I've wrote a small activity that is able to switch between two views. Now I am trying to add some animation (fade-in/fade-out effect). Can anybody explain me how to do that right?
My own attempt to do this works kinda buggy (if I will click buttons very fast, my application freezes). I use code listed below:
public class WelcomeActivity extends Activity {
private boolean isLogin = false;
private String KEY_IS_LOGIN = "KEY_IS_LOGIN";
private Animation anim_fadein;
private RelativeLayout welcome, login;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
welcome = (RelativeLayout)getLayoutInflater().inflate(R.layout.activity_welcome_menu, null);
login = (RelativeLayout)getLayoutInflater().inflate(R.layout.activity_welcome_login, null);
anim_fadein = AnimationUtils.loadAnimation(this, R.anim.anim_fadein);
if (savedInstanceState != null)
isLogin = savedInstanceState.getBoolean(KEY_IS_LOGIN, false);
if (isLogin)
setContentView(login);
else
setContentView(welcome);
}
@Override
public void onBackPressed() {
if (isLogin) {
setContentView(welcome);
welcome.startAnimation(anim_fadein);
isLogin = false;
} else {
super.onBackPressed();
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
outState.putBoolean(KEY_IS_LOGIN, isLogin);
super.onSaveInstanceState(outState);
}
public void onButton1Click(View v) {
setContentView(login);
login.startAnimation(anim_fadein);
}
public void onButtonLoginClick(View v) {
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
}
public void onButtonBackClick(View v) {
setContentView(welcome);
welcome.startAnimation(anim_fadein);
}
Animation XML file:
<?xml version="1.0" encoding="utf-8"?>
<alpha
xmlns:android="http://schemas.android.com/apk/res/android"
android:fromAlpha="0.0"
android:toAlpha="1.0"
android:duration="800" />
Thanks in advance!
The way I have done this in the past is by using the ViewFlipper class and utilizing the built-in animation functions that the package provides.
Here is an example on how to do this; in my experience the transitions have been very smooth:
<LinearLayout
//Ommitted...
<ViewFlipper
android:id="@+id/[your_id_here]"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<RelativeLayout
<!--Your first layout XML here...-->
</RelativeLayout>
<RelativeLayout
<!--Your second layout XML here...-->
</RelativeLayout>
</ViewFlipper>
</LinearLayout>
Please note that you do not have to use relative layouts, I simply used them for the sake of clarity.
Get a reference to the ViewFlipper
in your activity:
ViewFlipper v = (ViewFlipper) findViewById(R.id.[your_id]);
Set the animations as necessary:
v.setInAnimation(AnimationUtils.loadAnimation([your_activity_name].this, R.anim.[your_in_animation here]));
v.setOutAnimation(AnimationUtils.loadAnimation([your_activity_name].this, R.anim.[your_out_animation here]));
Please note that you can find some really good prebuilt animations in the Android class files located in the following directory:
[android-sdks]/samples/android-[VERSION_NUMBER_HERE]/ApiDemos/res/anim
I highly recommend using these if you can - it will save you much time.
Now, if you wish to switch between the views, use the following commands:
v.showNext();
v.showPrevious();
You might have to change the animation files slightly to make sure the animations transition properly (i.e. make a fade right and left animation).
Hope this helps!
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