ActionBarDrawerToggleSherlock.java

package com.actionbarsherlock.app;

/* 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.
 */

import java.lang.reflect.Method;

import android.annotation.TargetApi;
import android.app.Activity;
import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

/**
 * This class encapsulates some awful hacks.
 * 
 * Before JB-MR2 (API 18) it was not possible to change the home-as-up indicator
 * glyph in an action bar without some really gross hacks. Since the MR2 SDK is
 * not published as of this writing, the new API is accessed via reflection here
 * if available.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
class ActionBarDrawerToggleSherlock {
	private static final String TAG = "ActionBarDrawerToggleSherlock";

	private static final int[] THEME_ATTRS = new int[] { R.attr.homeAsUpIndicator };

	public static Object setActionBarUpIndicator(Object info,
			Activity activity, Drawable drawable, int contentDescRes) {
		SherlockFragmentActivity sherlockActivity = (SherlockFragmentActivity) activity;

		if (info == null) {
			info = new SetIndicatorInfo(activity);
		}
		final SetIndicatorInfo sii = (SetIndicatorInfo) info;
		if (sii.setHomeAsUpIndicator != null) {
			try {
				final ActionBar actionBar = sherlockActivity
						.getSupportActionBar();
				sii.setHomeAsUpIndicator.invoke(actionBar, drawable);
				sii.setHomeActionContentDescription.invoke(actionBar,
						contentDescRes);
			} catch (Exception e) {
				Log.w(TAG, "Couldn't set home-as-up indicator via JB-MR2 API",
						e);
			}
		} else if (sii.upIndicatorView != null) {
			sii.upIndicatorView.setImageDrawable(drawable);
		} else {
			Log.w(TAG, "Couldn't set home-as-up indicator");
		}
		return info;
	}

	public static Object setActionBarDescription(Object info,
			Activity activity, int contentDescRes) {
		SherlockFragmentActivity sherlockActivity = (SherlockFragmentActivity) activity;

		if (info == null) {
			info = new SetIndicatorInfo(activity);
		}
		final SetIndicatorInfo sii = (SetIndicatorInfo) info;
		if (sii.setHomeAsUpIndicator != null) {
			try {
				final ActionBar actionBar = sherlockActivity
						.getSupportActionBar();
				sii.setHomeActionContentDescription.invoke(actionBar,
						contentDescRes);
			} catch (Exception e) {
				Log.w(TAG, "Couldn't set content description via JB-MR2 API", e);
			}
		}
		return info;
	}

	public static Drawable getThemeUpIndicator(Activity activity) {
		final TypedArray a = activity.obtainStyledAttributes(THEME_ATTRS);
		final Drawable result = a.getDrawable(0);
		a.recycle();
		return result;
	}

	private static class SetIndicatorInfo {
		public Method setHomeAsUpIndicator;
		public Method setHomeActionContentDescription;
		public ImageView upIndicatorView;

		SetIndicatorInfo(Activity activity) {
			try {
				setHomeAsUpIndicator = ActionBar.class.getDeclaredMethod(
						"setHomeAsUpIndicator", Drawable.class);
				setHomeActionContentDescription = ActionBar.class
						.getDeclaredMethod("setHomeActionContentDescription",
								Integer.TYPE);

				// If we got the method we won't need the stuff below.
				return;
			} catch (NoSuchMethodException e) {
				// Oh well. We'll use the other mechanism below instead.
			}

			final View home = activity.findViewById(android.R.id.home);
			
			if (home == null) {
				// Action bar doesn't have a known configuration, an OEM messed
				// with things.
				
				// Try ActionBarSherlock up
				ViewGroup sherlockRoot = (ViewGroup)activity.findViewById(R.id.abs__action_bar_container);
				if(sherlockRoot != null){
					walkViewGroupForSherlockUpView(sherlockRoot);
				}
				
				return;
			}

			final ViewGroup parent = (ViewGroup) home.getParent();
			final int childCount = parent.getChildCount();
			if (childCount != 2) {
				// No idea which one will be the right one, an OEM messed with
				// things.
				return;
			}

			final View first = parent.getChildAt(0);
			final View second = parent.getChildAt(1);
			final View up = first.getId() == android.R.id.home ? second : first;

			if (up instanceof ImageView) {
				// Jackpot! (Probably...)
				upIndicatorView = (ImageView) up;
			}
		}
		
		/**
		 * Method to walk the View hierarchy and look for a visible
		 * ActionBarSherlock UP View. The problem is, that the View hierarchy of
		 * ActionBarSherlock 4.3.1 contains multiple Views with the id
		 * R.id.abs__up, so we look for the one that is actually visible to the
		 * user. This is a recursive method, ideally the root View
		 * ActionBarSherlock should be passed in as the parameter.
		 */
		private void walkViewGroupForSherlockUpView(ViewGroup group) {
			for (int i = 0; i < group.getChildCount(); i++) {
				View current = group.getChildAt(i);

				if (current.getId() == R.id.abs__up
						&& current.getVisibility() == View.VISIBLE) {
					upIndicatorView = (ImageView) current;
				}

				if (current instanceof ViewGroup) {
					walkViewGroupForSherlockUpView((ViewGroup) current);
				}
			}
		}
	}
}