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

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

Index: remoting/android/java/src/org/chromium/chromoting/Desktop.java
diff --git a/remoting/android/java/src/org/chromium/chromoting/Desktop.java b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
index ef9c582a3be8d6c67d1b947877b05e72e3c84784..b906a87b80b6bacaec05f5ee65192dbb2b6ae7b2 100644
--- a/remoting/android/java/src/org/chromium/chromoting/Desktop.java
+++ b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
@@ -11,6 +11,7 @@ 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;
@@ -20,6 +21,7 @@ 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;
@@ -40,8 +42,10 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
      * 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 = 5000;
 
     /** The surface that displays the remote host's desktop feed. */
     private DesktopView mRemoteHostDesktop;
@@ -51,10 +55,15 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
 
     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) {
@@ -78,9 +87,19 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         View decorView = getWindow().getDecorView();
         decorView.setOnSystemUiVisibilityChangeListener(this);
 
-        mActivityLifecycleListener = CapabilityManager.getInstance()
-            .onActivityAcceptingListener(this, Capabilities.CAST_CAPABILITY);
+        mActivityLifecycleListener = CapabilityManager.getInstance().onActivityAcceptingListener(
+                this, Capabilities.CAST_CAPABILITY);
         mActivityLifecycleListener.onActivityCreated(this, savedInstanceState);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            // 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();
+            attachKeyboardVisibilityListener();
+        } else {
+            mRemoteHostDesktop.setFitsSystemWindows(true);
+        }
     }
 
     @Override
@@ -98,6 +117,7 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         if (!mSwitchToCardboardDesktopActivity) {
             JniInterface.enableVideoChannel(false);
         }
+        stopActionBarAutoHideTimer();
     }
 
     @Override
@@ -105,6 +125,7 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         super.onResume();
         mActivityLifecycleListener.onActivityResumed(this);
         JniInterface.enableVideoChannel(true);
+        startActionBarAutoHideTimer();
     }
 
     @Override
@@ -127,8 +148,8 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
 
         boolean enableCardboard = false;
         try {
-            ApplicationInfo ai = getPackageManager()
-                    .getApplicationInfo(getPackageName(), PackageManager.GET_META_DATA);
+            ApplicationInfo ai = getPackageManager().getApplicationInfo(
+                    getPackageName(), PackageManager.GET_META_DATA);
             Bundle bundle = ai.metaData;
             enableCardboard = bundle.getInt("enable_cardboard") == 1;
         } catch (NameNotFoundException e) {
@@ -143,6 +164,41 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         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 (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
+            // The required flags for immersive full screen are not supported on pre-KitKat builds
+            // so don't enable the auto-hide timer for them as every transition on older versions
+            // causes resizing of the canvas and we want to minimize the number of layout changes.
+            return;
+        }
+
+        if (mActionBarAutoHideTask != null) {
+            stopActionBarAutoHideTimer();
+        }
+
+        mActionBarAutoHideTask = new Runnable() {

[Lambros, 2015/10/29 23:39:16]

optional: Don't really need to keep setting mActionBarAutoHideTask to null and
re-creating it. Just initialize it once (at declaration). Then, here, you can
unconditionally stop the timer, which will do nothing if the timer isn't
running.

[joedow, 2015/10/30 17:41:22]

Done.

+            public void run() {
+                hideActionBar();
+            }
+        };
+
+        View decorView = getWindow().getDecorView();
+        decorView.postDelayed(mActionBarAutoHideTask, ACTIONBAR_AUTO_HIDE_DELAY_MS);
+    }
+
+    // Clear an existing delayed task to prevent the ActionBar from being hidden.
+    private void stopActionBarAutoHideTimer() {
+        if (mActionBarAutoHideTask == null) {
+            return;
+        }
+
+        View decorView = getWindow().getDecorView();
+        decorView.removeCallbacks(mActionBarAutoHideTask);
+        mActionBarAutoHideTask = null;
+    }
+
     /** Called whenever the visibility of the system status bar or navigation bar changes. */
     @Override
     public void onSystemUiVisibilityChange(int visibility) {
@@ -176,12 +232,26 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         // 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;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;

[Lambros, 2015/10/29 23:39:16]

Since these are duplicated below, maybe have a getLayoutFlags() or similar
function?

[joedow, 2015/10/30 17:41:23]

Done.

