程序内通信：GIOChannel 与 Pipe
原文：http://caterpillar.onlyfun.net/Gossip/GTKGossip/GIOChannelPipe.html
使用pipe又称为无名管道，它直接在内存中划分区域进行通信，其最大的局限就是必须在有父子关系的进程中进行通信。
另外，还有一种称之为有名管道FIFO，可以进行程序间通信。
#include<gtk/gtk.h>#include<errno.h>#include<unistd.h>void value_changed_callback(GtkSpinButton *spinButton, GIOChannel *channel);gboolean iochannel_read(GIOChannel *channel, GIOCondition condition, GtkLabel *label);void setup_parent(gint output[]);void setup_child(gint input[]);int main(int argc, char *argv[]) { gint parent_to_child; if(pipe(parent_to_child) == -1) { // 開啟Pipe g_error("Error: %s\n", g_strerror(errno)); return 1; } // fork 子程序 switch(fork()) { case -1: g_error("錯誤: %s\n", g_strerror(errno)); break; case 0: // 這是子程序 gtk_init(&argc, &argv); setup_child(parent_to_child); break; default: // 這是父程序 gtk_init(&argc, &argv); setup_parent(parent_to_child); } gtk_main(); return 0;}// GtkSpinButton的callbackvoid value_changed_callback(GtkSpinButton *spinButton, GIOChannel *channel) { GIOStatus ret_value; gint value; GString *text; gsize length; value = gtk_spin_button_get_value_as_int(spinButton); text = g_string_new(""); g_string_sprintf(text, "%d\n", value); // 寫入資料至 GIOChannel ret_value = g_io_channel_write_chars(channel, text->str, -1, &length, NULL); if(ret_value == G_IO_STATUS_ERROR) { g_error("錯誤: 無法寫入 GIOChannel ！\n"); } else { g_io_channel_flush(channel, NULL); }}gboolean iochannel_read(GIOChannel *channel, GIOCondition condition, GtkLabel *label) { GIOStatus ret_value; gchar *message; gsize length; if(condition & G_IO_HUP) { g_error("錯誤: Pipe 已中斷！\n"); } ret_value = g_io_channel_read_line(channel, &message, &length, NULL, NULL); if(ret_value == G_IO_STATUS_ERROR) { g_error("錯誤: 無法讀取！\n"); } message = 0; gtk_label_set_text(label, message); return TRUE;}void setup_parent(gint output[]) { GtkWidget *window; GtkWidget *spinButton; GIOChannel *channel_write; window = gtk_window_new(GTK_WINDOW_TOPLEVEL); gtk_window_set_title(GTK_WINDOW(window), "Parent"); gtk_window_set_default_size(GTK_WINDOW(window), 250, 50); spinButton = gtk_spin_button_new_with_range(0.0, 100.0, 1.0); gtk_container_add(GTK_CONTAINER(window), spinButton); g_signal_connect(GTK_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL); // 關閉不用的 Pipe 輸出 close(output); // 建立 GIOChannel channel_write = g_io_channel_unix_new(output); if(channel_write == NULL) { g_error("錯誤: 無法建立 GIOChannels！\n"); } g_signal_connect(G_OBJECT(spinButton), "value_changed", G_CALLBACK(value_changed_callback), (gpointer) channel_write); gtk_widget_show_all(window);}void setup_child(gint input[]) { GtkWidget *window; GtkWidget *label; GIOChannel *channel_read; window = gtk_window_new(GTK_WINDOW_TOPLEVEL); gtk_window_set_title(GTK_WINDOW(window), "Child"); gtk_window_set_default_size(GTK_WINDOW(window), 250, 50); label = gtk_label_new("0"); gtk_container_add(GTK_CONTAINER(window), label); g_signal_connect(GTK_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL); // 關閉不必要的 Pipe 輸入 close(input); channel_read = g_io_channel_unix_new(input); if(channel_read == NULL) { g_error("錯誤: 無法建立 GIOChannels！\n"); } if(!g_io_add_watch(channel_read, G_IO_IN | G_IO_HUP, (GIOFunc) iochannel_read, (gpointer) label)) { g_error("錯誤: 無法對 GIOChannel 加入 watch！\n"); } gtk_widget_show_all(window);}
結果畫面如下所示：
http://caterpillar.onlyfun.net/Gossip/GTKGossip/images/GIOChannelPipe-1.jpg
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