ntp4: Horizontal swipes should only trigger history on mac when

chrome/browser/resources/ntp4/card_slider.js

Index: chrome/browser/resources/ntp4/card_slider.js
diff --git a/chrome/browser/resources/ntp4/card_slider.js b/chrome/browser/resources/ntp4/card_slider.js
index 0cd671119532bca94149892b8c09b87cd8354848..d6613a26a6c10f50186e31ed14839b11b3e8881a 100644
--- a/chrome/browser/resources/ntp4/card_slider.js
+++ b/chrome/browser/resources/ntp4/card_slider.js
@@ -221,7 +221,18 @@ var CardSlider = (function() {
       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)) {
@@ -229,7 +240,7 @@ var CardSlider = (function() {
         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;
@@ -244,6 +255,9 @@ var CardSlider = (function() {
         this.scrollClearTimeout_ =
             setTimeout(this.clearMouseWheelScroll_.bind(this), 500);
       }
+
+      if (preventDefault)
+        e.preventDefault();
     },
 
     /**