Android仿今日头条顶部导航栏效果的实例代码

随着时间的推移现在的软件要求显示的内容越来越多，所以要在小的屏幕上能够更好的显示更多的内容，首先我们会想到底部菜单栏，但是有时候像今日头条新闻客户端要显示的内容太多，而且又想在主界面全部显示出来，所以有加了顶部导航栏。

今日头条顶部导航栏区域的主要部分是一个导航菜单。导航菜单是一组标签的集合，在新闻客户端中，每个标签标示一个新闻类别，对应下面ViewPager控件的一个分页面。当用户在ViewPager区域滑动页面时，对应的导航菜单标签也会相应的被选中，选中的标签通过一个矩形红框高亮显示，红框背景中的标签文字变为白色，红框外的区域标签文字仍为灰色。当用户直接在导航菜单选中某个标签时，ViewPager会自动的切换到对应的分页面。在本文中导航菜单作为一个单独的UI控件实现，类名为CatagoryTabStrip，继承自HorizontalScrollView，这样就可以很容易的实现导航菜单的左右滑动效果以及与下面ViewPager控件的联动。

先看一下实现的效果对比：

顶部导航栏区域和ViewPager区域View层次结构

主界面布局

<RelativeLayout android:id="@+id/main_layout"
 android:background="@color/activity_bg_color"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 xmlns:android="http://schemas.android.com/apk/res/android">
 <RelativeLayout android:id="@+id/title_bar" style="@style/main_title_bar_style">
 <FrameLayout android:id="@+id/top_head_container"
 android:paddingLeft="10.0dip"
 android:paddingRight="10.0dip"
 android:layout_width="wrap_content"
 android:layout_height="fill_parent">
 <ImageView android:layout_gravity="center_vertical"
 android:id="@+id/top_head"
 android:contentDescription="@string/app_name"
 android:background="@drawable/bg_head"
 android:src="@drawable/default_round_head"
 android:padding="2.0dip"
 android:layout_width="@dimen/head_size"
 android:layout_height="@dimen/head_size"
 android:scaleType="fitXY" />
 </FrameLayout>
 <ImageView android:gravity="center"
 android:id="@+id/top_more"
 android:contentDescription="@string/app_name"
 android:layout_width="wrap_content"
 android:layout_height="fill_parent"
 android:layout_marginRight="12.0dip"
 android:src="@drawable/right_drawer"
 android:scaleType="centerInside"
 android:layout_alignParentRight="true"
 android:layout_centerVertical="true" />
 <RelativeLayout android:id="@+id/title_click_layout"
 android:paddingLeft="13.0dip"
 android:layout_width="wrap_content"
 android:layout_height="fill_parent"
 android:layout_centerInParent="true">
 <FrameLayout android:id="@+id/title_parent"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerVertical="true">
 <ImageView android:layout_gravity="center"
 android:id="@+id/title_recent"
 android:contentDescription="@string/app_name"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:src="@drawable/title" />
 </FrameLayout>
 <ImageView android:id="@+id/top_refresh"
 android:contentDescription="@string/app_name"
 android:padding="3.0dip"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:src="@drawable/refreshicon_titlebar"
 android:layout_toRightOf="@id/title_parent"
 android:layout_centerVertical="true" />
 </RelativeLayout>
 </RelativeLayout>
 <RelativeLayout android:id="@+id/category_layout"
 android:background="@drawable/bg_category_bar"
 android:layout_width="fill_parent"
 android:layout_height="@dimen/top_category_height"
 android:layout_below="@id/title_bar" >
 <ImageView android:id="@+id/icon_category"
 android:layout_width="@dimen/top_category_height"
 android:layout_height="@dimen/top_category_height"
 android:src="@drawable/ic_category_expand"
 android:contentDescription="@string/app_name"
 android:scaleType="center"
 android:layout_alignParentRight="true"
 android:layout_centerVertical="true" />
 <LinearLayout android:layout_width="wrap_content"
 android:layout_height="@dimen/top_category_height"
 android:layout_toLeftOf="@id/icon_category"
 android:layout_alignParentLeft="true"
 android:layout_centerVertical="true">
 <com.rainsong.toutiaotabdemo.CategoryTabStrip
 android:id="@+id/category_strip"
 android:paddingLeft="6.0dip"
 android:paddingRight="6.0dip"
 android:clipToPadding="false"
 android:layout_width="wrap_content"
 android:layout_height="@dimen/top_category_height" />
 </LinearLayout>
 </RelativeLayout>
 <android.support.v4.view.ViewPager android:id="@+id/view_pager"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:layout_below="@id/category_layout" />
</RelativeLayout>

