Refactor tutorial 02

02/tutorial-02.lisp

@@ -1,8 +1,8 @@
-(defpackage #:sdl2-tutorial-2
-  (:use :common-lisp)
-  (:export :main))
+(defpackage #:sdl2-tutorial-02
+  (:use :cl)
+  (:export :run))
 
-(in-package :sdl2-tutorial-2)
+(in-package :sdl2-tutorial-02)
 
 (defparameter *screen-width* 640)
 (defparameter *screen-height* 480)
@@ -17,14 +17,18 @@
        (let ((,surface (sdl2:get-window-surface ,window)))
          ,@body))))
 
-(defun main(&key (delay 2000))
+(defun load-image (pathname)
+  (let* ((fullpath (merge-pathnames pathname (asdf:system-source-directory :sdl2-tutorial)))
+         (image (sdl2:load-bmp fullpath)))
+    (if (autowrap:wrapper-null-p image)
+        (error "cannot load image ~a (check that file exists)" fullpath)
+        image)))
+
+(defun run()
   (with-window-surface (window screen-surface)
-    (sdl2:blit-surface (sdl2:load-bmp "2/hello_world.bmp")
-                       nil
-                       screen-surface
-                       nil)
-    (sdl2:update-window window)
-    (sdl2:with-event-loop (:method :poll)
-      (:quit () t)
-      (:idle ()
-	     (sdl2:delay delay)))))
+    (let ((image (load-image #p"./02/hello_world.bmp")))
+      (sdl2:blit-surface image nil screen-surface nil)
+      (sdl2:update-window window)
+      (sdl2:delay 2000)
+      ;; clean up
+      (sdl2:free-surface image))))