deploy dev version

dev/js/controller/drawing/DragHandler.js

@@ -0,0 +1,84 @@
+(function () {
+  var ns = $.namespace('pskl.controller.drawing');
+
+  /**
+   * Multiplier applied between the mouse movement and viewport movement
+   * @type {Number}
+   */
+  var MULTIPLIER = 2;
+
+  /**
+   * Dedicated handler to drag the drawing canvas using the mouse
+   * Will store the initial coordinates as well as the status of the drag
+   * @param {DrawingController} drawingController
+   */
+  ns.DragHandler = function (drawingController) {
+    this.drawingController = drawingController;
+
+    this.isDragging_ = false;
+    this.updateOrigin_(-1, -1);
+  };
+
+  /**
+   * Initialize a drag session.
+   * @param {Number} x : x coordinate of the mouse event that initiated the drag
+   * @param {Number} y : y coordinate of the mouse event that initiated the drag
+   */
+  ns.DragHandler.prototype.startDrag = function (x, y) {
+    var coords = this.drawingController.getSpriteCoordinates(x, y);
+    this.updateOrigin_(coords.x, coords.y);
+  };
+
+  /**
+   * Update the drag status
+   * @param {Number} x : x coordinate of the mouse event that triggered the update
+   * @param {Number} y : y coordinate of the mouse event that triggered the update
+   */
+  ns.DragHandler.prototype.updateDrag = function (x, y) {
+    var currentOffset = this.drawingController.getOffset();
+    var offset = this.calculateOffset_(x, y);
+    if (currentOffset.y !== offset.y || currentOffset.x !== offset.x) {
+      this.isDragging_ = true;
+      this.drawingController.setOffset(offset.x, offset.y);
+
+      // retrieve the updated coordinates after moving the sprite
+      // and store them as the new drag origin
+      var coords = this.drawingController.getSpriteCoordinates(x, y);
+      this.updateOrigin_(coords.x, coords.y);
+    }
+  };
+
+  /**
+   * Stop the drag session
+   */
+  ns.DragHandler.prototype.stopDrag = function () {
+    this.isDragging_ = false;
+    this.origin = null;
+  };
+
+  /**
+   * Will return true if the drag handler effectively MOVED the offset
+   * during the current drag session
+   */
+  ns.DragHandler.prototype.isDragging = function () {
+    return this.isDragging_;
+  };
+
+  ns.DragHandler.prototype.calculateOffset_ = function (x, y) {
+    var coords = this.drawingController.getSpriteCoordinates(x, y);
+    var currentOffset = this.drawingController.getOffset();
+
+    var offset = {
+      x : currentOffset.x - MULTIPLIER * (coords.x - this.origin.x),
+      y : currentOffset.y - MULTIPLIER * (coords.y - this.origin.y)
+    };
+
+    return offset;
+  };
+
+  ns.DragHandler.prototype.updateOrigin_ = function (x, y) {
+    this.origin = this.origin || {};
+    this.origin.x = x;
+    this.origin.y = y;
+  };
+})();