From 9d6eabcad45f5e871f22c56aac5bb84f4b2ddb73 Mon Sep 17 00:00:00 2001
From: Lewis Hemens <lewis@hemens.co.uk>
Date: Sun, 23 Feb 2014 21:06:37 +0000
Subject: [PATCH] Added pinch to zoom support for mobile

---
 js-lib/controller.js       |  9 ----
 js-lib/input-controller.js | 88 ++++++++++++++++++++++++++++++++++----
 2 files changed, 80 insertions(+), 17 deletions(-)

diff --git a/js-lib/controller.js b/js-lib/controller.js
index b2021d8..5d4f196 100644
--- a/js-lib/controller.js
+++ b/js-lib/controller.js
@@ -91,15 +91,6 @@ ascii.Controller.prototype.endAll = function() {
   this.lastMoveCell = null;
 };
 
-/**
- * @param {number} delta
- */
-ascii.Controller.prototype.handleZoom = function(delta) {
-  var newzoom = this.view.zoom * (delta > 0 ? 1.1 : 0.9);
-  newzoom = Math.max(Math.min(newzoom, 5), 0.2);
-  this.view.setZoom(newzoom);
-};
-
 /**
  * Installs input bindings for common use cases devices.
  */
diff --git a/js-lib/input-controller.js b/js-lib/input-controller.js
index 6d575a9..bb48af8 100644
--- a/js-lib/input-controller.js
+++ b/js-lib/input-controller.js
@@ -11,13 +11,22 @@ ascii.DesktopController = function(controller) {
   this.installBindings();
 };
 
+/**
+ * @param {number} delta
+ */
+ascii.DesktopController.prototype.handleZoom = function(delta) {
+  var newzoom = this.controller.view.zoom * (delta > 0 ? 1.1 : 0.9);
+  newzoom = Math.max(Math.min(newzoom, 5), 0.2);
+  this.controller.view.setZoom(newzoom);
+};
+
 /**
  * Installs input bindings associated with keyboard controls.
  */
 ascii.DesktopController.prototype.installBindings = function() {
   var canvas = this.controller.view.canvas;
   $(canvas).bind('mousewheel', function(e) {
-      this.controller.handleZoom(e.originalEvent.wheelDelta);
+      this.handleZoom(e.originalEvent.wheelDelta);
   }.bind(this));
 
   $(canvas).mousedown(function(e) {
@@ -53,8 +62,13 @@ ascii.TouchController = function(controller) {
   /** @type {ascii.Controller} */ this.controller = controller;
 
   /** @type {ascii.Vector} */ this.pressVector;
+
+  /** @type {number} */ this.originalZoom;
+  /** @type {number} */ this.zoomLength;
+
   /** @type {number} */ this.pressTimestamp;
   /** @type {boolean} */ this.dragStarted = false;
+  /** @type {boolean} */ this.zoomStarted = false;
 
   this.installBindings();
 };
@@ -69,12 +83,27 @@ ascii.TouchController.prototype.handlePress = function(position) {
 
   // If a drag didn't start, then handle it as a draw.
   window.setTimeout(function() {
-    if (!this.dragStarted) {
+    if (!this.dragStarted && !this.zoomStarted) {
       this.controller.startDraw(position);
     }
   }.bind(this), DRAG_LATENCY);
 };
 
+/**
+ * The multi-touch version of handlePress.
+ * @param {ascii.Vector} positionOne
+ * @param {ascii.Vector} positionTwo
+ */
+ascii.TouchController.prototype.handlePressMulti =
+    function(positionOne, positionTwo) {
+  // A second finger as been placed, cancel whatever we were doing.
+  this.controller.endAll();
+  this.zoomStarted = true;
+  this.dragStarted = false;
+  this.zoomLength = positionOne.subtract(positionTwo).length();
+  this.originalZoom = this.controller.view.zoom;
+};
+
 /**
  * @param {ascii.Vector} position
  */
@@ -90,6 +119,30 @@ ascii.TouchController.prototype.handleMove = function(position) {
   this.controller.handleMove(position);
 };
 
+/**
+ * The multi-touch version of handleMove, effectively only deals with zooming.
+ * @param {ascii.Vector} positionOne
+ * @param {ascii.Vector} positionTwo
+ */
+ascii.TouchController.prototype.handleMoveMulti =
+      function(positionOne, positionTwo) {
+  if (this.zoomStarted) {
+    var newZoom = this.originalZoom *
+        positionOne.subtract(positionTwo).length() / this.zoomLength;
+    newZoom = Math.max(Math.min(newZoom, 5), 0.5);
+    this.controller.view.setZoom(newZoom);
+  }
+};
+
+/**
+ * Ends all current actions, cleans up any state.
+ */
+ascii.TouchController.prototype.reset = function() {
+  this.dragStarted = false;
+  this.zoomStarted = false;
+  this.pressVector = null;
+};
+
 /**
  * Installs input bindings associated with touch controls.
  */
@@ -98,21 +151,40 @@ ascii.TouchController.prototype.installBindings = function() {
 
   $(canvas).bind('touchstart', function(e) {
       e.preventDefault();
-      this.handlePress(new ascii.Vector(
-         e.originalEvent.touches[0].pageX,
-         e.originalEvent.touches[0].pageY));
+      if (e.originalEvent.touches.length == 1) {
+        this.handlePress(new ascii.Vector(
+           e.originalEvent.touches[0].pageX,
+           e.originalEvent.touches[0].pageY));
+      } else if (e.originalEvent.touches.length > 1) {
+        this.handlePressMulti(new ascii.Vector(
+           e.originalEvent.touches[0].pageX,
+           e.originalEvent.touches[0].pageY),
+           new ascii.Vector(
+               e.originalEvent.touches[1].pageX,
+               e.originalEvent.touches[1].pageY));
+      }
   }.bind(this));
 
   $(canvas).bind('touchmove', function(e) {
       e.preventDefault();
-      this.handleMove(new ascii.Vector(
-         e.originalEvent.touches[0].pageX,
-         e.originalEvent.touches[0].pageY));
+      if (e.originalEvent.touches.length == 1) {
+        this.handleMove(new ascii.Vector(
+           e.originalEvent.touches[0].pageX,
+           e.originalEvent.touches[0].pageY));
+      } else if (e.originalEvent.touches.length > 1) {
+        this.handleMoveMulti(new ascii.Vector(
+           e.originalEvent.touches[0].pageX,
+           e.originalEvent.touches[0].pageY),
+           new ascii.Vector(
+               e.originalEvent.touches[1].pageX,
+               e.originalEvent.touches[1].pageY));
+      }
   }.bind(this));
 
   // Pass through, no special handling.
   $(canvas).bind('touchend', function(e) {
       e.preventDefault();
+      this.reset();
       this.controller.endAll();
   }.bind(this));
 };