Java tutorial
/* * Copyright 2015 Google Inc. * * 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.google.samples.apps.topeka.widget.quiz; import android.animation.ArgbEvaluator; import android.animation.ObjectAnimator; import android.annotation.SuppressLint; import android.content.Context; import android.content.res.ColorStateList; import android.graphics.Color; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.support.annotation.ColorInt; import android.support.v4.content.ContextCompat; import android.support.v4.view.MarginLayoutParamsCompat; import android.support.v4.view.animation.LinearOutSlowInInterpolator; import android.util.Property; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.Interpolator; import android.view.inputmethod.InputMethodManager; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.TextView; import com.google.samples.apps.topeka.R; import com.google.samples.apps.topeka.activity.QuizActivity; import com.google.samples.apps.topeka.helper.ApiLevelHelper; import com.google.samples.apps.topeka.helper.ViewUtils; import com.google.samples.apps.topeka.model.Category; import com.google.samples.apps.topeka.model.quiz.Quiz; import com.google.samples.apps.topeka.widget.fab.CheckableFab; /** * This is the base class for displaying a {@link com.google.samples.apps.topeka.model.quiz.Quiz}. * <p> * Subclasses need to implement {@link AbsQuizView#createQuizContentView()} * in order to allow solution of a quiz. * </p> * <p> * Also {@link AbsQuizView#allowAnswer(boolean)} needs to be called with * <code>true</code> in order to mark the quiz solved. * </p> * * @param <Q> The type of {@link com.google.samples.apps.topeka.model.quiz.Quiz} you want to * display. */ public abstract class AbsQuizView<Q extends Quiz> extends FrameLayout { private static final int ANSWER_HIDE_DELAY = 500; private static final int FOREGROUND_COLOR_CHANGE_DELAY = 750; private final int mSpacingDouble; private final LayoutInflater mLayoutInflater; private final Category mCategory; private final Q mQuiz; private final Interpolator mLinearOutSlowInInterpolator; private final Handler mHandler; private final InputMethodManager mInputMethodManager; private boolean mAnswered; private TextView mQuestionView; private CheckableFab mSubmitAnswer; private Runnable mHideFabRunnable; private Runnable mMoveOffScreenRunnable; /** * Enables creation of views for quizzes. * * @param context The context for this view. * @param category The {@link Category} this view is running in. * @param quiz The actual {@link Quiz} that is going to be displayed. */ public AbsQuizView(Context context, Category category, Q quiz) { super(context); mQuiz = quiz; mCategory = category; mSpacingDouble = getResources().getDimensionPixelSize(R.dimen.spacing_double); mLayoutInflater = LayoutInflater.from(context); mSubmitAnswer = getSubmitButton(); mLinearOutSlowInInterpolator = new LinearOutSlowInInterpolator(); mHandler = new Handler(); mInputMethodManager = (InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE); setId(quiz.getId()); setUpQuestionView(); LinearLayout container = createContainerLayout(context); View quizContentView = getInitializedContentView(); addContentView(container, quizContentView); addOnLayoutChangeListener(new OnLayoutChangeListener() { @Override public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) { removeOnLayoutChangeListener(this); addFloatingActionButton(); } }); } /** * Sets the behaviour for all question views. */ private void setUpQuestionView() { mQuestionView = (TextView) mLayoutInflater.inflate(R.layout.question, this, false); mQuestionView .setBackgroundColor(ContextCompat.getColor(getContext(), mCategory.getTheme().getPrimaryColor())); mQuestionView.setText(getQuiz().getQuestion()); } private LinearLayout createContainerLayout(Context context) { LinearLayout container = new LinearLayout(context); container.setId(R.id.absQuizViewContainer); container.setOrientation(LinearLayout.VERTICAL); return container; } private View getInitializedContentView() { View quizContentView = createQuizContentView(); quizContentView.setId(R.id.quiz_content); quizContentView.setSaveEnabled(true); setDefaultPadding(quizContentView); if (quizContentView instanceof ViewGroup) { ((ViewGroup) quizContentView).setClipToPadding(false); } setMinHeightInternal(quizContentView); return quizContentView; } private void addContentView(LinearLayout container, View quizContentView) { LayoutParams layoutParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); container.addView(mQuestionView, layoutParams); container.addView(quizContentView, layoutParams); addView(container, layoutParams); } private void addFloatingActionButton() { final int fabSize = getResources().getDimensionPixelSize(R.dimen.size_fab); int bottomOfQuestionView = findViewById(R.id.question_view).getBottom(); final LayoutParams fabLayoutParams = new LayoutParams(fabSize, fabSize, Gravity.END | Gravity.TOP); final int halfAFab = fabSize / 2; fabLayoutParams.setMargins(0, // left bottomOfQuestionView - halfAFab, //top 0, // right mSpacingDouble); // bottom MarginLayoutParamsCompat.setMarginEnd(fabLayoutParams, mSpacingDouble); if (ApiLevelHelper.isLowerThan(Build.VERSION_CODES.LOLLIPOP)) { // Account for the fab's emulated shadow. fabLayoutParams.topMargin -= (mSubmitAnswer.getPaddingTop() / 2); } addView(mSubmitAnswer, fabLayoutParams); } private CheckableFab getSubmitButton() { if (null == mSubmitAnswer) { mSubmitAnswer = (CheckableFab) getLayoutInflater().inflate(R.layout.answer_submit, this, false); mSubmitAnswer.hide(); mSubmitAnswer.