Java tutorial
/* * Copyright (C) 2016 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.animation.Animator; import android.animation.Animator.AnimatorListener; import android.content.Context; import android.content.res.Configuration; import android.support.v4.view.PagerAdapter; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.ViewStub; import android.view.ViewStub.OnInflateListener; import android.view.animation.AccelerateInterpolator; import android.view.animation.DecelerateInterpolator; import android.view.animation.Interpolator; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.ScrollView; /** * A PagerAdapter used by PreviewSeekBarPreferenceFragment that for showing multiple preview screen * regarding a single setting and allowing the user to swipe across them. */ public class PreviewPagerAdapter extends PagerAdapter { /** Duration to use when cross-fading between previews. */ private static final long CROSS_FADE_DURATION_MS = 400; /** Interpolator to use when cross-fading between previews. */ private static final Interpolator FADE_IN_INTERPOLATOR = new DecelerateInterpolator(); /** Interpolator to use when cross-fading between previews. */ private static final Interpolator FADE_OUT_INTERPOLATOR = new AccelerateInterpolator(); private FrameLayout[] mPreviewFrames; private boolean mIsLayoutRtl; private Runnable mAnimationEndAction; private int mAnimationCounter; private boolean[][] mViewStubInflated; public PreviewPagerAdapter(Context context, boolean isLayoutRtl, int[] previewSampleResIds, Configuration[] configurations) { mIsLayoutRtl = isLayoutRtl; mPreviewFrames = new FrameLayout[previewSampleResIds.length]; mViewStubInflated = new boolean[previewSampleResIds.length][configurations.length]; for (int i = 0; i < previewSampleResIds.length; ++i) { int p = mIsLayoutRtl ? previewSampleResIds.length - 1 - i : i; mPreviewFrames[p] = new FrameLayout(context); mPreviewFrames[p].setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT)); for (int j = 0; j < configurations.length; ++j) { // Create a new configuration for the specified value. It won't // have any theme set, so manually apply the current theme. final Context configContext = context.createConfigurationContext(configurations[j]); configContext.setTheme(context.getThemeResId()); final LayoutInflater configInflater = LayoutInflater.from(configContext); final ViewStub sampleViewStub = new ViewStub(configContext); sampleViewStub.setLayoutResource(previewSampleResIds[i]); final int fi = i, fj = j; sampleViewStub.setOnInflateListener(new OnInflateListener() { @Override public void onInflate(ViewStub stub, View inflated) { inflated.setVisibility(stub.getVisibility()); mViewStubInflated[fi][fj] = true; } }); mPreviewFrames[p].addView(sampleViewStub); } } } @Override public void destroyItem(ViewGroup container, int position, Object object) { container.removeView((View) object); } @Override public int getCount() { return mPreviewFrames.length; } @Override public Object instantiateItem(ViewGroup container, int position) { container.addView(mPreviewFrames[position]); return mPreviewFrames[position]; } @Override public boolean isViewFromObject(View view, Object object) { return (view == object); } boolean isAnimating() { return mAnimationCounter > 0; } void setAnimationEndAction(Runnable action) { mAnimationEndAction = action; } void setPreviewLayer(int newLayerIndex, int currentLayerIndex, int currentFrameIndex, final boolean animate) { for (FrameLayout previewFrame : mPreviewFrames) { if (currentLayerIndex >= 0) { final View lastLayer = previewFrame.getChildAt(currentLayerIndex); if (mViewStubInflated[currentFrameIndex][currentLayerIndex]) { // Explicitly set to INVISIBLE only when the stub has // already been inflated. if (previewFrame == mPreviewFrames[currentFrameIndex]) { setVisibility(lastLayer, View.INVISIBLE, animate); } else { setVisibility(lastLayer, View.INVISIBLE, false); } } } // Set next layer visible, as well as inflate necessary views. View nextLayer = previewFrame.getChildAt(newLayerIndex); if (previewFrame == mPreviewFrames[currentFrameIndex]) { // Inflate immediately if the stub has not yet been inflated. if (!mViewStubInflated[currentFrameIndex][newLayerIndex]) { nextLayer = ((ViewStub) nextLayer).inflate(); nextLayer.setAlpha(0.0f); } setVisibility(nextLayer, View.VISIBLE, animate); } else { setVisibility(nextLayer, View.VISIBLE, false); } } } private void setVisibility(final View view, final int visibility, boolean animate) { final float alpha = (visibility == View.VISIBLE ? 1.0f : 0.0f); if (!animate) { view.setAlpha(alpha); view.setVisibility(visibility); } else { final Interpolator interpolator = (visibility == View.VISIBLE ? FADE_IN_INTERPOLATOR : FADE_OUT_INTERPOLATOR); if (visibility == View.VISIBLE) { // Fade in animation. view.animate().alpha(alpha).setInterpolator(FADE_IN_INTERPOLATOR) .setDuration(CROSS_FADE_DURATION_MS).setListener(new PreviewFrameAnimatorListener()) .withStartAction(new Runnable() { @Override public void run() { view.setVisibility(visibility); } }); } else { // Fade out animation. view.animate().alpha(alpha).setInterpolator(FADE_OUT_INTERPOLATOR) .setDuration(CROSS_FADE_DURATION_MS).setListener(new PreviewFrameAnimatorListener()) .withEndAction(new Runnable() { @Override public void run() { view.setVisibility(visibility); } }); } } } private void runAnimationEndAction() { if (mAnimationEndAction != null && !isAnimating()) { mAnimationEndAction.run(); mAnimationEndAction = null; } } private class PreviewFrameAnimatorListener implements AnimatorListener { @Override public void onAnimationStart(Animator animation) { mAnimationCounter++; } @Override public void onAnimationEnd(Animator animation) { mAnimationCounter--; runAnimationEndAction(); } @Override public void onAnimationCancel(Animator animation) { // Empty method. } @Override public void onAnimationRepeat(Animator animation) { // Empty method. } } }