Honeycomb GMail animation mystery

There are a lot of questions on the Internet like these:

http://stackoverflow.com/questions/4817900/android-fragments-and-animation
http://stackoverflow.com/questions/5327636/animating-fragments-and-the-back-stack

GMail Honeycomb Android slide animation

If you are looking for a sample code – this post is for you.

Everybody wants to implement slide-in/slide-out animations like in GMail Tablet client. They try to use fragment animations (setCustomAnimations for FragmentTransaction). But if you take a deep look into GMail client implementation – they use LinearLayout and ObjectAnimator.

The code is quite simple – you just change left margin of the root view + change width of the right view.

package com.fragment.test;

import android.animation.ObjectAnimator;
import android.animation.PropertyValuesHolder;
import android.animation.TimeInterpolator;
import android.app.Activity;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.DecelerateInterpolator;

public class FragmentAnimationTestActivity extends Activity implements Fragment2.FragmentResultListener {

    private static final TimeInterpolator sCollapseInterpolator = new DecelerateInterpolator(2.5F);

    private View mPanel1;
    private View mPanel2;
    private View mLayout;

    boolean isCollapsed;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mLayout = findViewById(R.id.l1);
        mPanel1 = findViewById(R.id.fragment1);
        mPanel2 = findViewById(R.id.fragment2);
        FragmentTransaction ft = getFragmentManager().beginTransaction();
        ft.replace(R.id.fragment1, Fragment1.newInstance(), "f1");
        ft.replace(R.id.fragment2, Fragment2.newInstance(this), "f2");
        ft.commit();
    }

    public int getPanelLeft() {
        return ((ViewGroup.MarginLayoutParams) mLayout.getLayoutParams()).leftMargin;
    }

    public void setPanelLeft(int paramInt) {
        ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams) mLayout.getLayoutParams();
        lp.leftMargin = paramInt;
        mLayout.setLayoutParams(lp);
    }

    public int getPanel2W() {
        return ((ViewGroup.MarginLayoutParams) mPanel2.getLayoutParams()).width;
    }

    public void setPanel2W(int paramInt) {
        ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams) mPanel2.getLayoutParams();
        lp.width = paramInt;
        mPanel2.setLayoutParams(lp);
    }

    @Override
    public void onBtnClick() {
        if (isCollapsed) {
            PropertyValuesHolder[] arrayOfPropertyValuesHolder = new PropertyValuesHolder[2];
            arrayOfPropertyValuesHolder[0] = PropertyValuesHolder.ofInt("PanelLeft", -300, 0);
            arrayOfPropertyValuesHolder[1] = PropertyValuesHolder.ofInt("Panel2W", 1280, 980);
            ObjectAnimator localObjectAnimator = ObjectAnimator.ofPropertyValuesHolder(this,
                    arrayOfPropertyValuesHolder).setDuration(400);
            localObjectAnimator.setInterpolator(sCollapseInterpolator);
            localObjectAnimator.start();
        } else {
            PropertyValuesHolder[] arrayOfPropertyValuesHolder = new PropertyValuesHolder[2];
            arrayOfPropertyValuesHolder[0] = PropertyValuesHolder.ofInt("PanelLeft", 0, -300);
            arrayOfPropertyValuesHolder[1] = PropertyValuesHolder.ofInt("Panel2W", 980, 1280);
            ObjectAnimator localObjectAnimator = ObjectAnimator.ofPropertyValuesHolder(this,
                    arrayOfPropertyValuesHolder).setDuration(400);
            localObjectAnimator.setInterpolator(sCollapseInterpolator);
            localObjectAnimator.start();
        }
        isCollapsed = !isCollapsed;
    }

}

Of course, you can calculate all values dynamically. This is just a quick ugly sample. Full source code is available here.

Happy tabletting!

//DL