【Android开源项目分析】TAB导航栏PagerSlidingTabStrip的使用和源码分析

转载请注明出处：http://blog.csdn.net/zhoubin1992/article/details/47382021
本文分为两部分：

PagerSlidingTabStrip的使用
PagerSlidingTabStrip源码分析

PagerSlidingTabStrip项目源码下载：
https://github.com/astuetz/PagerSlidingTabStrip
PagerSlidingTabStrip是配合ViewPager使用的导航栏，导航栏会随着ViewPager滑动而滑动,如下图。打开源码会发现只有一个继承了HorizontalScrollView的类——PagerSlidingTabStrip.java，实现不是特别复杂。

PagerSlidingTabStrip的使用

我这里展示使用步骤，记录下当时遇到的问题以及解决方法。
1. 按照上面的地址下载，项目文件名PagerSlidingTabStrip-master。把library导入工程，加入library作为引用工程。
这里当时我导入后，library项目报错了。
首先是Unable to resolve target ‘Android-17’错误
解决方法：http://stackoverflow.com/questions/20975056/unable-to-resolve-target-android-17
还有是项目引用了android-support-v4，然而项目并没有导入android-support-v4.jar，出现The import android.support cannot be resolved错误
解决方法：http://stackoverflow.com/questions/18299898/the-import-android-support-cannot-be-resolved
再者当导入android-support-v4.jar后，出现multiple dex files define landroid/support/annotation/AnimRes错误
解决方法：http://stackoverflow.com/questions/26342444/multiple-dex-files-define-landroid-support-annotation-animres
2. 在layout布局文件里配置PagerSlidingTabStrip控件，它通常要在ViewPager控件之上。

   <!--  通常要在ViewPager控件之上 -->
    <com.astuetz.PagerSlidingTabStrip
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="48dip" />  
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tabs" />

3.在activity的onCreate方法或者fragment的onCreateView方法，获取PagerSlidingTabStrip控件，绑定控件到ViewPager上。
activity的onCreate方法:

        mTabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
        //初始化ViewPager并添加适配器
        mPager = (ViewPager) findViewById(R.id.pager);
        mAdapter = new MyPagerAdapter(getSupportFragmentManager());
        mPager.setAdapter(mAdapter);
        //绑定PagerSlidingTabStrip控件到ViewPager上
        mTabs.setViewPager(mPager);

我的需求是在fragment的onCreateView方法，注意代码如下：

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_recipe,
                container, false);

        mTabs = (PagerSlidingTabStrip) view.findViewById(R.id.tabs);
        //初始化ViewPager并且添加适配器
        mPager = (ViewPager) view.findViewById(R.id.pager);
        mAdapter = new MyPagerAdapter(getActivity().getSupportFragmentManager());
        mPager.setAdapter(mAdapter);
        //绑定PagerSlidingTabStrip控件到ViewPager上
        mTabs.setViewPager(mPager);  
        return view;
    }

要注意到findViewById前需要加view,getSupportFragmentManager()前需要加getActivity()。
当时一开始没有加。出现nullpointer exception in oncreateView() of fragment错误。
解决方法：http://stackoverflow.com/questions/15644617/nullpointer-exception-in-oncreateview-of-fragment
同时注意内部类MyPagerAdapter需要自己定义，参考官方demo。这样就完成了。
总结下PagerSlidingTabStrip的使用：

library导入工程，加入library作为引用工程；
布局文件配置PagerSlidingTabStrip控件；
在onCreate方法或onCreateView方法中获取PagerSlidingTabStrip控件，绑定到ViewPager上。

PagerSlidingTabStrip源码分析

首先我先总结下PagerSlidingTabStrip的主要原理，让大家有个整体把握。然后再进入源码一步步分析。

PagerSlidingTabStrip的主要原理：

首先在构造方法里创建Tab的LinearLayout容器，初始化样式值，创建指示器分割线画笔等；
进入setViewPager()绑定ViewPager，设置了viewpager的OnPageChangeListener为内部类PageListener，以及调用notifyDataSetChanged()；
在notifyDataSetChanged()根据adapter内容创建TAB导航栏标题(icon/text)；
在PageListener监听类里实现了导航栏会随着ViewPager滑动而滑动，以及调用invalidate()方法；
触发ondraw()函数完成最终的绘制。绘制指示器,下划线和分割线。



