AndroidUI组件SlidingTabLayout实现ViewPager页滑动效果

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.example.my.slidingtablayout;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Build;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TextView;

/**
 * To be used with ViewPager to provide a tab indicator component which give constant feedback as to
 * the user's scroll progress.
 * <p>
 * To use the component, simply add it to your view hierarchy. Then in your
 * {@link android.app.Activity} or {@link android.support.v4.app.Fragment} call
 * {@link #setViewPager(ViewPager)} providing it the ViewPager this layout is being used for.
 * <p>
 * The colors can be customized in two ways. The first and simplest is to provide an array of colors
 * via {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)}. The
 * alternative is via the {@link TabColorizer} interface which provides you complete control over
 * which color is used for any individual position.
 * <p>
 * The views used as tabs can be customized by calling {@link #setCustomTabView(int, int)},
 * providing the layout ID of your custom layout.
 */
public class SlidingTabLayout extends HorizontalScrollView {

 /**
  * Allows complete control over the colors drawn in the tab layout. Set with
  * {@link #setCustomTabColorizer(TabColorizer)}.
  */
 public interface TabColorizer {

  /**
   * @return return the color of the indicator used when {@code position} is selected.
   */
  int getIndicatorColor(int position);

  /**
   * @return return the color of the divider drawn to the right of {@code position}.
   */
  int getDividerColor(int position);

 }

 private static final int TITLE_OFFSET_DIPS = 24;
 private static final int TAB_VIEW_PADDING_DIPS = 16; //内边距
 private static int TAB_VIEW_TEXT_SIZE_SP = 16; //字体大小

 private int mTitleOffset;

 private int mTabViewLayoutId;
 private int mTabViewTextViewId;

 // 定义两种需要添加的选项卡颜色
 private int mDefaultTextColor;
 private int mSelectedTextColor;

 private ViewPager mViewPager;
 private ViewPager.OnPageChangeListener mViewPagerPageChangeListener;

 private final SlidingTabStrip mTabStrip;

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

 public SlidingTabLayout(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);

  // 获取选项卡颜色，如果未定义的话，则使用主题默认的颜色
  TypedArray a = context.obtainStyledAttributes(attrs,
    R.styleable.SlidingTabLayout);
  int defaultTextColor = a.getColor(
    R.styleable.SlidingTabLayout_android_textColorPrimary, 0);
  mDefaultTextColor = a.getColor(
    R.styleable.SlidingTabLayout_textColorTabDefault, defaultTextColor);
  mSelectedTextColor = a.getColor(
    R.styleable.SlidingTabLayout_textColorTabSelected ,defaultTextColor);
  a.recycle();


  // Disable the Scroll Bar
  setHorizontalScrollBarEnabled(false);
  // Make sure that the Tab Strips fills this View
  setFillViewport(true);

  mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density);

  mTabStrip = new SlidingTabStrip(context);
  addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
 }

 // 在每次选项改变时更新选项卡文本颜色的新方法
 private void updateSelectedTitle(int position) {
  final PagerAdapter adapter = mViewPager.getAdapter();
  for (int i = 0; i < adapter.getCount(); i++) {
   final View tabView = mTabStrip.getChildAt(i);
   if (TextView.class.isInstance(tabView)) {
    TextView titleView = (TextView)tabView;
    boolean isSelected = i == position;
    titleView.setTextColor(isSelected ? mSelectedTextColor : mDefaultTextColor);
   }
  }
 }
 /**
  * Set the custom {@link TabColorizer} to be used.
  * <p>
  * If you only require simple custmisation then you can use
  * {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)} to achieve
  * similar effects.
  */
 public void setCustomTabColorizer(TabColorizer tabColorizer) {
  mTabStrip.setCustomTabColorizer(tabColorizer);
 }


 /**
  * Sets the colors to be used for indicating the selected tab. These colors are treated as a
  * circular array. Providing one color will mean that all tabs are indicated with the same color.
  */
 public void setSelectedIndicatorColors(int... colors) {
  mTabStrip.setSelectedIndicatorColors(colors);
 }

 /**
  * Sets the colors to be used for tab dividers. These colors are treated as a circular array.
  * Providing one color will mean that all tabs are indicated with the same color.
  */
 public void setDividerColors(int... colors) {
  mTabStrip.setDividerColors(colors);
 }

 //...设置字体大小
 public void setTitleSize(int size) {
  this.TAB_VIEW_TEXT_SIZE_SP = size;
 }

 /**
  * Set the {@link ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are
  * required to set any {@link ViewPager.OnPageChangeListener} through this method. This is so
  * that the layout can update it's scroll position correctly.
  *
  * @see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener)
  */
 public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
  mViewPagerPageChangeListener = listener;
 }

