在gtk中应用线程

    在GTK+中应用线程，除了GLIB中的g_thread_init和g_thread_supported两个函数外，还要用到gdk_thread_init来在X WINDOW中初始化线程应用，另外在线程中要对GTK+控件进行操作时还要在操作前执行函数gdk_thread_enter来进入，操作完成后执行函数gdk_thread_leave来离开，在执行GTK+主循环时也是如此，GTK+以此来达到线程安全；下面代码利用线程创建了一个在屏幕上沿顺时针运动的图像（24x24像素）：

//thread.c
#include 
typedef struct _Ourarg Ourarg;
struct _Ourarg {
	GtkWidget *fixed;
	GtkWidget *image;
	gint right;
	gint left;
};
void	image_go(Ourarg *arg)
{
	gint x, y, toward;
	x = y = arg->left;
	toward = 1;
	for(;;)
	{
		g_usleep(1500);
		gdk_threads_enter();
		gtk_fixed_move(GTK_FIXED(arg->fixed),arg->image, x, y);
		switch(toward)
		{
		case 1:
			x = x + 10;
			if( x > arg->right ) toward = 2;
			break;
		case 2:
			y = y + 10;
			if( y > arg->right ) toward = 3;
			break;
		case 3:
			x = x - 10;
			if( x < arg->left ) toward = 4;
			break;
		case 4:
			y = y -10;
			if( y < arg->left ) toward = 1;
		}
		gdk_threads_leave();
	}
}
int	main(int argc, char* argv[])
{
	GtkWidget *window;
	GtkWidget *vbox, *viewport, *button;
	GtkWidget *image, *fixed;
	Ourarg *arg;
	if(!g_thread_supported()) g_thread_init(NULL);
	gdk_threads_init();
	gtk_init(&argc,&argv);
	window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
	gtk_window_set_title(GTK_WINDOW(window),"线程测试");
	g_signal_connect(G_OBJECT(window),"delete_event",
			G_CALLBACK(gtk_main_quit),NULL);
	gtk_container_set_border_width(GTK_CONTAINER(window),2);
	vbox = gtk_vbox_new(FALSE,0);
	gtk_container_add(GTK_CONTAINER(window),vbox);
	fixed = gtk_fixed_new();
	gtk_widget_set_usize(fixed,340,340);
	viewport = gtk_viewport_new(NULL,NULL);
	gtk_box_pack_start(GTK_BOX(vbox),viewport,FALSE,FALSE,5);
	gtk_container_add(GTK_CONTAINER(viewport),fixed);
	image = gtk_image_new_from_file("ss.png");
	gtk_fixed_put(GTK_FIXED(fixed),image,40,40);
	button = gtk_button_new_with_label("退出");
	gtk_box_pack_start(GTK_BOX(vbox),button,FALSE,FALSE,5);
	g_signal_connect(G_OBJECT(button),"clicked",
			G_CALLBACK(gtk_main_quit),NULL);
	gtk_widget_show_all(window);
	arg = g_new(Ourarg,1);
	arg->fixed = fixed;
	arg->image = image;
	arg->left = 40;
	arg->right = 260;
	g_thread_create(image_go, arg, FALSE, NULL);
	gdk_threads_enter();
	gtk_main();
	gdk_threads_leave();
	return FALSE;
}

基于线程安全考虑，你必须将下面代码放在gtk_init函数之前执行：

		if(!g_thread_supported()) g_thread_init(NULL);
	gdk_threads_init();
	

线程中执行一个死循环，不停的移动GtkFixed控件中的图像控件，根据图像的位置来改变方向。