教你制作Android中炫酷的ViewPagerIndicator(不仅仿MIUI)

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:zhy="http://schemas.android.com/apk/res/com.example.demo_zhy_mms_miui"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffffff"
    android:orientation="vertical" >
 
    <com.example.demo_zhy_mms_miui.ViewPagerIndicator
       android:id="@+id/id_indicator"
       android:layout_width="match_parent"
       android:layout_height="45dp"
       android:background="@drawable/title_bar_bg_one_row"
       android:orientation="horizontal"
       zhy:item_count="3" >
 
    </com.example.demo_zhy_mms_miui.ViewPagerIndicator>
 
    <android.support.v4.view.ViewPager
       android:id="@+id/id_vp"
       android:layout_width="match_parent"
       android:layout_height="0dp"
       android:layout_weight="1" >
    </android.support.v4.view.ViewPager>
 
</LinearLayout>

package com.example.demo_zhy_mms_miui;
 
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
 
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Window;
 
public class MainActivity extends FragmentActivity
{
   private List<Fragment> mTabContents = new ArrayList<Fragment>();
   private FragmentPagerAdapter mAdapter;
   private ViewPager mViewPager;
   // private List<String> mDatas = Arrays.asList("短信1", "短信2", "短信3", "短信4",
   //     "短信5", "短信6", "短信7", "短信8", "短信9");
   private List<String> mDatas = Arrays.asList("短信", "收藏", "推荐");
 
   private ViewPagerIndicator mIndicator;
 
   @Override
   protected void onCreate(Bundle savedInstanceState)
   {
      super.onCreate(savedInstanceState);
      requestWindowFeature(Window.FEATURE_NO_TITLE);
      setContentView(R.layout.vp_indicator);
 
      initView();
      initDatas();
      //设置Tab上的标题
      mIndicator.setTabItemTitles(mDatas);
      mViewPager.setAdapter(mAdapter);
      //设置关联的ViewPager
      mIndicator.setViewPager(mViewPager,0);
 
    }
 
    private void initDatas()
    {
 
       for (String data : mDatas)
       {
          VpSimpleFragment fragment = VpSimpleFragment.newInstance(data);
          mTabContents.add(fragment);
       }
 
       mAdapter = new FragmentPagerAdapter(getSupportFragmentManager())
            {
               @Override
               public int getCount()
               {
                  return mTabContents.size();
               }
 
               @Override
               public Fragment getItem(int position)
               {
                  return mTabContents.get(position);
               }
           };
    }
 
    private void initView()
    {
       mViewPager = (ViewPager) findViewById(R.id.id_vp);
       mIndicator = (ViewPagerIndicator) findViewById(R.id.id_indicator);
    }
 
}

//设置Tab上的标题
mIndicator.setTabItemTitles(mDatas);
 
//设置关联的ViewPager
mIndicator.setViewPager(mViewPager,0);

package com.example.demo_zhy_mms_miui;
 
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
 
public class VpSimpleFragment extends Fragment
{
   public static final String BUNDLE_TITLE = "title";
   private String mTitle = "DefaultValue";
 
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
   {
      Bundle arguments = getArguments();
      if (arguments != null)
      {
          mTitle = arguments.getString(BUNDLE_TITLE);
      }
 
      TextView tv = new TextView(getActivity());
      tv.setText(mTitle);
      tv.setGravity(Gravity.CENTER);
 
      return tv;
   }
 
   public static VpSimpleFragment newInstance(String title)
   {
      Bundle bundle = new Bundle();
      bundle.putString(BUNDLE_TITLE, title);
      VpSimpleFragment fragment = new VpSimpleFragment();
      fragment.setArguments(bundle);
      return fragment;
   }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
 
   <attr name="item_count" format="integer"></attr>
 
   <declare-styleable name="ViewPagerIndicator">
       <attr name="item_count" />
   </declare-styleable>
 
</resources>

public class ViewPagerIndicator extends LinearLayout
{
   /**
    * 绘制三角形的画笔
    */
   private Paint mPaint;
   /**
    * path构成一个三角形
    */
   private Path mPath;
   /**
    * 三角形的宽度
    */
   private int mTriangleWidth;
   /**
    * 三角形的高度
    */
   private int mTriangleHeight;
 
