Fixing image canvas resize problems when showing/hiding system UI.

remoting/android/java/src/org/chromium/chromoting/Desktop.java

 // Copyright 2013 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.chromoting;
 
 import android.annotation.SuppressLint;
 import android.app.AlertDialog;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
+import android.graphics.Rect;
 import android.os.Build;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.view.KeyCharacterMap;
 import android.view.KeyEvent;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
+import android.view.View.OnLayoutChangeListener;
 import android.view.inputmethod.InputMethodManager;
 
 import org.chromium.chromoting.cardboard.DesktopActivity;
 import org.chromium.chromoting.jni.JniInterface;
 
 import java.util.Set;
 import java.util.TreeSet;
 
 /**
  * A simple screen that does nothing except display a DesktopView and notify it of rotations.
  */
 public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibilityChangeListener {
     /** Web page to be displayed in the Help screen when launched from this activity. */
     private static final String HELP_URL =
             "https://support.google.com/chrome/?p=mobile_crd_connecthost";
 
     /**
      * Preference used for displaying an interestitial dialog only when the user first accesses the
      * Cardboard function.
      */
-    private static final String PREFERENCE_CARDBOARD_DIALOG_SEEN =
-            "cardboard_dialog_seen";
+    private static final String PREFERENCE_CARDBOARD_DIALOG_SEEN = "cardboard_dialog_seen";
+
+    /** The amount of time to wait to hide the Actionbar after user input is seen. */
+    private static final int ACTIONBAR_AUTO_HIDE_DELAY_MS = 3000;
 
     /** The surface that displays the remote host's desktop feed. */
     private DesktopView mRemoteHostDesktop;
 
     /** Set of pressed keys for which we've sent TextEvent. */
     private Set<Integer> mPressedTextKeys = new TreeSet<Integer>();
 
     private ActivityLifecycleListener mActivityLifecycleListener;
 
-    // Flag to indicate whether the current activity is going to switch to Cardboard
-    // desktop activity.
+    /** Flag to indicate whether the current activity is switching to Cardboard desktop activity. */
     private boolean mSwitchToCardboardDesktopActivity;
 
+    /** Indicates whether a Soft Input UI (such as a keyboard) is visible. */
+    private boolean mSoftInputVisible = false;
+
+    /** Holds the scheduled task object which will be called to hide the ActionBar. */
+    private Runnable mActionBarAutoHideTask;
+
     /** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.desktop);
 
         Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
 
         mRemoteHostDesktop = (DesktopView) findViewById(R.id.desktop_view);
         mRemoteHostDesktop.setDesktop(this);
         mSwitchToCardboardDesktopActivity = false;
 
         getSupportActionBar().setDisplayShowTitleEnabled(false);
         getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
         // For this Activity, the home button in the action bar acts as a Disconnect button, so
         // set the description for accessibility/screen readers.
         getSupportActionBar().setHomeActionContentDescription(R.string.disconnect_myself_button);
 
+        // The action bar is already shown when the activity is started however calling the
+        // function below will set our preferred system UI flags which will adjust the layout
+        // size of the canvas and we can avoid an initial resize event.
+        showActionBar();
+
         View decorView = getWindow().getDecorView();
         decorView.setOnSystemUiVisibilityChangeListener(this);
 
         mActivityLifecycleListener = CapabilityManager.getInstance()
-            .onActivityAcceptingListener(this, Capabilities.CAST_CAPABILITY);
+                .onActivityAcceptingListener(this, Capabilities.CAST_CAPABILITY);
         mActivityLifecycleListener.onActivityCreated(this, savedInstanceState);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            attachKeyboardVisibilityListener();
+
+            // Only create an Autohide task if the system supports immersive fullscreen mode.  Older
+            // versions of the OS benefit less from this functionality and we don't want to change
+            // the experience for them.
+            mActionBarAutoHideTask = new Runnable() {
+                public void run() {
+                    hideActionBar();
+                }
+            };
+        } else {
+            mRemoteHostDesktop.setFitsSystemWindows(true);
+        }
     }
 