 /**
  * Set the custom layout to be inflated for the tab views.
  *
  * @param layoutResId Layout id to be inflated
  * @param textViewId id of the {@link TextView} in the inflated view
  */
 public void setCustomTabView(int layoutResId, int textViewId) {
  mTabViewLayoutId = layoutResId;
  mTabViewTextViewId = textViewId;
 }

 /**
  * Sets the associated view pager. Note that the assumption here is that the pager content
  * (number of tabs and tab titles) does not change after this call has been made.
  */
 public void setViewPager(ViewPager viewPager) {
  mTabStrip.removeAllViews();

  mViewPager = viewPager;
  if (viewPager != null) {
   viewPager.setOnPageChangeListener(new InternalViewPagerListener());
   populateTabStrip();
  }
 }

 /**
  * Create a default view to be used for tabs. This is called if a custom tab view is not set via
  * {@link #setCustomTabView(int, int)}.
  */
 protected TextView createDefaultTabView(Context context) {
  TextView textView = new TextView(context);
  textView.setGravity(Gravity.CENTER);
  textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP);
  textView.setTypeface(Typeface.DEFAULT_BOLD);

  //...这会移除 Holo 的默认背景强调以及选项卡的粗体文本
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
   // If we're running on Honeycomb or newer, then we can use the Theme's
   // selectableItemBackground to ensure that the View has a pressed state
   TypedValue outValue = new TypedValue();
   getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
     outValue, true);
   textView.setBackgroundResource(outValue.resourceId);
  }

  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
   // If we're running on ICS or newer, enable all-caps to match the Action Bar tab style
   textView.setAllCaps(true);
  }

  int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density);
  textView.setPadding(padding, padding, padding, padding);

  return textView;
 }

 private void populateTabStrip() {
  final PagerAdapter adapter = mViewPager.getAdapter();
  final OnClickListener tabClickListener = new TabClickListener();

  for (int i = 0; i < adapter.getCount(); i++) {
   View tabView = null;
   TextView tabTitleView = null;

   if (mTabViewLayoutId != 0) {
    // If there is a custom tab view layout id set, try and inflate it
    tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip,
      false);
    tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId);
   }

   if (tabView == null) {
    tabView = createDefaultTabView(getContext());
   }

   if (tabTitleView == null && TextView.class.isInstance(tabView)) {
    tabTitleView = (TextView) tabView;
   }

   tabTitleView.setText(adapter.getPageTitle(i));
   //... 设置头部均分
   LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(0, LayoutParams.WRAP_CONTENT, 1.0f);
   tabView.setLayoutParams(layoutParams);
   tabView.setOnClickListener(tabClickListener);

   mTabStrip.addView(tabView);
  }
 }

 @Override
 protected void onAttachedToWindow() {
  super.onAttachedToWindow();

  if (mViewPager != null) {
   scrollToTab(mViewPager.getCurrentItem(), 0);
  }
 }

 private void scrollToTab(int tabIndex, int positionOffset) {
  final int tabStripChildCount = mTabStrip.getChildCount();
  if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) {
   return;
  }

  View selectedChild = mTabStrip.getChildAt(tabIndex);
  if (selectedChild != null) {

   // 调用在每次选项改变时更新文本颜色的新方案
   updateSelectedTitle(tabIndex);

   int targetScrollX = selectedChild.getLeft() + positionOffset;

   if (tabIndex > 0 || positionOffset > 0) {
    // If we're not at the first child and are mid-scroll, make sure we obey the offset
    targetScrollX -= mTitleOffset;
   }

   scrollTo(targetScrollX, 0);
  }
 }

 private class InternalViewPagerListener implements ViewPager.OnPageChangeListener {
  private int mScrollState;

  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
   int tabStripChildCount = mTabStrip.getChildCount();
   if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
    return;
   }

   mTabStrip.onViewPagerPageChanged(position, positionOffset);

   View selectedTitle = mTabStrip.getChildAt(position);
   int extraOffset = (selectedTitle != null)
     ? (int) (positionOffset * selectedTitle.getWidth())
     : 0;
   scrollToTab(position, extraOffset);

   if (mViewPagerPageChangeListener != null) {
    mViewPagerPageChangeListener.onPageScrolled(position, positionOffset,
      positionOffsetPixels);
   }
  }

  @Override
  public void onPageScrollStateChanged(int state) {
   mScrollState = state;

   if (mViewPagerPageChangeListener != null) {
    mViewPagerPageChangeListener.onPageScrollStateChanged(state);
   }
  }

  @Override
  public void onPageSelected(int position) {
   if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
    mTabStrip.onViewPagerPageChanged(position, 0f);
    scrollToTab(position, 0);
   }

   if (mViewPagerPageChangeListener != null) {
    mViewPagerPageChangeListener.onPageSelected(position);
   }
  }

