Question

我正在尝试使用GTK3动态更改窗口的光标，但gtk_widget_get_parent_window似乎不起作用。

有人可以指出我做错了什么吗？谢谢！

// https://developer.gnome.org/gtk3/stable/gtk-getting-started.html
// minimal example
#include <gtk/gtk.h>

static void
activate (GtkApplication* app,
          gpointer        user_data)
{
  GtkWidget *window;

  window = gtk_application_window_new (app);
  gtk_window_set_title (GTK_WINDOW (window), "Window");
  gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);

  // Here \/\/\/\/\/ .
  GdkWindow* w = gtk_widget_get_parent_window(window);
  GdkCursor* c = gdk_cursor_new_for_display(gdk_display_get_default(), GDK_WATCH);
  gdk_window_set_cursor(w, c);
  //      /\/\/\/\/\ .

  gtk_widget_show_all (window);
}

int
main (int    argc,
      char **argv)
{
  GtkApplication *app;
  int status;

  app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}

（main.exe：16508）：Gdk-CRITICAL **：gdk_window_set_cursor：断言 'GDK_IS_WINDOW（窗口）'失败

我正在使用带有msys2的GTK 3.16

非常感谢提前。

Answer 1

扩展@andlabs评论

在将窗口小部件添加到窗口小部件层次结构或GTK术语realized之后，需要尝试更改光标。

在为窗口小部件触发gtk_widget_get_parent_window()事件之前调用gtk_widget_get_window()甚至realize将导致两种情况下都出现NULL指针。

与@andlabs一样，将gtk_widget_get_window()与GtkWindow结合使用会更安全。

解决方案。

static GdkWindow* G_WINDOW = 0;
static GdkCursor* G_CURSOR = 0;

// call after WindowRealize()
void changecursor()
{
     assert(G_WINDOW != NULL);
     gdk_window_set_cursor(G_WINDOW, G_CURSOR);
}

static void WindowRealize(GtkWidget *window, gpointer data)
{
    G_CURSOR_HAND = gdk_cursor_new_for_display(gdk_display_get_default(), GDK_HAND2);
    G_WINDOW = gtk_widget_get_window(window);
}

static void activate(GtkApplication* app,gpointer user_data)
{
    GtkWidget *window = gtk_application_window_new(app);
    ...
    g_signal_connect(window, "realize", G_CALLBACK(WindowRealize), NULL);
    gtk_widget_show_all (window);
}

无法使用GTK3更改光标

1 个答案: