C 和 GTK g_signal_connect 传递参数

Question

无法让 g_signal_connect 正确传递参数。可能是因为我不理解“c_handler”或“data”参数。代码在这里:

#include <gtk/gtk.h>

// Function prototypes
void my_file_saveas();

// Function
void my_file_saveas(GtkTextBuffer *buf)
{
  // Get the start and end bounds of the buffer
  GtkTextIter start, end;
  gtk_text_buffer_get_bounds (buf, &start, &end);
}

int main(int argc, char *argv[])
{
  GtkWidget *menubar;
  GtkWidget *fileMenu;
  GtkWidget *fileMh;
  GtkWidget *saveasMi;

  GtkWidget *view;
  GtkTextBuffer *buffer;
  GtkWidget *scroll_window;
  GtkWidget *vbox;

  GtkWidget *window;

  // Call this function first
  gtk_init(&argc, &argv);

  // Create widgets
  menubar = gtk_menu_bar_new();
  fileMenu = gtk_menu_new();
  fileMh = gtk_menu_item_new_with_label("File");
  saveasMi = gtk_menu_item_new_with_label("Save As");

  view = gtk_text_view_new();
  buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));

  // Set out the menubar
  gtk_menu_shell_append(GTK_MENU_SHELL(fileMenu), saveasMi);
  gtk_menu_item_set_submenu(GTK_MENU_ITEM(fileMh), fileMenu);
  gtk_menu_shell_append(GTK_MENU_SHELL(menubar), fileMh);

  // Create a scroll window and add the view to it
  scroll_window = gtk_scrolled_window_new (NULL, NULL);
  gtk_container_add(GTK_CONTAINER(scroll_window), view);

  // Create a vertical box and add the menubar and scroll_window
  vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
  gtk_box_pack_start(GTK_BOX(vbox), menubar, FALSE, FALSE, 0);
  gtk_box_pack_start(GTK_BOX(vbox), scroll_window, TRUE, TRUE, 0);

  // Setup top level window
  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), 640, 480);

  // Put the box in the top level window
  gtk_container_add(GTK_CONTAINER(window), vbox);

  // Events
  g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);
  g_signal_connect(G_OBJECT(saveasMi), "activate", G_CALLBACK(my_file_saveas), buffer);

  // Display the window
  gtk_widget_show_all(window);

  // Runs main
  gtk_main();

  return 0;
}

编译成功。但我运行时的输出在这里:

graeme@graeme-HP-xw4300-Workstation ~/c/test $ ./ed10

(ed10:2974): Gtk-CRITICAL **: gtk_text_buffer_get_bounds: assertion 'GTK_IS_TEXT_BUFFER (buffer)' failed

Answer 1

您的错误是不言自明的(有点):

(debugsig:26923): Gtk-CRITICAL **: gtk_text_buffer_get_bounds: 
assertion 'GTK_IS_TEXT_BUFFER (buffer)' failed

查看您的代码 - 您没有声明独立的 GTK_TEXT_BUFFER(例如 GtkTextBuffer *)。 gtk_text_view_new 将提供默认缓冲区，但如果您独立声明缓冲区，则也可以使用 gtk_text_view_new_with_buffer (buffer)，例如gtk_text_buffer_new (NULL);(您将获得一个带有 gtk_text_view_new 或 gtk_text_view_new_with_buffer (NULL); 的默认缓冲区)。你的选择...，你所拥有的将会起作用。

你真正的问题是你的回调函数原型(prototype)是错误的，它应该包含你的menuitem(这是真正的问题，它正在占用你的缓冲区 作为 GtkMenuItem 导致错误 'GTK_IS_TEXT_BUFFER (buffer)' failed)，例如

void my_file_saveas (GtkMenuItem *menuitem, gpointer data)
{
  // Get the start and end bounds of the buffer
  GtkTextBuffer *buf = GTK_TEXT_BUFFER (data);
  GtkTextIter start, end;
  gtk_text_buffer_get_bounds (buf, &start, &end);

  /* print the number of lines to stdout */
  g_print ("Buffer has %d lines.\n", gtk_text_iter_get_line (&end) -
            gtk_text_iter_get_line (&start) + 1);

  if (menuitem) {}  /* stub to suppress warning of unused menuitem */
}

坦率地说，我不敢相信它可以让你编译时没有错误(或警告)，但它确实如此，我编译时使用:

gcc -Wall -Wextra -pedantic -finline-functions -std=gnu11 ...

它也让我用不正确的原型(prototype)进行编译 - 将我绕在轴上一点:)

这是您的代码的工作示例:

#include <gtk/gtk.h>

// Function
void my_file_saveas (GtkMenuItem *menuitem, gpointer data)
{
  // Get the start and end bounds of the buffer
  GtkTextBuffer *buf = GTK_TEXT_BUFFER (data);
  GtkTextIter start, end;
  gtk_text_buffer_get_bounds (buf, &start, &end);
  g_print ("Buffer has %d lines.\n", gtk_text_iter_get_line (&end) -
            gtk_text_iter_get_line (&start) + 1);

  if (menuitem) {}  /* stub to suppress warning of unused menuitem */
}

int main(int argc, char *argv[])
{
  GtkWidget *menubar;
  GtkWidget *fileMenu;
  GtkWidget *fileMh;
  GtkWidget *saveasMi;

  GtkWidget *view;
  GtkTextBuffer *buffer = NULL;
  GtkWidget *scroll_window;
  GtkWidget *vbox;

  GtkWidget *window;

  // Call this function first
  gtk_init(&argc, &argv);

  // Create widgets
  menubar = gtk_menu_bar_new();
  fileMenu = gtk_menu_new();
  fileMh = gtk_menu_item_new_with_label("File");
  saveasMi = gtk_menu_item_new_with_label("Save As");

  /** example declaring independent buffer 
   *
   *  buffer = gtk_text_buffer_new (NULL);
   *  view = gtk_text_view_new_with_buffer(buffer);
   */
  view = gtk_text_view_new();
  buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));
  if (!view || !buffer) {
    g_print ("error - no view or buf.\n");
    return 1;
  }

  // Set out the menubar
  gtk_menu_shell_append(GTK_MENU_SHELL(fileMenu), saveasMi);
  gtk_menu_item_set_submenu(GTK_MENU_ITEM(fileMh), fileMenu);
  gtk_menu_shell_append(GTK_MENU_SHELL(menubar), fileMh);

  // Create a scroll window and add the view to it
  scroll_window = gtk_scrolled_window_new (NULL, NULL);
  gtk_container_add(GTK_CONTAINER(scroll_window), view);

  // Create a vertical box and add the menubar and scroll_window
  vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
  gtk_box_pack_start(GTK_BOX(vbox), menubar, FALSE, FALSE, 0);
  gtk_box_pack_start(GTK_BOX(vbox), scroll_window, TRUE, TRUE, 0);

  // Setup top level window
  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), 640, 480);

  // Put the box in the top level window
  gtk_container_add(GTK_CONTAINER(window), vbox);

  // Events
  g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);
  g_signal_connect(G_OBJECT(saveasMi), "activate", G_CALLBACK(my_file_saveas), 
                    buffer);

  // Display the window
  gtk_widget_show_all(window);

  // Runs main
  gtk_main();

  return 0;
}

如果您想查看更大的示例(GTK+2，但此处 100% 适用)，请查看 https://github.com/drankinatty/gtkwrite 。 (textview 和缓冲区声明位于 gtk_windef.c 中)