     @Override
     protected void onStart() {
         super.onStart();
         mActivityLifecycleListener.onActivityStarted(this);
         JniInterface.enableVideoChannel(true);
         mRemoteHostDesktop.attachRedrawCallback();
     }
 
     @Override
     protected void onPause() {
         if (isFinishing()) mActivityLifecycleListener.onActivityPaused(this);
         super.onPause();
         if (!mSwitchToCardboardDesktopActivity) {
             JniInterface.enableVideoChannel(false);
         }
+        stopActionBarAutoHideTimer();
     }
 
     @Override
     public void onResume() {
         super.onResume();
         mActivityLifecycleListener.onActivityResumed(this);
         JniInterface.enableVideoChannel(true);
+        startActionBarAutoHideTimer();
     }
 
     @Override
     protected void onStop() {
         mActivityLifecycleListener.onActivityStopped(this);
         super.onStop();
         if (mSwitchToCardboardDesktopActivity) {
             mSwitchToCardboardDesktopActivity = false;
         } else {
             JniInterface.enableVideoChannel(false);
@@ skipping 13 matching lines @@
                     .getApplicationInfo(getPackageName(), PackageManager.GET_META_DATA);
             Bundle bundle = ai.metaData;
             enableCardboard = bundle.getInt("enable_cardboard") == 1;
         } catch (NameNotFoundException e) {
             // Does nothing since by default Cardboard activity is turned off.
         }
 
         MenuItem item = menu.findItem(R.id.actionbar_cardboard);
         item.setVisible(enableCardboard);
 
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            // We don't need to show a hide ActionBar button if immersive fullscreen is supported.
+            menu.findItem(R.id.actionbar_hide).setVisible(false);
+        }
+
         ChromotingUtil.tintMenuIcons(this, menu);
 
         return super.onCreateOptionsMenu(menu);
     }
 
+    // Posts a deplayed task to hide the ActionBar.  If an existing task has already been scheduled,
+    // then the previous task is removed and the new one scheduled, effectively resetting the timer.
+    private void startActionBarAutoHideTimer() {
+        if (mActionBarAutoHideTask == null) {
+            return;
+        }
+
+        stopActionBarAutoHideTimer();
+
+        View decorView = getWindow().getDecorView();
+        decorView.postDelayed(mActionBarAutoHideTask, ACTIONBAR_AUTO_HIDE_DELAY_MS);
+    }
+
+    // Clear all existing delayed tasks to prevent the ActionBar from being hidden.
+    private void stopActionBarAutoHideTimer() {
+        if (mActionBarAutoHideTask == null) {
+            return;
+        }
+
+        View decorView = getWindow().getDecorView();

[Lambros, 2015/11/02 19:48:54]

optional: getWindow().getDecorView().removeCallbacks(...)
and maybe invert the if (..) check?
Similarly for startActionBarAutoHideTimer() above?

+        decorView.removeCallbacks(mActionBarAutoHideTask);
+    }
+
     /** Called whenever the visibility of the system status bar or navigation bar changes. */
     @Override
     public void onSystemUiVisibilityChange(int visibility) {
         // Ensure the action-bar's visibility matches that of the system controls. This
         // minimizes the number of states the UI can be in, to keep things simple for the user.
 
         // Determine if the system is in fullscreen/lights-out mode. LOW_PROFILE is needed since
         // it's the only flag supported in 4.0. But it is not sufficient in itself; when
         // IMMERSIVE_STICKY mode is used, the system clears this flag (leaving the FULLSCREEN flag
         // set) when the user swipes the edge to reveal the bars temporarily. When this happens,
         // the action-bar should remain hidden.
-        int fullscreenFlags = getSystemUiFlags();
+        int fullscreenFlags = getFullscreenFlags();
         if ((visibility & fullscreenFlags) != 0) {
             hideActionBarWithoutSystemUi();
         } else {
             showActionBarWithoutSystemUi();
         }
     }
 
