如何在GTK3中的GtkDrawingArea上更改鼠标光标? [英] How do I change the mouse cursor over a GtkDrawingArea in GTK3?

问题描述

这是我以前的代码来自zetcode.到目前为止，我已经得到:

This follows from my previous question, I am trying to set the mouse cursor to cross hair when hovering over a GtkDrawingArea. I am trying to apply the answer from ebassi to the following code from zetcode. So far I have got:

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

static void do_drawing(cairo_t *);


struct {
  int count;
  double coordx[100];
  double coordy[100];
} glob;


static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr, 
    gpointer user_data)
{
  do_drawing(cr);

  return FALSE;
}


static void do_drawing(cairo_t *cr)
{
  cairo_set_source_rgb(cr, 0, 0, 0);
  cairo_set_line_width(cr, 0.5);

  int i, j;
  for (i = 0; i <= glob.count - 1; i++ ) {
      for (j = 0; j <= glob.count - 1; j++ ) {
          cairo_move_to(cr, glob.coordx[i], glob.coordy[i]);
          cairo_line_to(cr, glob.coordx[j], glob.coordy[j]);
      }
  }

  glob.count = 0;
  cairo_stroke(cr);    
}


static gboolean
on_crossing (GtkWidget *darea, GdkEventCrossing *event)
{
  switch (gdk_event_get_event_type (event))
    {
    case GDK_ENTER_NOTIFY:
      printf("Yey!");
      break;

    case GDK_LEAVE_NOTIFY:
      printf("Whooo!");
      break;
    }
}

static gboolean clicked(GtkWidget *widget, GdkEventButton *event,
    gpointer user_data)
{
    if (event->button == 1) {
        glob.coordx[glob.count] = event->x;
        glob.coordy[glob.count++] = event->y;
    }

    if (event->button == 3) {
        gtk_widget_queue_draw(widget);
    }

    return TRUE;
}


int main(int argc, char *argv[])
{
  GtkWidget *window;
  GtkWidget *darea;

  glob.count = 0;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

  darea = gtk_drawing_area_new();
  gtk_container_add(GTK_CONTAINER(window), darea);

  gtk_widget_set_has_window (GTK_WIDGET (darea), TRUE);

  int crossing_mask = GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK;


  gtk_widget_add_events (GTK_WIDGET (darea), crossing_mask);
  gtk_widget_add_events(window, GDK_BUTTON_PRESS_MASK);

  g_signal_connect (darea, "enter-notify-event", G_CALLBACK (on_crossing), NULL);
  g_signal_connect (darea, "leave-notify-event", G_CALLBACK (on_crossing), NULL);
  g_signal_connect(G_OBJECT(darea), "draw", 
      G_CALLBACK(on_draw_event), NULL); 
  g_signal_connect(window, "destroy",
      G_CALLBACK(gtk_main_quit), NULL);  

  g_signal_connect(window, "button-press-event", 
      G_CALLBACK(clicked), NULL);

  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 400, 300); 
  gtk_window_set_title(GTK_WINDOW(window), "Lines");

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

但是，它没有编译，gcc 5.3.0会告诉错误:

However, it is not compiling, gcc 5.3.0 tells the error:

 undefined reference to `gdk_event_get_event_type'

我在做什么错了?

我正在使用MinGW在Win10机器上工作.我尚未尝试在GNU/Linux系统中进行编译.

I am working on a Win10 machine, using MinGW. I have not tried yet to compile this in a GNU/Linux system.

推荐答案

未定义的引用"表示您使用的GTK +版本没有 2013年9月中发布，因此表示您的版本比该版本至少早4年，并且不受支持.

"Undefined reference" means that you're using a version of GTK+ that does not have gdk_event_get_event_type(). That function was introduced in GTK+ 3.10, as the documentation specifies; 3.10.0 was released in September 2013, so it means you have a version that is at least 4 years older than that, and very much unsupported.

在我撰写此答案时，最新版本的GTK +为

The latest version of GTK+ is, at the time I'm writing this answer, 3.22.12, released in April 2017.

请按照 GTK +网站上的说明有关如何在以下位置安装GTK + Windows.

Please, follow the instructions on the GTK+ website on how to install GTK+ on Windows.

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