在Activity中CatagoryTabStrip控件与ViewPager控件的联合使用
MainActivity.java

package com.rainsong.toutiaotabdemo;
import java.util.ArrayList;
import java.util.List;
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;
public class MainActivity extends FragmentActivity {
 private CategoryTabStrip tabs;
 private ViewPager pager;
 private MyPagerAdapter adapter;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 tabs = (CategoryTabStrip) findViewById(R.id.category_strip);
 pager = (ViewPager) findViewById(R.id.view_pager);
 adapter = new MyPagerAdapter(getSupportFragmentManager());
 pager.setAdapter(adapter);
 tabs.setViewPager(pager);
 }
 public class MyPagerAdapter extends FragmentPagerAdapter {
 private final List<String> catalogs = new ArrayList<String>();
 public MyPagerAdapter(FragmentManager fm) {
 super(fm);
 catalogs.add(getString(R.string.category_hot));
 catalogs.add("\u672c\u5730");
 catalogs.add(getString(R.string.category_video));
 catalogs.add(getString(R.string.category_society));
 catalogs.add(getString(R.string.category_entertainment));
 catalogs.add(getString(R.string.category_tech));
 catalogs.add(getString(R.string.category_finance));
 catalogs.add(getString(R.string.category_military));
 catalogs.add(getString(R.string.category_world));
 catalogs.add(getString(R.string.category_image_ppmm));
 catalogs.add(getString(R.string.category_health));
 catalogs.add(getString(R.string.category_government));
 }
 @Override
 public CharSequence getPageTitle(int position) {
 return catalogs.get(position);
 }
 @Override
 public int getCount() {
 return catalogs.size();
 }
 @Override
 public Fragment getItem(int position) {
 return NewsFragment.newInstance(position);
 }
 }
}

