Java tutorial
/* * Copyright (C) 2015 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.android.settings; import android.content.Context; import android.content.res.Configuration; import android.os.Bundle; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.view.accessibility.AccessibilityEvent; import android.widget.SeekBar; import android.widget.SeekBar.OnSeekBarChangeListener; import android.widget.TextView; import com.android.settings.widget.DotsPageIndicator; import com.android.settings.widget.LabeledSeekBar; /** * Preference fragment shows a preview and a seek bar to adjust a specific settings. */ public abstract class PreviewSeekBarPreferenceFragment extends SettingsPreferenceFragment { /** List of entries corresponding the settings being set. */ protected String[] mEntries; /** Index of the entry corresponding to initial value of the settings. */ protected int mInitialIndex; /** Index of the entry corresponding to current value of the settings. */ protected int mCurrentIndex; /** Resource id of the layout for this preference fragment. */ protected int mActivityLayoutResId; /** Resource id of the layout that defines the contents inside preview screen. */ protected int[] mPreviewSampleResIds; private ViewPager mPreviewPager; private PreviewPagerAdapter mPreviewPagerAdapter; private DotsPageIndicator mPageIndicator; private TextView mLabel; private View mLarger; private View mSmaller; private class onPreviewSeekBarChangeListener implements OnSeekBarChangeListener { private boolean mSeekByTouch; @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { setPreviewLayer(progress, true); if (!mSeekByTouch) { commit(); } } @Override public void onStartTrackingTouch(SeekBar seekBar) { mSeekByTouch = true; } @Override public void onStopTrackingTouch(SeekBar seekBar) { if (mPreviewPagerAdapter.isAnimating()) { mPreviewPagerAdapter.setAnimationEndAction(new Runnable() { @Override public void run() { commit(); } }); } else { commit(); } mSeekByTouch = false; } } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { final View root = super.onCreateView(inflater, container, savedInstanceState); final ViewGroup listContainer = (ViewGroup) root.findViewById(android.R.id.list_container); listContainer.removeAllViews(); final View content = inflater.inflate(mActivityLayoutResId, listContainer, false); listContainer.addView(content); mLabel = (TextView) content.findViewById(R.id.current_label); // The maximum SeekBar value always needs to be non-zero. If there's // only one available value, we'll handle this by disabling the // seek bar. final int max = Math.max(1, mEntries.length - 1); final LabeledSeekBar seekBar = (LabeledSeekBar) content.findViewById(R.id.seek_bar); seekBar.setLabels(mEntries); seekBar.setMax(max); seekBar.setProgress(mInitialIndex); seekBar.setOnSeekBarChangeListener(new onPreviewSeekBarChangeListener()); mSmaller = content.findViewById(R.id.smaller); mSmaller.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { final int progress = seekBar.getProgress(); if (progress > 0) { seekBar.setProgress(progress - 1, true); } } }); mLarger = content.findViewById(R.id.larger); mLarger.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { final int progress = seekBar.getProgress(); if (progress < seekBar.getMax()) { seekBar.setProgress(progress + 1, true); } } }); if (mEntries.length == 1) { // The larger and smaller buttons will be disabled when we call // setPreviewLayer() later in this method. seekBar.setEnabled(false); } final Context context = getContext(); final Configuration origConfig = context.getResources().getConfiguration(); final boolean isLayoutRtl = origConfig.getLayoutDirection() == View.LAYOUT_DIRECTION_RTL; Configuration[] configurations = new Configuration[mEntries.length]; for (int i = 0; i < mEntries.length; ++i) { configurations[i] = createConfig(origConfig, i); } mPreviewPager = (ViewPager) content.findViewById(R.id.preview_pager); mPreviewPagerAdapter = new PreviewPagerAdapter(context, isLayoutRtl, mPreviewSampleResIds, configurations); mPreviewPager.setAdapter(mPreviewPagerAdapter); mPreviewPager.setCurrentItem(isLayoutRtl ? mPreviewSampleResIds.length - 1 : 0); mPreviewPager.addOnPageChangeListener(mPreviewPageChangeListener); mPageIndicator = (DotsPageIndicator) content.findViewById(R.id.page_indicator); if (mPreviewSampleResIds.length > 1) { mPageIndicator.setViewPager(mPreviewPager); mPageIndicator.setVisibility(View.VISIBLE); mPageIndicator.setOnPageChangeListener(mPageIndicatorPageChangeListener); } else { mPageIndicator.setVisibility(View.GONE); } setPreviewLayer(mInitialIndex, false); return root; } /** * Creates new configuration based on the current position of the SeekBar. */ protected abstract Configuration createConfig(Configuration origConfig, int index); /** * Persists the selected value and sends a configuration change. */ protected abstract void commit(); private void setPreviewLayer(int index, boolean animate) { mLabel.setText(mEntries[index]); mSmaller.setEnabled(index > 0); mLarger.setEnabled(index < mEntries.length - 1); setPagerIndicatorContentDescription(mPreviewPager.getCurrentItem()); mPreviewPagerAdapter.setPreviewLayer(index, mCurrentIndex, mPreviewPager.getCurrentItem(), animate); mCurrentIndex = index; } private void setPagerIndicatorContentDescription(int position) { mPageIndicator.setContentDescription(getPrefContext().getString( R.string.preview_page_indicator_content_description, position + 1, mPreviewSampleResIds.length)); } private OnPageChangeListener mPreviewPageChangeListener = new OnPageChangeListener() { @Override public void onPageScrollStateChanged(int state) { // Do nothing. } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { // Do nothing. } @Override public void onPageSelected(int position) { mPreviewPager.sendAccessibilityEvent(AccessibilityEvent.TYPE_ANNOUNCEMENT); } }; private OnPageChangeListener mPageIndicatorPageChangeListener = new OnPageChangeListener() { @Override public void onPageScrollStateChanged(int state) { // Do nothing. } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { // Do nothing. } @Override public void onPageSelected(int position) { setPagerIndicatorContentDescription(position); } }; }