Make sure to copy arrays when using render queue

This commit ensures that input arrays are copied to new storage when
they are pushed onto the render queue.  This ensures that they are
not overwritten before they are eventually used.

Fixes #571

include/display.js

@@ -471,9 +471,14 @@ var Display;
 
         blitImage: function (x, y, width, height, arr, offset, from_queue) {
             if (this._renderQ.length !== 0 && !from_queue) {
+                // NB(directxman12): it's technically more performant here to use preallocated arrays,
+                // but it's a lot of extra work for not a lot of payoff -- if we're using the render queue,
+                // this probably isn't getting called *nearly* as much
+                var new_arr = new Uint8Array(width * height * 4);
+                new_arr.set(new Uint8Array(arr.buffer, 0, new_arr.length));
                 this.renderQ_push({
                     'type': 'blit',
-                    'data': arr,
+                    'data': new_arr,
                     'x': x,
                     'y': y,
                     'width': width,
@@ -488,9 +493,14 @@ var Display;
 
         blitRgbImage: function (x, y , width, height, arr, offset, from_queue) {
             if (this._renderQ.length !== 0 && !from_queue) {
+                // NB(directxman12): it's technically more performant here to use preallocated arrays,
+                // but it's a lot of extra work for not a lot of payoff -- if we're using the render queue,
+                // this probably isn't getting called *nearly* as much
+                var new_arr = new Uint8Array(width * height * 4);
+                new_arr.set(new Uint8Array(arr.buffer, 0, new_arr.length));
                 this.renderQ_push({
                     'type': 'blitRgb',
-                    'data': arr,
+                    'data': new_arr,
                     'x': x,
                     'y': y,
                     'width': width,
@@ -506,7 +516,7 @@ var Display;
 
         blitRgbxImage: function (x, y, width, height, arr, offset, from_queue) {
             if (this._renderQ.length !== 0 && !from_queue) {
-                // NB(directxman12): it's technically more performant here to use preallocated arrays, but it
+                // NB(directxman12): it's technically more performant here to use preallocated arrays,
                 // but it's a lot of extra work for not a lot of payoff -- if we're using the render queue,
                 // this probably isn't getting called *nearly* as much
                 var new_arr = new Uint8Array(width * height * 4);