仿微信底部TAG完善漸變

viewpager+fragment仿微信底部TAG完美漸變，在圖片漸變的同時字的顏色也在變，注意，是漸變哦！

效果圖：

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:zhy="http://schemas.android.com/apk/res/com.Sing.weixin"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <android.support.v4.view.ViewPager
        android:id="@+id/id_viewpager"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1" >
    </android.support.v4.view.ViewPager>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="60dp"
        android:background="@drawable/tabbg"
        android:orientation="horizontal" >

        <com.Sing.weixin.ChangeColorIconWithTextView
            android:id="@+id/id_indicator_one"
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:padding="5dp"
            zhy:icon="@drawable/ic_menu_start_conversation"
            zhy:text="@string/tab_one"
            zhy:text_size="12sp" />

        <com.Sing.weixin.ChangeColorIconWithTextView
            android:id="@+id/id_indicator_two"
            android:layout_width="0dp"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:padding="5dp"
            zhy:icon="@drawable/ic_menu_friendslist"
            zhy:text="@string/tab_two"
            zhy:text_size="12sp" />
    </LinearLayout>

</LinearLayout>

MainActivity.java

package com.Sing.weixin;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewConfiguration;

@SuppressLint("NewApi")
public class MainActivity extends FragmentActivity implements
		OnPageChangeListener, OnClickListener {
	private ViewPager mViewPager;
	// 選項卡一Fragment
	private FrgReturnVisit returnVisit;

	// 選項卡一Fragment
	private FrgMicroVisit microVisit;

	private List<ChangeColorIconWithTextView> mTabIndicator = new ArrayList<ChangeColorIconWithTextView>();

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		setOverflowShowingAlways();
		mViewPager = (ViewPager) findViewById(R.id.id_viewpager);
		mViewPager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
		initTabIndicator();

		mViewPager.setOnPageChangeListener(this);
 	}

	private void initTabIndicator() {
		ChangeColorIconWithTextView one = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_one);
		ChangeColorIconWithTextView two = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_two);

		mTabIndicator.add(one);
		mTabIndicator.add(two);

		one.setOnClickListener(this);
		two.setOnClickListener(this);

		one.setIconAlpha(1.0f);
	}

	@Override
	public void onPageSelected(int arg0) {
	}

	@Override
	public void onPageScrolled(int position, float positionOffset,
			int positionOffsetPixels) {

		if (positionOffset > 0) {
			ChangeColorIconWithTextView left = mTabIndicator.get(position);
			ChangeColorIconWithTextView right = mTabIndicator.get(position + 1);

			left.setIconAlpha(1 - positionOffset);
			right.setIconAlpha(positionOffset);
		}
	}

	@Override
	public void onPageScrollStateChanged(int state) {
	}

	@Override
	public void onClick(View v) {

		resetOtherTabs();

		switch (v.getId()) {
		case R.id.id_indicator_one:
			mTabIndicator.get(0).setIconAlpha(1.0f);
			mViewPager.setCurrentItem(0, false);
			break;
		case R.id.id_indicator_two:
			mTabIndicator.get(1).setIconAlpha(1.0f);
			mViewPager.setCurrentItem(1, false);
			break;
		}

	}

	/**
	 * 重置其他的Tab
	 */
	private void resetOtherTabs() {
		for (int i = 0; i < mTabIndicator.size(); i++) {
			mTabIndicator.get(i).setIconAlpha(0);
		}
	}

	private void setOverflowShowingAlways() {
		try {
			// true if a permanent menu key is present, false otherwise.
			ViewConfiguration config = ViewConfiguration.get(this);
			Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
			menuKeyField.setAccessible(true);
			menuKeyField.setBoolean(config, false);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public class MyPagerAdapter extends FragmentPagerAdapter {

		public MyPagerAdapter(FragmentManager fm) {
			super(fm);
		}

		private final String[] titles = { "選項一", "選項二"};

		@Override
		public CharSequence getPageTitle(int position) {
			return titles[position];
		}

		@Override
		public int getCount() {
			return titles.length;
		}

		@Override
		public Fragment getItem(int position) {
			switch (position) {
			case 0:
				if (returnVisit == null) {
					returnVisit = new FrgReturnVisit();
				}
				return returnVisit;
			case 1:
				if (microVisit == null) {
					microVisit = new FrgMicroVisit();
				}
				return microVisit;
			default:
				return null;
			}
		}
	}
}

ChangeColorIconWithTextView.java

package com.Sing.weixin;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Looper;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.View;

public class ChangeColorIconWithTextView extends View {

	private Bitmap mBitmap;
	private Canvas mCanvas;
	private Paint mPaint;
	/**
	 * 顏色
	 */
	private int mColor = 0xFF45C01A;
	/**
	 * 透明度 0.0-1.0
	 */
	private float mAlpha = 0f;
	/**
	 * 圖標
	 */
	private Bitmap mIconBitmap;
	/**
	 * 限制繪制icon的范圍
	 */
	private Rect mIconRect;
	/**
	 * icon底部文本
	 */
	private String mText = "demo";
	private int mTextSize = (int) TypedValue.applyDimension(
			TypedValue.COMPLEX_UNIT_SP, 10, getResources().getDisplayMetrics());
	private Paint mTextPaint;
	private Rect mTextBound = new Rect();

	public ChangeColorIconWithTextView(Context context) {
		super(context);
	}

	/**
	 * 初始化自定義屬性值
	 * 
	 * @param context
	 * @param attrs
	 */
	public ChangeColorIconWithTextView(Context context, AttributeSet attrs) {
		super(context, attrs);

