TabLayout用法详解及自定义样式

TabLayout的默认样式:

 app:theme="@style/Widget.Design.TabLayout"

从系统定义的该样式继续深入:

 <style name="Widget.Design.TabLayout" parent="Base.Widget.Design.TabLayout">
  <item name="tabGravity">fill</item>
  <item name="tabMode">fixed</item>
 </style>
 <style name="Base.Widget.Design.TabLayout" parent="android:Widget">
  <item name="tabMaxWidth">264dp</item>
  <item name="tabIndicatorColor">?attr/colorAccent</item>
  <item name="tabIndicatorHeight">2dp</item>
  <item name="tabPaddingStart">12dp</item>
  <item name="tabPaddingEnd">12dp</item>
  <item name="tabBackground">?attr/selectableItemBackground</item>
  <item name="tabTextAppearance">@style/TextAppearance.Design.Tab</item>
  <item name="tabSelectedTextColor">?android:textColorPrimary</item>
 </style>

接着,看看系统定义Tab文本的样式(注意textAllcaps这个属性):   

 <style name="TextAppearance.Design.Tab" parent="TextAppearance.AppCompat.Button">
  <item name="android:textSize">14dp</item>
  <item name="android:textColor">?android:textColorSecondary</item>
  <item name="textAllCaps">true</item>
 </style>

从系统定义TabLayout的默认样式可以看出,我们可以改变TabLayout对应的系统样式的属性值来适配我们自己的需求.

TabLayout的基本用法

TabLayout独立使用使用时,可以xml布局中静态添加tab个数及其样式,也可以动态添加Tab的个数及其样式,如:

 <android.support.design.widget.TabLayout
  android:id="@+id/tablayout"
  android:background="@color/colorPrimary"
  android:layout_width="match_parent"
  android:layout_height="wrap_content">
  <android.support.design.widget.TabItem
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:text="Android"/>
  <android.support.design.widget.TabItem
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:icon="@mipmap/ic_launcher"/>
 </android.support.design.widget.TabLayout>

或者:

 <android.support.design.widget.TabLayout
  android:id="@+id/tablayout"
  android:background="@color/colorPrimary"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"/>

    

private int[] images = new int[]{
     R.drawable.ic_account_balance_wallet_black,
     R.drawable.ic_android_black,
     R.drawable.ic_account_box_black};
 private String[] tabs = new String[]{"小说", "电影", "相声"};
 TabLayout tabLayout = (TabLayout) findViewById(R.id.tablayout);
 tabLayout.addTab(tabLayout.newTab().setIcon(images[0]).setText(tabs[0]),true);
 tabLayout.addTab(tabLayout.newTab().setIcon(images[1]).setText(tabs[1]),false);
 tabLayout.addTab(tabLayout.newTab().setIcon(images[2]).setText(tabs[2]),false);

TabLayout在实际开发中最多的是与ViewPager联合使用,实现TabLayout与ViewPager的联动:

<android.support.design.widget.TabLayout
  android:id="@+id/tablayout"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:background="@color/colorPrimary"
  app:tabGravity="fill"
  app:tabIndicatorColor="@android:color/holo_orange_dark"
  app:tabIndicatorHeight="2dp"
  app:tabMode="fixed"
  app:tabSelectedTextColor="@android:color/holo_orange_dark"
  app:tabTextAppearance="@style/CustomTabTextAppearanceStyle"
  app:tabTextColor="@android:color/white"
  app:theme="@style/Widget.Design.TabLayout"/>
 <android.support.v4.view.ViewPager
  android:id="@+id/view_pager"
  android:layout_width="match_parent"
  android:layout_height="match_parent"/>

 TabLayout tabLayout = (TabLayout) findViewById(R.id.tablayout);
 ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
 viewPager.setAdapter(new TabPagerAdapter(getSupportFragmentManager()));
 tabLayout.setupWithViewPager(viewPager);

值得注意的是:

在TabPagerAdapter中需要实现getPagerTitle()否则,TabLayout的Tab将不显示,先看TabLayout#setupWithPager()源码,发现Tab的添加是在populateFromPagerAdapter()中实现,实现源码如下,可以看出该方法调用了PagerAdpater#getPagerTitle()为Tab设置文本信息,如果我们自定义的Adapter没有实现getPagerTitle()将会导致Tab不显示文本信息.

void populateFromPagerAdapter() {
  removeAllTabs();
  if (mPagerAdapter != null) {
   final int adapterCount = mPagerAdapter.getCount();
   for (int i = 0; i < adapterCount; i++) {
    addTab(newTab().setText(mPagerAdapter.getPageTitle(i)), false);
   }
   // Make sure we reflect the currently set ViewPager item
   if (mViewPager != null && adapterCount > 0) {
    final int curItem = mViewPager.getCurrentItem();
    if (curItem != getSelectedTabPosition() && curItem < getTabCount()) {
     selectTab(getTabAt(curItem));
    }
   }
  }
 }

另外, 我们发现getPagerTitle()方法的返回值CharSequence而不是String,那么Tab的文本信息的设置将变得更加灵活,比如设置一个SpanableString,将图片和文本设置Tab的文本.       

