Q: custom GtkOverlay's child (GtkRevealer) position

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1

Hi everyone,

that’s about positioning GtkRevealer child with in GtkOvelay at some custom position:
is there any function in user space that indicate necessity for gtk_widget_measure() calls?
(something like gtk_widget_get_resize_needed())

example of code with that:

g_signal_connect(overlay, "get-child-position", G_CALLBACK(nt_legend_pos_cb), nt);
...

static gboolean nt_legend_pos_cb(GtkOverlay *overlay, GtkWidget *widget, GdkRectangle *r, t_notifier *nt) {
  if (GTK_IS_OVERLAY(overlay) && r && nt) {
    if (GTK_IS_WIDGET(widget) /* && gtk_widget_get_resize_needed(widget) */) {
      int unused;
      gtk_widget_measure(widget, GTK_ORIENTATION_HORIZONTAL, -1, &unused, NULL, NULL, NULL);
      gtk_widget_measure(widget, GTK_ORIENTATION_VERTICAL,   -1, &unused, NULL, NULL, NULL);
    }
    r->x = nt->x; r->y = nt->y;
    return true;
  }
  return false;
}
2

What are you trying to achieve? :slight_smile:

3

  • callback from g_signal_connect(, “get-child-position”,) is used to put a child widget in custom x,y position

  • gtk_widget_measure() is used to get rid of “Allocating size to GtkRevealer 0x… without calling gtk_widget_measure(). How does the code know the size to allocate?” messages

4

Hmm… looks like the underlying issue is that the callback nt_legend_pos_cb is supposed to return a valid allocation, but here I don’t see any width or height returned, so that’s probably why gtk complains the measurement was missing (the resulting allocation is basically null).

I don’t think you need to call gtk_widget_measure(), instead try to do something like

r->width  = gtk_widget_get_width (widget);
r->height = gtk_widget_get_height (widget);

(of course, adapt to what you want the widget to look like)

5

Width and height are not supposed to be changed by shifting x,y position, and it’s already valid at the time of callback call. The only reason of gtk_widget_measure call there is to get rid of annoying “Allocating size to … without calling gtk_widget_measure()” message.

For example with

static gboolean nt_legend_pos_cb(GtkOverlay *overlay, GtkWidget *widget, GdkRectangle *r, t_notifier *nt) {
  if (GTK_IS_OVERLAY(overlay) && r && nt) {
    if (GTK_IS_WIDGET(widget) /* && gtk_widget_get_resize_needed(widget) */) {
//      int unused;
//      gtk_widget_measure(widget, GTK_ORIENTATION_HORIZONTAL, -1, &unused, NULL, NULL, NULL);
//      gtk_widget_measure(widget, GTK_ORIENTATION_VERTICAL,   -1, &unused, NULL, NULL, NULL);
      g_print(">>> at %d,%d size of %dx%d\n", r->x, r->y, r->width, r->height);
      gtk_widget_get_width(widget);
      gtk_widget_get_height(widget);
    }
    r->x = nt->x; r->y = nt->y;
    return true;
  }
  return false;
}

there's still that message offering to call `gtk_widget_measure()` beforehand 
>>> at 0,0 size of 1022x613

(pingpath:202688): Gtk-WARNING **: 02:31:08.811: Allocating size to GtkRevealer 0x55bb96152df0 without calling gtk_widget_measure(). How does the code know the size to allocate?
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613
>>> at 0,0 size of 1022x613

With uncommented back `gtk_widget_measure()` call, that warning message is gone. And it's the reason why `gtk_widget_get_resize_needed` is asked for.

Is there any other ways (except of "get-child-position" callback) to put a revealing widget at x,y without changing its size?
6

p.s.
will that be okay to use gtk_widget_get_width()/_height() instead of gtk_widget_get_resize_needed()
as an indicator to call gtk_widget_measure() there?

static gboolean nt_legend_pos_cb(GtkOverlay *overlay, GtkWidget *widget, GdkRectangle *r, t_notifier *nt) {
  if (GTK_IS_OVERLAY(overlay) && r && nt) {
    if (GTK_IS_WIDGET(widget)) {
      if (!gtk_widget_get_width(widget))
        gtk_widget_measure(widget, GTK_ORIENTATION_HORIZONTAL, -1, NULL, NULL, NULL, NULL);
      if (!gtk_widget_get_height(widget))
        gtk_widget_measure(widget, GTK_ORIENTATION_VERTICAL,   -1, NULL, NULL, NULL, NULL);
    }
    r->x = nt->x; r->y = nt->y;
    return true;
  }
  return false;
}
7

OK, I see, now I’m confused too…

Let’s see if someone else has a better idea about what’s going on here.

8

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