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { submitAnswer(v); if (mInputMethodManager.isAcceptingText()) { mInputMethodManager.hideSoftInputFromWindow(v.getWindowToken(), 0); } mSubmitAnswer.setEnabled(false); } }); } return mSubmitAnswer; } private void setDefaultPadding(View view) { view.setPadding(mSpacingDouble, mSpacingDouble, mSpacingDouble, mSpacingDouble); } protected LayoutInflater getLayoutInflater() { return mLayoutInflater; } /** * Implementations should create the content view for the type of * {@link com.google.samples.apps.topeka.model.quiz.Quiz} they want to display. * * @return the created view to solve the quiz. */ protected abstract View createQuizContentView(); /** * Implementations must make sure that the answer provided is evaluated and correctly rated. * * @return <code>true</code> if the question has been correctly answered, else * <code>false</code>. */ protected abstract boolean isAnswerCorrect(); /** * Save the user input to a bundle for orientation changes. * * @return The bundle containing the user's input. */ public abstract Bundle getUserInput(); /** * Restore the user's input. * * @param savedInput The input that the user made in a prior instance of this view. */ public abstract void setUserInput(Bundle savedInput); public Q getQuiz() { return mQuiz; } protected boolean isAnswered() { return mAnswered; } /** * Sets the quiz to answered or unanswered. * * @param answered <code>true</code> if an answer was selected, else <code>false</code>. */ protected void allowAnswer(final boolean answered) { if (null != mSubmitAnswer) { if (answered) { mSubmitAnswer.show(); } else { mSubmitAnswer.hide(); } mAnswered = answered; } } /** * Sets the quiz to answered if it not already has been answered. * Otherwise does nothing. */ protected void allowAnswer() { if (!isAnswered()) { allowAnswer(true); } } /** * Allows children to submit an answer via code. */ protected void submitAnswer() { submitAnswer(findViewById(R.id.submitAnswer)); } @SuppressWarnings("UnusedParameters") private void submitAnswer(final View v) { final boolean answerCorrect = isAnswerCorrect(); mQuiz.setSolved(true); performScoreAnimation(answerCorrect); } /** * Animates the view nicely when the answer has been submitted. * * @param answerCorrect <code>true</code> if the answer was correct, else <code>false</code>. */ private void performScoreAnimation(final boolean answerCorrect) { ((QuizActivity) getContext()).lockIdlingResource(); // Decide which background color to use. final int backgroundColor = ContextCompat.getColor(getContext(), answerCorrect ? R.color.green : R.color.red); adjustFab(answerCorrect, backgroundColor); resizeView(); moveViewOffScreen(answerCorrect); // Animate the foreground color to match the background color. // This overlays all content within the current view. animateForegroundColor(backgroundColor); } @SuppressLint("NewApi") private void adjustFab(boolean answerCorrect, int backgroundColor) { mSubmitAnswer.setChecked(answerCorrect); mSubmitAnswer.setBackgroundTintList(ColorStateList.valueOf(backgroundColor)); mHideFabRunnable = new Runnable() { @Override public void run() { mSubmitAnswer.hide(); } }; mHandler.postDelayed(mHideFabRunnable, ANSWER_HIDE_DELAY); } private void resizeView() { final float widthHeightRatio = (float) getHeight() / (float) getWidth(); // Animate X and Y scaling separately to allow different start delays. // object animators for x and y with different durations and then run them independently resizeViewProperty(View.SCALE_X, .5f, 200); resizeViewProperty(View.SCALE_Y, .5f / widthHeightRatio, 300); } private void resizeViewProperty(Property<View, Float> property, float targetScale, int durationOffset) { ObjectAnimator animator = ObjectAnimator.ofFloat(this, property, 1f, targetScale); animator.setInterpolator(mLinearOutSlowInInterpolator); animator.setStartDelay(FOREGROUND_COLOR_CHANGE_DELAY + durationOffset); animator.start(); } @Override protected void onDetachedFromWindow() { if (mHideFabRunnable != null) { mHandler.removeCallbacks(mHideFabRunnable); } if (mMoveOffScreenRunnable != null) { mHandler.removeCallbacks(mMoveOffScreenRunnable); } super.onDetachedFromWindow(); } private void animateForegroundColor(@ColorInt final int targetColor) { ObjectAnimator animator = ObjectAnimator.ofInt(this, ViewUtils.FOREGROUND_COLOR, Color.TRANSPARENT, targetColor); animator.setEvaluator(new ArgbEvaluator()); animator.setStartDelay(FOREGROUND_COLOR_CHANGE_DELAY); animator.start(); } private void moveViewOffScreen(final boolean answerCorrect) { // Move the current view off the screen. mMoveOffScreenRunnable = new Runnable() { @Override public void run() { mCategory.setScore(getQuiz(), answerCorrect); if (getContext() instanceof QuizActivity) { ((QuizActivity) getContext()).proceed(); } } }; mHandler.postDelayed(mMoveOffScreenRunnable, FOREGROUND_COLOR_CHANGE_DELAY * 2); } private void setMinHeightInternal(View view) { view.setMinimumHeight(getResources().getDimensionPixelSize(R.dimen.min_height_question)); } }