		// 獲取設置的圖標
		TypedArray a = context.obtainStyledAttributes(attrs,
				R.styleable.ChangeColorIconView);

		int n = a.getIndexCount();
		for (int i = 0; i < n; i++) {

			int attr = a.getIndex(i);
			switch (attr) {
			case R.styleable.ChangeColorIconView_icon:
				BitmapDrawable drawable = (BitmapDrawable) a.getDrawable(attr);
				mIconBitmap = drawable.getBitmap();
				break;
			case R.styleable.ChangeColorIconView_color:
				mColor = a.getColor(attr, 0x45C01A);
				break;
			case R.styleable.ChangeColorIconView_text:
				mText = a.getString(attr);
				break;
			case R.styleable.ChangeColorIconView_text_size:
				mTextSize = (int) a.getDimension(attr, TypedValue
						.applyDimension(TypedValue.COMPLEX_UNIT_SP, 10,
								getResources().getDisplayMetrics()));
				break;

			}
		}

		a.recycle();

		mTextPaint = new Paint();
		mTextPaint.setTextSize(mTextSize);
		mTextPaint.setColor(0xff555555);
		// 得到text繪制范圍
		mTextPaint.getTextBounds(mText, 0, mText.length(), mTextBound);

	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		// 得到繪制icon的寬
		int bitmapWidth = Math.min(getMeasuredWidth() - getPaddingLeft()
				- getPaddingRight(), getMeasuredHeight() - getPaddingTop()
				- getPaddingBottom() - mTextBound.height());

		int left = getMeasuredWidth() / 2 - bitmapWidth / 2;
		int top = (getMeasuredHeight() - mTextBound.height()) / 2 - bitmapWidth
				/ 2;
		// 設置icon的繪制范圍
		mIconRect = new Rect(left, top, left + bitmapWidth, top + bitmapWidth);

	}

	@Override
	protected void onDraw(Canvas canvas) {

		int alpha = (int) Math.ceil((255 * mAlpha));
		canvas.drawBitmap(mIconBitmap, null, mIconRect, null);
		setupTargetBitmap(alpha);
		drawSourceText(canvas, alpha);
		drawTargetText(canvas, alpha);
		canvas.drawBitmap(mBitmap, 0, 0, null);

	}

	private void setupTargetBitmap(int alpha) {
		mBitmap = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(),
				Config.ARGB_8888);
		mCanvas = new Canvas(mBitmap);
		mPaint = new Paint();
		mPaint.setColor(mColor);
		mPaint.setAntiAlias(true);
		mPaint.setDither(true);
		mPaint.setAlpha(alpha);
		mCanvas.drawRect(mIconRect, mPaint);
		mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
		mPaint.setAlpha(255);
		mCanvas.drawBitmap(mIconBitmap, null, mIconRect, mPaint);
	}

	private void drawSourceText(Canvas canvas, int alpha) {
		mTextPaint.setTextSize(mTextSize);
		mTextPaint.setColor(0xff333333);
		mTextPaint.setAlpha(255 - alpha);
		canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2
				- mTextBound.width() / 2,
				mIconRect.bottom + mTextBound.height(), mTextPaint);
	}

	private void drawTargetText(Canvas canvas, int alpha) {
		mTextPaint.setColor(mColor);
		mTextPaint.setAlpha(alpha);
		canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2
				- mTextBound.width() / 2,
				mIconRect.bottom + mTextBound.height(), mTextPaint);

	}

	public void setIconAlpha(float alpha) {
		this.mAlpha = alpha;
		invalidateView();
	}

	private void invalidateView() {
		if (Looper.getMainLooper() == Looper.myLooper()) {
			invalidate();
		} else {
			postInvalidate();
		}
	}

	public void setIconColor(int color) {
		mColor = color;
	}

	public void setIcon(int resId) {
		this.mIconBitmap = BitmapFactory.decodeResource(getResources(), resId);
		if (mIconRect != null)
			invalidateView();
	}

	public void setIcon(Bitmap iconBitmap) {
		this.mIconBitmap = iconBitmap;
		if (mIconRect != null)
			invalidateView();
	}

	private static final String INSTANCE_STATE = "instance_state";
	private static final String STATE_ALPHA = "state_alpha";

	@Override
	protected Parcelable onSaveInstanceState() {
		Bundle bundle = new Bundle();
		bundle.putParcelable(INSTANCE_STATE, super.onSaveInstanceState());
		bundle.putFloat(STATE_ALPHA, mAlpha);
		return bundle;
	}

	@Override
	protected void onRestoreInstanceState(Parcelable state) {
		if (state instanceof Bundle) {
			Bundle bundle = (Bundle) state;
			mAlpha = bundle.getFloat(STATE_ALPHA);
			super.onRestoreInstanceState(bundle.getParcelable(INSTANCE_STATE));
		} else {
			super.onRestoreInstanceState(state);
		}

	}
}

github:https://github.com/ganchuanpu/Demo_Sing_weixin