1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.support.design.widget;
18
19import android.graphics.Matrix;
20import android.graphics.Rect;
21import android.graphics.RectF;
22import android.view.View;
23import android.view.ViewGroup;
24import android.view.ViewParent;
25
26class ViewGroupUtils {
27    private static final ThreadLocal<Matrix> sMatrix = new ThreadLocal<>();
28    private static final ThreadLocal<RectF> sRectF = new ThreadLocal<>();
29
30    /**
31     * This is a port of the common
32     * {@link ViewGroup#offsetDescendantRectToMyCoords(android.view.View, android.graphics.Rect)}
33     * from the framework, but adapted to take transformations into account. The result
34     * will be the bounding rect of the real transformed rect.
35     *
36     * @param descendant view defining the original coordinate system of rect
37     * @param rect (in/out) the rect to offset from descendant to this view's coordinate system
38     */
39    static void offsetDescendantRect(ViewGroup parent, View descendant, Rect rect) {
40        Matrix m = sMatrix.get();
41        if (m == null) {
42            m = new Matrix();
43            sMatrix.set(m);
44        } else {
45            m.reset();
46        }
47
48        offsetDescendantMatrix(parent, descendant, m);
49
50        RectF rectF = sRectF.get();
51        if (rectF == null) {
52            rectF = new RectF();
53            sRectF.set(rectF);
54        }
55        rectF.set(rect);
56        m.mapRect(rectF);
57        rect.set((int) (rectF.left + 0.5f), (int) (rectF.top + 0.5f),
58                (int) (rectF.right + 0.5f), (int) (rectF.bottom + 0.5f));
59    }
60
61    /**
62     * Retrieve the transformed bounding rect of an arbitrary descendant view.
63     * This does not need to be a direct child.
64     *
65     * @param descendant descendant view to reference
66     * @param out rect to set to the bounds of the descendant view
67     */
68    static void getDescendantRect(ViewGroup parent, View descendant, Rect out) {
69        out.set(0, 0, descendant.getWidth(), descendant.getHeight());
70        offsetDescendantRect(parent, descendant, out);
71    }
72
73    private static void offsetDescendantMatrix(ViewParent target, View view, Matrix m) {
74        final ViewParent parent = view.getParent();
75        if (parent instanceof View && parent != target) {
76            final View vp = (View) parent;
77            offsetDescendantMatrix(target, vp, m);
78            m.preTranslate(-vp.getScrollX(), -vp.getScrollY());
79        }
80
81        m.preTranslate(view.getLeft(), view.getTop());
82
83        if (!view.getMatrix().isIdentity()) {
84            m.preConcat(view.getMatrix());
85        }
86    }
87}
88