@Override
  public CharSequence getPageTitle(int position) {
   Drawable image = TablayoutActivity.this.getResources().getDrawable(images[position]);
   image.setBounds(0, 0, image.getIntrinsicWidth()/2, image.getIntrinsicHeight()/2);
   ImageSpan imageSpan = new ImageSpan(image, ImageSpan.ALIGN_BOTTOM);
   SpannableString ss = new SpannableString(" "+tabs[position]);
   ss.setSpan(imageSpan, 0, 1, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
   return ss;
  } 

但是Tab缺没有显示任何信息,一片空白,从上面提到的TabLayout的系统默认样式中我们发现: <item name="textAllCaps">true</item>,这会阻止ImageSpan渲染出来,我们只需要将textAllCaps改为false即可,如下定义,再次运行,成功显示

 <style name="CustomTabTextAppearanceStyle" parent="TextAppearance.Design.Tab">
  <item name="textAllCaps">false</item>
 </style>

  修改Indicator的长度:

从TabLayout的源码可以看出Indicator的绘制,是在其内部类SlidingTabStrip中绘制,而SlingTabStrip类继承LinearLayout,源码如下:

 @Override 
 public void draw(Canvas canvas) { 
  super.draw(canvas); 
  // Thick colored underline below the current selection 
  if (mIndicatorLeft >= 0 && mIndicatorRight > mIndicatorLeft) { 
   canvas.drawRect(mIndicatorLeft, getHeight() - mSelectedIndicatorHeight, 
     mIndicatorRight, getHeight(), mSelectedIndicatorPaint); 
  } 
 }

在onDraw()中主要是就绘制一个Rect,并且宽度是根据mIndicatorLeft和mIndicatorRight设置的,而mIndicatorLeft等的宽度来自SlidingTabStrip的child,而Child就相当于一个Tab,这样我们就通过修改Child的margin来设置mIndicatorLeft的值. 

public void setIndicator(TabLayout tabs, int leftDip, int rightDip) {
  Class<?> tabLayout = tabs.getClass();
  Field tabStrip = null;
  try {
   tabStrip = tabLayout.getDeclaredField("mTabStrip");
  } catch (NoSuchFieldException e) {
   e.printStackTrace();
  }
  tabStrip.setAccessible(true);
  LinearLayout llTab = null;
  try {
   llTab = (LinearLayout) tabStrip.get(tabs);
  } catch (IllegalAccessException e) {
   e.printStackTrace();
  }
  int left = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, leftDip, Resources.getSystem().getDisplayMetrics());
  int right = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, rightDip, Resources.getSystem().getDisplayMetrics());
  for (int i = 0; i < llTab.getChildCount(); i++) {
   View child = llTab.getChildAt(i);
   child.setPadding(0, 0, 0, 0);
   LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.MATCH_PARENT, 1);
   params.leftMargin = left;
   params.rightMargin = right;
   child.setLayoutParams(params);
   child.invalidate();
  }
 }

然后在代码中调用即可,但是要注意,必须要在Tablayout渲染出来后调用,我们可以选择view.post()方法来实现:

 tabLayout.post(new Runnable() {
   @Override
   public void run() {
    setIndicator(tabLayout, 20, 20);
   }
 });

最后得到效果图如下:

自定义TabLayout的TabItem及TabItem的点击事件

在TabLayout的Api是没有提供TabItem点击事件的方法,如果我们想实现如下效果图,怎么办?

先自定义一个TabItem:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:gravity="center"
 android:orientation="horizontal">
 <TextView
  android:id="@+id/txt_title"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:gravity="center"
  android:textSize="14sp" />
 <ImageView
  android:id="@+id/img_title"
  android:src="@drawable/indicator"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_marginLeft="5dp" />
</LinearLayout>

在自定义的Adapter中可以定义一个getTabView的方法:

 public View getTabView(int position){
  View view = LayoutInflater.from(context).inflate(R.layout.tab_item, null);
  TextView tv= (TextView) view.findViewById(R.id.textView);
  tv.setText(tabTitles[position]);
  ImageView img = (ImageView) view.findViewById(R.id.imageView);
  img.setImageResource(imageResId[position]);
  return view;
 }

  重新设置点击事件:

viewPager.setAdapter(pagerAdapter);
 tabLayout.setupWithViewPager(viewPager);
 for (int i = 0; i < tabLayout.getTabCount(); i++) {
  TabLayout.Tab tab = tabLayout.getTabAt(i);
  if (tab != null) {
   tab.setCustomView(pagerAdapter.getTabView(i));
   if (tab.getCustomView() != null) {
    View tabView = (View) tab.getCustomView().getParent();
    tabView.setTag(i);
    tabView.setOnClickListener(mTabOnClickListener);
   }
  }
 }
 viewPager.setCurrentItem(1);

以上所述是小编给大家介绍的TabLayout用法详解及自定义样式，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对小牛知识库网站的支持！