   /**
    * 三角形的宽度为单个Tab的1/6
    */
   private static final float RADIO_TRIANGEL = 1.0f / 6;
   /**
    * 三角形的最大宽度
    */
   private final int DIMENSION_TRIANGEL_WIDTH = (int) (getScreenWidth() / 3 * RADIO_TRIANGEL);
 
   /**
    * 初始时，三角形指示器的偏移量
    */
   private int mInitTranslationX;
   /**
    * 手指滑动时的偏移量
    */
   private float mTranslationX;
 
   /**
    * 默认的Tab数量
    */
   private static final int COUNT_DEFAULT_TAB = 4;
   /**
    * tab数量
    */
   private int mTabVisibleCount = COUNT_DEFAULT_TAB;
 
   /**
    * tab上的内容
    */
   private List<String> mTabTitles;
   /**
    * 与之绑定的ViewPager
    */
   public ViewPager mViewPager;
 
   /**
    * 标题正常时的颜色
    */
   private static final int COLOR_TEXT_NORMAL = 0x77FFFFFF;
   /**
    * 标题选中时的颜色
    */
   private static final int COLOR_TEXT_HIGHLIGHTCOLOR = 0xFFFFFFFF;
 
   public ViewPagerIndicator(Context context)
   {
      this(context, null);
   }
 
   public ViewPagerIndicator(Context context, AttributeSet attrs)
   {
      super(context, attrs);
 
      // 获得自定义属性，tab的数量
      TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ViewPagerIndicator);
      mTabVisibleCount = a.getInt(R.styleable.ViewPagerIndicator_item_count, COUNT_DEFAULT_TAB);
      if (mTabVisibleCount < 0)
          mTabVisibleCount = COUNT_DEFAULT_TAB;
          a.recycle();
 
      // 初始化画笔
      mPaint = new Paint();
      mPaint.setAntiAlias(true);
      mPaint.setColor(Color.parseColor("#ffffffff"));
      mPaint.setStyle(Style.FILL);
      mPaint.setPathEffect(new CornerPathEffect(3));
 
    }
}

/**
* 设置布局中view的一些必要属性；如果设置了setTabTitles，布局中view则无效
*/
@Override
protected void onFinishInflate()
{
   Log.e("TAG", "onFinishInflate");
   super.onFinishInflate();
 
   int cCount = getChildCount();
 
   if (cCount == 0)
      return;
 
   for (int i = 0; i < cCount; i++)
   {
      View view = getChildAt(i);
      LinearLayout.LayoutParams lp = (LayoutParams) view.getLayoutParams();
      lp.weight = 0;
      lp.width = getScreenWidth() / mTabVisibleCount;
      view.setLayoutParams(lp);
   }
   // 设置点击事件
   setItemClickEvent();
 
}

/**
* 设置点击事件
*/
public void setItemClickEvent()
{
   int cCount = getChildCount();
   for (int i = 0; i < cCount; i++)
   {
      final int j = i;
      View view = getChildAt(i);
      view.setOnClickListener(new OnClickListener()
      {
          @Override
          public void onClick(View v)
          {
             mViewPager.setCurrentItem(j);
          }
       });
   }
}

/**
* 初始化三角形的宽度
*/
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh)
{
    super.onSizeChanged(w, h, oldw, oldh);
    mTriangleWidth = (int) (w / mTabVisibleCount * RADIO_TRIANGEL);// 1/6 of
    // width
    mTriangleWidth = Math.min(DIMENSION_TRIANGEL_WIDTH, mTriangleWidth);
 
    // 初始化三角形
    initTriangle();
 
    // 初始时的偏移量
    mInitTranslationX = getWidth() / mTabVisibleCount / 2 - mTriangleWidth / 2;
}
 
/**
* 初始化三角形指示器
*/
private void initTriangle()
{
    mPath = new Path();
 
    mTriangleHeight = (int) (mTriangleWidth / 2 / Math.sqrt(2));
    mPath.moveTo(0, 0);
    mPath.lineTo(mTriangleWidth, 0);
    mPath.lineTo(mTriangleWidth / 2, -mTriangleHeight);
    mPath.close();
}

