[RTM] Refactored ScrollableViewHelper to interface

library/src/com/sothree/slidinguppanel/ScrollableViewHelper.java

@@ -1,63 +1,30 @@
 package com.sothree.slidinguppanel;
 
+import android.support.v4.view.ViewCompat;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
 import android.widget.ListView;
 import android.widget.ScrollView;
 
 /**
- * Helper class for determining the current scroll positions for scrollable views. Currently works
- * for ListView, ScrollView & RecyclerView, but the library users can override it to add support
- * for other views.
+ * Helper class for determining the scroll capability for scrollable views.
  */
-public class ScrollableViewHelper {
+public interface ScrollableViewHelper {
     /**
-     * Returns the current scroll position of the scrollable view. If this method returns zero or
-     * less, it means at the scrollable view is in a position such as the panel should handle
-     * scrolling. If the method returns anything above zero, then the panel will let the scrollable
-     * view handle the scrolling
+     * If this method returns zero false or it means at the scrollable view is in a position such
+     * as the panel should handle scrolling. If the method returns anything above zero,
+     * then the panel will let the scrollable view handle the scrolling
      *
      * @param scrollableView the scrollable view
-     * @param isSlidingUp whether or not the panel is sliding up or down
+     * @param direction negative to check scrolling up, positive to check scrolling down.
      * @return the scroll position
      */
-    public int getScrollableViewScrollPosition(View scrollableView, boolean isSlidingUp) {
-        if (scrollableView == null) return 0;
-        if (scrollableView instanceof ScrollView) {
-            if (isSlidingUp) {
-                return scrollableView.getScrollY();
-            } else {
-                ScrollView sv = ((ScrollView) scrollableView);
-                View child = sv.getChildAt(0);
-                return (child.getBottom() - (sv.getHeight() + sv.getScrollY()));
-            }
-        } else if (scrollableView instanceof ListView && ((ListView) scrollableView).getChildCount() > 0) {
-            ListView lv = ((ListView) scrollableView);
-            if (lv.getAdapter() == null) return 0;
-            if (isSlidingUp) {
-                View firstChild = lv.getChildAt(0);
-                // Approximate the scroll position based on the top child and the first visible item
-                return lv.getFirstVisiblePosition() * firstChild.getHeight() - firstChild.getTop();
-            } else {
-                View lastChild = lv.getChildAt(lv.getChildCount() - 1);
-                // Approximate the scroll position based on the bottom child and the last visible item
-                return (lv.getAdapter().getCount() - lv.getLastVisiblePosition() - 1) * lastChild.getHeight() + lastChild.getBottom() - lv.getBottom();
-            }
-        } else if (scrollableView instanceof RecyclerView && ((RecyclerView) scrollableView).getChildCount() > 0) {
-            RecyclerView rv = ((RecyclerView) scrollableView);
-            RecyclerView.LayoutManager lm = rv.getLayoutManager();
-            if (rv.getAdapter() == null) return 0;
-            if (isSlidingUp) {
-                View firstChild = rv.getChildAt(0);
-                // Approximate the scroll position based on the top child and the first visible item
-                return rv.getChildLayoutPosition(firstChild) * lm.getDecoratedMeasuredHeight(firstChild) - lm.getDecoratedTop(firstChild);
-            } else {
-                View lastChild = rv.getChildAt(rv.getChildCount() - 1);
-                // Approximate the scroll position based on the bottom child and the last visible item
-                return (rv.getAdapter().getItemCount() - 1) * lm.getDecoratedMeasuredHeight(lastChild) + lm.getDecoratedBottom(lastChild) - rv.getBottom();
-            }
-        } else {
-            return 0;
+    public boolean canScrollVertically(View scrollableView, int direction);
+
+    static final ScrollableViewHelper DEFAULT = new ScrollableViewHelper() {
+        @Override
+        public boolean canScrollVertically(View scrollableView, int direction) {
+            return ViewCompat.canScrollVertically(scrollableView, direction);
         }
-    }
+    };
 }

library/src/com/sothree/slidinguppanel/SlidingUpPanelLayout.java

@@ -146,7 +146,7 @@ public class SlidingUpPanelLayout extends ViewGroup {
      */
     private View mScrollableView;
     private int mScrollableViewResId;
-    private ScrollableViewHelper mScrollableViewHelper = new ScrollableViewHelper();
+    private ScrollableViewHelper mScrollableViewHelper = ScrollableViewHelper.DEFAULT;
 
     /**
      * The child view that can slide, if any.
@@ -984,7 +984,7 @@ public boolean dispatchTouchEvent(@NonNull MotionEvent ev) {
             if (dy * (mIsSlidingUp ? 1 : -1) > 0) { // Collapsing
                 // Is the child less than fully scrolled?
                 // Then let the child handle it.
-                if (mScrollableViewHelper.getScrollableViewScrollPosition(mScrollableView, mIsSlidingUp) > 0) {
+                if (mScrollableViewHelper.canScrollVertically(mScrollableView, mIsSlidingUp ? -1 : 1)) {
                     mIsScrollableViewHandlingTouch = true;
                     return super.dispatchTouchEvent(ev);
                 }