/*
 * Copyright (C) 2013 Andreas Stuetz <andreas.stuetz@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.astuetz;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Typeface;
import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.widget.HorizontalScrollView;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.util.Locale;

import com.astuetz.pagerslidingtabstrip.R;
//继承HorizontalScrillView，拥有HorizontalScrillView的超出界面时可左右滑动的功能。
public class PagerSlidingTabStrip extends HorizontalScrollView {
    //通过 viewpager 的 adapter 可以实现接口IconTabProvider
    public interface IconTabProvider {
        public int getPageIconResId(int position);
    }

    // @formatter:off
    private static final int[] ATTRS = new int[] {
        android.R.attr.textSize,
        android.R.attr.textColor
    };
    // @formatter:on

    private LinearLayout.LayoutParams defaultTabLayoutParams;
    private LinearLayout.LayoutParams expandedTabLayoutParams;

    private final PageListener pageListener = new PageListener();
    public OnPageChangeListener delegatePageListener;

    private LinearLayout tabsContainer;
    private ViewPager pager;

    private int tabCount;

    private int currentPosition = 0;
    private float currentPositionOffset = 0f;

    private Paint rectPaint;
    private Paint dividerPaint;

    private int indicatorColor = 0xFF666666;
    private int underlineColor = 0x1A000000;
    private int dividerColor = 0x1A000000;

    private boolean shouldExpand = false;
    private boolean textAllCaps = true;

    private int scrollOffset = 52;
    private int indicatorHeight = 8;
    private int underlineHeight = 2;
    private int dividerPadding = 12;
    private int tabPadding = 24;
    private int dividerWidth = 1;

    private int tabTextSize = 12;
    private int tabTextColor = 0xFF666666;
    private Typeface tabTypeface = null;
    private int tabTypefaceStyle = Typeface.BOLD;

    private int lastScrollX = 0;

    private int tabBackgroundResId = R.drawable.background_tab;

    private Locale locale;

    public PagerSlidingTabStrip(Context context) {
        this(context, null);
    }

    public PagerSlidingTabStrip(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }
    //构造方法
    public PagerSlidingTabStrip(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        setFillViewport(true);
        setWillNotDraw(false);
        //动态生成横向的LinearLayout，并添加
        tabsContainer = new LinearLayout(context);
        tabsContainer.setOrientation(LinearLayout.HORIZONTAL);
        tabsContainer.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
        addView(tabsContainer);

        DisplayMetrics dm = getResources().getDisplayMetrics();
        //初始化样式值（指示器，下划线，分隔线和TAB文字等样式）
        scrollOffset = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, scrollOffset, dm);
        indicatorHeight = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, indicatorHeight, dm);
        underlineHeight = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, underlineHeight, dm);
        dividerPadding = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dividerPadding, dm);
        tabPadding = (int) TypedValue.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:textColor)

        TypedArray a = context.obtainStyledAttributes(attrs, ATTRS);

        tabTextSize = a.getDimensionPixelSize(0, tabTextSize);
        tabTextColor = a.getColor(1, tabTextColor);

        a.recycle();

        // get custom attrs

        a = context.obtainStyledAttributes(attrs, R.styleable.PagerSlidingTabStrip);
        //获取布局文件的配置样式值
        indicatorColor = a.getColor(R.styleable.PagerSlidingTabStrip_pstsIndicatorColor, indicatorColor);
        underlineColor = a.getColor(R.styleable.PagerSlidingTabStrip_pstsUnderlineColor, underlineColor);
        dividerColor = a.getColor(R.styleable.PagerSlidingTabStrip_pstsDividerColor, dividerColor);
        indicatorHeight = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsIndicatorHeight, indicatorHeight);
        underlineHeight = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsUnderlineHeight, underlineHeight);
        dividerPadding = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsDividerPadding, dividerPadding);
        tabPadding = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsTabPaddingLeftRight, tabPadding);
        tabBackgroundResId = a.getResourceId(R.styleable.PagerSlidingTabStrip_pstsTabBackground, tabBackgroundResId);
        shouldExpand = a.getBoolean(R.styleable.PagerSlidingTabStrip_pstsShouldExpand, shouldExpand);
        scrollOffset = a.getDimensionPixelSize(R.styleable.PagerSlidingTabStrip_pstsScrollOffset, scrollOffset);
        textAllCaps = a.getBoolean(R.styleable.PagerSlidingTabStrip_pstsTextAllCaps, textAllCaps);

