compositor: Add internal support to track idle inhibition requests

Adds a helper routine weston_output_inhibited_outputs() which returns a
mask of outputs that should inhibit screen idling.

Use this routine to check for inhibiting outputs for handling of idle
behaviors in core:  In sleep mode, only halt repainting outputs that
don't have valid inhibits.  Don't send these monitors DPMS off commands
either, if the system would otherwise be powering them down.

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>

v5: Drop unused view variable

libweston/compositor.c

@@ -485,6 +485,8 @@ weston_surface_create(struct weston_compositor *compositor)
 
 	wl_list_init(&surface->pointer_constraints);
 
+	surface->inhibit_idling = false;
+
 	return surface;
 }
 
@@ -2320,15 +2322,42 @@ weston_output_schedule_repaint_reset(struct weston_output *output)
 	TL_POINT("core_repaint_exit_loop", TLP_OUTPUT(output), TLP_END);
 }
 
+/** Retrieves a mask of outputs that should inhibit screensaving
+ *
+ * \param compositor The compositor instance.
+ * \return An output mask indicating the ids of all inhibiting outputs
+ *
+ *  Checks for surfaces whose clients have requested that they
+ *  disable the screenserver and display powersaving.  Note
+ *  the output ids for these surfaces.
+ */
+WL_EXPORT uint32_t
+weston_compositor_inhibited_outputs(struct weston_compositor *compositor)
+{
+	struct weston_view *view;
+	uint32_t inhibited_outputs_mask = 0;
+
+	wl_list_for_each(view, &compositor->view_list, link) {
+		/* Does the view's surface inhibit this output? */
+		if (!view->surface->inhibit_idling)
+			continue;
+
+		inhibited_outputs_mask |= view->output_mask;
+	}
+	return inhibited_outputs_mask;
+}
+
 static int
 output_repaint_timer_handler(void *data)
 {
 	struct weston_output *output = data;
 	struct weston_compositor *compositor = output->compositor;
+	uint32_t inhibited_outputs_mask = weston_compositor_inhibited_outputs(compositor);
 
 	if (output->repaint_needed &&
-	    compositor->state != WESTON_COMPOSITOR_SLEEPING &&
 	    compositor->state != WESTON_COMPOSITOR_OFFSCREEN &&
+	    (compositor->state != WESTON_COMPOSITOR_SLEEPING
+	     || inhibited_outputs_mask & (1 << output->id)) &&
 	    weston_output_repaint(output) == 0)
 		return 0;
 
@@ -2450,9 +2479,15 @@ weston_output_schedule_repaint(struct weston_output *output)
 {
 	struct weston_compositor *compositor = output->compositor;
 	struct wl_event_loop *loop;
+	uint32_t inhibited_outputs_mask = weston_compositor_inhibited_outputs(compositor);
 
-	if (compositor->state == WESTON_COMPOSITOR_SLEEPING ||
-	    compositor->state == WESTON_COMPOSITOR_OFFSCREEN)
+	/* If we're offscreen, or if we're sleeping and the monitor
+	 * isn't currently being inhibited by an active surface, then
+	 * skip repainting.
+	 */
+	if (compositor->state == WESTON_COMPOSITOR_OFFSCREEN ||
+	    (compositor->state == WESTON_COMPOSITOR_SLEEPING &&
+	     !(inhibited_outputs_mask & (1 << output->id))))
 		return;
 
 	if (!output->repaint_needed)
@@ -3902,10 +3937,19 @@ weston_compositor_dpms(struct weston_compositor *compositor,
 		       enum dpms_enum state)
 {
         struct weston_output *output;
+	uint32_t inhibited_outputs_mask = weston_compositor_inhibited_outputs(compositor);
 
-        wl_list_for_each(output, &compositor->output_list, link)
-		if (output->set_dpms)
-			output->set_dpms(output, state);
+	wl_list_for_each(output, &compositor->output_list, link) {
+		if (!output->set_dpms)
+			continue;
+
+		/* If output is idle-inhibited, don't toggle to any DPMS state except ON. */
+		if (state != WESTON_DPMS_ON &&
+		    inhibited_outputs_mask & (1 << output->id))
+			continue;
+
+		output->set_dpms(output, state);
+	}
 }
 
 /** Restores the compositor to active status

libweston/compositor.h

@@ -1155,6 +1155,14 @@ struct weston_surface {
 
 	/* An list of per seat pointer constraints. */
 	struct wl_list pointer_constraints;
+
+	/*
+	 * Indicates the surface prefers no screenblanking, screensaving,
+	 * or other automatic obscurement to kick in while the surface is
+	 * considered "active" by the shell.
+	 */
+	bool inhibit_idling;
+
 };
 
 struct weston_subsurface {
@@ -1331,6 +1339,8 @@ void
 weston_output_schedule_repaint(struct weston_output *output);
 void
 weston_output_damage(struct weston_output *output);
+uint32_t
+weston_compositor_inhibited_outputs(struct weston_compositor *compositor);
 void
 weston_compositor_schedule_repaint(struct weston_compositor *compositor);
 void