Android仿今日頭條滑動頁面導航效果

2020-04-11 10:54:11

字體：大中小

來源：轉載

供稿：網友

最近項目中用到了滑動頁面,也就是和目前市場上很火的"今日頭條"頁面滑動類似,在網上找了一下,大部分都是用ViewPager來實現的,剛開始我用的是ViewPager+ViewGroup,上面的標題按鈕用的是HorizontalScrollView,寫完之后感覺效果比較生硬,果斷換掉,發現了一個效果比較好的第三方,也就是今天的主題:PagerSlidingTabStrip.好了,下面來具體介紹一下PagerSlidingTabStrip,進行一下源碼解析.

一、看一下demo的樣子吧

二、把PagerSlidingTabStrip導入我們的項目中
然后在我們的布局文件中進行聲明:

<span style="font-size:14px;"><?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res/com.hankkin.PagerSlidingTabStrip"     android:orientation="vertical"     android:layout_width="fill_parent"     android:layout_height="fill_parent"   >   <com.hankkin.PagerSlidingTabStrip.view.PagerSlidingTabStrip    android:id="@+id/tab"    app:pstsShouldExpand="false"    app:pstsUnderlineHeight="2dp"    app:pstsIndicatorHeight="2dp"    app:pstsIndicatorColor="@android:color/holo_blue_light"    app:selectedTabTextColor="@android:color/holo_blue_light"    app:pstsDividerColor="@android:color/transparent"    app:pstsTabBackground="@drawable/background"    android:background="@android:color/white"    android:layout_width="match_parent"    android:layout_height="55dp"/>   <android.support.v4.view.ViewPager    android:id="@+id/pager"    android:layout_width="match_parent"    android:layout_height="match_parent"/>  </LinearLayout></span><span style="font-size:18px;"> </span>

上面的也就是我們的標題滑動按鈕,下面的ViewPager用來存放我們的內容
三、創建Adapter

<span style="font-size:14px;">package com.hankkin.PagerSlidingTabStrip.adapter;  import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import com.hankkin.PagerSlidingTabStrip.fragment.AndroidFragment; import com.hankkin.PagerSlidingTabStrip.fragment.JavaFragment; import com.hankkin.PagerSlidingTabStrip.fragment.ObjectCFragment;  import java.util.List;  public class MyAdapter extends FragmentPagerAdapter {  private AndroidFragment androidFragment;  private JavaFragment javaFragment;  private ObjectCFragment objectCFragment;  private String[] titles;  public MyAdapter(FragmentManager fm,String[] titles) {   super(fm);   this.titles = titles;  }   @Override  public Fragment getItem(int position) {   switch (position) {    case 0:     if (androidFragment == null) {      androidFragment = new AndroidFragment();     }     return androidFragment;    case 1:     if (javaFragment == null) {      javaFragment = new JavaFragment();     }     return javaFragment;    case 2:     if (objectCFragment == null) {      objectCFragment = new ObjectCFragment();     }     return objectCFragment;    default:     return null;   }  }   @Override  public int getCount() {   return titles.length;  }   public String getPageTitle(int i){   return titles[i];  }  } </span>

我這里用的是碎片Fragment,最下面的getPageTitle()是我們的PagerSlidingTabStrip中的方法,用來獲取標題
接下來我們初始化PagerSlidingTabStrip和ViewPager還有我們的碎片

<span style="font-size:14px;"> private void initViews(){   fragments = new ArrayList<>();   pagerTab = (PagerSlidingTabStrip) findViewById(R.id.tab);   pager = (ViewPager) findViewById(R.id.pager);    for (int i=0;i<titles.length;i++){    Fragment fragment = new Fragment();    fragments.add(fragment);   }    adapter = new MyAdapter(getSupportFragmentManager(),titles);   pager.setAdapter(adapter);   pagerTab.setViewPager(pager);  }</span>

在Adapter中利用碎片管理器獲取我們的碎片和標題相對應上.這里面需要注意提一下,如果碎片的個數比較少我們可以手動創建碎片,如果像今日頭條很多的話也沒關系,動態創建Fragment,因為我們可以看到頭條的每個碎片中的內容都是類似的,所以說動態創建也未嘗不可,只有個別特殊的我們也可以特殊處理.

