修正从右侧滑动返回失效的问题

Author: Issac

library/src/main/java/me/imid/swipebacklayout/lib/SwipeBackLayout.java

@@ -501,7 +501,7 @@ public void onViewPositionChanged(View changedView, int left, int top, int dx, i
                 mScrollPercent = Math.abs((float) left
                         / (mContentView.getWidth() + mShadowLeft.getIntrinsicWidth()));
             } else if ((mTrackingEdge & EDGE_RIGHT) != 0) {
-                mScrollPercent = Math.abs((float) top
+                mScrollPercent = Math.abs((float) left
                         / (mContentView.getWidth() + mShadowRight.getIntrinsicWidth()));
             } else if ((mTrackingEdge & EDGE_BOTTOM) != 0) {
                 mScrollPercent = Math.abs((float) top