Java tutorial
/* * Copyright (C) 2013 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.datetimepicker; import android.animation.Keyframe; import android.animation.ObjectAnimator; import android.animation.PropertyValuesHolder; import android.annotation.SuppressLint; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Color; import android.os.Build; import android.support.annotation.AttrRes; import android.support.v4.content.ContextCompat; import android.text.format.Time; import android.util.TypedValue; import android.view.View; import java.util.Calendar; /** * Utility helper functions for time and date pickers. */ public class Utils { public static final int MONDAY_BEFORE_JULIAN_EPOCH = Time.EPOCH_JULIAN_DAY - 3; public static final int PULSE_ANIMATOR_DURATION = 544; // Alpha level for time picker selection. public static final int SELECTED_ALPHA = 255; public static final int SELECTED_ALPHA_THEME_DARK = 255; // Alpha level for fully opaque. public static final int FULL_ALPHA = 255; static final String SHARED_PREFS_NAME = "com.android.calendar_preferences"; public static boolean isJellybeanOrLater() { return Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN; } /** * Try to speak the specified text, for accessibility. Only available on JB or later. * @param text Text to announce. */ @SuppressLint("NewApi") public static void tryAccessibilityAnnounce(View view, CharSequence text) { if (isJellybeanOrLater() && view != null && text != null) { view.announceForAccessibility(text); } } public static int getDaysInMonth(int month, int year) { switch (month) { case Calendar.JANUARY: case Calendar.MARCH: case Calendar.MAY: case Calendar.JULY: case Calendar.AUGUST: case Calendar.OCTOBER: case Calendar.DECEMBER: return 31; case Calendar.APRIL: case Calendar.JUNE: case Calendar.SEPTEMBER: case Calendar.NOVEMBER: return 30; case Calendar.FEBRUARY: return (year % 4 == 0) ? 29 : 28; default: throw new IllegalArgumentException("Invalid Month"); } } /** * Takes a number of weeks since the epoch and calculates the Julian day of * the Monday for that week. * * This assumes that the week containing the {@link Time#EPOCH_JULIAN_DAY} * is considered week 0. It returns the Julian day for the Monday * {@code week} weeks after the Monday of the week containing the epoch. * * @param week Number of weeks since the epoch * @return The julian day for the Monday of the given week since the epoch */ public static int getJulianMondayFromWeeksSinceEpoch(int week) { return MONDAY_BEFORE_JULIAN_EPOCH + week * 7; } /** * Returns the week since {@link Time#EPOCH_JULIAN_DAY} (Jan 1, 1970) * adjusted for first day of week. * * This takes a julian day and the week start day and calculates which * week since {@link Time#EPOCH_JULIAN_DAY} that day occurs in, starting * at 0. *Do not* use this to compute the ISO week number for the year. * * @param julianDay The julian day to calculate the week number for * @param firstDayOfWeek Which week day is the first day of the week, * see {@link Time#SUNDAY} * @return Weeks since the epoch */ public static int getWeeksSinceEpochFromJulianDay(int julianDay, int firstDayOfWeek) { int diff = Time.THURSDAY - firstDayOfWeek; if (diff < 0) { diff += 7; } int refDay = Time.EPOCH_JULIAN_DAY - diff; return (julianDay - refDay) / 7; } /** * Render an animator to pulsate a view in place. * @param labelToAnimate the view to pulsate. * @return The animator object. Use .start() to begin. */ public static ObjectAnimator getPulseAnimator(View labelToAnimate, float decreaseRatio, float increaseRatio) { Keyframe k0 = Keyframe.ofFloat(0f, 1f); Keyframe k1 = Keyframe.ofFloat(0.275f, decreaseRatio); Keyframe k2 = Keyframe.ofFloat(0.69f, increaseRatio); Keyframe k3 = Keyframe.ofFloat(1f, 1f); PropertyValuesHolder scaleX = PropertyValuesHolder.ofKeyframe("scaleX", k0, k1, k2, k3); PropertyValuesHolder scaleY = PropertyValuesHolder.ofKeyframe("scaleY", k0, k1, k2, k3); ObjectAnimator pulseAnimator = ObjectAnimator.ofPropertyValuesHolder(labelToAnimate, scaleX, scaleY); pulseAnimator.setDuration(PULSE_ANIMATOR_DURATION); return pulseAnimator; } /** * Gets the colorAccent from the current context, if possible/available * @param context The context to use as reference for the color * @return the accent color of the current context */ // Source from MDTP public static int getAccentColorFromThemeIfAvailable(Context context) { TypedValue typedValue = new TypedValue(); // First, try the android:colorAccent if (Build.VERSION.SDK_INT >= 21) { context.getTheme().resolveAttribute(android.R.attr.colorAccent, typedValue, true); return typedValue.data; } // Next, try colorAccent from support lib int colorAccentResId = context.getResources().getIdentifier("colorAccent", "attr", context.getPackageName()); if (colorAccentResId != 0 && context.getTheme().resolveAttribute(colorAccentResId, typedValue, true)) { return typedValue.data; } return ContextCompat.getColor(context, R.color.accent_color); } // See http://stackoverflow.com/a/4928826/5055032 public static int darkenColor(int color) { float[] hsv = new float[3]; Color.colorToHSV(color, hsv); hsv[2] *= 0.8f; // value component return Color.HSVToColor(hsv); } // See http://stackoverflow.com/a/4928826/5055032 public static int lightenColor(int color) { float[] hsv = new float[3]; Color.colorToHSV(color, hsv); hsv[2] = 1.0f - 0.8f * (1.0f - hsv[2]); return Color.HSVToColor(hsv); } /** * Gets dialog type (Light/Dark) from current theme * @param context The context to use as reference for the boolean * @param current Default value to return if cannot resolve the attribute * @return true if dark mode, false if light. */ public static boolean isDarkTheme(Context context, boolean current) { return resolveBoolean(context, R.attr.theme_dark, current); } /** * Gets the required boolean value from the current context, if possible/available * @param context The context to use as reference for the boolean * @param attr Attribute id to resolve * @param fallback Default value to return if no value is specified in theme * @return the boolean value from current theme */ private static boolean resolveBoolean(Context context, @AttrRes int attr, boolean fallback) { TypedArray a = context.getTheme().obtainStyledAttributes(new int[] { attr }); try { return a.getBoolean(0, fallback); } finally { a.recycle(); } } }