/**
* 绘制指示器
*/
@Override
protected void dispatchDraw(Canvas canvas)
{
   canvas.save();
   // 画笔平移到正确的位置
   canvas.translate(mInitTranslationX + mTranslationX, getHeight() + 1);
   canvas.drawPath(mPath, mPaint);
   canvas.restore();
 
   super.dispatchDraw(canvas);
}

// 设置关联的ViewPager
public void setViewPager(ViewPager mViewPager, int pos)
{
   this.mViewPager = mViewPager;
 
   mViewPager.setOnPageChangeListener(new OnPageChangeListener()
   {
       @Override
       public void onPageSelected(int position)
       {
          // 设置字体颜色高亮
          resetTextViewColor();
          highLightTextView(position);
 
          // 回调
          if (onPageChangeListener != null)
          {
              onPageChangeListener.onPageSelected(position);
          }
       }
 
       @Override
       public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
       {
          // 滚动
          scroll(position, positionOffset);
 
          // 回调
          if (onPageChangeListener != null)
          {
              onPageChangeListener.onPageScrolled(position,
              positionOffset, positionOffsetPixels);
          }
 
       }
 
       @Override
       public void onPageScrollStateChanged(int state)
       {
          // 回调
          if (onPageChangeListener != null)
          {
             onPageChangeListener.onPageScrollStateChanged(state);
          }
 
       }
    });
    // 设置当前页
    mViewPager.setCurrentItem(pos);
    // 高亮
    highLightTextView(pos);
}

// 滚动
scroll(position, positionOffset);这行后面介绍~

/**
* 对外的ViewPager的回调接口
*
* @author zhy
*
*/
public interface PageChangeListener
{
   public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels);
 
   public void onPageSelected(int position);
 
   public void onPageScrollStateChanged(int state);
}
 
// 对外的ViewPager的回调接口
private PageChangeListener onPageChangeListener;
 
// 对外的ViewPager的回调接口的设置
public void setOnPageChangeListener(PageChangeListener pageChangeListener)
{
   this.onPageChangeListener = pageChangeListener;
}

/**
* 高亮文本
*
* @param position
*/
protected void highLightTextView(int position)
{
    View view = getChildAt(position);
    if (view instanceof TextView)
    {
       ((TextView) view).setTextColor(COLOR_TEXT_HIGHLIGHTCOLOR);
    }
}
 
/**
* 重置文本颜色
*/
private void resetTextViewColor()
{
   for (int i = 0; i < getChildCount(); i++)
   {
      View view = getChildAt(i);
      if (view instanceof TextView)
      {
          ((TextView) view).setTextColor(COLOR_TEXT_NORMAL);
      }
   }
}

/**
* 指示器跟随手指滚动，以及容器滚动
*
* @param position
* @param offset
*/
public void scroll(int position, float offset)
{
   /**
    * <pre>
    * 0-1:position=0 ;1-0:postion=0;
    * </pre>
    */
   // 不断改变偏移量，invalidate
   mTranslationX = getWidth() / mTabVisibleCount * (position + offset);
 
   int tabWidth = getScreenWidth() / mTabVisibleCount;
 
   // 容器滚动，当移动到倒数最后一个的时候，开始滚动
   if (offset > 0 && position >= (mTabVisibleCount - 2) && getChildCount() > mTabVisibleCount)
   {
      if (mTabVisibleCount != 1)
      {
         this.scrollTo((position - (mTabVisibleCount - 2)) * tabWidth + (int) (tabWidth * offset), 0;
      } else
      // 为count为1时 的特殊处理
      {
         this.scrollTo(position * tabWidth + (int) (tabWidth * offset), 0);
      }
   }
 
   invalidate();
}

/**
* 设置可见的tab的数量
*
* @param count
*/
public void setVisibleTabCount(int count)
{
   this.mTabVisibleCount = count;
}
 
/**
* 设置tab的标题内容 可选，可以自己在布局文件中写死
*
* @param datas
*/
public void setTabItemTitles(List<String> datas)
{
   // 如果传入的list有值，则移除布局文件中设置的view
   if (datas != null && datas.size() > 0)
   {
     this.removeAllViews();
     this.mTabTitles = datas;
 
     for (String title : mTabTitles)
     {
        // 添加view
        addView(generateTextView(title));
     }
     // 设置item的click事件
     setItemClickEvent();
   }
 
}