gtk回调多个参数

Question

#include <gtk/gtk.h> 
#include <stdio.h> 

typedef struct { 
    const gchar *host; 
} example; 

void b_clicked (GtkButton *c_button, example *test){ 
    g_print("Hostname: %s\n", test->host); 
} 

int main (int argc, char *argv[]){ 

GtkWidget *window; 
GtkWidget *grid; 
GtkWidget *c_button; 
GtkWidget *q_button; 
GtkWidget *label_host; 
GtkWidget *h_name; 

gtk_init (&argc, &argv); 

window = gtk_window_new (GTK_WINDOW_TOPLEVEL); 
gtk_window_set_title (GTK_WINDOW (window), "FTP Client"); 
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER); 
g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL); 
gtk_container_set_border_width (GTK_CONTAINER (window), 10); 
gtk_window_set_resizable(GTK_WINDOW(window), FALSE); 

grid = gtk_grid_new(); 
gtk_container_add (GTK_CONTAINER (window), grid); 
gtk_grid_set_row_spacing (GTK_GRID (grid), 3); 

label_host = gtk_label_new("Hostname"); 

example test; 
h_name = gtk_entry_new(); 
test.host = gtk_entry_get_text(GTK_ENTRY (h_name)); 
gtk_entry_set_placeholder_text (GTK_ENTRY (h_name), "Hostname"); 
c_button = gtk_button_new_with_label ("Connect"); 
g_signal_connect (c_button, "clicked", G_CALLBACK (b_clicked), (gpointer*)&test); 
q_button = gtk_button_new_with_label ("Quit"); 
g_signal_connect (q_button, "clicked", G_CALLBACK (gtk_main_quit), NULL); 

gtk_grid_attach (GTK_GRID (grid), label_host, 0, 0, 1, 1); 
gtk_grid_attach (GTK_GRID (grid), h_name, 1, 0, 1, 1); 
gtk_grid_attach (GTK_GRID (grid), c_button, 0, 3, 2, 1); 
gtk_grid_attach (GTK_GRID (grid), q_button, 0, 4, 2, 1); 

gtk_widget_show_all (window); 

gtk_main(); 

return 0; 
} 

这是什么问题？
我没有错误，没有警告，但在终端上，该程序不能写什么:(
如果我写：

test.host="trying something" 

它的工作原理但gtk_entry_get_text它并没有显示什么:(
我不明白...为什么它不适用于gtk_entry_get_text？

Answer 1

你需要明白，GTK是一个事件驱动的工具包（就像其他很多），你需要与事件交互，但它赢得了'在你运行gtk_main之前检查事件，所以你的问题是你正在使用主机名test.host = gtk_entry_get_text(GTK_ENTRY (h_name))，但那时候，小部件还没有显示出来，甚至没有输入任何东西！所以你基本上只是从中得到一个空字符串，这就是你点击“连接”按钮时显示的内容。

做到这一点的一种方法是将指针指向结构中的小部件。这样，您可以从b_clicked回调中调用gtk_entry_get_text。这样，您获得的价值就是那个文本条目窗口小部件当时的价格。

#include <gtk/gtk.h> 
#include <stdio.h> 

typedef struct { 
     GtkWidget *host; 
} example; 

void b_clicked (GtkButton *c_button, example *test){ 
     g_print("Hostname: %s\n", gtk_entry_get_text (GTK_ENTRY(test->host))); 
} 

int main (int argc, char *argv[]){ 

     GtkWidget *window; 
     GtkWidget *grid; 
     GtkWidget *c_button; 
     GtkWidget *q_button; 
     GtkWidget *label_host; 
     GtkWidget *h_name; 

     gtk_init (&argc, &argv); 

     window = gtk_window_new (GTK_WINDOW_TOPLEVEL); 
     gtk_window_set_title (GTK_WINDOW (window), "FTP Client"); 
     gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER); 
     g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL); 
     gtk_container_set_border_width (GTK_CONTAINER (window), 10); 
     gtk_window_set_resizable(GTK_WINDOW(window), FALSE); 

     grid = gtk_grid_new(); 
     gtk_container_add (GTK_CONTAINER (window), grid); 
     gtk_grid_set_row_spacing (GTK_GRID (grid), 3); 

     label_host = gtk_label_new("Hostname"); 

     example test; 
     h_name = gtk_entry_new(); 
     test.host = h_name; 
     gtk_entry_set_placeholder_text (GTK_ENTRY (h_name), "Hostname"); 
     c_button = gtk_button_new_with_label ("Connect"); 
     g_signal_connect (c_button, "clicked", G_CALLBACK (b_clicked), &test); 
     q_button = gtk_button_new_with_label ("Quit"); 
     g_signal_connect (q_button, "clicked", G_CALLBACK (gtk_main_quit), NULL); 

     gtk_grid_attach (GTK_GRID (grid), label_host, 0, 0, 1, 1); 
     gtk_grid_attach (GTK_GRID (grid), h_name, 1, 0, 1, 1); 
     gtk_grid_attach (GTK_GRID (grid), c_button, 0, 3, 2, 1); 
     gtk_grid_attach (GTK_GRID (grid), q_button, 0, 4, 2, 1); 

     gtk_widget_show_all (window); 

     gtk_main(); 

     return 0; 
} 

另一种更好的方式来做到这一点，不修改你的结构，是要求在文本发生变化时得到通知。为此，请使用“changed”信号，因为GtkEntry实现了GtkEditable接口。参见“GtkEntry text change signal”。

请注意，(gpointer*)&test是错误的。测试是一个结构，&测试是结构的地址。 gpointer是一个void *，即。已经是一个指针了，所以gpointer *是一个指向指针的指针，这不是&测试的结果。所以只需写&test。