From 0064ec20c393653a6a7c3d89d30f01ce4f615928 Mon Sep 17 00:00:00 2001
From: Vishesh Yadav <vyadav@ccs.neu.edu>
Date: Tue, 5 May 2015 15:54:16 -0400
Subject: [PATCH] Implement last-picture in world

Last picture is used to render world once it has ended. This patch
takes last-picture function and creates a ToDraw handler and calls its
listener manually when stop-when returns true.
---
 whalesong/world/js-impl.js      | 10 ++++++++--
 whalesong/world/kernel.js       | 15 +++++++++++----
 whalesong/world/racket-impl.rkt |  7 +++++--
 whalesong/world/raw-jsworld.js  | 17 +++++++++++------
 4 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/whalesong/world/js-impl.js b/whalesong/world/js-impl.js
index b32c3ce..ce0deba 100644
--- a/whalesong/world/js-impl.js
+++ b/whalesong/world/js-impl.js
@@ -87,10 +87,16 @@ EXPORTS['to-draw'] =
 EXPORTS['stop-when'] =
     makePrimitiveProcedure(
         'stop-when',
-        1,
+        plt.baselib.lists.makeList(1, 2),
         function(MACHINE) {
             var f = checkProcedure1(MACHINE, "on-tick", 0);
-            return new StopWhen(f);
+            if (MACHINE.a === 2) {
+                var lp = checkProcedure1(MACHINE, "to-draw", 1);
+            } else {
+                var lp = null;
+            }
+
+            return new StopWhen(f, lp);
         });
 
 
diff --git a/whalesong/world/kernel.js b/whalesong/world/kernel.js
index 9cf716f..8f27a40 100644
--- a/whalesong/world/kernel.js
+++ b/whalesong/world/kernel.js
@@ -282,8 +282,6 @@ ToDraw.prototype = plt.baselib.heir(OutputConfig.prototype);
  
 ToDraw.prototype.toRawHandler = function(MACHINE, toplevelNode) {
     var that = this;
-    var reusableCanvas;
-    var reusableCanvasNode;
     var adaptedWorldFunction = adaptWorldFunction(this.handler);
 
     var worldFunction = function(world, success) {
@@ -291,6 +289,12 @@ ToDraw.prototype.toRawHandler = function(MACHINE, toplevelNode) {
         adaptedWorldFunction(
             world,
             function(v) {
+                var reusableCanvas = toplevelNode.getElementsByTagName('canvas')[0];
+                var reusableCanvasNode;
+                if (reusableCanvas) {
+                    reusableCanvasNode = rawJsworld.node_to_tree(reusableCanvas);
+                }
+
                 // fixme: once jsworld supports fail continuations, use them
                 // to check the status of the scene object and make sure it's an
                 // image.
@@ -325,6 +329,7 @@ ToDraw.prototype.toRawHandler = function(MACHINE, toplevelNode) {
     };
 
     var cssFunction = function(w, k) { 
+        var reusableCanvas = toplevelNode.getElementsByTagName('canvas')[0];
         if (reusableCanvas) {
  	    k([[reusableCanvas, 
                 ["padding", "0px"],
@@ -369,9 +374,10 @@ DefaultDrawingOutput.prototype.toRawHandler = function(MACHINE, toplevelNode) {
 
 
 
-var StopWhen = function(handler) {
+var StopWhen = function(handler, last_picture) {
     WorldConfigOption.call(this, 'stop-when');
     this.handler = handler;
+    this.last_picture = new ToDraw(last_picture);
 };
 
 StopWhen.prototype = plt.baselib.heir(WorldConfigOption.prototype);
@@ -379,5 +385,6 @@ StopWhen.prototype = plt.baselib.heir(WorldConfigOption.prototype);
 StopWhen.prototype.toRawHandler = function(MACHINE, toplevelNode) {
     var that = this;
     var worldFunction = adaptWorldFunction(that.handler);
-    return rawJsworld.stop_when(worldFunction);
+    var lastPictureHandler = that.last_picture.toRawHandler(MACHINE, toplevelNode);
+    return rawJsworld.stop_when(worldFunction, undefined, lastPictureHandler);
 };
diff --git a/whalesong/world/racket-impl.rkt b/whalesong/world/racket-impl.rkt
index 25ac53e..596b52f 100644
--- a/whalesong/world/racket-impl.rkt
+++ b/whalesong/world/racket-impl.rkt
@@ -40,5 +40,8 @@
 (define (key=? key-1 key-2)
   (error 'key=? "must be run in JavaScript context"))
 
-(define (stop-when handler)
-  (error 'stop-when "must be run in JavaScript context"))
+(define stop-when
+  (case-lambda [(handler)
+                (error 'stop-when "must be run in JavaScript context")]
+               [(handler last-picture)
+                (error 'stop-when "must be run in JavaScript context")]))
diff --git a/whalesong/world/raw-jsworld.js b/whalesong/world/raw-jsworld.js
index 26f801e..4e91d25 100644
--- a/whalesong/world/raw-jsworld.js
+++ b/whalesong/world/raw-jsworld.js
@@ -663,9 +663,13 @@ var rawJsworld = {};
             stopWhen.test(w,
                           function(stop) {
                               if (stop) {
-                                  Jsworld.shutdown({cleanShutdown: true});
-                              }
-                              else { k2(); }
+                                  var handler = stopWhen.last_picture_handler();
+                                  handler.onRegister(top);
+                                  handler._listener(w, oldW, function(v) {
+                                      Jsworld.shutdown({cleanShutdown: true});
+                                      k2();
+                                  })
+                              } else { k2(); }
                           });
         };
         add_world_listener(watchForTermination);
@@ -863,17 +867,18 @@ var rawJsworld = {};
 
 
 
-    StopWhenHandler = function(test, receiver) {
+    StopWhenHandler = function(test, receiver, last_picture_handler) {
         this.test = test;
         this.receiver = receiver;
+        this.last_picture_handler = last_picture_handler;
     };
     // stop_when: CPS(world -> boolean) CPS(world -> boolean) -> handler
-    function stop_when(test, receiver) {
+    function stop_when(test, receiver, last_picture_handler) {
         return function() {
             if (receiver === undefined) {
                 receiver = function(w, k) { k(w); };
             }
-            return new StopWhenHandler(test, receiver);
+            return new StopWhenHandler(test, receiver, last_picture_handler);
         };
     }
     Jsworld.stop_when = stop_when;