From 8e8a573876b00d74db520ea5609294628c02e5c9 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Thu, 25 Nov 2021 17:52:27 +0900
Subject: [PATCH] [input] Add listeners to buttons

The listener is invoked when the button state changes.
---
 include/QF/input/binding.h | 13 +++++++++++++
 libs/input/in_button.c     | 26 ++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/QF/input/binding.h b/include/QF/input/binding.h
index ddcb4c35a..704cd61e7 100644
--- a/include/QF/input/binding.h
+++ b/include/QF/input/binding.h
@@ -31,6 +31,7 @@
 
 #ifndef __QFCC__
 
+#include "QF/listener.h"
 #include "QF/mathlib.h"
 
 /*** Recipe for converting an axis to a floating point value.
@@ -114,10 +115,18 @@ typedef enum {
 typedef struct in_button_s {
 	int         down[2];    ///< button ids holding this button down
 	int         state;      ///< in_button_state
+	struct button_listener_set_s *listeners;
 	const char *name;
 	const char *description;
 } in_button_t;
 
+typedef struct button_listener_set_s LISTENER_SET_TYPE (in_button_t)
+	button_listener_set_t;
+
+/*** Function type for button listeners.
+*/
+typedef void (*button_listener_t) (void *data, const in_button_t *button);
+
 typedef struct in_axisbinding_s {
 	in_recipe_t *recipe;
 	in_axis_t   *axis;
@@ -307,6 +316,10 @@ int IN_RegisterButton (in_button_t *button);
 int IN_RegisterAxis (in_axis_t *axis);
 in_button_t *IN_FindButton (const char *name);
 in_axis_t *IN_FindAxis (const char *name);
+void IN_ButtonAddListener (in_button_t *button, button_listener_t listener,
+						   void *data);
+void IN_ButtonRemoveListener (in_button_t *button, button_listener_t listener,
+							  void *data);
 
 struct IE_event_s;
 int IN_Binding_HandleEvent (const struct IE_event_s *ie_event);
diff --git a/libs/input/in_button.c b/libs/input/in_button.c
index 17cfc5944..15d28160d 100644
--- a/libs/input/in_button.c
+++ b/libs/input/in_button.c
@@ -87,6 +87,9 @@ button_press (in_button_t *button, int id)
 		return;
 	}
 	button->state |= inb_down | inb_edge_down;
+	if (button->listeners) {
+		LISTENER_INVOKE (button->listeners, button);
+	}
 }
 
 static void
@@ -118,6 +121,9 @@ button_release (in_button_t *button, int id)
 	}
 	button->state &= ~inb_down;			// now up
 	button->state |= inb_edge_up;
+	if (button->listeners) {
+		LISTENER_INVOKE (button->listeners, button);
+	}
 }
 
 void
@@ -196,6 +202,26 @@ IN_FindButton (const char *name)
 	return 0;
 }
 
+void
+IN_ButtonAddListener (in_button_t *button, button_listener_t listener,
+					  void *data)
+{
+	if (!button->listeners) {
+		button->listeners = malloc (sizeof (*button->listeners));
+		LISTENER_SET_INIT (button->listeners, 8);
+	}
+	LISTENER_ADD (button->listeners, listener, data);
+}
+
+void
+IN_ButtonRemoveListener (in_button_t *button, button_listener_t listener,
+						 void *data)
+{
+	if (button->listeners) {
+		LISTENER_REMOVE (button->listeners, listener, data);
+	}
+}
+
 static void __attribute__((constructor))
 in_button_init (void)
 {