From 5ea8048f0cf6a1a158087f224b57db84b67f0634 Mon Sep 17 00:00:00 2001
From: Sam El-Husseini <samelh@microsoft.com>
Date: Wed, 12 Jul 2017 12:26:14 +0300
Subject: [PATCH] Limit screen updates to once every 30ms and only if needed.

---
 sim/state/screen.ts  | 3 ++-
 sim/visuals/board.ts | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/sim/state/screen.ts b/sim/state/screen.ts
index 929fd62d..8ea2a2e4 100644
--- a/sim/state/screen.ts
+++ b/sim/state/screen.ts
@@ -2,6 +2,7 @@
 namespace pxsim {
 
     export class EV3ScreenState {
+        shouldUpdate: boolean;
         points: {[x: number]: {[y: number]: number}};
         constructor() {
             this.points = {};
@@ -14,6 +15,7 @@ namespace pxsim {
             const xPoints = this.points[x]
             if (!xPoints) this.points[x] = {};
             this.points[x][y] = v;
+            this.shouldUpdate = true;
         }
     }
 }
@@ -24,7 +26,6 @@ namespace pxsim.screen {
     export function _setPixel(x: number, y: number, mode: Draw) {
         const screenState = (board() as DalBoard).screenState;
         screenState.setPixel(x, y, mode);
-        runtime.queueDisplayUpdate();
     }
 
 
diff --git a/sim/visuals/board.ts b/sim/visuals/board.ts
index 235105ef..a86ceb4e 100644
--- a/sim/visuals/board.ts
+++ b/sim/visuals/board.ts
@@ -284,6 +284,11 @@ namespace pxsim.visuals {
                 this.updateState();
                 this.attachEvents();
             }
+
+            let board = this;
+            window.setInterval(function(){
+                board.updateScreen();
+            }, 30);
         }
 
         public getView(): SVGAndSize<SVGSVGElement> {
@@ -459,6 +464,9 @@ namespace pxsim.visuals {
             let state = this.board;
             if (!state || !state.screenState) return;
 
+            if (!state.screenState.shouldUpdate) return;
+            state.screenState.shouldUpdate = false;
+
             this.screenCanvasData = this.screenCanvasCtx.getImageData(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
 
             Object.keys(state.screenState.points).forEach(xStr => {