[Android] Focus/Blur contents when window focus changes

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.content.browser;
 
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.assist.AssistStructure.ViewNode;
 import android.content.ClipData;
@@ skipping 1317 matching lines @@
         // Zero-ing the rect will prevent |updateAfterSizeChanged()| from
         // issuing the delayed form focus event.
         mFocusPreOSKViewportRect.setEmpty();
     }
 
     /**
      * @see View#onWindowFocusChanged(boolean)
      */
     public void onWindowFocusChanged(boolean hasWindowFocus) {
         mImeAdapter.onWindowFocusChanged(hasWindowFocus);
-        if (!hasWindowFocus) resetGestureDetection();
+        if (!hasWindowFocus) {
+            resetGestureDetection();
+            if (hasFocus()) onFocusChanged(false, true /* hideKeyboardOnBlur */);

[aelias_OOO_until_Jul13, 2017/03/29 21:54:04]

This is stacking the effects of the view focus and window focus booleans in a
way that's hard to reason about.  I suggest changing
ContentViewCore.onFocusChanged to not take the first boolean argument, and
instead directly within itself call the view and window focus methods to
determine the new focus status.

Please also add an early-return at the top of ContentViewCore.onFocusChanged if
focus did not wind up changing, which probably should involve a boolean which is
also set correctly at ContentViewCore construction.

[mthiesse, 2017/03/30 00:49:26]

Done.

+        } else {
+            if (hasFocus()) onFocusChanged(true, true /* hideKeyboardOnBlur */);
+        }

[Changwan Ryu, 2017/03/30 00:05:49]

Because ImeAdapter and SelectionPopupController already handle window and view
focus changes separately, could we refactor this into something like the
following?

public void onWindowFocusChanged(boolean hasWindowFocus) {
    ...
    onFocusChangeInternal();
}

public void onFocusChanged(boolean gainFocus, boolean hideKeyboardOnBlur) {
    ...
    onFocusChangeInternal();
}

private void onFocusChangeInternal() {
    boolean focused = hasWindowFocus() && hasFocus();
    if (focused != mFocused) {
        if (mNativeContentViewCore != 0) { 
            nativeSetFocus(mNativeContentViewCore, hasWindowFocus() &&
hasFocus());
        }
        mFocused = focused;
    }
}

I think this should be enough for now.

Otherwise, at least ThreadedInputConnectionFactory's logging will be messed up.

BTW, as aelias@ pointed out, window and view focus change order can be quite
complex and hard to predict. In the case of web app, the normal order would be
window focus loss --> view focus loss, but some webview app may change view
focus in the middle of window focus loss which will end up as view focus loss
--> window focus loss.

[mthiesse, 2017/03/30 00:12:45]

Thanks, that's essentially what I'm writing now.

However, I'm bashing my head against a wall because View#hasWindowFocus()
returns false when we first get a ContainerView, but then OnWindowFocusChanged
is *never* called until the app first loses window focus.

I'm trying to find some other way of setting the initial state correctly, but it
seems that View#hasWindowFocus() really can't be trusted.

[mthiesse, 2017/03/30 00:49:26]

Done.

         mSelectionPopupController.onWindowFocusChanged(hasWindowFocus);
         for (mGestureStateListenersIterator.rewind(); mGestureStateListenersIterator.hasNext();) {
             mGestureStateListenersIterator.next().onWindowFocusChanged(hasWindowFocus);
         }
     }
 
     public void onFocusChanged(boolean gainFocus, boolean hideKeyboardOnBlur) {
         mImeAdapter.onViewFocusChanged(gainFocus, hideKeyboardOnBlur);
 
         // Used in test that bypasses initialize().
@@ skipping 1327 matching lines @@
     private native void nativeSetTextTrackSettings(long nativeContentViewCoreImpl,
             boolean textTracksEnabled, String textTrackBackgroundColor, String textTrackFontFamily,
             String textTrackFontStyle, String textTrackFontVariant, String textTrackTextColor,
             String textTrackTextShadow, String textTrackTextSize);
 
     private native void nativeSetBackgroundOpaque(long nativeContentViewCoreImpl, boolean opaque);
     private native boolean nativeIsTouchDragDropEnabled(long nativeContentViewCoreImpl);
     private native void nativeOnDragEvent(long nativeContentViewCoreImpl, int action, int x, int y,
             int screenX, int screenY, String[] mimeTypes, String content);
 }