steve_patrick steve_patrick - 4 days ago 6
Android Question

Permanently hide navigation bar on activity

Is it possible to permanently remove the navigation bar on an activity? I want to remove the bar with the buttons that appear at the button of the screen on tablets, not the action bar.
http://developer.android.com/design/get-started/ui-overview.html

I know is not recommended to do that (I didn't decide that), but I really need to do it. On my layout there is another button in order to leave the activiy. The rest of my app do have the navigation bar.
Is it possible?

I found this code and adapted a little bit. The problem is that even when I hide the navigation bar there is a black space behind. I guess the system calculates the screen size having into account the navigation bar, isn't it?

public static class Content extends ImageView implements View.OnSystemUiVisibilityChangeListener, View.OnClickListener, ActionBar.OnMenuVisibilityListener {
Activity mActivity;
TextView mTitleView;
Button mPlayButton;
SeekBar mSeekView;
boolean mAddedMenuListener;
boolean mMenusOpen;
boolean mPaused;
boolean mNavVisible;
int mLastSystemUiVis;

Runnable mNavHider = new Runnable() {
@Override public void run() {
setNavVisibility(false);
}
};

public Content(Context context, AttributeSet attrs) {
super(context, attrs);
setOnSystemUiVisibilityChangeListener(this);
setOnClickListener(this);
}

public void init(Activity activity, TextView title, Button playButton,
SeekBar seek) {
// This called by the containing activity to supply the surrounding
// state of the video player that it will interact with.
mActivity = activity;
mTitleView = title;
mPlayButton = playButton;
mSeekView = seek;
mPlayButton.setOnClickListener(this);
setPlayPaused(true);
}

@Override protected void onAttachedToWindow() {
super.onAttachedToWindow();
if (mActivity != null) {
mAddedMenuListener = true;
mActivity.getActionBar().addOnMenuVisibilityListener(this);
}
}

@Override protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mAddedMenuListener) {
mActivity.getActionBar().removeOnMenuVisibilityListener(this);
}
}

@Override public void onSystemUiVisibilityChange(int visibility) {
// Detect when we go out of nav-hidden mode, to clear our state
// back to having the full UI chrome up. Only do this when
// the state is changing and nav is no longer hidden.
int diff = mLastSystemUiVis ^ visibility;
mLastSystemUiVis = visibility;
if ((diff&SYSTEM_UI_FLAG_HIDE_NAVIGATION) != 0
&& (visibility&SYSTEM_UI_FLAG_HIDE_NAVIGATION) == 0) {
setNavVisibility(true);
}
}

@Override protected void onWindowVisibilityChanged(int visibility) {
super.onWindowVisibilityChanged(visibility);

// When we become visible or invisible, play is paused.
setPlayPaused(true);
}

@Override public void onClick(View v) {
if (v == mPlayButton) {
// Clicking on the play/pause button toggles its state.
setPlayPaused(!mPaused);
} else {
// Clicking elsewhere makes the navigation visible.
setNavVisibility(true);
}
}

@Override public void onMenuVisibilityChanged(boolean isVisible) {
mMenusOpen = isVisible;
setNavVisibility(true);
}

void setPlayPaused(boolean paused) {
mPaused = paused;
mPlayButton.setText(paused ? R.string.play : R.string.pause);
setKeepScreenOn(!paused);
setNavVisibility(true);
}

void setNavVisibility(boolean visible) {
int newVis = SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
| SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
| SYSTEM_UI_FLAG_LAYOUT_STABLE;
if (!visible) {
newVis |= SYSTEM_UI_FLAG_LOW_PROFILE | SYSTEM_UI_FLAG_FULLSCREEN
| SYSTEM_UI_FLAG_HIDE_NAVIGATION;
}

// If we are now visible, schedule a timer for us to go invisible.
if (visible) {
Handler h = getHandler();
if (h != null) {
h.removeCallbacks(mNavHider);
if (!mMenusOpen && !mPaused) {
// If the menus are open or play is paused, we will not auto-hide.
h.postDelayed(mNavHider, 1500);
}
}
}

// Set the new desired visibility.
setSystemUiVisibility(newVis);
mTitleView.setVisibility(visible ? VISIBLE : INVISIBLE);
mPlayButton.setVisibility(visible ? VISIBLE : INVISIBLE);
mSeekView.setVisibility(visible ? VISIBLE : INVISIBLE);
}
}


Any solution for this?

Answer

AFAIK, this is not possible without root access. It would be a security issue to be able to have an app that cannot be exited with system buttons.

Edit, see here: Hide System Bar in Tablets

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