From 5a8e5314cceaa73d438c0b3f7a2fdb26ea9b3a2c Mon Sep 17 00:00:00 2001
From: Javier Sancho <jsf@jsancho.org>
Date: Tue, 14 Feb 2017 20:10:33 +0100
Subject: [PATCH] Customizing quit event behaviour

---
 .../02-event-driven-programming.scm           | 11 ++++++++-
 gacela.scm                                    |  1 +
 gacela/game.scm                               | 23 ++++++++++++++-----
 gacela/scene.scm                              |  2 +-
 4 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/examples/02-event-driven-programming/02-event-driven-programming.scm b/examples/02-event-driven-programming/02-event-driven-programming.scm
index 505f4b0..b151233 100644
--- a/examples/02-event-driven-programming/02-event-driven-programming.scm
+++ b/examples/02-event-driven-programming/02-event-driven-programming.scm
@@ -19,7 +19,16 @@
 
 (use-modules (gacela))
 
+(define counter-quit #f)
+(let ((n 0))
+  (set! counter-quit
+    (lambda ()
+      (set! n (+ n 1))
+      (format #t "Quit clicked ~a times !!~%" n)
+      (if (> n 2)
+	  (stop-game)))))
+
 (display-scene
  (window ((resolution '(640 480))
-	  (when-quit (lambda () (format #t "Quit clicked!!~%"))))
+	  (when-quit counter-quit))
    (bitmap "x.bmp")))
diff --git a/gacela.scm b/gacela.scm
index d49cbfa..90840bf 100644
--- a/gacela.scm
+++ b/gacela.scm
@@ -23,6 +23,7 @@
   (begin
     (define %public-modules
       '((gacela image)
+	(gacela game)
 	(gacela math)
 	(gacela scene)
 	(gacela window)))
diff --git a/gacela/game.scm b/gacela/game.scm
index 86136cd..48bf129 100644
--- a/gacela/game.scm
+++ b/gacela/game.scm
@@ -24,7 +24,8 @@
   #:use-module ((sdl2 video) #:prefix sdl2:)
   #:use-module (gl)
   #:use-module (srfi srfi-11)
-  #:export (play-game
+  #:export (start-game
+	    stop-game
 	    %sdl-renderer))
 
 
@@ -38,7 +39,8 @@
 (define* (run-game-loop scene #:key
                         (frame-rate 60)
                         (tick-rate 60)
-                        (max-ticks-per-frame 4))
+                        (max-ticks-per-frame 4)
+			(when-quit #f))
   "Run the game loop.  SCENE is a signal which contains the current
 scene renderer procedure.  FRAME-RATE specifies the optimal number of
 frames to draw SCENE per second.  TICK-RATE specifies the optimal game
@@ -74,6 +76,8 @@ unused accumulator time."
 	       lag)
 	      ((>= lag tick-interval)
 	       (process-events)
+	       (if (and (quit?) (procedure? when-quit))
+		   (when-quit))
 					;(agenda-tick!)
 	       (iter (- lag tick-interval) (1+ ticks)))
 	      (else
@@ -143,7 +147,7 @@ milliseconds of the last iteration of the game loop."
   (set! %gl-context (sdl2:make-gl-context %sdl-window))
   (sdl2:set-gl-swap-interval! 'vsync))
 
-(define* (open-window #:key (title "Untitled") (resolution '(640 480)) (fullscreen? #f))
+(define (open-window title resolution fullscreen?)
   (sdl2:set-window-title! %sdl-window title)
   (sdl2:set-window-size! %sdl-window resolution)
   (sdl2:set-window-fullscreen! %sdl-window fullscreen?)
@@ -153,8 +157,15 @@ milliseconds of the last iteration of the game loop."
   (sdl2:hide-window! %sdl-window)
   (sdl2:sdl-quit))
 
-(define (play-game scene . args)
+(define* (start-game scene #:key
+		    (title "Untitled")
+		    (resolution '(640 480))
+		    (fullscreen? #f)
+		    (when-quit (lambda () (stop-game))))
   (init-window)
-  (apply open-window args)
-  (run-game-loop scene)
+  (open-window title resolution fullscreen?)
+  (run-game-loop scene #:when-quit when-quit)
   (close-window))
+
+(define (stop-game)
+  (stop-game-loop))
diff --git a/gacela/scene.scm b/gacela/scene.scm
index e969432..ccdc23e 100644
--- a/gacela/scene.scm
+++ b/gacela/scene.scm
@@ -43,5 +43,5 @@
   (apply (scene-procedure scene) args))
 
 (define (run-scene scene . args)
-  (apply play-game
+  (apply start-game
 	 (cons (scene-procedure scene) args)))
-- 
2.39.2