Three pane behavior changes

- Now pressing back on the message view on portrait expands the message
  list.  Pressing back again closes the message view and navigates
  to the mailbox list + message list view.
- Fixed the bug where the app icon on the action bar will lose the back arrow
  on screen rotation.
- Code clean up.

Bug 3137919
Bug 3198987

Change-Id: Ia452f90ebe5599a2a8de905f4dabec6bd3ceb4a2

src/com/android/email/activity/MessageListXL.java

@@ -174,6 +174,7 @@ public class MessageListXL extends Activity implements
     protected void onResume() {
         if (Email.DEBUG_LIFECYCLE && Email.DEBUG) Log.d(Email.LOG_TAG, "MessageListXL onResume");
         super.onResume();
+        mFragmentManager.onResume();
 
         // On MessageList.onResume, we go back to Welcome if an account has been added/removed.
         // We don't need to do that here, because when the activity resumes, the account list loader
@@ -212,11 +213,25 @@ public class MessageListXL extends Activity implements
         if (Email.DEBUG_LIFECYCLE && Email.DEBUG) {
             Log.d(Email.LOG_TAG, "MessageListXL onBackPressed");
         }
+        onBackPressed(true);
+    }
+
+    /**
+     * Performs the back action.
+     *
+     * @param mayCloseActivity if true, the activity will close if it's already on top of the
+     * internal back state stack.
+     */
+    private boolean onBackPressed(boolean mayCloseActivity) {
         if (mFragmentManager.onBackPressed()) {
-            return;
+            return true;
         }
-        // Perform the default behavior.
+        if (mayCloseActivity) {
-        super.onBackPressed();
+            // Perform the default behavior.
+            super.onBackPressed();
+            return true;
+        }
+        return false;
     }
 
     private void onCurrentMessageGone() {
@@ -601,7 +616,8 @@ public class MessageListXL extends Activity implements
         switch (item.getItemId()) {
             case android.R.id.home:
                 // Comes from the action bar when the app icon on the left is pressed.
-                return mFragmentManager.onBackPressed();
+                // It works like a back press, but it won't close the activity.
+                return onBackPressed(false);
             case R.id.compose:
                 return onCompose();
             case R.id.refresh:

src/com/android/email/activity/MessageListXLFragmentManager.java

@@ -124,8 +124,6 @@ class MessageListXLFragmentManager {
                 mThreePane.getMiddlePaneId());
         mMessageViewFragment = (MessageViewFragment) fm.findFragmentById(
                 mThreePane.getRightPaneId());
-
-        updateActionBar();
     }
 
     /** Set callback for fragment. */
@@ -197,6 +195,8 @@ class MessageListXLFragmentManager {
             return;
         }
         mIsActivityResumed = true;
+
+        updateActionBar();
     }
 
     /**
@@ -303,7 +303,7 @@ class MessageListXLFragmentManager {
         // Open mailbox list, clear message list / message view
         mMailboxListFragment.openMailboxes(mAccountId);
         mMessageListFragment.clearContent();
-        hideMessageView();
+        mThreePane.showLeftPane(); // Show mailbox list
 
         if ((accountId == Account.ACCOUNT_ID_COMBINED_VIEW) && (mailboxId == -1)) {
             // When opening the Combined view, the right pane will be "combined inbox".
@@ -321,12 +321,7 @@ class MessageListXLFragmentManager {
      * @return true "back" is handled.
      */
     public boolean onBackPressed() {
-        if (isMessageSelected()) {
+        return mThreePane.onBackPressed();
-            // Go back to the message list.
-            goBackToMailbox();
-            return true;
-        }
-        return false; // Not handled.
     }
 
     /**
@@ -334,7 +329,6 @@ class MessageListXLFragmentManager {
      */
     public void goBackToMailbox() {
         if (isMessageSelected()) {
-            hideMessageView();
             selectMailbox(getMailboxId(), false);
         }
     }
@@ -374,7 +368,7 @@ class MessageListXLFragmentManager {
 
         mMailboxListFragment.setSelectedMailbox(mMailboxId);
         mTargetActivity.onMailboxChanged(mAccountId, mMailboxId);
-        hideMessageView();
+        mThreePane.showLeftPane(); // Show mailbox list
     }
 
     /**
@@ -402,16 +396,17 @@ class MessageListXLFragmentManager {
         // Open message
         mMessageListFragment.setSelectedMessage(mMessageId);
         mMessageViewFragment.openMessage(mMessageId);
-        hideMessageBoxList();
+        mThreePane.showRightPane(); // Show message view
     }
 
