Add current page change while scroll in ContentLayout

app/src/main/java/com/hippo/ehviewer/widget/ContentLayout.java

@@ -144,13 +144,6 @@ public class ContentLayout extends FrameLayout {
 
         private ViewTransition mViewTransition;
 
-        private RecyclerView.OnScrollListener mOnScrollListener = new RecyclerView.OnScrollListener() {
-            @Override
-            public void onScrolled(RecyclerView recyclerView, int dx, int dy){
-                ContentHelper.this.onScrolled(recyclerView, dx, dy);
-            }
-        };
-
         /**
          * Store data
          */
@@ -185,6 +178,38 @@ public class ContentLayout extends FrameLayout {
         private int mCurrentTaskType;
         private int mCurrentTaskPage;
 
+        private RecyclerView.OnScrollListener mOnScrollListener = new RecyclerView.OnScrollListener() {
+
+            @Override
+            public void onScrollStateChanged(RecyclerView recyclerView, int newState){
+                if (newState == RecyclerView.SCROLL_STATE_IDLE) {
+                    if (mPageVolume <= 0) {
+                        return;
+                    }
+                    if (mLastIndex == 0) {
+                        mCurrentPage = 0;
+                        mFirstIndex = 0;
+                        mLastIndex = mPageVolume;
+                    }
+
+                    int firstVisiblePosition = LayoutManagerUtils.getFirstVisibleItemPostion(mLayoutManager);
+                    int lastVisiblePosition = LayoutManagerUtils.getLastVisibleItemPostion(mLayoutManager);
+
+                    int pageChanged = (firstVisiblePosition - mFirstIndex) / mPageVolume;
+                    if (pageChanged <= 0) {
+                        pageChanged = (lastVisiblePosition - mLastIndex + 1) / mPageVolume;
+                    }
+
+                    if (pageChanged != 0) {
+                        mCurrentPage = mCurrentPage + pageChanged;
+                        int offset = pageChanged * mPageVolume;
+                        mFirstIndex += offset;
+                        mLastIndex += offset;
+                    }
+                }
+            }
+        };
+
         public ContentHelper() {
             mData = new ArrayList<>();
             mIdGenerator = IntIdGenerator.create();
@@ -209,10 +234,6 @@ public class ContentLayout extends FrameLayout {
             mRefreshLayout.setOnFooterRefreshListener(this);
         }
 
-        private RecyclerView.OnScrollListener getOnScrollListener() {
-            return mOnScrollListener;
-        }
-
         protected abstract RecyclerView.LayoutManager generateLayoutManager();
 
         public void showContent() {
@@ -429,10 +450,6 @@ public class ContentLayout extends FrameLayout {
             LayoutManagerUtils.scrollToPositionWithOffset(mLayoutManager, 0, 0);
         }
 
-        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
-
-        }
-
         @Override
         public int getItemCount() {
             return mData.size();

app/src/main/java/com/hippo/scene/SceneApplication.java

@@ -23,6 +23,8 @@ public class SceneApplication extends Application {
 
     @Override
     public void onCreate() {
+        super.onCreate();
+
         mSceneManager = new SceneManager();
         StageActivity.setSceneManager(mSceneManager);
         Scene.setSceneManager(mSceneManager);

app/src/main/java/com/hippo/util/LayoutManagerUtils.java

@@ -32,4 +32,28 @@ public final class LayoutManagerUtils {
                     layoutManager.getClass().getName());
         }
     }
+
+    public static int getFirstVisibleItemPostion(RecyclerView.LayoutManager layoutManager) {
+        if (layoutManager instanceof LinearLayoutManager) {
+            return ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
+        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
+            int[] positions = ((StaggeredGridLayoutManager) layoutManager).findFirstVisibleItemPositions(null);
+            return MathUtils.min(positions);
+        } else {
+            throw new IllegalStateException("Can't do getFirstVisibleItemPostion for " +
+                    layoutManager.getClass().getName());
+        }
+    }
+
+    public static int getLastVisibleItemPostion(RecyclerView.LayoutManager layoutManager) {
+        if (layoutManager instanceof LinearLayoutManager) {
+            return ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
+        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
+            int[] positions = ((StaggeredGridLayoutManager) layoutManager).findLastVisibleItemPositions(null);
+            return MathUtils.max(positions);
+        } else {
+            throw new IllegalStateException("Can't do getFirstVisibleItemPostion for " +
+                    layoutManager.getClass().getName());
+        }
+    }
 }

app/src/main/java/com/hippo/util/MathUtils.java

@@ -103,15 +103,15 @@ public final class MathUtils {
         return a < b ? (a < c ? a : c) : (b < c ? b : c);
     }
 
-    public static float min(float... arg) {
-        int length = arg.length;
+    public static float min(float... args) {
+        int length = args.length;
         if (length <= 0) {
             throw new IllegalArgumentException("Empty argument");
         } else {
-            float n = arg[0];
+            float n = args[0];
             float m;
             for (int i = 1; i < length; i++) {
-                m = arg[i];
+                m = args[i];
                 if (m < n)
                     n = m;
             }
@@ -119,15 +119,15 @@ public final class MathUtils {
         }
     }
 
-    public static int min(int... arg) {
-        int length = arg.length;
+    public static int min(int... args) {
+        int length = args.length;
         if (length <= 0) {
             throw new IllegalArgumentException("Empty argument");
         } else {
-            int n = arg[0];
+            int n = args[0];
             int m;
             for (int i = 1; i < length; i++) {
-                m = arg[i];
+                m = args[i];
                 if (m < n)
                     n = m;
             }