glib之gobject G_DEFINE_TYPE用法

1.my_demo.h

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#ifndef _MY_DEMO_H_
#define _MY_DEMO_H_
#include <glib-object.h>

#ifdef __cplusplus
extern "C" {
#endif

//宏
#define MY_TYPE_DEMO (my_demo_get_type())
#define MY_DEMO(object) G_TYPE_CHECK_INSTANCE_CAST((object), MY_TYPE_DEMO, MyDemo)
#define MY_DEMO_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST((klass), MY_TYPE_DEMO, MyDemoClass))
#define MY_IS_DEMO(object) G_TYPE_CHECK_INSTANCE_TYPE((object), MY_TYPE_DEMO))
#define MY_IS_DEMO_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass), MY_TYPE_DEMO))
#define MY_DEMO_GET_CLASS(object) (G_TYPE_INSTANCE_GET_CLASS((object), MY_TYPE_DEMO, MyDemoClass))

typedef struct MyDemoPrivate MyDemoPrivate;

struct MyDemoPrivate
{
gchar *name;
gint64 age;
};

//实例结构体
typedef struct _MyDemo MyDemo;

struct _MyDemo {
GObject parent;
MyDemoPrivate *priv;
};

//类结构体
typedef struct _MyDemoClass MyDemoClass;

struct _MyDemoClass {
GObjectClass parent_class;
};

GType my_demo_get_type(void) G_GNUC_CONST;//my_demo_get_type将会使用宏G_DEFINE_TYPE去实现(G_DEFINE_TYPE(MyDemo,my_demo,G_TYPE_OBJECT))，其中的my通常表示命名空间，demo表示对象名字，get_type为固定字段

MyDemo *my_demo_new(const gchar *name, gint64 age);

#ifdef __cplusplus
}
#endif

#endif // _MY_DEMO_H_

2.my_demo.c

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#include "my_demo.h"
#include <stdio.h>

enum
{
PROP_0,
PROP_NAME,
PROP_AGE,
N_PROPERTIES
};

#define MY_DEMO_GET_PRIVATE(o) (G_TYPE_INSTANCE_GET_PRIVATE ((o), MY_TYPE_DEMO, MyDemoPrivate))

static void my_demo_init(MyDemo *self);
static void my_demo_class_init(MyDemoClass *klass);

/*
* G_DEFINE_TYPE 可以让 GObject 库的数据类型系统能够识别我们所定义的 MyDemo 类类型，
* 它接受三个参数，第一个参数是类名，即 MyDemo；第二个参数则是类的成员函数名称的前缀，例如 my_demo_get_type 函数即为 MyDemo 类的一个成员函数，"my_demo"是它的前缀；第三个参数则指明 MyDemo 类类型的父类型为G_TYPE_OBJECT。
* G_DEFINE_TYPE中会调用一个 g_type_register_static_simple 的函数，这个函数的作用就是将用户自己定义的类型注册到系统中，
* G_DEFINE_TYPE还定义了2个函数（my_demo_init 和 my_demo_class_init），需要自己实现这两个函数。它们是对象的初始化函数，相当于c++的构造函数，第一个函数在每个对象创建的时候都会被调用，
* 第二个函数只有在第一次创建对象的时候被调用(比如在调用g_type_class_ref的时候，如果class没有初始化，就会调用my_demo_class_init)
*/
G_DEFINE_TYPE (MyDemo, my_demo, G_TYPE_OBJECT);

static void my_demo_dispose(GObject *object);
static void my_demo_finalize(GObject *object);

/*
//以下代码为替换宏G_DEFINE_TYPE的另外一种对my_demo_get_type函数的实现方法，代码不好理解，不建议使用这种方法
static gpointer my_demo_parent_class = ((void*) 0);
static void my_demo_class_intern_init(gpointer klass)
{
my_demo_parent_class = g_type_class_peek_parent(klass);
my_demo_class_init ((MyDemoClass*)klass);
}
GType my_demo_get_type (void)
{
static volatile gsize g_define_type_id__volatile = 0;
if (g_once_init_enter(&g_define_type_id__volatile))
{
GType g_define_type_id =
g_type_register_static_simple (((GType)((20) << (2))),
g_intern_static_string("MyDemo"),
sizeof(MyDemoClass),
(GClassInitFunc)my_demo_class_intern_init,
sizeof(MyDemo),
(GInstanceInitFunc)my_demo_init,
(GTypeFlags)0);
{ {{};} }
g_once_init_leave(&g_define_type_id__volatile, g_define_type_id);
}
return g_define_type_id__volatile;
}
*/

static void my_demo_set_property(GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec)
{
MyDemo *self;

g_return_if_fail(object != NULL);

self = MY_DEMO (object);
//self->priv = MY_DEMO_GET_PRIVATE(self);

switch (prop_id)
{
case PROP_NAME:
self->priv->name = g_value_dup_string(value);
break;
case PROP_AGE:
self->priv->age = g_value_get_int64(value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
break;
}
}

static void my_demo_get_property(GObject *object, guint prop_id, GValue *value, GParamSpec *pspec)
{
MyDemo *self;

g_return_if_fail(object != NULL);

self = MY_DEMO(object);

switch (prop_id)
{
case PROP_NAME:
g_value_set_string(value, self->priv->name);
break;
case PROP_AGE:
g_value_set_int64(value, self->priv->age);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
break;
}
}

