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 android.support.v7.app; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Color; import android.support.annotation.IntDef; import android.support.v4.graphics.ColorUtils; import android.support.v7.mediarouter.R; import android.util.TypedValue; import android.view.ContextThemeWrapper; import android.view.View; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; final class MediaRouterThemeHelper { private static final float MIN_CONTRAST = 3.0f; @IntDef({ COLOR_DARK_ON_LIGHT_BACKGROUND, COLOR_WHITE_ON_DARK_BACKGROUND }) @Retention(RetentionPolicy.SOURCE) private @interface ControllerColorType { } private static final int COLOR_DARK_ON_LIGHT_BACKGROUND = 0xDE000000; /* Opacity of 87% */ private static final int COLOR_WHITE_ON_DARK_BACKGROUND = Color.WHITE; private MediaRouterThemeHelper() { } /** * Creates a themed context based on the explicit style resource or the parent context's default * theme. * <p> * The theme which will be applied on top of the parent {@code context}'s theme is determined * by the primary color defined in the given {@code style}, or in the parent {@code context}. * * @param context the parent context * @param style the resource ID of the style against which to inflate this context, or * {@code 0} to use the parent {@code context}'s default theme. * @return The themed context. */ public static Context createThemedContext(Context context, int style) { int theme; if (isLightTheme(context)) { if (getControllerColor(context, style) == COLOR_DARK_ON_LIGHT_BACKGROUND) { theme = R.style.Theme_MediaRouter_Light; } else { theme = R.style.Theme_MediaRouter_Light_DarkControlPanel; } } else { if (getControllerColor(context, style) == COLOR_DARK_ON_LIGHT_BACKGROUND) { theme = R.style.Theme_MediaRouter_LightControlPanel; } else { theme = R.style.Theme_MediaRouter; } } return new ContextThemeWrapper(context, theme); } public static int getThemeResource(Context context, int attr) { TypedValue value = new TypedValue(); return context.getTheme().resolveAttribute(attr, value, true) ? value.resourceId : 0; } public static float getDisabledAlpha(Context context) { TypedValue value = new TypedValue(); return context.getTheme().resolveAttribute(android.R.attr.disabledAlpha, value, true) ? value.getFloat() : 0.5f; } public static @ControllerColorType int getControllerColor(Context context, int style) { int primaryColor = getThemeColor(context, style, android.support.v7.appcompat.R.attr.colorPrimary); if (ColorUtils.calculateContrast(COLOR_WHITE_ON_DARK_BACKGROUND, primaryColor) >= MIN_CONTRAST) { return COLOR_WHITE_ON_DARK_BACKGROUND; } return COLOR_DARK_ON_LIGHT_BACKGROUND; } public static int getButtonTextColor(Context context) { int primaryColor = getThemeColor(context, 0, android.support.v7.appcompat.R.attr.colorPrimary); int backgroundColor = getThemeColor(context, 0, android.R.attr.colorBackground); if (ColorUtils.calculateContrast(primaryColor, backgroundColor) < MIN_CONTRAST) { // Default to colorAccent if the contrast ratio is low. return getThemeColor(context, 0, android.support.v7.appcompat.R.attr.colorAccent); } return primaryColor; } public static void setMediaControlsBackgroundColor(Context context, View mainControls, View groupControls, boolean hasGroup) { int primaryColor = getThemeColor(context, 0, android.support.v7.appcompat.R.attr.colorPrimary); int primaryDarkColor = getThemeColor(context, 0, android.support.v7.appcompat.R.attr.colorPrimaryDark); if (hasGroup && getControllerColor(context, 0) == COLOR_DARK_ON_LIGHT_BACKGROUND) { // Instead of showing dark controls in a possibly dark (i.e. the primary dark), model // the white dialog and use the primary color for the group controls. primaryDarkColor = primaryColor; primaryColor = Color.WHITE; } mainControls.setBackgroundColor(primaryColor); groupControls.setBackgroundColor(primaryDarkColor); // Also store the background colors to the view tags. They are used in // setVolumeSliderColor() below. mainControls.setTag(primaryColor); groupControls.setTag(primaryDarkColor); } public static void setVolumeSliderColor(Context context, MediaRouteVolumeSlider volumeSlider, View backgroundView) { int controllerColor = getControllerColor(context, 0); if (Color.alpha(controllerColor) != 0xFF) { // Composite with the background in order not to show the underlying progress bar // through the thumb. int backgroundColor = (int) backgroundView.getTag(); controllerColor = ColorUtils.compositeColors(controllerColor, backgroundColor); } volumeSlider.setColor(controllerColor); } private static boolean isLightTheme(Context context) { TypedValue value = new TypedValue(); return context.getTheme().resolveAttribute(android.support.v7.appcompat.R.attr.isLightTheme, value, true) && value.data != 0; } private static int getThemeColor(Context context, int style, int attr) { if (style != 0) { int[] attrs = { attr }; TypedArray ta = context.obtainStyledAttributes(style, attrs); int color = ta.getColor(0, 0); ta.recycle(); if (color != 0) { return color; } } TypedValue value = new TypedValue(); context.getTheme().resolveAttribute(attr, value, true); if (value.resourceId != 0) { return context.getResources().getColor(value.resourceId); } return value.data; } }