@Override 
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
// 得到绘制icon的宽 
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; 
// 设置icon的绘制范围 
mIconRect = new Rect(left, top, left + bitmapWidth, top + bitmapWidth); 
// 设置指示点的范围 
int indicatorRadius = mIndicatorSize / 2; 
int tabRealHeight = bitmapWidth + mTextBound.height(); 
mIndicatorRect = new Rect(left + tabRealHeight* 4/5 - indicatorRadius, top, left+tabRealHeight* 4/5 + indicatorRadius, top + mIndicatorSize); 
} 

@Override 
protected void onDraw(Canvas canvas) { 
super.onDraw(canvas); 
setupTargetBitmap(canvas); 
drawIndicator(canvas); 
if(null != mText) { 
drawTargetText(canvas); 
} 
} 
/** 
* 绘制图标图片 
* @param canvas 
*/ 
private void setupTargetBitmap(Canvas canvas) { 
canvas.drawBitmap(isSelected ? mSelectedIconBitmap : mUnselectedIconBitmap, null, mIconRect, null); 
} 
/** 
* 绘制指示点 
* @param canvas 
*/ 
protected void drawIndicator(Canvas canvas) { 
if(isIndicateDisplay) { 
canvas.drawBitmap(mIndicatorBitmap, null, mIndicatorRect, null); 
} 
} 
/** 
* 绘制文字 
* @param canvas 
*/ 
protected void drawTargetText(Canvas canvas) { 
mTextPaint.setColor(isSelected ? mSelectedColor : mUnselectedColor); 
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2 
- mTextBound.width() / 2, 
mIconRect.bottom + mTextBound.height(), mTextPaint); 
}

@Override 
protected void onDraw(Canvas canvas) { 
super.onDraw(canvas); 
int alpha = (int) Math.ceil((255 * mAlpha)); 
drawSourceBitmap(canvas, alpha); 
drawTargetBitmap(canvas, alpha); 
if(null != mText) { 
drawSourceText(canvas, alpha); 
drawTargetText(canvas, alpha); 
} 
drawIndicator(canvas); 
} 
/** 
* 绘制未选中图标 
* @param canvas 
* @param alpha 
*/ 
private void drawSourceBitmap(Canvas canvas, int alpha) { 
mPaint.setAntiAlias(true); 
mPaint.setDither(true); 
mPaint.setAlpha(255 - alpha); 
canvas.drawBitmap(mUnselectedIconBitmap, null, mIconRect, mPaint); 
} 
/** 
* 绘制选中图标 
* @param canvas 
* @param alpha 
*/ 
private void drawTargetBitmap(Canvas canvas, int alpha) { 
mPaint.setAntiAlias(true); 
mPaint.setDither(true); 
mPaint.setAlpha(alpha); 
canvas.drawBitmap(mSelectedIconBitmap, null, mIconRect, mPaint); 
} 
/** 
* 画未选中文字 
* @param canvas 
* @param alpha 
*/ 
private void drawSourceText(Canvas canvas, int alpha) { 
mTextPaint.setTextSize(mTextSize); 
mTextPaint.setColor(mUnselectedColor); 
mTextPaint.setAlpha(255 - alpha); 
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2 
- mTextBound.width() / 2, 
mIconRect.bottom + mTextBound.height(), mTextPaint); 
} 
/** 
* 画选中文字 
* @param canvas 
* @param alpha 
*/ 
private void drawTargetText(Canvas canvas, int alpha) { 
mTextPaint.setColor(mSelectedColor); 
mTextPaint.setAlpha(alpha); 
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2 
- mTextBound.width() / 2, 
mIconRect.bottom + mTextBound.height(), mTextPaint); 
}

private void setupTargetBitmap(int alpha) { 
mBitmap = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(), Config.ARGB_8888); 
mCanvas = new Canvas(mBitmap); 
mPaint = new Paint(); 
mPaint.setColor(mSelectedColor); 
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(mUnselectedColor); 
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(mSelectedColor); 
mTextPaint.setAlpha(alpha); 
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2 
- mTextBound.width() / 2, 
mIconRect.bottom + mTextBound.height(), mTextPaint); 
}

