Android – open the drawer layout with animation programmatically

androidandroid-support-librarynavigation-drawer

I created the app drawer by using the following library:
http://developer.android.com/training/implementing-navigation/nav-drawer.html

I want to show the Navigation Drawer with animation when opening the app.
How can I do that?

Best Answer

Predraw listener, aka the safeway

Here is the predraw listener example. It will literally start the animation as soon as it can which maybe a little too fast. You might want to do a combination of this with a runnable shown second. I will not show the two combined, only separate.

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...
    // Building NavDrawer logic here. Just a method call would be best.
    ...

    ViewTreeObserver vto = drawer.getViewTreeObserver();
    if (vto != null) vto.addOnPreDrawListener(new ShouldShowListener(drawer));
}

private static class ShouldShowListener implements OnPreDrawListener {

    private final DrawerLayout drawerLayout;

    private ShouldShowListener(DrawerLayout drawerLayout) {
        this.drawerLayout= drawerLayout;
    }

    @Override
    public boolean onPreDraw() {
        if (view != null) {
            ViewTreeObserver vto = view.getViewTreeObserver();
            if (vto != null) {
                vto.removeOnPreDrawListener(this);
            }
        }

        drawerLayout.openDrawer(Gravity.LEFT);
        return true;
    }
}

PostDelay Runnable, aka living dangerous

// Delay is in milliseconds
static final int DRAWER_DELAY = 200;

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...
    // Building NavDrawer logic here. Just a method call would be best.
    ...
    new Handler().postDelayed(openDrawerRunnable(), DRAWER_DELAY);
}

private Runnable openDrawerRunnable() {
    return new Runnable() {

        @Override
        public void run() {
            drawerLayout.openDrawer(Gravity.LEFT);
        }
    }
}

WARNING

If they rotate on the start of the app for the first time BOOM! Read this blog post for more information http://corner.squareup.com/2013/12/android-main-thread-2.html. Best thing to do would be to use the predraw listener or remove your runnable in onPause.

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