 }

 private class TabClickListener implements OnClickListener {
  @Override
  public void onClick(View v) {
   for (int i = 0; i < mTabStrip.getChildCount(); i++) {
    if (v == mTabStrip.getChildAt(i)) {
     mViewPager.setCurrentItem(i);
     return;
    }
   }
  }
 }

}

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.example.my.slidingtablayout;

import android.R;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.View;
import android.widget.LinearLayout;

class SlidingTabStrip extends LinearLayout {

 private static final int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 0; //去除阴影
 private static final byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0x26;
 private static final int SELECTED_INDICATOR_THICKNESS_DIPS = 4;  //设置滚动条的高度
 private static final int DEFAULT_SELECTED_INDICATOR_COLOR = 0xFF33B5E5;


 private static final int DEFAULT_DIVIDER_THICKNESS_DIPS = 1;
 private static final byte DEFAULT_DIVIDER_COLOR_ALPHA = 0x20;
 private static final float DEFAULT_DIVIDER_HEIGHT = 0.5f;

 private final int mBottomBorderThickness;
 private final Paint mBottomBorderPaint;

 private final int mSelectedIndicatorThickness;
 private final Paint mSelectedIndicatorPaint;

 private final int mDefaultBottomBorderColor;

 private final Paint mDividerPaint;
 private final float mDividerHeight;

 private int mSelectedPosition;
 private float mSelectionOffset;

 private SlidingTabLayout.TabColorizer mCustomTabColorizer;
 private final SimpleTabColorizer mDefaultTabColorizer;

 SlidingTabStrip(Context context) {
  this(context, null);
 }

 SlidingTabStrip(Context context, AttributeSet attrs) {
  super(context, attrs);
  setWillNotDraw(false);

  final float density = getResources().getDisplayMetrics().density;

  TypedValue outValue = new TypedValue();
  context.getTheme().resolveAttribute(R.attr.colorForeground, outValue, true);
  final int themeForegroundColor = outValue.data;

  mDefaultBottomBorderColor = setColorAlpha(themeForegroundColor,
    DEFAULT_BOTTOM_BORDER_COLOR_ALPHA);

  mDefaultTabColorizer = new SimpleTabColorizer();
  mDefaultTabColorizer.setIndicatorColors(DEFAULT_SELECTED_INDICATOR_COLOR);
  mDefaultTabColorizer.setDividerColors(setColorAlpha(themeForegroundColor,
    DEFAULT_DIVIDER_COLOR_ALPHA));

  mBottomBorderThickness = (int) (DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density);
  mBottomBorderPaint = new Paint();
  mBottomBorderPaint.setColor(mDefaultBottomBorderColor);

  mSelectedIndicatorThickness = (int) (SELECTED_INDICATOR_THICKNESS_DIPS * density);
  mSelectedIndicatorPaint = new Paint();

  mDividerHeight = DEFAULT_DIVIDER_HEIGHT;
  mDividerPaint = new Paint();
  mDividerPaint.setStrokeWidth((int) (DEFAULT_DIVIDER_THICKNESS_DIPS * density));
 }

 void setCustomTabColorizer(SlidingTabLayout.TabColorizer customTabColorizer) {
  mCustomTabColorizer = customTabColorizer;
  invalidate();
 }

 void setSelectedIndicatorColors(int... colors) {
  // Make sure that the custom colorizer is removed
  mCustomTabColorizer = null;
  mDefaultTabColorizer.setIndicatorColors(colors);
  invalidate();
 }

 void setDividerColors(int... colors) {
  // Make sure that the custom colorizer is removed
  mCustomTabColorizer = null;
  mDefaultTabColorizer.setDividerColors(colors);
  invalidate();
 }

 void onViewPagerPageChanged(int position, float positionOffset) {
  mSelectedPosition = position;
  mSelectionOffset = positionOffset;
  invalidate();
 }

 @Override
 protected void onDraw(Canvas canvas) {
  final int height = getHeight();
  final int childCount = getChildCount();
  final int dividerHeightPx = (int) (Math.min(Math.max(0f, mDividerHeight), 1f) * height);
  final SlidingTabLayout.TabColorizer tabColorizer = mCustomTabColorizer != null
    ? mCustomTabColorizer
    : mDefaultTabColorizer;

  // Thick colored underline below the current selection
  if (childCount > 0) {
   View selectedTitle = getChildAt(mSelectedPosition);
   int left = selectedTitle.getLeft();
   int right = selectedTitle.getRight();
   int color = tabColorizer.getIndicatorColor(mSelectedPosition);

   if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) {
    int nextColor = tabColorizer.getIndicatorColor(mSelectedPosition + 1);
    if (color != nextColor) {
     color = blendColors(nextColor, color, mSelectionOffset);
    }