        a.recycle();
        //指示器画笔
        rectPaint = new Paint();
        rectPaint.setAntiAlias(true);
        rectPaint.setStyle(Style.FILL);
        //分割线画笔
        dividerPaint = new Paint();
        dividerPaint.setAntiAlias(true);
        dividerPaint.setStrokeWidth(dividerWidth);
        //创建两个LinearLayout.LayoutParams，一个为适应内容长度
        defaultTabLayoutParams = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
        //一个为长度比例相同
        expandedTabLayoutParams = new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1.0f);

        if (locale == null) {
            locale = getResources().getConfiguration().locale;
        }
    }
    //绑定ViewPager
    public void setViewPager(ViewPager pager) {
        this.pager = pager;
        //viewpager的adapter不能为空否则会异常，
        if (pager.getAdapter() == null) {
            throw new IllegalStateException("ViewPager does not have adapter instance.");
        }
        //设置了viewpager的OnPageChangeListener,注意是pagerSlidingTabStrip 内部类PageListener
        pager.setOnPageChangeListener(pageListener);

        notifyDataSetChanged();
    }

    public void setOnPageChangeListener(OnPageChangeListener listener) {
        this.delegatePageListener = listener;
    }
    //创建TAB导航栏标题，初始化默认第一个标题内容
    public void notifyDataSetChanged() {
        //移除全部子视图，根据adapter内容addTab
        tabsContainer.removeAllViews();

        tabCount = pager.getAdapter().getCount();

        for (int i = 0; i < tabCount; i++) {
            //如果是 icon 的话，通过 viewpager 的 adapter 实现接口IconTabProvider 否则是 text 
            if (pager.getAdapter() instanceof IconTabProvider) {
                addIconTab(i, ((IconTabProvider) pager.getAdapter()).getPageIconResId(i));
            } else {
                addTextTab(i, pager.getAdapter().getPageTitle(i).toString());
            }

        }

        updateTabStyles();

        getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {

            @SuppressWarnings("deprecation")
            @SuppressLint("NewApi")
            @Override
            public void onGlobalLayout() {

                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
                    getViewTreeObserver().removeGlobalOnLayoutListener(this);
                } else {
                    getViewTreeObserver().removeOnGlobalLayoutListener(this);
                }

                currentPosition = pager.getCurrentItem();
                scrollToChild(currentPosition, 0);
            }
        });

    }
    //添加文字TAB导航栏内容
    private void addTextTab(final int position, String title) {

        TextView tab = new TextView(getContext());
        tab.setText(title);
        tab.setGravity(Gravity.CENTER);
        tab.setSingleLine();

        addTab(position, tab);
    }
    //添加图片TAB导航栏内容
    private void addIconTab(final int position, int resId) {

        ImageButton tab = new ImageButton(getContext());
        tab.setImageResource(resId);

        addTab(position, tab);

    }

    private void addTab(final int position, View tab) {
        tab.setFocusable(true);
        tab.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                pager.setCurrentItem(position);
            }
        });
        //设置每个tab左右的padding
        tab.setPadding(tabPadding, 0, tabPadding, 0);
        //往container里面动态添加tab,哪个TabLayoutParams注意看前文
        tabsContainer.addView(tab, position, shouldExpand ? expandedTabLayoutParams : defaultTabLayoutParams);
    }
    //设置每个tab的样式
    @SuppressLint("NewApi") private void updateTabStyles() {

        for (int i = 0; i < tabCount; i++) {

            View v = tabsContainer.getChildAt(i);

            v.setBackgroundResource(tabBackgroundResId);
            //背景、文字大小、颜色、字体、是否大写
            if (v instanceof TextView) {

                TextView tab = (TextView) v;
                tab.setTextSize(TypedValue.COMPLEX_UNIT_PX, tabTextSize);
                tab.setTypeface(tabTypeface, tabTypefaceStyle);
                tab.setTextColor(tabTextColor);
                //API控制
                // setAllCaps() is only available from API 14, so the upper case is made manually if we are on a
                // pre-ICS-build
                if (textAllCaps) {
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
                        tab.setAllCaps(true);
                    } else {
                        tab.setText(tab.getText().toString().toUpperCase(locale));
                    }
                }
            }
        }

