Java tutorial
/* * Copyright (C) 2011 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.ereader.client.ui.view; import java.util.ArrayList; import android.content.Context; import android.content.res.TypedArray; import android.graphics.drawable.Drawable; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.util.AttributeSet; import android.view.Gravity; import android.view.View; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; import com.ereader.client.R; // http://www.it165.net/pro/html/201410/24734.html public class ScrollingTabsView extends HorizontalScrollView implements OnPageChangeListener { @SuppressWarnings("unused") private static final String TAG = "com.astuetz.viewpager.extensions"; private Context mContext; private ViewPager mPager; private TabsAdapter mAdapter; private LinearLayout mContainer; private ArrayList<View> mTabs = new ArrayList<View>(); private Drawable mDividerDrawable; private TabClickListener mClickListener; private int mDividerColor = 0xFF636363; private int mDividerMarginTop = 12; private int mDividerMarginBottom = 12; private int mDividerWidth = 1; public ScrollingTabsView(Context context) { this(context, null); } public ScrollingTabsView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public ScrollingTabsView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs); this.mContext = context; mDividerMarginTop = (int) (getResources().getDisplayMetrics().density * mDividerMarginTop); mDividerMarginBottom = (int) (getResources().getDisplayMetrics().density * mDividerMarginBottom); mDividerWidth = (int) (getResources().getDisplayMetrics().density * mDividerWidth); final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ViewPagerExtensions, defStyle, 0); mDividerColor = a.getColor(R.styleable.ViewPagerExtensions_dividerColor, mDividerColor); mDividerMarginTop = a.getDimensionPixelSize(R.styleable.ViewPagerExtensions_dividerMarginTop, mDividerMarginTop); mDividerMarginBottom = a.getDimensionPixelSize(R.styleable.ViewPagerExtensions_dividerMarginBottom, mDividerMarginBottom); mDividerDrawable = a.getDrawable(R.styleable.ViewPagerExtensions_dividerDrawable); a.recycle(); this.setHorizontalScrollBarEnabled(false); this.setHorizontalFadingEdgeEnabled(false); mContainer = new LinearLayout(context); LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT); mContainer.setLayoutParams(params); mContainer.setOrientation(LinearLayout.HORIZONTAL); mContainer.setGravity(Gravity.CENTER); this.addView(mContainer); } public void setTabClickListener(TabClickListener listener) { this.mClickListener = listener; } /** * Sets the data behind this ScrollingTabsView. * * @param adapter * The {@link TabsAdapter} which is responsible for maintaining the * data backing this FixedTabsView and for producing a view to * represent an item in that data set. */ public void setAdapter(TabsAdapter adapter) { this.mAdapter = adapter; if (mPager != null && mAdapter != null) initTabs(); } /** * Binds the {@link ViewPager} to this View * */ public void setViewPager(ViewPager pager) { this.mPager = pager; mPager.setOnPageChangeListener(this); if (mPager != null && mAdapter != null) initTabs(); } /** * Initialize and add all tabs to the layout */ private void initTabs() { mContainer.removeAllViews(); mTabs.clear(); if (mAdapter == null) return; for (int i = 0; i < mPager.getAdapter().getCount(); i++) { final int index = i; View tab = mAdapter.getView(i); mContainer.addView(tab); tab.setFocusable(true); mTabs.add(tab); if (i != mPager.getAdapter().getCount() - 1) { mContainer.addView(getSeparator()); } tab.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (mClickListener != null) mClickListener.onClick(index); if (mPager.getCurrentItem() == index) selectTab(index); else mPager.setCurrentItem(index); } }); } selectTab(mPager.getCurrentItem()); } @Override public void onPageScrollStateChanged(int state) { } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { selectTab(position); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); if (changed) selectTab(mPager.getCurrentItem()); } /** * Creates and returns a new Separator View * * @return */ private View getSeparator() { View v = new View(mContext); LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(mDividerWidth, LayoutParams.FILL_PARENT); params.setMargins(0, mDividerMarginTop, 0, mDividerMarginBottom); v.setLayoutParams(params); /*if (mDividerDrawable != null) v.setBackgroundDrawable(mDividerDrawable); else v.setBackgroundColor(mDividerColor);*/ return v; } /** * Runs through all tabs and sets if they are currently selected. * * @param position * The position of the currently selected tab. */ private void selectTab(int position) { for (int i = 0, pos = 0; i < mContainer.getChildCount(); i += 2, pos++) { View tab = mContainer.getChildAt(i); tab.setSelected(pos == position); } View selectedTab = mContainer.getChildAt(position * 2); if (selectedTab != null) { final int w = selectedTab.getMeasuredWidth(); final int l = selectedTab.getLeft(); final int x = l - this.getWidth() / 2 + w / 2; smoothScrollTo(x, this.getScrollY()); } } public interface TabClickListener { public void onClick(int position); } }