Fix TaskViewTouchController crash in seascape

Previously, we were using scroll direction POSITIVE as a catch all
to mean "up" but in seascape, we actually want NEGATIVE. Added
getUpDirection() to capture that. Tried to clarify the code a bit
by putting all the methods used solely by TaskViewTouchController
together with documentation. It's still pretty confusing and feels
redundant, but couldn't think of an obvious way to simplify.

Test: Swipe up and down on a task in all permutations of:
- 3 button mode
- Gesture navigation
- Portrait
- Landscape
- Seascape
- LTR
- RTL
- Home rotation allowed
- Home rotation disallowed

Fixes: 174009771
Fixes: 173567204
Change-Id: Id0f8d6f4365d888eb46182d8544d18206795dfb8

src/com/android/launcher3/touch/PortraitPagedViewHandler.java

@@ -72,12 +72,6 @@ public class PortraitPagedViewHandler implements PagedOrientationHandler {
         out.screenCenter = insets.left + view.getPaddingLeft() + out.scroll + out.halfPageSize;
     }
 
-    @Override
-    public boolean isGoingUp(float displacement, boolean isRtl) {
-        // Ignore rtl since it only affects X value displacement, Y displacement doesn't change
-        return displacement < 0;
-    }
-
     @Override
     public boolean isLayoutNaturalToLauncher() {
         return true;
@@ -211,11 +205,6 @@ public class PortraitPagedViewHandler implements PagedOrientationHandler {
         return view.getWidth() - view.getPaddingRight() - insets.right;
     }
 
-    @Override
-    public SingleAxisSwipeDetector.Direction getOppositeSwipeDirection() {
-        return VERTICAL;
-    }
-
     @Override
     public int getPrimaryTranslationDirectionFactor() {
         return 1;
@@ -225,12 +214,6 @@ public class PortraitPagedViewHandler implements PagedOrientationHandler {
         return -1;
     }
 
-    @Override
-    public int getTaskDragDisplacementFactor(boolean isRtl) {
-        // Ignore rtl since it only affects X value displacement, Y displacement doesn't change
-        return 1;
-    }
-
     @Override
     public float getTaskMenuX(float x, View thumbnailView) {
         return x;
@@ -257,6 +240,33 @@ public class PortraitPagedViewHandler implements PagedOrientationHandler {
         // no-op, defaults are fine
     }
 
+    /* ---------- The following are only used by TaskViewTouchHandler. ---------- */
+
+    @Override
+    public SingleAxisSwipeDetector.Direction getUpDownSwipeDirection() {
+        return VERTICAL;
+    }
+
+    @Override
+    public int getUpDirection(boolean isRtl) {
+        // Ignore rtl since it only affects X value displacement, Y displacement doesn't change
+        return SingleAxisSwipeDetector.DIRECTION_POSITIVE;
+    }
+
+    @Override
+    public boolean isGoingUp(float displacement, boolean isRtl) {
+        // Ignore rtl since it only affects X value displacement, Y displacement doesn't change
+        return displacement < 0;
+    }
+
+    @Override
+    public int getTaskDragDisplacementFactor(boolean isRtl) {
+        // Ignore rtl since it only affects X value displacement, Y displacement doesn't change
+        return 1;
+    }
+
+    /* -------------------- */
+
     @Override
     public ChildBounds getChildBounds(View child, int childStart, int pageCenter,
         boolean layoutChild) {