     @SuppressLint("InlinedApi")
-    private int getSystemUiFlags() {
+    private static int getFullscreenFlags() {
         int flags = View.SYSTEM_UI_FLAG_LOW_PROFILE;
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
             flags |= View.SYSTEM_UI_FLAG_FULLSCREEN;
         }
         return flags;
     }
 
+    @SuppressLint("InlinedApi")
+    private static int getImmersiveLayoutFlags() {
+        int flags = 0;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION;
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
+        }
+        return flags;
+    }
+
     public void showActionBar() {
         // Request exit from any fullscreen mode. The action-bar controls will be shown in response
         // to the SystemUiVisibility notification. The visibility of the action-bar should be tied
         // to the fullscreen state of the system, so there's no need to explicitly show it here.
         View decorView = getWindow().getDecorView();
-        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE);
+        int flags = View.SYSTEM_UI_FLAG_VISIBLE;
+        flags |= getImmersiveLayoutFlags();

[Lambros, 2015/11/02 19:48:54]

optional:
int flags = getImmersiveLayoutFlags() | View.SYSTEM_UI_FLAG_VISIBLE;

+        decorView.setSystemUiVisibility(flags);

[Lambros, 2015/11/02 19:48:54]

optional: remove |decorView| temporary.

+
+        // The OS will not call onSystemUiVisibilityChange() if the keyboard is visible which means
+        // our ActionBar will not be visible until then.  This check allows us to work around this
+        // issue and still allow the system to show the ActionBar normally with the soft keyboard.
+        if (mSoftInputVisible) {
+            showActionBarWithoutSystemUi();
+        }
     }
 
     /** Shows the action bar without changing SystemUiVisibility. */
     private void showActionBarWithoutSystemUi() {
         getSupportActionBar().show();
+        startActionBarAutoHideTimer();
     }
 
     @SuppressLint("InlinedApi")
     public void hideActionBar() {
         // Request the device to enter fullscreen mode. Don't hide the controls yet, because the
         // system might not honor the fullscreen request immediately (for example, if the
         // keyboard is visible, the system might delay fullscreen until the keyboard is hidden).
         // The controls will be hidden in response to the SystemUiVisibility notification.
         // This helps ensure that the visibility of the controls is synchronized with the
         // fullscreen state.
         View decorView = getWindow().getDecorView();
 
         // LOW_PROFILE gives the status and navigation bars a "lights-out" appearance.
         // FULLSCREEN hides the status bar on supported devices (4.1 and above).
-        int flags = getSystemUiFlags();
+        int flags = getFullscreenFlags();
 
         // HIDE_NAVIGATION hides the navigation bar. However, if the user touches the screen, the
         // event is not seen by the application and instead the navigation bar is re-shown.
         // IMMERSIVE(_STICKY) fixes this problem and allows the user to interact with the app while
         // keeping the navigation controls hidden. This flag was introduced in 4.4, later than
         // HIDE_NAVIGATION, and so a runtime check is needed before setting either of these flags.
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-            flags |= (View.SYSTEM_UI_FLAG_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_IMMERSIVE);
+            flags |= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
+            flags |= View.SYSTEM_UI_FLAG_IMMERSIVE;
+            flags |= getImmersiveLayoutFlags();
         }
 
         decorView.setSystemUiVisibility(flags);
+
+        // The OS will not call onSystemUiVisibilityChange() until the keyboard has been dismissed
+        // which means our ActionBar will still be visible.  This check allows us to work around
+        // this issue when the keyboard is visible and the user wants additional space on the screen
+        // and still allow the system to hide the ActionBar normally when no keyboard is present.
+        if (mSoftInputVisible) {
+            hideActionBarWithoutSystemUi();
+        }
     }
 
     /** Hides the action bar without changing SystemUiVisibility. */
     private void hideActionBarWithoutSystemUi() {
         getSupportActionBar().hide();
+        stopActionBarAutoHideTimer();
     }
 
