From 22eb1d57b2d99a5d16ce930baa84cac932804e29 Mon Sep 17 00:00:00 2001
From: Thomas A Caswell <tcaswell@gmail.com>
Date: Sun, 11 Jan 2015 17:39:14 -0500
Subject: [PATCH] Merge pull request #3968 from blink1073/web-scroll-event

ENH : Add Support for `scroll_event` in WebAgg and NbAgg
---
 lib/matplotlib/backends/backend_webagg_core.py  |  4 +++-
 lib/matplotlib/backends/web_backend/mpl.js      | 17 ++++++++++++++++-
 .../backends/web_backend/nbagg_uat.ipynb        |  7 ++++---
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/lib/matplotlib/backends/backend_webagg_core.py b/lib/matplotlib/backends/backend_webagg_core.py
index 100437fd3b9e..d8e32c263e87 100644
--- a/lib/matplotlib/backends/backend_webagg_core.py
+++ b/lib/matplotlib/backends/backend_webagg_core.py
@@ -193,7 +193,7 @@ def handle_event(self, event):
         elif e_type == 'draw':
             self.draw()
         elif e_type in ('button_press', 'button_release', 'motion_notify',
-                        'figure_enter', 'figure_leave'):
+                        'figure_enter', 'figure_leave', 'scroll'):
             x = event['x']
             y = event['y']
             y = self.get_renderer().height - y
@@ -219,6 +219,8 @@ def handle_event(self, event):
                 self.enter_notify_event(xy=(x, y))
             elif e_type == 'figure_leave':
                 self.leave_notify_event()
+            elif e_type == 'scroll':
+                self.scroll_event(x, y, event['step'])
         elif e_type in ('key_press', 'key_release'):
             key = event['key']
 
diff --git a/lib/matplotlib/backends/web_backend/mpl.js b/lib/matplotlib/backends/web_backend/mpl.js
index a98047edbfdd..086fc0f31bd8 100644
--- a/lib/matplotlib/backends/web_backend/mpl.js
+++ b/lib/matplotlib/backends/web_backend/mpl.js
@@ -94,6 +94,8 @@ mpl.figure.prototype._init_header = function() {
     this.header = titletext[0];
 }
 
+
+
 mpl.figure.prototype._canvas_extra_style = function(canvas_div) {
 
 }
@@ -143,6 +145,17 @@ mpl.figure.prototype._init_canvas = function() {
     rubberband.mouseenter('figure_enter', mouse_event_fn);
     rubberband.mouseleave('figure_leave', mouse_event_fn);
 
+    canvas_div.on("wheel", function (event) {
+        event = event.originalEvent;
+        event['data'] = 'scroll'
+        if (event.deltaY < 0) {
+            event.step = 1;
+        } else {
+            event.step = -1;
+        }
+        mouse_event_fn(event);
+    });
+
     canvas_div.append(canvas);
     canvas_div.append(rubberband);
 
@@ -168,6 +181,7 @@ mpl.figure.prototype._init_canvas = function() {
     // upon first draw.
     this._resize_canvas(600, 600);
 
+
     function set_focus () {
         canvas.focus();
         canvas_div.focus();
@@ -425,7 +439,8 @@ mpl.figure.prototype.mouse_event = function(event, name) {
     var x = canvas_pos.x;
     var y = canvas_pos.y;
 
-    this.send_message(name, {x: x, y: y, button: event.button});
+    this.send_message(name, {x: x, y: y, button: event.button,
+                             step: event.step});
 
     /* This prevents the web browser from automatically changing to
      * the text insertion cursor when the button is pressed.  We want
diff --git a/lib/matplotlib/backends/web_backend/nbagg_uat.ipynb b/lib/matplotlib/backends/web_backend/nbagg_uat.ipynb
index 488b0279defe..9e795319bc81 100644
--- a/lib/matplotlib/backends/web_backend/nbagg_uat.ipynb
+++ b/lib/matplotlib/backends/web_backend/nbagg_uat.ipynb
@@ -1,7 +1,7 @@
 {
  "metadata": {
   "name": "",
-  "signature": "sha256:43daeaae8ae9fd496fc33d7a64639194bc009b755d28c23cd6329f225628197c"
+  "signature": "sha256:7f7ec6a6e2a63837a45a88a501ba3c5b1eb88e744925456a9bfeb0d6faa896a5"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -400,9 +400,9 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "### UAT 16 - key events\n",
+      "### UAT 16 - Events\n",
       "\n",
-      "Pressing any keyboard key or mouse button should cycle the line line while the figure has focus.  The figure should have focus by default when it is created and re-gain it by clicking on the canvas.  Clicking anywhere outside of the figure should release focus, but moving the mouse out of the figure should not release focus."
+      "Pressing any keyboard key or mouse button (or scrolling) should cycle the line line while the figure has focus.  The figure should have focus by default when it is created and re-gain it by clicking on the canvas.  Clicking anywhere outside of the figure should release focus, but moving the mouse out of the figure should not release focus."
      ]
     },
     {
@@ -423,6 +423,7 @@
       "    fig.canvas.draw_idle()\n",
       "fig.canvas.mpl_connect('button_press_event', on_event)\n",
       "fig.canvas.mpl_connect('key_press_event', on_event)\n",
+      "fig.canvas.mpl_connect('scroll_event', on_event)\n",
       "plt.show()"
      ],
      "language": "python",