CatagoryTabStrip控件的实现代码

CategoryTabStrip.java

package com.rainsong.toutiaotabdemo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
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.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TextView;
public class CategoryTabStrip extends HorizontalScrollView {
 private LayoutInflater mLayoutInflater;
 private final PageListener pageListener = new PageListener();
 private ViewPager pager;
 private LinearLayout tabsContainer;
 private int tabCount;
 private int currentPosition = 0;
 private float currentPositionOffset = 0f;
 private Rect indicatorRect;
 private LinearLayout.LayoutParams defaultTabLayoutParams;
 private int scrollOffset = 10;
 private int lastScrollX = 0;
 private Drawable indicator;
 private TextDrawable[] drawables;
 private Drawable left_edge;
 private Drawable right_edge;
 public CategoryTabStrip(Context context) {
 this(context, null);
 }
 public CategoryTabStrip(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
 }
 public CategoryTabStrip(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 mLayoutInflater = LayoutInflater.from(context);
 drawables = new TextDrawable[3];
 int i = 0;
 while (i < drawables.length) {
 drawables[i] = new TextDrawable(getContext());
 i++;
 }
 indicatorRect = new Rect();
 setFillViewport(true);
 setWillNotDraw(false);
 // 标签容器
 tabsContainer = new LinearLayout(context);
 tabsContainer.setOrientation(LinearLayout.HORIZONTAL);
 tabsContainer.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
 addView(tabsContainer);
 DisplayMetrics dm = getResources().getDisplayMetrics();
 scrollOffset = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, scrollOffset, dm);
 defaultTabLayoutParams = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
 // 绘制高亮区域作为滑动分页指示器
 indicator = getResources().getDrawable(R.drawable.bg_category_indicator);
 // 左右边界阴影效果
 left_edge = getResources().getDrawable(R.drawable.ic_category_left_edge);
 right_edge = getResources().getDrawable(R.drawable.ic_category_right_edge);
 }
 // 绑定与CategoryTabStrip控件对应的ViewPager控件，实现联动
 public void setViewPager(ViewPager pager) {
 this.pager = pager;
 if (pager.getAdapter() == null) {
 throw new IllegalStateException("ViewPager does not have adapter instance.");
 }
 pager.setOnPageChangeListener(pageListener);
 notifyDataSetChanged();
 }
 // 当附加在ViewPager适配器上的数据发生变化时,应该调用该方法通知CategoryTabStrip刷新数据
 public void notifyDataSetChanged() {
 tabsContainer.removeAllViews();
 tabCount = pager.getAdapter().getCount();
 for (int i = 0; i < tabCount; i++) {
 addTab(i, pager.getAdapter().getPageTitle(i).toString());
 }
 }
 // 添加一个标签到导航菜单
 private void addTab(final int position, String title) {
 ViewGroup tab = (ViewGroup)mLayoutInflater.inflate(R.layout.category_tab, this, false);
 TextView category_text = (TextView) tab.findViewById(R.id.category_text);
 category_text.setText(title);
 category_text.setGravity(Gravity.CENTER);
 category_text.setSingleLine();
 category_text.setFocusable(true);
 category_text.setTextColor(getResources().getColor(R.color.category_tab_text));
 tab.setOnClickListener(new OnClickListener() {
 @Override
 public void onClick(View v) {
 pager.setCurrentItem(position);
 }
 });
 tabsContainer.addView(tab, position, defaultTabLayoutParams);
 }
 // 计算滑动过程中矩形高亮区域的上下左右位置
 private void calculateIndicatorRect(Rect rect) {
 ViewGroup currentTab = (ViewGroup)tabsContainer.getChildAt(currentPosition);
 TextView category_text = (TextView) currentTab.findViewById(R.id.category_text);
 float left = (float) (currentTab.getLeft() + category_text.getLeft());
 float width = ((float) category_text.getWidth()) + left;
 if (currentPositionOffset > 0f && currentPosition < tabCount - 1) {
 ViewGroup nextTab = (ViewGroup)tabsContainer.getChildAt(currentPosition + 1);
 TextView next_category_text = (TextView) nextTab.findViewById(R.id.category_text);
 float next_left = (float) (nextTab.getLeft() + next_category_text.getLeft());
 left = left * (1.0f - currentPositionOffset) + next_left * currentPositionOffset;
