title: How to create text fading effect when user swipes across tabs using PageIndicator
body: <p>What's the minimum amount of effort required to change Jake Wharton's <strong>TitlePagerIndicator</strong> 
  into one that produces the text fading effect you see on Google Play Store as you swipe 
  between tabs? I think the key lies in modifying <strong>onDraw()</strong> but that requires me figuring out his code and his math. If there's an easier solution I'd prefer that.</p>
  
  <p>I also tried <strong>TitlePagerIndicator.setFadingEdgeLength(100)</strong>, but that doesn't seem to do anything. I am aware you have to do <strong>TitlePagerIndicator.setHorizontalFadingEdgeEnabled(true)</strong> but 
  still no fading effect whatsoever.</p>
  
  <p>Here's the code based off from one of Jake's samples:</p>
  
  <pre><code>public class SampleTitlesStyledMethods extends BaseSampleActivity {
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.simple_titles);
  
          mAdapter = new TestTitleFragmentAdapter(getSupportFragmentManager());
  
          mPager = (ViewPager)findViewById(R.id.pager);
          mPager.setAdapter(mAdapter);
  
          TitlePageIndicator indicator = (TitlePageIndicator)findViewById(R.id.indicator);
          mIndicator = indicator;
          indicator.setViewPager(mPager);
  
          final float density = getResources().getDisplayMetrics().density;
          indicator.setBackgroundColor(0x18FF0000);
          indicator.setFooterColor(0xFFAA2222);
          indicator.setFooterLineHeight(1 * density); //1dp
          indicator.setFooterIndicatorHeight(3 * density); //3dp
          indicator.setFooterIndicatorStyle(IndicatorStyle.Underline);
          indicator.setTextColor(0xAA000000);
          indicator.setSelectedColor(0xFF000000);
          indicator.setSelectedBold(true);
  
          //my code, doesn't seem to do anything though...
          indicator.setHorizontalFadingEdgeEnabled(true);
          indicator.setFadingEdgeLength(1000);
      }
  }
  </code></pre>