Java tutorial
/* * Copyright (c) 2016 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.iosched.ui.widget; import android.content.Context; import android.content.res.TypedArray; import android.graphics.drawable.Drawable; import android.os.Build; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.content.res.ResourcesCompat; import android.util.AttributeSet; import android.view.View; import android.view.accessibility.AccessibilityEvent; import android.view.accessibility.AccessibilityManager; import android.widget.ImageView; import android.widget.LinearLayout; import com.google.samples.apps.iosched.R; import com.google.samples.apps.iosched.util.AccessibilityUtils; /** * Replacement for a {@link android.widget.RatingBar} widget for providing ratings for sessions. * Provides ease of use for accessibility for use with Talkback and other assistive technologies. * <p/> * TODO: add explanation of attributes. */ public class CustomRatingBar extends LinearLayout implements View.OnClickListener { /** * The default maximum rating value if no specific value is specified. */ private static final int DEFAULT_MAX_RATING = 5; /** * The drawable used if no unfilled drawable resource is specified. */ private static final int DEFAULT_UNFILLED_DRAWABLE_ID = R.drawable.ratingbar_star_unfilled; /** * The drawable used if no filled drawable resource is specified. */ private static final int DEFAULT_FILLED_DRAWABLE_ID = R.drawable.ratingbar_star_filled; /** * The maximum permitted rating. */ private int mMaxRating; /** * The {@link Drawable} used to show a filled value. A rating of M out of N stars is * represented by M filled drawables and N - M unfilled drawables. */ private Drawable mFilledDrawable; /** * The {@link Drawable} used to show an unfilled value. A rating of M out of N stars is * represented by M filled drawables and N - M unfilled drawables. */ private Drawable mUnfilledDrawable; /** * The rating specified by the user. */ private int mRating = 0; public CustomRatingBar(Context context) { this(context, null, 0); } public CustomRatingBar(Context context, AttributeSet attrs) { this(context, attrs, 0); } public CustomRatingBar(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); TypedArray typedArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomRatingBar, 0, 0); try { mMaxRating = typedArray.getInt(R.styleable.CustomRatingBar_maxRating, DEFAULT_MAX_RATING); mFilledDrawable = typedArray.getDrawable(R.styleable.CustomRatingBar_filledDrawable); if (mFilledDrawable == null) { mFilledDrawable = ResourcesCompat.getDrawable(getResources(), DEFAULT_FILLED_DRAWABLE_ID, null); } mUnfilledDrawable = typedArray.getDrawable(R.styleable.CustomRatingBar_unfilledDrawable); if (mUnfilledDrawable == null) { mUnfilledDrawable = ResourcesCompat.getDrawable(getResources(), DEFAULT_UNFILLED_DRAWABLE_ID, null); } } finally { typedArray.recycle(); } setSaveEnabled(true); } public int getRating() { return mRating; } @Override public void onClick(final View v) { mRating = (int) v.getTag(); drawRatingViews(); int eventType = Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN ? AccessibilityEvent.TYPE_ANNOUNCEMENT : AccessibilityEvent.TYPE_VIEW_FOCUSED; sendAccessibilityEvent(eventType); } @Override protected void onFinishInflate() { super.onFinishInflate(); drawRatingViews(); } @Override public void sendAccessibilityEvent(final int eventType) { if (!AccessibilityUtils.isAccessibilityEnabled(getContext())) { return; } super.sendAccessibilityEvent(eventType); AccessibilityEvent event = AccessibilityEvent.obtain(eventType); // Get the Talkback text. event.getText().add( getContext().getResources().getString(R.string.feedback_rating_confirmation, mRating, mMaxRating)); event.setEnabled(true); AccessibilityManager accessibilityManager = (AccessibilityManager) getContext() .getSystemService(Context.ACCESSIBILITY_SERVICE); accessibilityManager.sendAccessibilityEvent(event); } /** * Creates or updates the views used for creating a rating. */ private void drawRatingViews() { if (this.getChildCount() == 0) { createRatingViews(); } else { updateRatingViews(); } } /** * Creates ({@link ImageView}s) used to submit a rating using unfilled drawables and adds them to * the layout. */ private void createRatingViews() { for (int i = 0; i < mMaxRating; i++) { ImageView imageView = new ImageView(getContext()); imageView.setLayoutParams( new android.view.ViewGroup.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); int tagValue = i + 1; imageView.setTag(tagValue); imageView.setContentDescription(getContext().getString(R.string.feedback_rating_value, tagValue)); imageView.setImageDrawable(mUnfilledDrawable); imageView.setOnClickListener(this); addView(imageView); } } /** * Updates ({@link ImageView}s) used to submit a rating, using filled drawables to denote the * rating created by the user. */ private void updateRatingViews() { for (int i = 0; i < mMaxRating; i++) { ImageView view = (ImageView) this.getChildAt(i); view.setImageDrawable(i + 1 <= mRating ? mFilledDrawable : mUnfilledDrawable); } } @Override protected Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState savedState = new SavedState(superState); savedState.rating = mRating; return savedState; } @Override protected void onRestoreInstanceState(final Parcelable state) { SavedState ss = (SavedState) state; super.onRestoreInstanceState(ss.getSuperState()); mRating = ss.rating; drawRatingViews(); } /** * Helper class to help retain state during orientation change. */ private static class SavedState extends BaseSavedState { int rating; SavedState(Parcelable superState) { super(superState); } private SavedState(Parcel in) { super(in); rating = in.readInt(); } @Override public void writeToParcel(Parcel out, int flags) { super.writeToParcel(out, flags); out.writeInt(rating); } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } }