Ignore touch on the center of the slide

Author: Weera Wu

index.html

@@ -230,7 +230,19 @@
     nextTheme: function() {
       state.setTheme((state.theme + 1) % Object.keys(Theme).length);
     },
-    touchType: function() {
+    getTouchDirection: function(x, width) {
+      if (!x || !width) {
+        return null;
+      }
+      if (x > width * 2 / 3) {
+        return TouchDirection.RIGHT;
+      } else if (x > width / 2) {
+        return TouchDirection.CENTER;
+      } else {
+        return TouchDirection.LEFT;
+      }
+    },
+    getTouchType: function() {
       if (!state.touch.start) {
         return null;
       }
@@ -287,10 +299,8 @@
         return;
       }
       var touch = event.touches[0];
-      var pageCenter = document.body.clientWidth / 2;
-      state.setTouch(
-        touch.pageX < pageCenter ? TouchDirection.LEFT : TouchDirection.RIGHT
-      );
+      var direction = state.getTouchDirection(touch.pageX, document.body.clientWidth);
+      state.setTouch(direction);
     },
     handleTouchmove: function(event) {
       event.preventDefault();
@@ -301,7 +311,7 @@
       if (event.touches.length > 0) {
         return;
       }
-      var type = state.touchType();
+      var type = state.getTouchType();
       var direction = state.touch.direction;
       if (type === TouchType.HOLD) {
         state.nextTheme();