ntp4: Horizontal swipes should only trigger history on mac when

chrome/browser/resources/ntp4/card_slider.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview Card slider implementation. Allows you to create interactions
  * that have items that can slide left to right to reveal additional items.
  * Works by adding the necessary event handlers to a specific DOM structure
  * including a frame, container and cards.
  * - The frame defines the boundary of one item. Each card will be expanded to
@@ skipping 203 matching lines @@
     },
 
     /**
      * Handle horizontal scrolls to flip between pages.
      * @private
      */
     onMouseWheel_: function(e) {
       if (e.wheelDeltaX == 0)
         return;
 
-      var scrollAmountPerPage = ntp4.isRTL() ? 120 : -120;
+      var preventDefault = true;
+      // If the horizontal scroll didn't change cards (on the far right of
+      // the NTP), let the browser take a shot at the event as well.
+      if (this.currentCard === 0 && this.mouseWheelScrollAmount_ > 0)
+        preventDefault = false;
+      if (this.currentCard === this.cards_.length - 1 &&
+          this.mouseWheelScrollAmount_ < 0)

[Evan Stade, 2011/08/19 22:35:40]

curlies

[Nico, 2011/08/19 22:54:47]

Done.

+        preventDefault = false;
+
+      var scrollAmountPerPage = cr.isMac ? 400 : 120;

[Evan Stade, 2011/08/19 22:35:40]

it strikes me you should test this with a mouse with a scroll wheel (on mac), if
you have one handy. I assume you just tried it with a touchpad. Shift+scroll
does horizontal, at least for me, although my wheel also has left and right
clickers.

[Nico, 2011/08/19 22:54:47]

I tested with a multitouch touch pad (feels good), a magic mouse with a physical
scroll ball (feels good) and a logitech mouse with shift-scrolling (I believe
120 would feel better for that, but it's bearable). I added a comment for this.

[Evan Stade, 2011/08/19 23:10:56]

you could do something hacky like "if the scroll value is exactly 120 then move
the page by 1".

+      if (!ntp4.isRTL())
+        scrollAmountPerPage *= -1;
       this.mouseWheelScrollAmount_ += e.wheelDeltaX;
       if (Math.abs(this.mouseWheelScrollAmount_) >=
           Math.abs(scrollAmountPerPage)) {
         var pagesToScroll = this.mouseWheelScrollAmount_ / scrollAmountPerPage;
         pagesToScroll =
             (pagesToScroll > 0 ? Math.floor : Math.ceil)(pagesToScroll);
         var newCardIndex = this.currentCard + pagesToScroll;
-        newCardIndex = Math.min(this.cards_.length,
+        newCardIndex = Math.min(this.cards_.length - 1,
                                 Math.max(0, newCardIndex));
         this.selectCard(newCardIndex, true);
         this.mouseWheelScrollAmount_ -= pagesToScroll * scrollAmountPerPage;
       }
 
       // We got a mouse wheel event, so cancel any pending scroll wheel timeout.
       if (this.scrollClearTimeout_ != null)
         clearTimeout(this.scrollClearTimeout_);
       // If we didn't use up all the scroll, hold onto it for a little bit, but
       // drop it after a delay.
       if (this.mouseWheelScrollAmount_ != 0) {
         this.scrollClearTimeout_ =
             setTimeout(this.clearMouseWheelScroll_.bind(this), 500);
       }
+
+      if (preventDefault)
+        e.preventDefault();
     },
 
     /**
      * Resets the amount of horizontal scroll we've seen to 0. See
      * onMouseWheel_.
      * @private
      */
     clearMouseWheelScroll_: function() {
       this.mouseWheelScrollAmount_ = 0;
     },
@@ skipping 143 matching lines @@
       // Stop listening to any current touch
       this.touchHandler_.cancelTouch();
 
       // Ensure we're at a card bounary
       this.transformToCurrentCard_(true);
     },
   };
 
   return CardSlider;
 })();