Make IMS.setBackDisposition() work.

InputMethodService.setBackDisposition() has been broken from a long
time. This is how setBackDisposition() is supposed to work
1. BACK_DISPOSITION_WILL_DISMISS:
When Keyboard is visible back button will show as down arrow (in
navigation bar) and tapping it will dismiss keyboard.
2. BACK_DISPOSITION_WILL_NOT_DISMISS:
When keyboard is visible, back button will be shown as BACK arrow and
tapping it will send the back event to current activity. If activity
doesn't handle onKeyDown() for back button, activity will finish and
keyboard will hide.

Note: backDisposition flags reset when finishInput() is called.

Bug: 38513361
Test: Manual with apk attached in bug
Test: atest InputMethodServiceTest
Change-Id: I99e7c413fe1a93f8d8cff897b5c5f0947690d2c0

1 files changed, 24 insertions, 3 deletions

diff --git a/core/java/android/inputmethodservice/InputMethodService.java b/core/java/android/inputmethodservice/InputMethodService.java
index 7528bc3989c2..a817f33ce7ba 100644
--- a/core/java/android/inputmethodservice/InputMethodService.java
+++ b/core/java/android/inputmethodservice/InputMethodService.java
@@ -265,6 +265,10 @@ public class InputMethodService extends AbstractInputMethodService {
      */
     public static final int IME_VISIBLE = 0x2;
 
+    // Min and max values for back disposition.
+    private static final int BACK_DISPOSITION_MIN = BACK_DISPOSITION_DEFAULT;
+    private static final int BACK_DISPOSITION_MAX = BACK_DISPOSITION_WILL_DISMISS;
+
     InputMethodManager mImm;
     
     int mTheme = 0;
@@ -501,9 +505,8 @@ public class InputMethodService extends AbstractInputMethodService {
             }
             clearInsetOfPreviousIme();
             // If user uses hard keyboard, IME button should always be shown.
-            boolean showing = isInputViewShown();
             mImm.setImeWindowStatus(mToken, mStartInputToken,
-                    IME_ACTIVE | (showing ? IME_VISIBLE : 0), mBackDisposition);
+                    mapToImeWindowStatus(isInputViewShown()), mBackDisposition);
             if (resultReceiver != null) {
                 resultReceiver.send(wasVis != isInputViewShown()
                         ? InputMethodManager.RESULT_SHOWN
@@ -1014,7 +1017,16 @@ public class InputMethodService extends AbstractInputMethodService {
     }
     
     public void setBackDisposition(int disposition) {
+        if (disposition == mBackDisposition) {
+            return;
+        }
+        if (disposition > BACK_DISPOSITION_MAX || disposition < BACK_DISPOSITION_MIN) {
+            Log.e(TAG, "Invalid back disposition value (" + disposition + ") specified.");
+            return;
+        }
         mBackDisposition = disposition;
+        mImm.setImeWindowStatus(mToken, mStartInputToken, mapToImeWindowStatus(isInputViewShown()),
+                mBackDisposition);
     }
 
     public int getBackDisposition() {
@@ -1762,7 +1774,7 @@ public class InputMethodService extends AbstractInputMethodService {
             startExtractingText(false);
         }
 
-        final int nextImeWindowStatus = IME_ACTIVE | (isInputViewShown() ? IME_VISIBLE : 0);
+        final int nextImeWindowStatus = mapToImeWindowStatus(isInputViewShown());
         if (previousImeWindowStatus != nextImeWindowStatus) {
             mImm.setImeWindowStatus(mToken, mStartInputToken, nextImeWindowStatus,
                     mBackDisposition);
@@ -1889,6 +1901,7 @@ public class InputMethodService extends AbstractInputMethodService {
         mInputStarted = false;
         mStartedInputConnection = null;
         mCurCompletions = null;
+        mBackDisposition = BACK_DISPOSITION_DEFAULT;
     }
 
     void doStartInput(InputConnection ic, EditorInfo attribute, boolean restarting) {
@@ -2104,7 +2117,11 @@ public class InputMethodService extends AbstractInputMethodService {
      * them to perform navigation in the underlying application.
      */
     public boolean onKeyDown(int keyCode, KeyEvent event) {
+
         if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
+            if (mBackDisposition == BACK_DISPOSITION_WILL_NOT_DISMISS) {
+                return false;
+            }
             final ExtractEditText eet = getExtractEditTextIfVisible();
             if (eet != null && eet.handleBackInTextActionModeIfNeeded(event)) {
                 return true;
@@ -2738,6 +2755,10 @@ public class InputMethodService extends AbstractInputMethodService {
         mImm.exposeContent(mToken, inputContentInfo, getCurrentInputEditorInfo());
     }
 
+    private static int mapToImeWindowStatus(boolean isInputViewShown) {
+        return IME_ACTIVE | (isInputViewShown ? IME_VISIBLE : 0);
+    }
+
     /**
      * Performs a dump of the InputMethodService's internal state.  Override
      * to add your own information to the dump.