PagerSlidingTabStrip从头到脚解析

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2、依赖dependencies compile com.astuetz:pagerslidingtabstrip:1.0.1 定义布局文件vcom.astuet z. PagerSlidingTabStrip android:id=+id/psts_i ndicatorandroid:layout_width=match_parent android:layout_height=40dp/关联 ViewPagerpublic class MainActivity extends AppCompatActivity BindView(R.id.psts_indicator)PagerSliding

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4、=pstsUnderlineColor format=color /vattr name=pstsDividerColor format=color /vattr name=pstslndicatorHeight format=dimension /v!-底部区域的咼度-vattr name=pstsUnderlineHeight format=dimension /v!-分割线与上下的间距-vattr name=pstsDividerPadding format=dimension /v!-每个 Tab 的左右边距-vattr name=pstsTabPaddingLeftRight for

5、mat=dimension /v!-选中 tab 的滚动偏移量，个人基本没有用到过-vattr name=pstsScrollOffset format=dimension /v!-每个 Tab 的背景图，StateListDrawable-vattr name=pstsTabBackground format=reference /v!-是否根据 tab 均为位置，true 的时候均分，默认为 false,一般都是使用默认值-vattr name=pstsShouldExpand format=boolean /v!-标题文本是否大写，默认为true-vattr name=pstsTextA

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10、Zi孫野的两亍麗性，文本字体大小和字体颜色pageLi stener内部使用SJOnf agerChangeLi stener,通过set% ewFager实现和i ewfager的联动delegat eFageLi stener暴壽给开炭者的接口， 类本身使用到了两个OnPageChgeLiztener,一个用来实现自己的逻 辑而遠平则是留绪开水者实现自己需要针对“我連钛的页面娈化的倉辑t&bsCont&in 电 f内部客器，用尸所见文本指示盏和国标指示爲的父书点所以，如果需要軒对文本指示器或 者是图标指示器做卄么操作，邇过这催找孩子节点即可bttA曲吕甘aM&tiT

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13、d updatevodIconTabProvider类中比较关键的一些内容，接口IconTabProvider, ViewPager 对应的 Adapter 实现该方法并返回每个ViewPager 对应的图标即可实现图标指示器。PageListener private class PageListener implements OnPageChangeListener Overridepublic void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) /存储当前位置信息currentP

14、osition = position;currentPositionOffset = positionOffset;/滑动到子视图scrollToChild(position, (int) (positionOffset * tabsContainer.getChildAt(position).getWidth();invalidate。;/ 触发重绘/用户自定义的 OnPagerChangeListener 事件之 onPagerScrolledif (delegatePageListener != ull) delegatePageListener.onPageScrolled(posit

15、ion,positionOffset, positionOffsetPixels);Overridepublic void onPageScrollStateChanged(int state) /已经滑动完成，offset 归 0if (state = ViewPager.SCROLL_STATE_IDLE) scrollToChild(pager.getCurrentItem(), 0);/用户自定义的 OnPagerChangeListener 事件之 onPageScrollStateChanged if(delegatePageListener != null) delegatePa

16、geListener.onPageScrollStateChanged(state);Overridepublic void onPageSelected(int position) 这里类内部没有做什么处理，只处理用户自定义的OnPagerSelected 方法if (delegatePageListener != null) delegatePageListener.onPageSelected(position);/*滑动指定子视图*/private void scrollToChild(int position, int offset) if (tabCount = 0) return

17、;int newScrollX = tabsContainer.getChildAt(position).getLeft() + offset;if (position 0 | offset 0) newScrollX -= scrollOffset;if (newScrollX != lastScrollX) lastScrollX = newScrollX;scrollTo(newScrollX, 0);PagerSlidingTabStrip 构造方法 构造方法的内容不多，基本上全是基本属性的获取，自定义View 中常用的TypedArray ，记得回收recycle。，这里关注一下Ty

18、pedValue.applyDimension 方法的使用，全部转换成 px。public PagerSlidingTabStrip(Context context, AttributeSet attrs, int defStyle) super(context, attrs, defStyle);setFillViewport(true);setWillNotDraw(false);tabsContainer = new LinearLayout(context);tabsContainer.setOrientation(LinearLayout.HORIZONTAL);tabsContai

19、ner.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MA TCH_PARENT);addView(tabsContainer);DisplayMetrics dm = getResources().getDisplayMetrics();scrollOffset = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, scrollOffset,dividerPadding, dm);tabPadding = (int) Typ

20、edValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, tabPadding,dm);dividerWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dividerWidth,dm);tabTextSize = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, tabTextSize,dm);/ get system attrs (android:textSize and android:t

21、extColor)TypedArray a = context.obtainStyledAttributes(attrs, A TTRS); tabTextSize =a.getDimensionPixelSize(0, tabTextSize);tabTextColor = a.getColor(1, tabTextColor);a.recycle();/ get custom attrsa = context.obtainStyledAttributes(attrs, R.styleable.PagerSlidingTabStrip);indicatorColor = a.getColor