就這么簡單就可以實現類似頭條的頁面滑動效果,下面我們來看一下PagerSlidingTabStrip的源碼吧,看懂了之后也方便我們進行改進.
四、PagerSlidingTabStrip源碼解析
首先我們看幾個比較重要的屬性

private int indicatorColor = 0xFF666666;// 滑動指示器顏色 private int underlineColor = 0x1A000000;//在視圖的底部的全寬度的線pstsunderlinecolor顏色 private int dividerColor = 0x1A000000;//選項卡之間的分隔pstsdividercolor顏色  private boolean shouldExpand = false;//pstsshouldexpand如果設置為TRUE，每個標簽都給予同樣的重量，默認為false private boolean textAllCaps = true;//pststextallcaps如果為真，所有選項卡標題都是大寫，默認為true  private int scrollOffset = 52;//pstsscrolloffset卷軸被選擇的標簽的偏移 private int indicatorHeight = 8;//滑動指示器pstsindicatorheight private int underlineHeight = 2;//在視圖的底部的全寬度的線pstsunderlineheight高度 private int dividerPadding = 12;//pstsdividerpadding頂部和底部填充的分頻器 private int tabPadding = 24;//pststabpaddingleftright左、右填充每個選項卡 private int dividerWidth = 1;//選項卡分割線寬度  private int tabTextSize = 12;//選項卡字體大小 private int tabTextColor = 0xFF666666;//選項卡字體顏色 private int selectedTabTextColor = 0xFF666666;//當前選中字體顏色 private Typeface tabTypeface = null; private int tabTypefaceStyle = Typeface.NORMAL;  private int lastScrollX = 0;  private int tabBackgroundResId = R.drawable.background;//pststabbackground背景繪制的每個標簽，應該是一個statelistdrawable

我們可以自己定義這些屬性的值,因為可能默認的不太好看
1.首先看一下我們的構造會初始化一些什么屬性

<span style="font-size:14px;">public PagerSlidingTabStrip(Context context, AttributeSet attrs, int defStyle) {   super(context, attrs, defStyle);    setFillViewport(true);//默認使子view可以拉伸來填滿整個屏幕   setWillNotDraw(false);//默認不執行OnDraw()方法   //初始化盛放按鈕標題的線性布局   tabsContainer = new LinearLayout(context);   tabsContainer.setOrientation(LinearLayout.HORIZONTAL);   tabsContainer.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));   addView(tabsContainer);    DisplayMetrics dm = getResources().getDisplayMetrics();   //導入相應資源文件   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);    indicatorColor = a.getColor(R.styleable.PagerSlidingTabStrip_pstsIndicatorColor, indicatorColor);    //tab文字選中時的顏色,默認和滑動指示器的顏色一致   selectedTabTextColor=a.getColor(R.styleable.PagerSlidingTabStrip_selectedTabTextColor, indicatorColor);   //初始化屬性樣式   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();    rectPaint = new Paint();   rectPaint.setAntiAlias(true);   rectPaint.setStyle(Style.FILL);    dividerPaint = new Paint();   dividerPaint.setAntiAlias(true);   dividerPaint.setStrokeWidth(dividerWidth);    defaultTabLayoutParams = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);   expandedTabLayoutParams = new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1.0f);    if (locale == null) {    locale = getResources().getConfiguration().locale;   }  }</span>

這些基本都能看懂,主要都是初始化一些屬性,代碼中也有相應的注釋,就不一一介紹了

2.定義ViewPager滑動監聽器,設置當前pager的位置

<span style="font-size:14px;">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();     if (delegatePageListener != null) {     delegatePageListener.onPageScrolled(position, positionOffset, positionOffsetPixels);    }   }    @Override   public void onPageScrollStateChanged(int state) {    if (state == ViewPager.SCROLL_STATE_IDLE) {     scrollToChild(pager.getCurrentItem(), 0);    }     if (delegatePageListener != null) {     delegatePageListener.onPageScrollStateChanged(state);    }   }    @Override   public void onPageSelected(int position) {    selectedPosition = position;    updateTabStyles();    if (delegatePageListener != null) {     delegatePageListener.onPageSelected(position);    }   }   }</span>

3.更新標題樣式,也就是滑動到當前標題下設置標題狀態

<span style="font-size:14px;">private void updateTabStyles() {    for (int i = 0; i < tabCount; i++) {     View v = tabsContainer.getChildAt(i);     v.setBackgroundResource(tabBackgroundResId);     if (v instanceof TextView) {      TextView tab = (TextView) v;     tab.setTextSize(TypedValue.COMPLEX_UNIT_PX, tabTextSize);     tab.setTypeface(tabTypeface, tabTypefaceStyle);     tab.setTextColor(tabTextColor);      // 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));      }     }     if (i == selectedPosition) {      tab.setTextColor(selectedTabTextColor);     }    }   }   }</span>

大體就差不多這些了,好了,給大家看一下我自己完善后的樣子吧