = reinterpret_cast<int *>(_a[0]);
{
using _t = void (XTest::*)(void * );
if (*reinterpret_cast<_t *>(_a[1]) == static_cast<_t>(&XTest::sig1)) {
*result = 0;
return;
}
}
{
using _t = void (XTest::*)();
if (*reinterpret_cast<_t *>(_a[1]) == static_cast<_t>(&XTest::sigAutoStartup)) {
*result = 1;
return;
}
}
}
#ifndef QT_NO_PROPERTIES
else if (_c == QMetaObject::ReadProperty) {
auto *_t = static_cast<XTest *>(_o);
Q_UNUSED(_t)
void *_v = _a[0];
switch (_id) {
case 0: *reinterpret_cast< bool*>(_v) = _t->autoStartup(); break;
default: break;
}
} else if (_c == QMetaObject::WriteProperty) {
auto *_t = static_cast<XTest *>(_o);
Q_UNUSED(_t)
void *_v = _a[0];
switch (_id) {
case 0: _t->setAutoStartup(*reinterpret_cast< bool*>(_v)); break;
default: break;
}
} else if (_c == QMetaObject::ResetProperty) {
}
#endif // QT_NO_PROPERTIES
}
QT_INIT_METAOBJECT const QMetaObject XTest::staticMetaObject = { {
QMetaObject::SuperData::link<QObject::staticMetaObject>(),
qt_meta_stringdata_XTest.data,
qt_meta_data_XTest,
qt_static_metacall,
nullptr,
nullptr
} };
const QMetaObject *XTest::metaObject() const
{
return QObject::d_ptr->metaObject ? QObject::d_ptr->dynamicMetaObject() : &staticMetaObject;
}
void *XTest::qt_metacast(const char *_clname)
{
if (!_clname) return nullptr;
if (!strcmp(_clname, qt_meta_stringdata_XTest.stringdata0))
return static_cast<void*>(this);
return QObject::qt_metacast(_clname);
}
int XTest::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
{
_id = QObject::qt_metacall(_c, _id, _a);
if (_id < 0)
return _id;
if (_c == QMetaObject::InvokeMetaMethod) {
if (_id < 6)
qt_static_metacall(this, _c, _id, _a);
_id -= 6;
} else if (_c == QMetaObject::RegisterMethodArgumentMetaType) {
if (_id < 6)
*reinterpret_cast<int*>(_a[0]) = -1;
_id -= 6;
}
#ifndef QT_NO_PROPERTIES
else if (_c == QMetaObject::ReadProperty || _c == QMetaObject::WriteProperty
|| _c == QMetaObject::ResetProperty || _c == QMetaObject::RegisterPropertyMetaType) {
qt_static_metacall(this, _c, _id, _a);
_id -= 1;
} else if (_c == QMetaObject::QueryPropertyDesignable) {
_id -= 1;
} else if (_c == QMetaObject::QueryPropertyScriptable) {
_id -= 1;
} else if (_c == QMetaObject::QueryPropertyStored) {
_id -= 1;
} else if (_c == QMetaObject::QueryPropertyEditable) {
_id -= 1;
} else if (_c == QMetaObject::QueryPropertyUser) {
_id -= 1;
}
#endif // QT_NO_PROPERTIES
return _id;
}
// SIGNAL 0
void XTest::sig1(void * _t1)
{
void *_a[] = { nullptr, const_cast<void*>(reinterpret_cast<const void*>(std::addressof(_t1))) };
QMetaObject::activate(this, &staticMetaObject, 0, _a);
}
// SIGNAL 1
void XTest::sigAutoStartup()
{
QMetaObject::activate(this, &staticMetaObject, 1, nullptr);
}
QT_WARNING_POP
QT_END_MOC_NAMESPACE
函数解析：
静态函数
bool QMetaObject::checkConnectArgs(const char *signal, const char *method)
检查2个字符串参数是否相同。传入参数字符串需要是QMetaObject::normalizedSignature返回的字符串。例如slots2函数签名是“slots2(int*)”。就是上一篇QMetaMethod::methodSignature函数返回值
bool QMetaObject::checkConnectArgs(const QMetaMethod &signal, const QMetaMethod &method)
检查信号与槽参数连接参数是否相同
QByteArray QMetaObject::normalizedSignature
获取函数签名。例如slots2函数签名是“slots2(int*)”。就是上一篇QMetaMethod::methodSignature函数返回值
