Factor out sound and rendering procedures.

1 files changed, 14 insertions, 1 deletions

diff --git a/lisparuga/utils.scm b/lisparuga/utils.scm
index 0c67504..db7c1d8 100644
--- a/lisparuga/utils.scm
+++ b/lisparuga/utils.scm
@@ -15,12 +15,25 @@
 ;;; along with Lisparuga.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (lisparuga utils)
+  #:use-module (sly input keyboard)
   #:use-module (sly math rect)
   #:use-module (sly math vector)
+  #:use-module (sly signal)
   #:export (resolution
             origin2
-            bounds))
+            bounds
+            key-toggle))
 
 (define resolution (vector2 120 160))
 (define origin2 (vector2 0 0))
 (define bounds (make-rect (vector2 0 0) resolution))
+
+(define (key-toggle key)
+  "Create a signal that is initially #f and toggles between #t and #f
+each time KEY is pressed."
+  (signal-fold (lambda (down? previous)
+                 (and down? (not previous)))
+               #f
+               (signal-filter identity #f
+                              ;; Ignore repeated key down signals.
+                              (signal-drop-repeats (key-down? key)))))