support zoom and move image by mouse.

ui/file_manager/gallery/js/slide_mode.js

Index: ui/file_manager/gallery/js/slide_mode.js
diff --git a/ui/file_manager/gallery/js/slide_mode.js b/ui/file_manager/gallery/js/slide_mode.js
index a550d201a91c9d1e8fe7717b7eca3cc60db54a11..9e15dcfd2d7c6bf543c794336d7f01a9cadced25 100644
--- a/ui/file_manager/gallery/js/slide_mode.js
+++ b/ui/file_manager/gallery/js/slide_mode.js
@@ -1826,6 +1826,13 @@ function TouchHandler(targetElement, slideMode) {
   this.touchStarted_ = false;
 
   /**
+   * Whether the element is being clicked now or not.
+   * @type {boolean}
+   * @private
+   */
+  this.clickStarted_ = false;
+
+  /**
    * The swipe action that should happen only once in an operation is already
    * done or not.
    * @type {boolean}
@@ -1867,6 +1874,11 @@ function TouchHandler(targetElement, slideMode) {
   targetElement.ownerDocument.addEventListener('touchmove', onTouchEventBound);
   targetElement.ownerDocument.addEventListener('touchend', onTouchEventBound);
 
+  targetElement.addEventListener('mousedown', this.onMouseDown_.bind(this));
+  targetElement.ownerDocument.addEventListener('mousemove',
+      this.onMouseMove_.bind(this));
+  targetElement.ownerDocument.addEventListener('mouseup',
+      this.onMouseUp_.bind(this));
   targetElement.addEventListener('mousewheel', this.onMouseWheel_.bind(this));
 }
 
@@ -2049,11 +2061,79 @@ TouchHandler.prototype.onTouchEvent_ = function(event) {
 TouchHandler.prototype.onMouseWheel_ = function(event) {
   var event = assertInstanceof(event, MouseEvent);
   var viewport = this.slideMode_.getViewport();
-  if (!this.enabled_ || !viewport.isZoomed())
+  if (!this.enabled_)
     return;
+
   this.stopOperation();
-  viewport.setOffset(
-      viewport.getOffsetX() + event.wheelDeltaX,
-      viewport.getOffsetY() + event.wheelDeltaY);
-  this.slideMode_.applyViewportChange();
+  this.lastZoom_ = viewport.getZoom();
+  var zoom = this.lastZoom_;
+  if (event.wheelDeltaY > 0) {
+    zoom = zoom * 1.05;
+  } else {
+    zoom = zoom / 1.05;
+  }
+  viewport.setZoom(zoom);
+  this.slideMode_.imageView_.applyViewportChange();
+};
+
+/**
+ * Handles mouse wheel events.
+ * @param {!Event} event Wheel event.
+ * @private
+ */
+TouchHandler.prototype.onMouseWheel_ = function(event) {

[hirono, 2016/02/06 07:27:59]

nit: It looks we have two onMouseWheel_.

[ryoh, 2016/02/08 04:58:01]

Done.

+  var event = assertInstanceof(event, MouseEvent);
+  var viewport = this.slideMode_.getViewport();
+  if (!this.enabled_)
+    return;
+
+  this.stopOperation();
+  this.lastZoom_ = viewport.getZoom();
+  var zoom = this.lastZoom_;
+  if (event.wheelDeltaY > 0) {
+    zoom = zoom * 1.05;
+  } else {
+    zoom = zoom / 1.05;
+  }
+  viewport.setZoom(zoom);
+  this.slideMode_.imageView_.applyViewportChange();
 };
+
+/**
+ * Handles mouse down events.
+ * @param {!Event} event Wheel event.
+ * @private
+ */
+TouchHandler.prototype.onMouseDown_ = function(event) {
+  var event = assertInstanceof(event, MouseEvent);
+  var viewport = this.slideMode_.getViewport();
+  if (!this.enabled_)
+    return;
+  this.clickStarted_ = true;
+}
+
+/**
+ * Handles mouse move events.
+ * @param {!Event} event Wheel event.
+ * @private
+ */
+TouchHandler.prototype.onMouseMove_ = function(event) {
+  var event = assertInstanceof(event, MouseEvent);
+  var viewport = this.slideMode_.getViewport();
+  if (!this.enabled_ || !this.clickStarted_)
+    return;
+  viewport.setOffset(
+      viewport.getOffsetX() + event.movementX,
+      viewport.getOffsetY() + event.movementY);
+  this.slideMode_.imageView_.applyViewportChange();
+  console.log(event);
+}
+
+/**
+ * Handles mouse up events.
+ * @param {!Event} event Wheel event.
+ * @private
+ */
+TouchHandler.prototype.onMouseUp_ = function(event) {
+  this.clickStarted_ = false;
+}