-    private void hideMessageBoxList() {
+    /**
-        mThreePane.showRightPane(true);
+     * Unselect the currently viewed message, if any, and release the resoruce grabbed by the
-    }
+     * message view.
-
+     *
-    private void hideMessageView() {
+     * This must be called when the three pane reports that the message view pane gets hidden.
+     */
+    private void onMessageViewClosed() {
         mMessageId = -1;
-        mThreePane.showRightPane(false);
         mMessageListFragment.setSelectedMessage(-1);
         mMessageViewFragment.clearContent();
     }
@@ -469,8 +464,14 @@ class MessageListXLFragmentManager {
 
     private class ThreePaneLayoutCallback implements ThreePaneLayout.Callback {
         @Override
-        public void onVisiblePanesChanged() {
+        public void onVisiblePanesChanged(int previousVisiblePanes) {
             updateActionBar();
+            final int visiblePanes = mThreePane.getVisiblePanes();
+            if (((visiblePanes & ThreePaneLayout.PANE_RIGHT) == 0) &&
+                    ((previousVisiblePanes & ThreePaneLayout.PANE_RIGHT) != 0)) {
+                // Message view just got hidden
+                onMessageViewClosed();
+            }
         }
     }
 }

src/com/android/email/activity/ThreePaneLayout.java

@@ -50,9 +50,10 @@ public class ThreePaneLayout extends LinearLayout implements View.OnClickListene
     /** Portrait mode only: message view + expanded message list */
     private static final int STATE_PORTRAIT_MIDDLE_EXPANDED = 3;
 
-    public static final int PANE_LEFT = 1 << 0;
+    // Flags for getVisiblePanes()
+    public static final int PANE_LEFT = 1 << 2;
     public static final int PANE_MIDDLE = 1 << 1;
-    public static final int PANE_RIGHT = 1 << 2;
+    public static final int PANE_RIGHT = 1 << 0;
 
     private int mPaneState = STATE_LEFT_UNINITIALIZED;
 
@@ -69,13 +70,13 @@ public class ThreePaneLayout extends LinearLayout implements View.OnClickListene
 
     public interface Callback {
         /** Called when {@link ThreePaneLayout#getVisiblePanes()} has changed. */
-        public void onVisiblePanesChanged();
+        public void onVisiblePanesChanged(int previousVisiblePanes);
     }
 
     private static final class EmptyCallback implements Callback {
         public static final Callback INSTANCE = new EmptyCallback();
 
-        @Override public void onVisiblePanesChanged() {}
+        @Override public void onVisiblePanesChanged(int previousVisiblePanes) {}
     }
 
     public ThreePaneLayout(Context context, AttributeSet attrs, int defStyle) {
@@ -162,11 +163,38 @@ public class ThreePaneLayout extends LinearLayout implements View.OnClickListene
         return ret;
     }
 
+    public boolean onBackPressed() {
+        if (isLandscape()) {
+            switch (mPaneState) {
+            case STATE_RIGHT_VISIBLE:
+                changePaneState(STATE_LEFT_VISIBLE, true); // Close the right pane
+                return true;
+            }
+        } else {
+            switch (mPaneState) {
+                case STATE_RIGHT_VISIBLE:
+                    changePaneState(STATE_PORTRAIT_MIDDLE_EXPANDED, true);
+                    return true;
+                case STATE_PORTRAIT_MIDDLE_EXPANDED:
+                    changePaneState(STATE_LEFT_VISIBLE, true);
+                    return true;
+                }
+        }
+        return false;
+    }
+
     /**
-     * Show/hide the right most pane.  (i.e. message view)
+     * Show the left most pane.  (i.e. mailbox list)
      */
-    public void showRightPane(boolean show) {
+    public void showLeftPane() {
-        changePaneState(show ? STATE_RIGHT_VISIBLE : STATE_LEFT_VISIBLE, true);
+        changePaneState(STATE_LEFT_VISIBLE, true);
+    }
+
+    /**
+     * Show the right most pane.  (i.e. message view)
+     */
+    public void showRightPane() {
+        changePaneState(STATE_RIGHT_VISIBLE, true);
     }
 
     private void changePaneState(int newState, boolean animate) {
@@ -176,6 +204,7 @@ public class ThreePaneLayout extends LinearLayout implements View.OnClickListene
         if (newState == mPaneState) {
             return;
         }
+        final int previousVisiblePanes = getVisiblePanes();
         mPaneState = newState;
         switch (mPaneState) {
             case STATE_LEFT_VISIBLE:
@@ -217,7 +246,7 @@ public class ThreePaneLayout extends LinearLayout implements View.OnClickListene
                 mFoggedGlass.setVisibility(View.VISIBLE);
                 break;
         }
-        mCallback.onVisiblePanesChanged();
+        mCallback.onVisiblePanesChanged(previousVisiblePanes);
     }
 
     /**