1
我从here下面的例子中,它显示了“增加 - 减少”标题下的这个例子。Gtk +回调函数和信号帮助
#include <gtk/gtk.h>
gint count = 0;
char buf[5];
void increase(GtkWidget *widget, gpointer label)
{
count++;
sprintf(buf, "%d", count);
gtk_label_set_text(label, buf);
}
void decrease(GtkWidget *widget, gpointer label)
{
count--;
sprintf(buf, "%d", count);
gtk_label_set_text(label, buf);
}
int main(int argc, char** argv) {
GtkWidget *label;
GtkWidget *window;
GtkWidget *frame;
GtkWidget *plus;
GtkWidget *minus;
gtk_init(&argc, &argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_default_size(GTK_WINDOW(window), 250, 180);
gtk_window_set_title(GTK_WINDOW(window), "+-");
frame = gtk_fixed_new();
gtk_container_add(GTK_CONTAINER(window), frame);
plus = gtk_button_new_with_label("+");
gtk_widget_set_size_request(plus, 80, 35);
gtk_fixed_put(GTK_FIXED(frame), plus, 50, 20);
minus = gtk_button_new_with_label("-");
gtk_widget_set_size_request(minus, 80, 35);
gtk_fixed_put(GTK_FIXED(frame), minus, 50, 80);
label = gtk_label_new("0");
gtk_fixed_put(GTK_FIXED(frame), label, 190, 58);
gtk_widget_show_all(window);
g_signal_connect(window, "destroy",
G_CALLBACK (gtk_main_quit), NULL);
g_signal_connect(plus, "clicked",
G_CALLBACK(increase), label);
g_signal_connect(minus, "clicked",
G_CALLBACK(decrease), label);
gtk_main();
return 0;
}
什么我不知道就是,g_signal_connect(plus, "clicked",G_CALLBACK(increase), label);
函数发送了“标签”的功能增加,其中它的参数是void increase(GtkWidget *widget, gpointer label)
。现在在增加功能中,gtk_label_set_text()
函数需要一个数据类型GtkLabel
作为它的第一个参数,但我只看到一个GtkWidget
变量和一个空指针label
作为增量函数的参数。如果那样gtk_label_set_text()是如何工作的?
谢谢,另一件事,为什么我们包括它与
malloc
分配内存时,它返回一个void*
很常见增加函数中的`GtkWidget *小部件?“。 – silent 2010-12-05 08:39:53