//类结构体初始化函数
static void my_demo_class_init(MyDemoClass *klass)
{
printf("%s\n", __FUNCTION__);

int signal_id = g_signal_new("broadcast_msg",
my_demo_get_type(),/*G_OBJECT_CLASS_TYPE(kclass)*/
G_SIGNAL_RUN_LAST,
0,
NULL,
NULL,
g_cclosure_marshal_VOID__STRING,
G_TYPE_NONE,/*返回值，因为信号没有返回，所以为NONE*/
1,/*参数数目*/
G_TYPE_STRING/*参数类型*/
);

GObjectClass *object_class = G_OBJECT_CLASS(klass);
object_class->finalize = my_demo_finalize;
object_class->dispose = my_demo_dispose;

object_class->set_property = my_demo_set_property;
object_class->get_property = my_demo_get_property;

g_object_class_install_property(object_class,
PROP_NAME,
g_param_spec_string("name",
"name",
"Specify the name of demo",
"Unknown",
G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY));

g_object_class_install_property(object_class,
PROP_AGE,
g_param_spec_int64 ("age",
"age",
"Specify age number",
G_MININT64, G_MAXINT64, 0,
G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY));

// 如果对struct MyDemoPrivate 里面添加了成员变量，则执行下面这行代码
g_type_class_add_private(klass, sizeof(MyDemoPrivate));
}

//实例结构体初始化函数
static void my_demo_init(MyDemo *self)
{
printf("%s\n", __FUNCTION__);
self->priv = MY_DEMO_GET_PRIVATE(self);
}

static void my_demo_dispose(GObject *object)
{
printf("%s\n", __FUNCTION__);
}

static void my_demo_finalize(GObject *object)
{
printf("%s\n", __FUNCTION__);

MyDemo *self;

g_return_if_fail(object != NULL);

self = MY_DEMO(object);

if (self->priv->name)
g_free (self->priv->name);

G_OBJECT_CLASS(my_demo_parent_class)->finalize(object);
}

MyDemo *my_demo_new(const gchar *name, gint64 age)
{
MyDemo *demo;

demo = MY_DEMO(g_object_new(MY_TYPE_DEMO,
"name", name,
"age", age,
NULL));

printf("get property name:%s, age:%ld\n", demo->priv->name, demo->priv->age);

return demo;
}

3.main.c

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#include <glib.h>
#include <glib-unix.h>
#include <stdio.h>

#include "my_demo.h"

static GMainLoop *loop = NULL;

static gboolean signal_handler(gpointer user_data)
{
g_main_loop_quit(loop);
return FALSE;
}

void handler_receive_msg(GObject *sender, char *name, gpointer data)
{
MyDemo *demo = G_TYPE_CHECK_INSTANCE_CAST(sender, my_demo_get_type(), MyDemo);
printf("handler: [%s] from [%s: %ld]\n", name, demo->priv->name, demo->priv->age);
}

int main(int argc, char* argv[])
{
#if !GLIB_CHECK_VERSION(2,32,0)
if (! g_thread_supported ())
g_thread_init (NULL);
#endif
#if !GLIB_CHECK_VERSION(2,36,0)
g_type_init ();
#endif

loop = g_main_loop_new(NULL, FALSE);
g_unix_signal_add_full(G_PRIORITY_DEFAULT,
SIGINT,
signal_handler,
NULL,
NULL);
int i;
MyDemo *demos[3];
int len = sizeof(demos) / sizeof(demos[0]);

for (i = 0; i < len; i++) {
printf("construction demos[%d]\n", i);
//创建对象
//demos[i]= g_object_new(MY_TYPE_DEMO, NULL);
/*demos[i]= g_object_new(MY_TYPE_DEMO,
"name", "kobe",
"age", i,
NULL);*/
gchar *name = g_strdup_printf("kobe%d", i);
demos[i] = my_demo_new(name, i);
g_free(name);
//绑定信号
g_signal_connect(demos[i], "broadcast_msg", G_CALLBACK(handler_receive_msg), NULL);
//发送信号
g_signal_emit_by_name(demos[i], "broadcast_msg", "lixiang");
}

//析构
for(i = 0; i < len; i++){
printf("destruction demos[%d]\n", i);
g_object_unref(demos[i]);
}

g_main_loop_run(loop);
g_main_loop_unref(loop);

return 0;
}

4.Makefile

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CC = gcc
CC_FLAGS = $(shell pkg-config --cflags glib-2.0 gthread-2.0 gobject-2.0)
CC_FLAGS += -std=c99 -g
LD_FLAGS = $(shell pkg-config --libs glib-2.0 gthread-2.0 gobject-2.0)

gobjectdemo:main.o my_demo.o
$(CC) -o $@ $+ $(LD_FLAGS)

%.o:%.c
$(CC) $(CC_FLAGS) -c -o $@ $<

clean:
rm -rf *.o gobjectdemo

5.安装、编译glib

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# sudo apt install libglib2.0-dev
# make
# ./gobjectdemo

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