From fb65711f08770b469287f41a05f72df044db3e67 Mon Sep 17 00:00:00 2001
From: Peli de Halleux <jhalleux@microsoft.com>
Date: Mon, 14 Mar 2016 21:37:03 -0700
Subject: [PATCH] fixing scroll issues

---
 sim/libmbit.ts | 12 +++++++-----
 sim/state.ts   | 12 ++++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/sim/libmbit.ts b/sim/libmbit.ts
index 1f076143..6bd0fb49 100644
--- a/sim/libmbit.ts
+++ b/sim/libmbit.ts
@@ -92,6 +92,7 @@ namespace ks.rt.micro_bit {
     export function showDigit(v: number) {
         if (!quiet)
             console.log("DIGIT:", v)
+        plotLeds(createImageFromString(v.toString()[0]));
     }
 
     export function clearScreen() {
@@ -106,14 +107,15 @@ namespace ks.rt.micro_bit {
     function scrollImage(leds: micro_bit.Image, interval: number, stride: number): void {
         let cb = getResume()
         let off = stride > 0 ? 0 : leds.width - 1;
+        let display = board().image;
 
         board().animationQ.enqueue({
             interval: interval,
             frame: () => {
-                if (off >= leds.width || off < 0)
-                    return false;
-                let c = Math.min(5, leds.width - off);
-                leds.copyTo(off, 5, board().image, 0)
+                if (off >= leds.width || off < 0) return false;
+                stride > 0 ? display.shiftLeft(stride) : display.shiftRight(-stride);
+                let c = Math.min(stride, leds.width - off);
+                leds.copyTo(off, c, display, 5 - stride)
                 off += stride;
                 return true;
             },
@@ -129,7 +131,7 @@ namespace ks.rt.micro_bit {
         if (interval < 0) return;
 
         let leds = createImageFromString(x.toString());
-        if (x < 0 || x >= 10) scrollImage(leds, interval, 5);
+        if (x < 0 || x >= 10) scrollImage(leds, interval, 1);
         else showLeds(leds, interval * 5);
     }
 
diff --git a/sim/state.ts b/sim/state.ts
index 3992a8c9..53bbfbf0 100644
--- a/sim/state.ts
+++ b/sim/state.ts
@@ -298,6 +298,18 @@ namespace ks.rt.micro_bit {
                 }
             }
         }
+        public shiftLeft(cols: number) {
+            for(let x = 0; x < this.width;++x)
+                for(let y = 0; y < 5;++y)
+                    this.set(x, y, x < this.width - cols ? this.get(x + cols,y) : 0);
+        }
+
+        public shiftRight(cols: number) {
+            for(let x = this.width -1; x <=0;--x)
+                for(let y = 0; y < 5;++y)
+                    this.set(x, y, x > cols ? this.get(x - cols,y) : 0);
+        }
+        
         public clear(): void {
             for (var i = 0; i < this.data.length; ++i)
                 this.data[i] = 0;