design/honeycomb/android/support/design/widget/ViewGroupUtilsHoneycomb.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.Matrix;
import android.graphics.Rect;
import android.graphics.RectF;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;

class ViewGroupUtilsHoneycomb {
    private static final ThreadLocal<Matrix> sMatrix = new ThreadLocal<>();
    private static final ThreadLocal<RectF> sRectF = new ThreadLocal<>();
    private static final Matrix IDENTITY = new Matrix();

    public static void offsetDescendantRect(ViewGroup group, View child, Rect rect) {
        Matrix m = sMatrix.get();
        if (m == null) {
            m = new Matrix();
            sMatrix.set(m);
        } else {
            m.set(IDENTITY);
        }

        offsetDescendantMatrix(group, child, m);

        RectF rectF = sRectF.get();
        if (rectF == null) {
            rectF = new RectF();
        }
        rectF.set(rect);
        m.mapRect(rectF);
        rect.set((int) (rectF.left + 0.5f), (int) (rectF.top + 0.5f),
                (int) (rectF.right + 0.5f), (int) (rectF.bottom + 0.5f));
    }

    static void offsetDescendantMatrix(ViewParent target, View view, Matrix m) {
        final ViewParent parent = view.getParent();
        if (parent instanceof View && parent != target) {
            final View vp = (View) parent;
            offsetDescendantMatrix(target, vp, m);
            m.preTranslate(-vp.getScrollX(), -vp.getScrollY());
        }

        m.preTranslate(view.getLeft(), view.getTop());

        if (!view.getMatrix().isIdentity()) {
            m.preConcat(view.getMatrix());
        }
    }
}