root/ui/android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java

DEFINITIONS

1. JNINamespace
2. registerListener
3. updateNativeViewConfigurationIfNecessary
4. getDoubleTapTimeout
5. getLongPressTimeout
6. getTapTimeout
7. getScrollFriction
8. getScaledMaximumFlingVelocity
9. getScaledMinimumFlingVelocity
10. getScaledTouchSlop
11. getScaledDoubleTapSlop
12. getScaledMinScalingSpan
13. getScaledMinScalingTouchMajor
14. createWithListener
15. nativeUpdateSharedViewConfiguration

// Copyright 2014 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.ui.gfx;

import android.content.ComponentCallbacks;
import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.view.ViewConfiguration;

import org.chromium.base.CalledByNative;
import org.chromium.base.JNINamespace;
import org.chromium.ui.R;

/**
 * This class facilitates access to ViewConfiguration-related properties, also
 * providing native-code notifications when such properties have changed.
 *
 */
@JNINamespace("gfx")
public class ViewConfigurationHelper {
    private final Context mAppContext;
    private ViewConfiguration mViewConfiguration;

    private ViewConfigurationHelper(Context context) {
        mAppContext = context.getApplicationContext();
        mViewConfiguration = ViewConfiguration.get(mAppContext);
    }

    private void registerListener() {
        mAppContext.registerComponentCallbacks(
                new ComponentCallbacks() {
                    @Override
                    public void onConfigurationChanged(Configuration configuration) {
                        updateNativeViewConfigurationIfNecessary();
                    }

                    @Override
                    public void onLowMemory() {
                    }
                });
    }

    private void updateNativeViewConfigurationIfNecessary() {
        // The ViewConfiguration will differ only if the density has changed.
        ViewConfiguration configuration = ViewConfiguration.get(mAppContext);
        if (mViewConfiguration == configuration) return;

        mViewConfiguration = configuration;
        nativeUpdateSharedViewConfiguration(
                getScaledMaximumFlingVelocity(),
                getScaledMinimumFlingVelocity(),
                getScaledTouchSlop(),
                getScaledDoubleTapSlop(),
                getScaledMinScalingSpan(),
                getScaledMinScalingTouchMajor());
    }

    @CalledByNative
    private static int getDoubleTapTimeout() {
        return ViewConfiguration.getDoubleTapTimeout();
    }

    @CalledByNative
    private static int getLongPressTimeout() {
        return ViewConfiguration.getLongPressTimeout();
    }

    @CalledByNative
    private static int getTapTimeout() {
        return ViewConfiguration.getTapTimeout();
    }

    @CalledByNative
    private static float getScrollFriction() {
        return ViewConfiguration.getScrollFriction();
    }

    @CalledByNative
    private int getScaledMaximumFlingVelocity() {
        return mViewConfiguration.getScaledMaximumFlingVelocity();
    }

    @CalledByNative
    private int getScaledMinimumFlingVelocity() {
        return mViewConfiguration.getScaledMinimumFlingVelocity();
    }

    @CalledByNative
    private int getScaledTouchSlop() {
        return mViewConfiguration.getScaledTouchSlop();
    }

    @CalledByNative
    private int getScaledDoubleTapSlop() {
        return mViewConfiguration.getScaledDoubleTapSlop();
    }

    @CalledByNative
    private int getScaledMinScalingSpan() {
        final Resources res = mAppContext.getResources();
        int id = res.getIdentifier("config_minScalingSpan", "dimen", "android");
        // Fall back to a sensible default if the internal identifier does not exist.
        if (id == 0) id = R.dimen.config_min_scaling_span;
        return res.getDimensionPixelSize(id);

    }

    @CalledByNative
    private int getScaledMinScalingTouchMajor() {
        final Resources res = mAppContext.getResources();
        int id = res.getIdentifier("config_minScalingTouchMajor", "dimen", "android");
        // Fall back to a sensible default if the internal identifier does not exist.
        if (id == 0) id = R.dimen.config_min_scaling_touch_major;
        return res.getDimensionPixelSize(id);
    }

    @CalledByNative
    private static ViewConfigurationHelper createWithListener(Context context) {
        ViewConfigurationHelper viewConfigurationHelper = new ViewConfigurationHelper(context);
        viewConfigurationHelper.registerListener();
        return viewConfigurationHelper;
    }

    private native void nativeUpdateSharedViewConfiguration(
            int scaledMaximumFlingVelocity, int scaledMinimumFlingVelocity,
            int scaledTouchSlop, int scaledDoubleTapSlop,
            int scaledMinScalingSpan, int scaledMinScalingTouchMajor);
}