design/src/android/support/design/widget/ViewGroupUtils.java

/*
 * Copyright (C) 2015 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.design.widget;

import android.graphics.Rect;
import android.os.Build;
import android.view.View;
import android.view.ViewGroup;

class ViewGroupUtils {

    private interface ViewGroupUtilsImpl {
        void offsetDescendantRect(ViewGroup parent, View child, Rect rect);
    }

    private static class ViewGroupUtilsImplBase implements ViewGroupUtilsImpl {
        @Override
        public void offsetDescendantRect(ViewGroup parent, View child, Rect rect) {
            parent.offsetDescendantRectToMyCoords(child, rect);
        }
    }

    private static class ViewGroupUtilsImplHoneycomb implements ViewGroupUtilsImpl {
        @Override
        public void offsetDescendantRect(ViewGroup parent, View child, Rect rect) {
            ViewGroupUtilsHoneycomb.offsetDescendantRect(parent, child, rect);
        }
    }

    private static final ViewGroupUtilsImpl IMPL;

    static {
        final int version = Build.VERSION.SDK_INT;
        if (version >= 11) {
            IMPL = new ViewGroupUtilsImplHoneycomb();
        } else {
            IMPL = new ViewGroupUtilsImplBase();
        }
    }

    /**
     * This is a port of the common
     * {@link ViewGroup#offsetDescendantRectToMyCoords(android.view.View, android.graphics.Rect)}
     * from the framework, but adapted to take transformations into account. The result
     * will be the bounding rect of the real transformed rect.
     *
     * @param descendant view defining the original coordinate system of rect
     * @param rect (in/out) the rect to offset from descendant to this view's coordinate system
     */
    static void offsetDescendantRect(ViewGroup parent, View descendant, Rect rect) {
        IMPL.offsetDescendantRect(parent, descendant, rect);
    }

    /**
     * Retrieve the transformed bounding rect of an arbitrary descendant view.
     * This does not need to be a direct child.
     *
     * @param descendant descendant view to reference
     * @param out rect to set to the bounds of the descendant view
     */
    static void getDescendantRect(ViewGroup parent, View descendant, Rect out) {
        out.set(0, 0, descendant.getWidth(), descendant.getHeight());
        offsetDescendantRect(parent, descendant, out);
    }

}