Fix mouse wheel scrolling of ComboBox in IE11 (#16918)

IE11 is broken so that the simple implementation always moves up on any
mouse wheel event. Therefore, this change borrows the approach taken by
Escalator for low-level handling of mouse wheel events in a way compatible
with all supported browsers.

Change-Id: I98c89d3ccfeea38d6a454ef708f0eb7d1d3f480c

2 files changed, 154 insertions, 18 deletions

diff --git a/client/src/com/vaadin/client/ui/JsniMousewheelHandler.java b/client/src/com/vaadin/client/ui/JsniMousewheelHandler.java
new file mode 100644
index 0000000000..82ea768871
--- /dev/null
+++ b/client/src/com/vaadin/client/ui/JsniMousewheelHandler.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2000-2014 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.client.ui;
+
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwt.dom.client.Element;
+import com.google.gwt.user.client.Event;
+import com.google.gwt.user.client.ui.Widget;
+import com.vaadin.client.widgets.Escalator;
+
+/**
+ * A mousewheel handling class to get around the limits of
+ * {@link Event#ONMOUSEWHEEL}.
+ * 
+ * For internal use only. May be removed or replaced in the future.
+ * 
+ * @see Escalator.JsniWorkaround
+ */
+abstract class JsniMousewheelHandler {
+
+    /**
+     * A JavaScript function that handles the mousewheel DOM event, and passes
+     * it on to Java code.
+     * 
+     * @see #createMousewheelListenerFunction(Widget)
+     */
+    protected final JavaScriptObject mousewheelListenerFunction;
+
+    protected JsniMousewheelHandler(final Widget widget) {
+        mousewheelListenerFunction = createMousewheelListenerFunction(widget);
+    }
+
+    /**
+     * A method that constructs the JavaScript function that will be stored into
+     * {@link #mousewheelListenerFunction}.
+     * 
+     * @param widget
+     *            a reference to the current instance of {@link Widget}
+     */
+    protected abstract JavaScriptObject createMousewheelListenerFunction(
+            Widget widget);
+
+    public native void attachMousewheelListener(Element element)
+    /*-{
+        if (element.addEventListener) {
+            // FireFox likes "wheel", while others use "mousewheel"
+            var eventName = 'onmousewheel' in element ? 'mousewheel' : 'wheel';
+            element.addEventListener(eventName, this.@com.vaadin.client.ui.JsniMousewheelHandler::mousewheelListenerFunction);
+        } else {
+            // IE8
+            element.attachEvent("onmousewheel", this.@com.vaadin.client.ui.JsniMousewheelHandler::mousewheelListenerFunction);
+        }
+    }-*/;
+
+    public native void detachMousewheelListener(Element element)
+    /*-{
+        if (element.addEventListener) {
+            // FireFox likes "wheel", while others use "mousewheel"
+            var eventName = element.onwheel===undefined?"mousewheel":"wheel";
+            element.removeEventListener(eventName, this.@com.vaadin.client.ui.JsniMousewheelHandler::mousewheelListenerFunction);
+        } else {
+            // IE8
+            element.detachEvent("onmousewheel", this.@com.vaadin.client.ui.JsniMousewheelHandler::mousewheelListenerFunction);
+        }
+    }-*/;
+
+}
diff --git a/client/src/com/vaadin/client/ui/VFilterSelect.java b/client/src/com/vaadin/client/ui/VFilterSelect.java
index 6ddce3d93c..99ebde1910 100644
--- a/client/src/com/vaadin/client/ui/VFilterSelect.java
+++ b/client/src/com/vaadin/client/ui/VFilterSelect.java
@@ -25,9 +25,11 @@ import java.util.List;
 import java.util.Set;
 
 import com.google.gwt.aria.client.Roles;
+import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.Scheduler;
 import com.google.gwt.core.client.Scheduler.ScheduledCommand;
 import com.google.gwt.dom.client.Element;
+import com.google.gwt.dom.client.NativeEvent;
 import com.google.gwt.dom.client.Style;
 import com.google.gwt.dom.client.Style.Display;
 import com.google.gwt.dom.client.Style.Unit;
@@ -219,6 +221,50 @@ public class VFilterSelect extends Composite implements Field, KeyDownHandler,
         }
     }
 