22、(R.styleable.PagerSlidingTabStrip_pstsIndicatorColor, indicatorColor);underlineColor = a.getColor(R.styleable.PagerSlidingTabStrip_pstsUnderlineColor,dm);indicatorHeight = (int)indicatorHeight, dm);underlineHeight = (int)underlineHeight, dm);dividerPadding = (int)TypedValue.applyDimension(TypedValue

23、.COMPLEX_UNIT_DIP,TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,underlineColor);dividerColor = a.getColor(R.styleable.PagerSlidingTabStrip_pstsDividerColor, dividerColor);indicatorHeight = a.getDimensionPixelSize(R.styleable.PagerSlidingT

24、abStrip_pstsIndicatorHeight, indicatorHeight);underlineHeight = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsUnderlineHeight,underlineHeight);dividerPadding = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsDividerPadding,dividerPadding);tabPadding = a.getDimensionPixelS

25、ize(R.styleable.PagerSlidingTabStrip_pstsTabPaddingLeftRight,tabPadding);tabBackgroundResId = a.getResourceId(R.styleable.PagerSlidingTabStrip_pstsTabBackground,tabBackgroundResId);shouldExpand = a.getBoolean(R.styleable.PagerSlidingTabStrip_pstsShouldExpand, shouldExpand);scrollOffset = a.getDimens

26、ionPixelSize(R.styleable.PagerSlidingTabStrip_pstsScrollOffset,scrollOffset);textAllCaps = a.getBoolean(R.styleable.PagerSlidingTabStrip_pstsTextAllCaps, textAllCaps);a.recycle();/* 初始化矩形 Paint */rectPaint = new Paint();rectPaint.setAntiAlias(true); rectPaint.setStyle(Style.FILL);/* 初始化分割线 Paint */

27、dividerPaint = new Paint(); dividerPaint.setAntiAlias(true);dividerPaint.setStrokeWidth(dividerWidth);/* 是否延伸，默认 WRAP_CONTENT, 这种比较合理 */ defaultTabLayoutParams = newLinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MA TCH_PARENT);expandedTabLayoutParams = new LinearLayout.LayoutParam

28、s(0, LayoutParams.MA TCH_PARENT,1.0f);if (locale = null) locale = getResources().getConfiguration().locale;onDrawOverrideprotected void onDraw(Canvas canvas) super.onDraw(canvas);if (isInEditMode() | tabCount = 0) return;final int height = getHeight();/ 设置 Indicator 颜色 rectPaint.setColor(indicatorCo

29、lor);/ 获取当前选中 TabView currentTab = tabsContainer.getChildAt(currentPosition);/获取 Left,Right 值float lineLeft = currentTab.getLeft();float lineRight = currentTab.getRight();/ if there is an offset, start interpolating left and right coordinates between current and next tabif (currentPositionOffset 0f

30、& currentPosition tabCount - 1) /结合下一个 Tab 获取当前要绘制的 indicator 的位置 , 这里的 currentPositionOffset 比较关 键，可以看到这个值是与 ViewPager 相关的，在 onPagerScrolled 方法中，这个值在不断的更新View nextTab = tabsContainer.getChildAt(currentPosition + 1);final float nextTabLeft = nextTab.getLeft();final float nextTabRight = nextTab.g

31、etRight();lineLeft = (currentPositionOffset * nextTabLeft + (1f - currentPositionOffset) * lineLeft); lineRight =(currentPositionOffset * nextTabRight + (1f - currentPositionOffset) * lineRight);/ 绘制 Indicator canvas.drawRect(lineLeft, height - indicatorHeight, lineRight, height, rectPaint);/ 绘制 Und

32、erLine rectPaint.setColor(underlineColor);canvas.drawRect(0, height - underlineHeight, tabsContainer.getWidth(), height, rectPaint);/ 绘制分割线 dividerPaint.setColor(dividerColor);for (int i = 0; i tabCount - 1; i+) View tab = tabsContainer.getChildAt(i);canvas.drawLine(tab.getRight(), dividerPadding, t

33、ab.getRight(), height - dividerPadding,dividerPaint);setViewPager， setOnPageChangeListener 一个用来与 ViewPager 联动，一个用来处理自定义的OnPagerListener 逻辑public void setViewPager(ViewPager pager) this.pager = ager;if (pager.getAdapter() = null) throw new lllegalStateException(ViewPager does not have adapter instanc

34、e.);pager.setOnPageChangeListener(pageListener); notifyDataSetChanged(); public void setOnPageChangeListener(OnPageChangeListener listener) this.delegatePageListener = listener;3. PagerS 1 i dingTabStrip环口关键点在于实现自己的OnPagerListenerOverrideprotected void onCreate(Bundle savedInstanceState) super.onCre

35、ate(savedInstanceState);setContentView(R.layout.activity_main);文本指示器选中后文本大小和酸色变化IndicaforDmoButterKnife.bind(this);MainPagerAdapter mainPagerAdapter = new MainPagerAdapter(getSupportFragmentManager();vpContent.setAdapter(mainPagerAdapter);pstsIndicator.setViewPager(vpContent); vpContent.addOnPageChangeListener(newViewPager.OnPageChangeListener() Overridepublic void onPageScrolled(int position, float positionOffset, int positionOffsetPixel