HorizontalHoverCardSwitcher.java revision 8b068ddbbf22a246eab49ec25a2f7c3abfbdca51 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14package android.support.v17.leanback.widget;
15
16import android.graphics.Rect;
17import android.view.View;
18import android.view.ViewGroup;
19import android.view.View.MeasureSpec;
20import android.view.ViewGroup.MarginLayoutParams;
21
22/**
23 * Helper class that stay bellow a HorizontalGridView and shows a hover card and align
24 * the hover card left to left of selected child view.  If there is no space when scroll
25 * to the end, right edge hover card will be aligned to right of parent view excluding
26 * right padding.
27 */
28public final class HorizontalHoverCardSwitcher extends PresenterSwitcher {
29    // left and right of selected card view
30    int mCardLeft, mCardRight;
31
32    private int[] mTmpOffsets = new int[2];
33    private Rect mTmpRect = new Rect();
34
35    @Override
36    protected void insertView(View view) {
37        // append hovercard to the end of container
38        getParentViewGroup().addView(view);
39    }
40
41    @Override
42    protected void onViewSelected(View view) {
43        int rightLimit = getParentViewGroup().getWidth() -
44                getParentViewGroup().getPaddingRight();
45        // measure the hover card width, if it's too large,  align hover card
46        // right edge with row view's right edge
47        view.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
48        MarginLayoutParams params = (MarginLayoutParams) view.getLayoutParams();
49        if (mCardLeft + view.getMeasuredWidth() > rightLimit) {
50            params.leftMargin = rightLimit  - view.getMeasuredWidth();
51        } else {
52            params.leftMargin = mCardLeft;
53        }
54        view.requestLayout();
55    }
56
57    /**
58     * Select a childView inside a grid view and create/bind a corresponding hover card view
59     * for the object.
60     */
61    public void select(BaseListView gridView, View childView, Object object) {
62        ViewGroup parent = getParentViewGroup();
63        gridView.getViewSelectedOffsets(childView, mTmpOffsets);
64        mTmpRect.set(0, 0, childView.getWidth(), childView.getHeight());
65        parent.offsetDescendantRectToMyCoords(childView, mTmpRect);
66        mCardLeft = mTmpRect.left - mTmpOffsets[0];
67        mCardRight = mTmpRect.right - mTmpOffsets[0];
68        select(object);
69    }
70
71}