Allow multiple range selections using the shift key.

- Introduce an API on MultiSelectManager for starting/ending range
  selections.

- Navigation with the shift key pressed extends the current range
  selection (or starts a new one, if one isn't in progress).

- Navigation without the shift key pressed will end the current range
  selection.

BUG=27124371

Change-Id: Ieddf3ee816812bf5210463536fe63179ef1809ad
(cherry picked from commit 09792ef1506f4cbd944e16651508be435d92c5be)

4 files changed, 100 insertions, 36 deletions

diff --git a/packages/DocumentsUI/src/com/android/documentsui/dirlist/DirectoryFragment.java b/packages/DocumentsUI/src/com/android/documentsui/dirlist/DirectoryFragment.java
index 726538e34402..1e3cae7fac6a 100644
--- a/packages/DocumentsUI/src/com/android/documentsui/dirlist/DirectoryFragment.java
+++ b/packages/DocumentsUI/src/com/android/documentsui/dirlist/DirectoryFragment.java
@@ -101,7 +101,6 @@ import com.android.documentsui.model.RootInfo;
 import com.android.documentsui.services.FileOperationService;
 import com.android.documentsui.services.FileOperationService.OpType;
 import com.android.documentsui.services.FileOperations;
-
 import com.google.common.collect.Lists;
 
 import java.lang.annotation.Retention;
@@ -264,7 +263,7 @@ public class DirectoryFragment extends Fragment implements DocumentsAdapter.Envi
         mSelectionManager.addCallback(selectionListener);
 
         // Make sure this is done after the RecyclerView is set up.
-        mFocusManager = new FocusManager(mRecView, mSelectionManager);
+        mFocusManager = new FocusManager(mRecView);
 
         mModel = new Model();
         mModel.addUpdateListener(mAdapter);
@@ -1262,6 +1261,18 @@ public class DirectoryFragment extends Fragment implements DocumentsAdapter.Envi
             }
 
             if (mFocusManager.handleKey(doc, keyCode, event)) {
+                // Handle range selection adjustments. Extending the selection will adjust the
+                // bounds of the in-progress range selection. Each time an unshifted navigation
+                // event is received, the range selection is restarted.
+                if (shouldExtendSelection(event)) {
+                    if (!mSelectionManager.isRangeSelectionActive()) {
+                        // Start a range selection if one isn't active
+                        mSelectionManager.startRangeSelection(doc.getAdapterPosition());
+                    }
+                    mSelectionManager.snapRangeSelection(mFocusManager.getFocusPosition());
+                } else {
+                    mSelectionManager.endRangeSelection();
+                }
                 return true;
             }
 
@@ -1272,6 +1283,11 @@ public class DirectoryFragment extends Fragment implements DocumentsAdapter.Envi
 
             return false;
         }
+
+        private boolean shouldExtendSelection(KeyEvent event) {
+            return Events.isNavigationKeyCode(event.getKeyCode()) &&
+                    event.isShiftPressed();
+        }
     }
 
     private final class ModelUpdateListener implements Model.UpdateListener {
diff --git a/packages/DocumentsUI/src/com/android/documentsui/dirlist/FocusManager.java b/packages/DocumentsUI/src/com/android/documentsui/dirlist/FocusManager.java
index ad010a6891fe..e1e39438a776 100644
--- a/packages/DocumentsUI/src/com/android/documentsui/dirlist/FocusManager.java
+++ b/packages/DocumentsUI/src/com/android/documentsui/dirlist/FocusManager.java
@@ -33,15 +33,13 @@ class FocusManager implements View.OnFocusChangeListener {
     private RecyclerView mView;
     private RecyclerView.Adapter<?> mAdapter;
     private LinearLayoutManager mLayout;
-    private MultiSelectManager mSelectionManager;
 
     private int mLastFocusPosition = RecyclerView.NO_POSITION;
 
-    public FocusManager(RecyclerView view, MultiSelectManager selectionManager) {
+    public FocusManager(RecyclerView view) {
         mView = view;
         mAdapter = view.getAdapter();
         mLayout = (LinearLayoutManager) view.getLayoutManager();
-        mSelectionManager = selectionManager;
     }
 
     /**
@@ -60,13 +58,6 @@ class FocusManager implements View.OnFocusChangeListener {
 
             if (endPos != RecyclerView.NO_POSITION) {
                 focusItem(endPos);
-                boolean extendSelection = event.isShiftPressed();
-
-                // Handle any necessary adjustments to selection.
-                if (extendSelection) {
-                    int startPos = doc.getAdapterPosition();
-                    mSelectionManager.selectRange(startPos, endPos);
-                }
             }
             // Swallow all navigation keystrokes. Otherwise they go to the app's global
             // key-handler, which will route them back to the DF and cause focus to be reset.
@@ -97,6 +88,13 @@ class FocusManager implements View.OnFocusChangeListener {
     }
 