private void init(Context context, AttributeSet attrs) { 
setOrientation(LinearLayout.HORIZONTAL); 
setGravity(Gravity.CENTER); 
//Load defaults from resources 
final Resources res = getResources(); 
final int defaultSelectedColor = res.getColor(R.color.default_tab_view_selected_color); 
final int defaultUnselectedColor = res.getColor(R.color.default_tab_view_unselected_color); 
final float defaultTextSize = res.getDimension(R.dimen.default_tab_view_text_size); 
final float defaultTabPadding = res.getDimension(R.dimen.default_tab_view_padding); 
final float defaultIndicatorSize = res.getDimension(R.dimen.default_tab_view_indicator_size); 
// Styleables from XML 
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TabIndicator); 
// 读取布局中，各个tab使用的文字 
if (a.hasValue(R.styleable.TabIndicator_tabLabels)) { 
mLabels = a.getTextArray(R.styleable.TabIndicator_tabLabels); 
} 
mSelectedColor = a.getColor(R.styleable.TabIndicator_tabSelectedColor, defaultSelectedColor); 
mUnselectedColor = a.getColor(R.styleable.TabIndicator_tabUnselectedColor, defaultUnselectedColor); 
mTextSize = (int) a.getDimension(R.styleable.TabIndicator_tabTextSize, defaultTextSize); 
mIndicatorSize = (int) a.getDimension(R.styleable.TabIndicator_TabIndicatorSize, defaultIndicatorSize); 
mTabPadding = (int) a.getDimension(R.styleable.TabIndicator_tabItemPadding, defaultTabPadding); 
handleStyledAttributes(a); 
a.recycle(); 
initView(); 
}

/** 
* 初始化控件 
*/ 
private void initView() { 
LayoutParams params = new LayoutParams(0, LayoutParams.MATCH_PARENT, 1); 
params.gravity = Gravity.CENTER; 
int size = getTabSize(); 
for (int i = 0; i < size; i++) { 
final int index = i; 
T tabItemView = createTabView(); 
tabItemView.setPadding(mTabPadding, mTabPadding, mTabPadding, mTabPadding); 
// 图标及文字 
if(null != mLabels) { 
tabItemView.setText(mLabels[index]); 
tabItemView.setTextSize(mTextSize); 
} 
tabItemView.setSelectedColor(mSelectedColor); 
tabItemView.setUnselectedColor(mUnselectedColor); 
tabItemView.setIndicatorSize(mIndicatorSize); 
setProperties(tabItemView, i); 
this.addView(tabItemView, params); 
tabItemView.setTag(index); // CheckedTextView设置索引作为tag，以便后续更改颜色、图片等 
mCheckedList.add(tabItemView); // 将CheckedTextView添加到list中，便于操作 
tabItemView.setOnClickListener(new OnClickListener() 
@Override 
public void onClick(View v) { 
setTabsDisplay(index); // 设置底部图片和文字的显示 
if (null != mTabListener) { 
mTabListener.onTabSelected(index); // tab项被选中的回调事件 
} 
} 
}); 
// 初始化 底部菜单选中状态,默认第一个选中 
if (i == 0) { 
tabItemView.setSelected(true); 
} else { 
tabItemView.setSelected(false); 
} 
} 
}

/** 
* 生成TabView 
* @return 
*/ 
protected abstract T createTabView(); 
/** 
* 设置特殊属性 
* @param t 
*/ 
protected abstract void setProperties(T t, int index); 

@Override 
protected void handleStyledAttributes(TypedArray a) { 
// 读取布局中，各个tab使用的图标 
int selectedIconsResId = a.getResourceId(R.styleable.TabIndicator_tabSelectedIcons, 0); 
TypedArray ta = getContext().getResources().obtainTypedArray(selectedIconsResId); 
int len = ta.length(); 
mSelectedDrawableIds = new int[len]; 
for(int i = 0; i < len; i++) { 
mSelectedDrawableIds[i] = ta.getResourceId(i, 0); 
} 
int unselectedIconsResId = a.getResourceId(R.styleable.TabIndicator_tabUnselectedIcons, 0); 
ta = getContext().getResources().obtainTypedArray(unselectedIconsResId); 
len = ta.length(); 
mUnselectedDrawableIds = new int[len]; 
for(int i = 0; i < len; i++) { 
mUnselectedDrawableIds[i] = ta.getResourceId(i, 0); 
} 
ta.recycle(); 
}

@Override 
protected TabView createTabView() { 
return new TabView(getContext()); 
} 

@Override 
protected void setProperties(TabView tabView, int index) { 
tabView.setSelectedIcon(mSelectedDrawableIds[index]); 
tabView.setUnselectedIcon(mUnselectedDrawableIds[index]); 
} 

@Override 
protected int getTabSize() { 
return mSelectedDrawableIds.length; 
}