 width = width * (1.0f - currentPositionOffset) + currentPositionOffset * (((float) next_category_text.getWidth()) + next_left);
 }
 rect.set(((int) left) + getPaddingLeft(), getPaddingTop() + currentTab.getTop() + category_text.getTop(),
 ((int) width) + getPaddingLeft(), currentTab.getTop() + getPaddingTop() + category_text.getTop() + category_text.getHeight());
 }
 // 计算滚动范围
 private int getScrollRange() {
 return getChildCount() > 0 ? Math.max(0, getChildAt(0).getWidth() - getWidth() + getPaddingLeft() + getPaddingRight()) : 0;
 }
 // CategoryTabStrip与ViewPager联动逻辑
 private void scrollToChild(int position, int offset) {
 if (tabCount == 0) {
 return;
 }
 calculateIndicatorRect(indicatorRect);
 int newScrollX = lastScrollX;
 if (indicatorRect.left < getScrollX() + scrollOffset) {
 newScrollX = indicatorRect.left - scrollOffset;
 } else if (indicatorRect.right > getScrollX() + getWidth() - scrollOffset) {
 newScrollX = indicatorRect.right - getWidth() + scrollOffset;
 }
 if (newScrollX != lastScrollX) {
 lastScrollX = newScrollX;
 scrollTo(newScrollX, 0);
 }
 }
 // 自定义绘图
 @Override
 public void draw(Canvas canvas) {
 super.draw(canvas);
 // 绘制高亮背景矩形红框
 calculateIndicatorRect(indicatorRect);
 if(indicator != null) {
 indicator.setBounds(indicatorRect);
 indicator.draw(canvas);
 }
 // 绘制背景红框内标签文本
 int i = 0;
 while (i < tabsContainer.getChildCount()) {
 if (i < currentPosition - 1 || i > currentPosition + 1) {
 i++;
 } else {
 ViewGroup tab = (ViewGroup)tabsContainer.getChildAt(i);
 TextView category_text = (TextView) tab.findViewById(R.id.category_text);
 if (category_text != null) {
 TextDrawable textDrawable = drawables[i - currentPosition + 1];
 int save = canvas.save();
 calculateIndicatorRect(indicatorRect);
 canvas.clipRect(indicatorRect);
 textDrawable.setText(category_text.getText());
 textDrawable.setTextSize(0, category_text.getTextSize());
 textDrawable.setTextColor(getResources().getColor(R.color.category_tab_highlight_text));
 int left = tab.getLeft() + category_text.getLeft() + (category_text.getWidth() - textDrawable.getIntrinsicWidth()) / 2 + getPaddingLeft();
 int top = tab.getTop() + category_text.getTop() + (category_text.getHeight() - textDrawable.getIntrinsicHeight()) / 2 + getPaddingTop();
 textDrawable.setBounds(left, top, textDrawable.getIntrinsicWidth() + left, textDrawable.getIntrinsicHeight() + top);
 textDrawable.draw(canvas);
 canvas.restoreToCount(save);
 }
 i++;
 }
 }
 // 绘制左右边界阴影效果
 i = canvas.save();
 int top = getScrollX();
 int height = getHeight();
 int width = getWidth();
 canvas.translate((float) top, 0.0f);
 if (left_edge == null || top <= 0) {
 if (right_edge == null || top >= getScrollRange()) {
 canvas.restoreToCount(i);
 }
 right_edge.setBounds(width - right_edge.getIntrinsicWidth(), 0, width, height);
 right_edge.draw(canvas);
 canvas.restoreToCount(i);
 }
 left_edge.setBounds(0, 0, left_edge.getIntrinsicWidth(), height);
 left_edge.draw(canvas);
 if (right_edge == null || top >= getScrollRange()) {
 canvas.restoreToCount(i);
 }
 right_edge.setBounds(width - right_edge.getIntrinsicWidth(), 0, width, height);
 right_edge.draw(canvas);
 canvas.restoreToCount(i);
 }
 private class PageListener implements OnPageChangeListener {
 @Override
 public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
 currentPosition = position;
 currentPositionOffset = positionOffset;
 scrollToChild(position, (int) (positionOffset * tabsContainer.getChildAt(position).getWidth()));
 invalidate();
 }
 @Override
 public void onPageScrollStateChanged(int state) {
 if (state == ViewPager.SCROLL_STATE_IDLE) {
 if(pager.getCurrentItem() == 0) {
 // 滑动到最左边
 scrollTo(0, 0);
 } else if (pager.getCurrentItem() == tabCount - 1) {
 // 滑动到最右边
 scrollTo(getScrollRange(), 0);
 } else {
 scrollToChild(pager.getCurrentItem(), 0);
 }
 }
 }
 @Override
 public void onPageSelected(int position) {
 }
 }
}

完整项目源代码的资源下载 TouTiaoTabDemo.

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