    // Draw the selection partway between the tabs
    View nextTitle = getChildAt(mSelectedPosition + 1);
    left = (int) (mSelectionOffset * nextTitle.getLeft() +
      (1.0f - mSelectionOffset) * left);
    right = (int) (mSelectionOffset * nextTitle.getRight() +
      (1.0f - mSelectionOffset) * right);
   }

   mSelectedIndicatorPaint.setColor(color);

   canvas.drawRect(left, height - mSelectedIndicatorThickness, right,
     height, mSelectedIndicatorPaint);
  }

  // Thin underline along the entire bottom edge
  canvas.drawRect(0, height - mBottomBorderThickness, getWidth(), height, mBottomBorderPaint);

  // Vertical separators between the titles
  int separatorTop = (height - dividerHeightPx) / 2;
  for (int i = 0; i < childCount - 1; i++) {
   View child = getChildAt(i);
   mDividerPaint.setColor(tabColorizer.getDividerColor(i));
   canvas.drawLine(child.getRight(), separatorTop, child.getRight(),
     separatorTop + dividerHeightPx, mDividerPaint);
  }
 }

 /**
  * Set the alpha value of the {@code color} to be the given {@code alpha} value.
  */
 private static int setColorAlpha(int color, byte alpha) {
  return Color.argb(alpha, Color.red(color), Color.green(color), Color.blue(color));
 }

 /**
  * Blend {@code color1} and {@code color2} using the given ratio.
  *
  * @param ratio of which to blend. 1.0 will return {@code color1}, 0.5 will give an even blend,
  *    0.0 will return {@code color2}.
  */
 private static int blendColors(int color1, int color2, float ratio) {
  final float inverseRation = 1f - ratio;
  float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRation);
  float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRation);
  float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRation);
  return Color.rgb((int) r, (int) g, (int) b);
 }

 private static class SimpleTabColorizer implements SlidingTabLayout.TabColorizer {
  private int[] mIndicatorColors; //
  private int[] mDividerColors;  //


  @Override
  public final int getIndicatorColor(int position) {
   return mIndicatorColors[position % mIndicatorColors.length];
  }

  @Override
  public final int getDividerColor(int position) {
   return mDividerColors[position % mDividerColors.length];
  }

  void setIndicatorColors(int... colors) {
   mIndicatorColors = colors;
  }

  void setDividerColors(int... colors) {
   mDividerColors = colors;
  }
 }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="SlidingTabLayout">
  <attr name="android:textColorPrimary" />
  <attr name="textColorTabDefault" format="color" />
  <attr name="textColorTabSelected" format="color" />
 </declare-styleable>
</resources>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:id="@+id/activity_main"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context="com.example.my.slidingtablayout.MainActivity">
 <!-- 在上方就在上面，在下方就在下面（tab栏） -->
 <com.example.my.slidingtablayout.SlidingTabLayout
  android:id="@+id/sliding"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  app:textColorTabDefault="#000000"
  app:textColorTabSelected="@color/colorAccent"
  />

 <android.support.v4.view.ViewPager
  android:id="@+id/view_pager"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  />
</LinearLayout>

package com.example.my.slidingtablayout;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
 //创建 颜色数组 用来做viewpager的背景
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  ViewPager pager = (ViewPager) findViewById(R.id.view_pager);
  SlidingTabLayout tab = (SlidingTabLayout) findViewById(R.id.sliding);
  tab.setDividerColors(Color.TRANSPARENT); //设置标题的分割线
  tab.setSelectedIndicatorColors(Color.rgb(51, 181, 229)); //设置滚动条的颜色
  tab.setTitleSize(18); //...设置字体的颜色，默认16

  MyAdapte adapter = new MyAdapte();
  pager.setAdapter(adapter);
  tab.setViewPager(pager);
 }

 int[] colors = {0xFF123456, 0xFF654321, 0xFF336699};

 class MyAdapte extends PagerAdapter {
  //可以考虑把这个数组添加到集合里面
  String[] titles = {"AA", "BB", "CC"};


  ArrayList<LinearLayout> layouts = new ArrayList<LinearLayout>();

  MyAdapte() {

   for (int i = 0; i < 3; i++) {
    LinearLayout l = new LinearLayout(MainActivity.this);
    l.setBackgroundColor(colors[i]);
    l.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
    layouts.add(l);
   }

  }

  @Override
  public int getCount() {
   return layouts.size();
  }

  @Override
  public boolean isViewFromObject(View view, Object o) {
   return view == o;
  }

  @Override
  public Object instantiateItem(ViewGroup container, int position) {
   LinearLayout l = layouts.get(position);
   container.addView(l);
   return l;
  }

  @Override
  public void destroyItem(ViewGroup container, int position, Object object) {
   container.removeView(layouts.get(position));
  }

  @Override
  public CharSequence getPageTitle(int position) {
   //...可以返回集合list.get(position);
   return titles[position];
  }
 }
}