PresenterSwitcher.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.view.View;
17import android.view.ViewGroup;
18
19/**
20 * An abstract helper class that switches view in parent view using {@link PresenterSelector}
21 * subclass should define {@link #insertView(View)} of how to add the view
22 * in parent and optionally override {@link #onViewSelected(View)}.
23 */
24public abstract class PresenterSwitcher {
25
26    private ViewGroup mParent;
27    private PresenterSelector mPresenterSelector;
28    private Presenter mCurrentPresenter;
29    private Presenter.ViewHolder mCurrentViewHolder;
30
31    /**
32     * Initialize switcher with a parent view to insert view into and a
33     * {@link PresenterSelector} for choose {@link Presenter} for object.
34     * This will destroy any existing views.
35     */
36    public void init(ViewGroup parent, PresenterSelector presenterSelector) {
37        clear();
38        mParent = parent;
39        mPresenterSelector = presenterSelector;
40    }
41
42    public void select(Object object) {
43        switchView(object);
44        showView(true);
45    }
46
47    public void unselect() {
48        showView(false);
49    }
50
51    public final ViewGroup getParentViewGroup() {
52        return mParent;
53    }
54
55    private void showView(boolean show) {
56        if (mCurrentViewHolder != null) {
57            showView(mCurrentViewHolder.view, show);
58        }
59    }
60
61    private void switchView(Object object) {
62        Presenter presenter = mPresenterSelector.getPresenter(object);
63        if (presenter != mCurrentPresenter) {
64            showView(false);
65            clear();
66            mCurrentPresenter = presenter;
67            if (mCurrentPresenter == null) {
68                return;
69            }
70            mCurrentViewHolder = mCurrentPresenter.onCreateViewHolder(mParent);
71            insertView(mCurrentViewHolder.view);
72        } else {
73            if (mCurrentPresenter == null) {
74                return;
75            }
76            mCurrentPresenter.onUnbindViewHolder(mCurrentViewHolder);
77        }
78        mCurrentPresenter.onBindViewHolder(mCurrentViewHolder, object);
79        onViewSelected(mCurrentViewHolder.view);
80    }
81
82    protected abstract void insertView(View view);
83
84    /**
85     * Called when a view is bound to the object of {@link #select(Object)}.
86     */
87    protected void onViewSelected(View view) {
88    }
89
90    protected void showView(View view, boolean visible) {
91        view.setVisibility(visible ? View.VISIBLE : View.GONE);
92    }
93
94    /**
95     * Destroy created views.
96     */
97    public void clear() {
98        if (mCurrentPresenter != null) {
99            mCurrentPresenter.onUnbindViewHolder(mCurrentViewHolder);
100            mParent.removeView(mCurrentViewHolder.view);
101            mCurrentViewHolder = null;
102            mCurrentPresenter = null;
103        }
104    }
105
106}
107