    }
    //滚动到特定位置,调用父类scrollTo，布局超出边界才会起作用
    private void scrollToChild(int position, int offset) {

        if (tabCount == 0) {
            return;
        }

        int newScrollX = tabsContainer.getChildAt(position).getLeft() + offset;

        if (position > 0 || offset > 0) {
            newScrollX -= scrollOffset;
        }
        //滑动到的位置。
        if (newScrollX != lastScrollX) {
            lastScrollX = newScrollX;
            scrollTo(newScrollX, 0);
        }

    }
    //onDraw方法绘制分隔线，绘制指示器。
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        if (isInEditMode() || tabCount == 0) {
            return;
        }
        final int height = getHeight();

        // draw indicator line
        //画笔颜色
        rectPaint.setColor(indicatorColor);

        // default: line below current tab
        View currentTab = tabsContainer.getChildAt(currentPosition);
        float lineLeft = currentTab.getLeft();
        float lineRight = currentTab.getRight();

        // if there is an offset, start interpolating left and right coordinates between current and next tab
        if (currentPositionOffset > 0f && currentPosition < tabCount - 1) {

            View nextTab = tabsContainer.getChildAt(currentPosition + 1);
            final float nextTabLeft = nextTab.getLeft();
            final float nextTabRight = nextTab.getRight();

            lineLeft = (currentPositionOffset * nextTabLeft + (1f - currentPositionOffset) * lineLeft);
            lineRight = (currentPositionOffset * nextTabRight + (1f - currentPositionOffset) * lineRight);
        }
        //根据当前tab坐标和下一个tab坐标和currentPositionOffset计算指示器坐标并绘制指示器线
        canvas.drawRect(lineLeft, height - indicatorHeight, lineRight, height, rectPaint);

        // draw underline
        //绘制指示器矩形长条
        rectPaint.setColor(underlineColor);
        canvas.drawRect(0, height - underlineHeight, tabsContainer.getWidth(), height, rectPaint);

        // draw divider
        //绘制各个tab之间的分隔线长度为dividerPadding
        dividerPaint.setColor(dividerColor);
        for (int i = 0; i < tabCount - 1; i++) {
            View tab = tabsContainer.getChildAt(i);
            canvas.drawLine(tab.getRight(), dividerPadding, tab.getRight(), height - dividerPadding, dividerPaint);
        }
    }
    //内部PageListener类，用于监听滑动事件得到当前滑动偏移量和当前tab
    private class PageListener implements OnPageChangeListener {
        //在此就实现了导航栏会随着ViewPager滑动而滑动
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            //当前 view 的位置也即 tab 的位置
            currentPosition = position;
            //当前 view 滑动的距离。其中 currentPositionOffset 为 float，介于 0~1 代表相对于 tab 宽偏移的比例
            currentPositionOffset = positionOffset;
            //根据上面得到的 view 的位置和偏移位置，来同步 tab 的位置和偏移距离。
            scrollToChild(position, (int) (positionOffset * tabsContainer.getChildAt(position).getWidth()));
             //重绘 view，实现 tab 滑动的效果。
            invalidate();
            //给pagerslidingtab加滑动监听delegatePageListener
            //下面的 delegatePageListener 就是我们设置的 viewpager.setOnPageChangeListener.而现在把它封装在整个 pagerSlidingTabStrip 中，实现 viewpager 滑动的效果。
            if (delegatePageListener != null) {
                delegatePageListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }
        }
        //重写onPageScrollStateChanged
        @Override
        public void onPageScrollStateChanged(int state) {
            //滑动结束。positionOffset 归零
            if (state == ViewPager.SCROLL_STATE_IDLE) {
                scrollToChild(pager.getCurrentItem(), 0);
            }
            //调用 viewpager.setOnPageChangeListener
            if (delegatePageListener != null) {
                delegatePageListener.onPageScrollStateChanged(state);
            }
        }
        //重写onPageSelected
        @Override
        public void onPageSelected(int position) {
            //调用 viewpager.setOnPageChangeListener
            if (delegatePageListener != null) {
                delegatePageListener.onPageSelected(position);
            }
        }

