Java tutorial
/* * Copyright (C) 2014 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.frozendevs.periodictable.view; import android.annotation.TargetApi; import android.content.Context; import android.content.res.ColorStateList; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Outline; 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.View; import android.view.ViewOutlineProvider; import android.widget.FrameLayout; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; import android.widget.TextView; import android.widget.Toast; import com.frozendevs.periodictable.R; /** * Lightweight implementation of ViewPager tabs. This looks similar to traditional actionBar tabs, * but allows for the view containing the tabs to be placed anywhere on screen. Text-related * attributes can also be assigned in XML - these will get propogated to the child TextViews * automatically. */ public class ViewPagerTabs extends HorizontalScrollView implements ViewPager.OnPageChangeListener { ViewPager mPager; private ViewPagerTabStrip mTabStrip; /** * Linearlayout that will contain the TextViews serving as tabs. This is the only child * of the parent HorizontalScrollView. */ final int mTextStyle; final ColorStateList mTextColor; final int mTextSize; final int mTextBackground; int mPrevSelected = -1; int mSidePadding; // TODO: This should use <declare-styleable> in the future private static final int[] ATTRS = new int[] { android.R.attr.textSize, android.R.attr.textStyle, android.R.attr.textColor }; /** * Simulates actionbar tab behavior by showing a toast with the tab title when long clicked. */ private class OnTabLongClickListener implements OnLongClickListener { final int mPosition; public OnTabLongClickListener(int position) { mPosition = position; } @Override public boolean onLongClick(View view) { final int[] screenPos = new int[2]; view.getLocationOnScreen(screenPos); Toast toast = Toast.makeText(getContext(), mPager.getAdapter().getPageTitle(mPosition), Toast.LENGTH_SHORT); // Show the toast under the tab toast.setGravity(Gravity.TOP | Gravity.CENTER_HORIZONTAL, screenPos[0] - (view.getWidth() / 2), screenPos[1] + (view.getHeight() / 2)); toast.show(); return true; } } public ViewPagerTabs(Context context) { this(context, null); } public ViewPagerTabs(Context context, AttributeSet attrs) { this(context, attrs, 0); } @TargetApi(Build.VERSION_CODES.LOLLIPOP) public ViewPagerTabs(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); setFillViewport(true); mSidePadding = getResources().getDimensionPixelOffset(R.dimen.tab_side_padding); final TypedArray a = context.obtainStyledAttributes(attrs, ATTRS); mTextSize = a.getDimensionPixelSize(0, 0); mTextStyle = a.getInt(1, 0); mTextColor = a.getColorStateList(2); a.recycle(); Resources.Theme theme = getContext().getTheme(); TypedValue typedValue = new TypedValue(); theme.resolveAttribute(R.attr.theme, typedValue, true); TypedArray typedArray = theme.obtainStyledAttributes(typedValue.resourceId, new int[] { R.attr.selectableItemBackground }); mTextBackground = typedArray.getResourceId(0, 0); typedArray.recycle(); mTabStrip = new ViewPagerTabStrip(context); addView(mTabStrip, new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT)); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { // enable shadow casting from view bounds setOutlineProvider(new ViewOutlineProvider() { @TargetApi(Build.VERSION_CODES.LOLLIPOP) @Override public void getOutline(View view, Outline outline) { outline.setRect(0, 0, view.getWidth(), view.getHeight()); } }); } } public void setViewPager(ViewPager viewPager) { mPager = viewPager; addTabs(mPager.getAdapter()); mPager.setOnPageChangeListener(this); } private void addTabs(PagerAdapter adapter) { mTabStrip.removeAllViews(); final int count = adapter.getCount(); for (int i = 0; i < count; i++) { addTab(adapter.getPageTitle(i), i); } } private void addTab(CharSequence tabTitle, final int position) { final TextView textView = new TextView(getContext()); textView.setText(tabTitle); textView.setGravity(Gravity.CENTER); textView.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mPager.setCurrentItem(getRtlPosition(position)); } }); /* We don't need this as far as we use text tabs only textView.setOnLongClickListener(new OnTabLongClickListener(position));*/ // Assign various text appearance related attributes to child views. if (mTextStyle > 0) { textView.setTypeface(textView.getTypeface(), mTextStyle); } if (mTextSize > 0) { textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize); } if (mTextColor != null) { textView.setTextColor(mTextColor); } if (mTextBackground > 0) { textView.setBackgroundResource(mTextBackground); } textView.setText( textView.getText().toString().toUpperCase(getContext().getResources().getConfiguration().locale)); textView.setPadding(mSidePadding, 0, mSidePadding, 0); mTabStrip.addView(textView, new LinearLayout.LayoutParams(0, LayoutParams.MATCH_PARENT, 1)); // Default to the first child being selected if (position == 0) { mPrevSelected = 0; textView.setSelected(true); } } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { position = getRtlPosition(position); int tabStripChildCount = mTabStrip.getChildCount(); if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) { return; } mTabStrip.onPageScrolled(position, positionOffset, positionOffsetPixels); } @Override public void onPageSelected(int position) { position = getRtlPosition(position); if (mPrevSelected >= 0) { mTabStrip.getChildAt(mPrevSelected).setSelected(false); } final View selectedChild = mTabStrip.getChildAt(position); selectedChild.setSelected(true); // Update scroll position final int scrollPos = selectedChild.getLeft() - (getWidth() - selectedChild.getWidth()) / 2; smoothScrollTo(scrollPos, 0); mPrevSelected = position; } @Override public void onPageScrollStateChanged(int state) { } @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1) private int getRtlPosition(int position) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) { if (getLayoutDirection() == View.LAYOUT_DIRECTION_RTL) { return mTabStrip.getChildCount() - 1 - position; } } return position; } }