+    /** An inner class that handles all logic related to mouse wheel. */
+    private class MouseWheeler extends JsniMousewheelHandler {
+
+        public MouseWheeler() {
+            super(VFilterSelect.this);
+        }
+
+        @Override
+        protected native JavaScriptObject createMousewheelListenerFunction(
+                Widget widget)
+        /*-{
+            return $entry(function(e) {
+                var deltaX = e.deltaX ? e.deltaX : -0.5*e.wheelDeltaX;
+                var deltaY = e.deltaY ? e.deltaY : -0.5*e.wheelDeltaY;
+                
+                // IE8 has only delta y
+                if (isNaN(deltaY)) {
+                    deltaY = -0.5*e.wheelDelta;
+                }
+
+                @com.vaadin.client.ui.VFilterSelect.JsniUtil::moveScrollFromEvent(*)(widget, deltaX, deltaY, e);
+            });
+        }-*/;
+
+    }
+
+    /**
+     * A utility class that contains utility methods that are usually called
+     * from JSNI.
+     * <p>
+     * The methods are moved in this class to minimize the amount of JSNI code
+     * as much as feasible.
+     */
+    static class JsniUtil {
+        public static void moveScrollFromEvent(final Widget widget,
+                final double deltaX, final double deltaY,
+                final NativeEvent event) {
+
+            if (!Double.isNaN(deltaY)) {
+                ((VFilterSelect) widget).suggestionPopup.scroll(deltaY);
+            }
+        }
+    }
+
     /**
      * Represents the popup box with the selection options. Wraps a suggestion
      * menu.
@@ -243,6 +289,8 @@ public class VFilterSelect extends Composite implements Field, KeyDownHandler,
 
         private int topPosition;
 
+        private final MouseWheeler mouseWheeler = new MouseWheeler();
+
         /**
          * Default constructor
          */
@@ -275,6 +323,18 @@ public class VFilterSelect extends Composite implements Field, KeyDownHandler,
             setPreviewingAllNativeEvents(true);
         }
 
+        @Override
+        protected void onLoad() {
+            super.onLoad();
+            mouseWheeler.attachMousewheelListener(getElement());
+        }
+
+        @Override
+        protected void onUnload() {
+            mouseWheeler.detachMousewheelListener(getElement());
+            super.onUnload();
+        }
+
         /**
          * Shows the popup where the user can see the filtered options
          * 
@@ -531,6 +591,20 @@ public class VFilterSelect extends Composite implements Field, KeyDownHandler,
             }
         }
 
+        private void scroll(double deltaY) {
+            boolean scrollActive = menu.isScrollActive();
+
+            debug("VFS.SP: scroll() scrollActive: " + scrollActive);
+
+            if (!scrollActive) {
+                if (deltaY > 0d) {
+                    lazyPageScroller.scrollDown();
+                } else {
+                    lazyPageScroller.scrollUp();
+                }
+            }
+        }
+
         @Override
         public void onBrowserEvent(Event event) {
             debug("VFS.SP: onBrowserEvent()");
@@ -543,24 +617,6 @@ public class VFilterSelect extends Composite implements Field, KeyDownHandler,
                     lazyPageScroller.scrollDown();
                 }
 
-            } else if (event.getTypeInt() == Event.ONMOUSEWHEEL) {
-
-                boolean scrollNotActive = !menu.isScrollActive();
-
-                debug("VFS.SP: onBrowserEvent() scrollNotActive: "
-                        + scrollNotActive);
-
-                if (scrollNotActive) {
-                    int velocity = event.getMouseWheelVelocityY();
-
-                    debug("VFS.SP: onBrowserEvent() velocity: " + velocity);
-
-                    if (velocity > 0) {
-                        lazyPageScroller.scrollDown();
-                    } else {
-                        lazyPageScroller.scrollUp();
-                    }
-                }
             }
 
             /*