     /**
+     * @return The adapter position of the last focused item.
+     */
+    public int getFocusPosition() {
+        return mLastFocusPosition;
+    }
+
+    /**
      * Finds the destination position where the focus should land for a given navigation event.
      *
      * @param view The view that received the event.
diff --git a/packages/DocumentsUI/src/com/android/documentsui/dirlist/MultiSelectManager.java b/packages/DocumentsUI/src/com/android/documentsui/dirlist/MultiSelectManager.java
index d60825baa7cf..c8b6f8528272 100644
--- a/packages/DocumentsUI/src/com/android/documentsui/dirlist/MultiSelectManager.java
+++ b/packages/DocumentsUI/src/com/android/documentsui/dirlist/MultiSelectManager.java
@@ -370,39 +370,41 @@ public final class MultiSelectManager {
     }
 
     /**
-     * Handle a range selection event.
-     * <li> If the MSM is currently in single-select mode, only the last item in the range will
-     * actually be selected.
-     * <li>If a range selection is not already active, one will be started, and the given range of
-     * items will be selected.  The given startPos becomes the anchor for the range selection.
-     * <li>If a range selection is already active, the anchor is not changed. The range is extended
-     * from its current anchor to endPos.
+     * Starts a range selection. If a range selection is already active, this will start a new range
+     * selection (which will reset the range anchor).
      *
-     * @param startPos
-     * @param endPos
+     * @param pos The anchor position for the selection range.
      */
-    public void selectRange(int startPos, int endPos) {
-        // In single-select mode, just select the last item in the range.
-        if (mSingleSelect) {
-            attemptSelect(mAdapter.getModelId(endPos));
-            return;
-        }
+    void startRangeSelection(int pos) {
+      attemptSelect(mAdapter.getModelId(pos));
+      setSelectionRangeBegin(pos);
+    }
 
-        // In regular (i.e. multi-select) mode
-        if (!isRangeSelectionActive()) {
-            // If a range selection isn't active, start one up
-            attemptSelect(mAdapter.getModelId(startPos));
-            setSelectionRangeBegin(startPos);
-        }
-        // Extend the range selection
-        mRanger.snapSelection(endPos);
+    /**
+     * Sets the end point for the current range selection, started by a call to
+     * {@link #startRangeSelection(int)}. This function should only be called when a range selection
+     * is active (see {@link #isRangeSelectionActive()}. Items in the range [anchor, end] will be
+     * selected.
+     *
+     * @param pos The new end position for the selection range.
+     */
+    void snapRangeSelection(int pos) {
+        checkNotNull(mRanger);
+        mRanger.snapSelection(pos);
         notifySelectionChanged();
     }
 
     /**
+     * Stops an in-progress range selection.
+     */
+    void endRangeSelection() {
+        mRanger = null;
+    }
+
+    /**
      * @return Whether or not there is a current range selection active.
      */
-    private boolean isRangeSelectionActive() {
+    boolean isRangeSelectionActive() {
         return mRanger != null;
     }
 
diff --git a/packages/DocumentsUI/tests/src/com/android/documentsui/dirlist/MultiSelectManagerTest.java b/packages/DocumentsUI/tests/src/com/android/documentsui/dirlist/MultiSelectManagerTest.java
index d95fb490d81e..9447d9c18a83 100644
--- a/packages/DocumentsUI/tests/src/com/android/documentsui/dirlist/MultiSelectManagerTest.java
+++ b/packages/DocumentsUI/tests/src/com/android/documentsui/dirlist/MultiSelectManagerTest.java
@@ -189,6 +189,54 @@ public class MultiSelectManagerTest extends AndroidTestCase {
         assertSelection(items.get(20));
     }
 
+    public void testRangeSelection() {
+        mManager.startRangeSelection(15);
+        mManager.snapRangeSelection(19);
+        assertRangeSelection(15, 19);
+    }
+
+    public void testRangeSelection_snapExpand() {
+        mManager.startRangeSelection(15);
+        mManager.snapRangeSelection(19);
+        mManager.snapRangeSelection(27);
+        assertRangeSelection(15, 27);
+    }
+
+    public void testRangeSelection_snapContract() {
+        mManager.startRangeSelection(15);
+        mManager.snapRangeSelection(27);
+        mManager.snapRangeSelection(19);
+        assertRangeSelection(15, 19);
+    }
+
+    public void testRangeSelection_snapInvert() {
+        mManager.startRangeSelection(15);
+        mManager.snapRangeSelection(27);
+        mManager.snapRangeSelection(3);
+        assertRangeSelection(3, 15);
+    }
+
+    public void testRangeSelection_multiple() {
+        mManager.startRangeSelection(15);
+        mManager.snapRangeSelection(27);
+        mManager.endRangeSelection();
+        mManager.startRangeSelection(42);
+        mManager.snapRangeSelection(57);
+        assertSelectionSize(29);
+        assertRangeSelected(15, 27);
+        assertRangeSelected(42, 57);
+
+    }
+
+    public void testRangeSelection_singleSelect() {
+        mManager = new MultiSelectManager(mEnv, mAdapter, MultiSelectManager.MODE_SINGLE, null);
+        mManager.addCallback(mCallback);
+        mManager.startRangeSelection(11);
+        mManager.snapRangeSelection(19);
+        assertSelectionSize(1);
+        assertSelection(items.get(19));
+    }
+
     public void testProvisionalSelection() {
         Selection s = mManager.getSelection();
         assertSelection();