    }

    public void setIndicatorColor(int indicatorColor) {
        this.indicatorColor = indicatorColor;
        invalidate();
    }

    public void setIndicatorColorResource(int resId) {
        this.indicatorColor = getResources().getColor(resId);
        invalidate();
    }

    public int getIndicatorColor() {
        return this.indicatorColor;
    }

    public void setIndicatorHeight(int indicatorLineHeightPx) {
        this.indicatorHeight = indicatorLineHeightPx;
        invalidate();
    }

    public int getIndicatorHeight() {
        return indicatorHeight;
    }

    public void setUnderlineColor(int underlineColor) {
        this.underlineColor = underlineColor;
        invalidate();
    }

    public void setUnderlineColorResource(int resId) {
        this.underlineColor = getResources().getColor(resId);
        invalidate();
    }

    public int getUnderlineColor() {
        return underlineColor;
    }

    public void setDividerColor(int dividerColor) {
        this.dividerColor = dividerColor;
        invalidate();
    }

    public void setDividerColorResource(int resId) {
        this.dividerColor = getResources().getColor(resId);
        invalidate();
    }

    public int getDividerColor() {
        return dividerColor;
    }

    public void setUnderlineHeight(int underlineHeightPx) {
        this.underlineHeight = underlineHeightPx;
        invalidate();
    }

    public int getUnderlineHeight() {
        return underlineHeight;
    }

    public void setDividerPadding(int dividerPaddingPx) {
        this.dividerPadding = dividerPaddingPx;
        invalidate();
    }

    public int getDividerPadding() {
        return dividerPadding;
    }

    public void setScrollOffset(int scrollOffsetPx) {
        this.scrollOffset = scrollOffsetPx;
        invalidate();
    }

    public int getScrollOffset() {
        return scrollOffset;
    }

    public void setShouldExpand(boolean shouldExpand) {
        this.shouldExpand = shouldExpand;
        requestLayout();
    }

    public boolean getShouldExpand() {
        return shouldExpand;
    }

    public boolean isTextAllCaps() {
        return textAllCaps;
    }

    public void setAllCaps(boolean textAllCaps) {
        this.textAllCaps = textAllCaps;
    }

    public void setTextSize(int textSizePx) {
        this.tabTextSize = textSizePx;
        updateTabStyles();
    }

    public int getTextSize() {
        return tabTextSize;
    }

    public void setTextColor(int textColor) {
        this.tabTextColor = textColor;
        updateTabStyles();
    }

    public void setTextColorResource(int resId) {
        this.tabTextColor = getResources().getColor(resId);
        updateTabStyles();
    }

    public int getTextColor() {
        return tabTextColor;
    }

    public void setTypeface(Typeface typeface, int style) {
        this.tabTypeface = typeface;
        this.tabTypefaceStyle = style;
        updateTabStyles();
    }

    public void setTabBackground(int resId) {
        this.tabBackgroundResId = resId;
    }

    public int getTabBackground() {
        return tabBackgroundResId;
    }

    public void setTabPaddingLeftRight(int paddingPx) {
        this.tabPadding = paddingPx;
        updateTabStyles();
    }

    public int getTabPaddingLeftRight() {
        return tabPadding;
    }
    //activity销毁时在onSaveInstanceState记录当前页数，
    //当onRestoreInstanceState获得当前页数并重新
    //requestLayout进行测量、布局和绘制
    @Override
    public void onRestoreInstanceState(Parcelable state) {
        SavedState savedState = (SavedState) state;
        super.onRestoreInstanceState(savedState.getSuperState());
        currentPosition = savedState.currentPosition;
        requestLayout();
    }

    @Override
    public Parcelable onSaveInstanceState() {
        Parcelable superState = super.onSaveInstanceState();
        SavedState savedState = new SavedState(superState);
        savedState.currentPosition = currentPosition;
        return savedState;
    }

    static class SavedState extends BaseSavedState {
        int currentPosition;

        public SavedState(Parcelable superState) {
            super(superState);
        }

        private SavedState(Parcel in) {
            super(in);
            currentPosition = in.readInt();
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            dest.writeInt(currentPosition);
        }

        public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {
            @Override
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in);
            }

            @Override
            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }

}

总结

LinearLayout创建Tab容器；
在PageListener监听类里获取当前偏移量并随着ViewPager滑动而滑动；
在onDraw方法绘制指示器、下划线和分割线。

参考文献：

公共技术点之 View 绘制流程
 PagerSlidingTabStrip 源码解析

posted @ 2016-11-05 18:43 天涯海角路阅读(157) 评论(0) 收藏举报

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天涯海角路

【Android开源项目分析】TAB导航栏PagerSlidingTabStrip的使用和源码分析

PagerSlidingTabStrip的使用

PagerSlidingTabStrip源码分析

PagerSlidingTabStrip的主要原理：

总结

参考文献：

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