chrome/android/java/src/org/chromium/chrome/browser/device/DeviceClassManager.java

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.chrome.browser.device;

import org.chromium.base.CommandLine;
import org.chromium.base.SysUtils;
import org.chromium.chrome.browser.ChromeSwitches;
import org.chromium.chrome.browser.preferences.ChromePreferenceManager;
import org.chromium.chrome.browser.preferences.SharedPreferencesManager;
import org.chromium.chrome.browser.util.AccessibilityUtil;
import org.chromium.ui.base.DeviceFormFactor;

/**
 * This class is used to turn on and off certain features for different types of
 * devices.
 */
public class DeviceClassManager {
    private static DeviceClassManager sInstance;

    // Set of features that can be enabled/disabled
    private boolean mEnableSnapshots;
    private boolean mEnableLayerDecorationCache;
    private boolean mEnableAccessibilityLayout;
    private boolean mEnableAnimations;
    private boolean mEnablePrerendering;
    private boolean mEnableToolbarSwipe;

    private final boolean mEnableFullscreen;

    private static DeviceClassManager getInstance() {
        if (sInstance == null) {
            sInstance = new DeviceClassManager();
        }
        return sInstance;
    }

    /**
     * The {@link DeviceClassManager} constructor should be self contained and
     * rely on system information and command line flags.
     */
    private DeviceClassManager() {
        // Device based configurations.
        if (SysUtils.isLowEndDevice()) {
            mEnableSnapshots = false;
            mEnableLayerDecorationCache = true;
            mEnableAccessibilityLayout = true;
            mEnableAnimations = false;
            mEnablePrerendering = false;
            mEnableToolbarSwipe = false;
        } else {
            mEnableSnapshots = true;
            mEnableLayerDecorationCache = true;
            mEnableAccessibilityLayout = false;
            mEnableAnimations = true;
            mEnablePrerendering = true;
            mEnableToolbarSwipe = true;
        }

        if (DeviceFormFactor.isTablet()) {
            mEnableAccessibilityLayout = false;
        }

        // Flag based configurations.
        CommandLine commandLine = CommandLine.getInstance();
        assert commandLine.isNativeImplementation();
        mEnableAccessibilityLayout |= commandLine
                .hasSwitch(ChromeSwitches.ENABLE_ACCESSIBILITY_TAB_SWITCHER);
        mEnableFullscreen =
                !commandLine.hasSwitch(ChromeSwitches.DISABLE_FULLSCREEN);

        // Related features.
        if (mEnableAccessibilityLayout) {
            mEnableAnimations = false;
        }
    }

    /**
     * @return Whether or not we can take screenshots.
     */
    public static boolean enableSnapshots() {
        return getInstance().mEnableSnapshots;
    }

    /**
     * @return Whether or not we can use the layer decoration cache.
     */
    public static boolean enableLayerDecorationCache() {
        return getInstance().mEnableLayerDecorationCache;
    }

    /**
     * @return Whether or not should use the accessibility tab switcher.
     */
    public static boolean enableAccessibilityLayout() {
        if (getInstance().mEnableAccessibilityLayout) return true;
        if (!AccessibilityUtil.isAccessibilityEnabled()) return false;
        return SharedPreferencesManager.getInstance().readBoolean(
                ChromePreferenceManager.ACCESSIBILITY_TAB_SWITCHER, true);
    }

    /**
     * @return Whether or not full screen is enabled.
     */
    public static boolean enableFullscreen() {
        return getInstance().mEnableFullscreen;
    }

    /**
     * @return Whether or not we are showing animations.
     */
    public static boolean enableAnimations() {
        if (!getInstance().mEnableAnimations) return false;
        if (!AccessibilityUtil.isAccessibilityEnabled()) return true;
        return !SharedPreferencesManager.getInstance().readBoolean(
                ChromePreferenceManager.ACCESSIBILITY_TAB_SWITCHER, true);
    }

    /**
     * @return Whether or not prerendering is enabled.
     */
    public static boolean enablePrerendering() {
        return getInstance().mEnablePrerendering;
    }

    /**
     * @return Whether or not we can use the toolbar swipe.
     */
    public static boolean enableToolbarSwipe() {
        return getInstance().mEnableToolbarSwipe;
    }
}