+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION;
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
+        }
+        decorView.setSystemUiVisibility(flags);
+
+        // 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")
@@ -204,15 +274,28 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         // 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 |= View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION;
+            flags |= View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
         }
 
         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. */
@@ -222,6 +305,9 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
 
         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;
@@ -240,9 +326,8 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         }
         if (id == R.id.actionbar_send_ctrl_alt_del) {
             int[] keys = {
-                KeyEvent.KEYCODE_CTRL_LEFT,
-                KeyEvent.KEYCODE_ALT_LEFT,
-                KeyEvent.KEYCODE_FORWARD_DEL,
+                    KeyEvent.KEYCODE_CTRL_LEFT, KeyEvent.KEYCODE_ALT_LEFT,
+                    KeyEvent.KEYCODE_FORWARD_DEL,
             };
             for (int key : keys) {
                 JniInterface.sendKeyEvent(0, key, true);
@@ -259,6 +344,35 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         return super.onOptionsItemSelected(item);
     }
 
+    private void attachKeyboardVisibilityListener() {
+        View keyboardVisibilityDetector = findViewById(R.id.resize_detector);
+        keyboardVisibilityDetector.addOnLayoutChangeListener(new OnLayoutChangeListener() {
+            // Represents the initial size of the viewable area sans the soft keyboard.
+            private Rect mInitialRect;
+
+            @Override
+            public void onLayoutChange(View v, int left, int top, int right, int bottom,
+                    int oldLeft, int oldTop, int oldRight, int oldBottom) {
+                if (mInitialRect == null || bottom > mInitialRect.bottom) {

[Lambros, 2015/10/29 23:39:16]

Maybe initialize mInitialRect and mutate it instead of creating new Rect() each
time?

[joedow, 2015/10/30 17:41:22]

Done.

+                    // When the activity is started fresh we will see a single layout change event,
+                    // however if we are transitioning between orientations and the keyboard was
+                    // previously visible, we might receive several layout changes sequentially.
+                    mInitialRect = new Rect(left, top, right, 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 = ((mInitialRect.bottom - bottom) > 0);

[Lambros, 2015/10/29 23:39:16]

Maybe replace Rect with int, since you only use |bottom|?

[joedow, 2015/10/30 17:41:22]

Done.

+                mRemoteHostDesktop.onSoftInputMethodVisibilityChanged(
+                        mSoftInputVisible, new Rect(left, top, right, bottom));
+            }
+        });
+    }
+
     private void onCardboardItemSelected() {
         if (getPreferences(MODE_PRIVATE).getBoolean(PREFERENCE_CARDBOARD_DIALOG_SEEN, false)) {
             switchToCardboardMode();
@@ -269,21 +383,22 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
                 .setTitle(getTitle())
                 .setMessage(R.string.cardboard_warning_message)
                 .setIcon(R.drawable.ic_cardboard)
-                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
-                    @Override
-                    public void onClick(DialogInterface dialog, int id) {
-                        getPreferences(MODE_PRIVATE)
-                                .edit()
-                                .putBoolean(PREFERENCE_CARDBOARD_DIALOG_SEEN, true)
-                                .apply();
-                        switchToCardboardMode();
-                    }
-                })
-                .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
-                    @Override
-                    public void onClick(DialogInterface dialog, int id) {
-                    }
-                })
+                .setPositiveButton(android.R.string.ok,
+                        new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int id) {
+                                getPreferences(MODE_PRIVATE)
+                                        .edit()
+                                        .putBoolean(PREFERENCE_CARDBOARD_DIALOG_SEEN, true)
+                                        .apply();
+                                switchToCardboardMode();
+                            }
+                        })
+                .setNegativeButton(android.R.string.cancel,
+                        new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int id) {}
+                        })
                 .create()
                 .show();
     }
@@ -336,12 +451,12 @@ public class Desktop extends AppCompatActivity implements View.OnSystemUiVisibil
         // want to send it as KeyEvent.
         int unicode = keyCode != KeyEvent.KEYCODE_ENTER ? event.getUnicodeChar() : 0;
 
-        boolean no_modifiers = !event.isAltPressed()
-                && !event.isCtrlPressed() && !event.isMetaPressed();
+        boolean no_modifiers =
+                !event.isAltPressed() && !event.isCtrlPressed() && !event.isMetaPressed();
 
         if (pressed && unicode != 0 && no_modifiers) {
             mPressedTextKeys.add(keyCode);
-            int[] codePoints = { unicode };
+            int[] codePoints = {unicode};
             JniInterface.sendTextEvent(new String(codePoints, 0, 1));
             return true;
         }