     /** Called whenever an action bar button is pressed. */
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         int id = item.getItemId();
 
         mActivityLifecycleListener.onActivityOptionsItemSelected(this, item);
 
+        // Whenever a user selects an option from the ActionBar, reset the auto-hide timer.
+        startActionBarAutoHideTimer();
+
         if (id == R.id.actionbar_cardboard) {
             onCardboardItemSelected();
             return true;
         }
         if (id == R.id.actionbar_keyboard) {
             ((InputMethodManager) getSystemService(INPUT_METHOD_SERVICE)).toggleSoftInput(0, 0);
             return true;
         }
         if (id == R.id.actionbar_hide) {
             hideActionBar();
@@ skipping 17 matching lines @@
             }
             return true;
         }
         if (id == R.id.actionbar_help) {
             HelpActivity.launch(this, HELP_URL);
             return true;
         }
         return super.onOptionsItemSelected(item);
     }
 
+    private void attachKeyboardVisibilityListener() {
+        View keyboardVisibilityDetector = findViewById(R.id.resize_detector);
+        keyboardVisibilityDetector.addOnLayoutChangeListener(new OnLayoutChangeListener() {
+            // Tracks the maximum 'bottom' value seen during layout changes.  This value represents
+            // the top of the SystemUI displayed at the bottom of the screen.
+            // Note: This value is a screen coordinate so a larger value means lower on the screen.
+            private int mInitialBottomValue = 0;

[Lambros, 2015/11/02 19:48:54]

Maybe rename to mMaximumBottomValue ?

[Lambros, 2015/11/02 19:48:54]

optional: remove '= 0', int members are 0 by default.

+
+            @Override
+            public void onLayoutChange(View v, int left, int top, int right, int bottom,
+                    int oldLeft, int oldTop, int oldRight, int oldBottom) {
+                // As the activity is started, a number of layout changes will flow through.  If
+                // this is a fresh start, then we will see one layout change which will represent
+                // the steady state of the UI and will include an accurate 'bottom' value.  If we
+                // are transitioning from another activity/orientation, then there may be several
+                // layout change events as the view is updated (i.e. the OSK might have been
+                // displayed previously but is being dismissed).  Therefore we want to track the
+                // largest value we have seen and use it to determine if a new system UI (such as
+                // the OSK) is being displayed.
+                if (mInitialBottomValue < bottom) {
+                    mInitialBottomValue = bottom;
+                    return;
+                }
+
+                // If the delta between lowest bound we have seen (should be a systemUI such as
+                // the navigation bar) and the current bound does not match, then we have a form
+                // of soft input displayed.  Note that the size of a soft input device can change
+                // when the input method is changed so we want to send updates to the image canvas
+                // whenever they occur.
+                mSoftInputVisible = (bottom < mInitialBottomValue);
+                mRemoteHostDesktop.onSoftInputMethodVisibilityChanged(
+                        mSoftInputVisible, new Rect(left, top, right, bottom));
+            }
+        });
+    }
+
     private void onCardboardItemSelected() {
         if (getPreferences(MODE_PRIVATE).getBoolean(PREFERENCE_CARDBOARD_DIALOG_SEEN, false)) {
             switchToCardboardMode();
             return;
         }
 
         new AlertDialog.Builder(this)
                 .setTitle(getTitle())
                 .setMessage(R.string.cardboard_warning_message)
                 .setIcon(R.drawable.ic_cardboard)
@@ skipping 103 matching lines @@
                 JniInterface.sendKeyEvent(0, KeyEvent.KEYCODE_SHIFT_LEFT, pressed);
                 JniInterface.sendKeyEvent(0, KeyEvent.KEYCODE_EQUALS, pressed);
                 return true;
 
             default:
                 // We try to send all other key codes to the host directly.
                 return JniInterface.sendKeyEvent(0, keyCode, pressed);
         }
     }
 }