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 com.android.setupwizardlib.view;
18
19import android.annotation.TargetApi;
20import android.content.Context;
21import android.content.res.TypedArray;
22import android.graphics.Canvas;
23import android.graphics.RectF;
24import android.os.Build;
25import android.util.AttributeSet;
26import android.view.LayoutInflater;
27import android.view.MotionEvent;
28import android.view.View;
29import android.view.WindowInsets;
30import android.view.accessibility.AccessibilityEvent;
31import android.widget.ListView;
32
33import com.android.setupwizardlib.R;
34
35/**
36 * This class provides sticky header functionality in a list view, to use with
37 * SetupWizardIllustration. To use this, add a header tagged with "sticky", or a header tagged with
38 * "stickyContainer" and one of its child tagged as "sticky". The sticky container will be drawn
39 * when the sticky element hits the top of the view.
40 *
41 * <p>There are a few things to note:
42 * <ol>
43 *   <li>The two supported scenarios are StickyHeaderListView -> Header (stickyContainer) -> sticky,
44 *   and StickyHeaderListView -> Header (sticky). The arrow (->) represents parent/child
45 *   relationship and must be immediate child.
46 *   <li>The view does not work well with padding. b/16190933
47 *   <li>If fitsSystemWindows is true, then this will offset the sticking position by the height of
48 *   the system decorations at the top of the screen.
49 * </ol>
50 *
51 * @see StickyHeaderScrollView
52 */
53public class StickyHeaderListView extends ListView {
54
55    private View mSticky;
56    private View mStickyContainer;
57    private int mStatusBarInset = 0;
58    private RectF mStickyRect = new RectF();
59
60    public StickyHeaderListView(Context context) {
61        super(context);
62        init(null, android.R.attr.listViewStyle);
63    }
64
65    public StickyHeaderListView(Context context, AttributeSet attrs) {
66        super(context, attrs);
67        init(attrs, android.R.attr.listViewStyle);
68    }
69
70    public StickyHeaderListView(Context context, AttributeSet attrs, int defStyleAttr) {
71        super(context, attrs, defStyleAttr);
72        init(attrs, defStyleAttr);
73    }
74
75    private void init(AttributeSet attrs, int defStyleAttr) {
76        final TypedArray a = getContext().obtainStyledAttributes(attrs,
77                R.styleable.SuwStickyHeaderListView, defStyleAttr, 0);
78        int headerResId = a.getResourceId(R.styleable.SuwStickyHeaderListView_suwHeader, 0);
79        if (headerResId != 0) {
80            LayoutInflater inflater = LayoutInflater.from(getContext());
81            View header = inflater.inflate(headerResId, this, false);
82            addHeaderView(header, null, false);
83        }
84        a.recycle();
85    }
86
87    @Override
88    protected void onLayout(boolean changed, int l, int t, int r, int b) {
89        super.onLayout(changed, l, t, r, b);
90        if (mSticky == null) {
91            updateStickyView();
92        }
93    }
94
95    public void updateStickyView() {
96        mSticky = findViewWithTag("sticky");
97        mStickyContainer = findViewWithTag("stickyContainer");
98    }
99
100    @Override
101    public boolean dispatchTouchEvent(MotionEvent ev) {
102        if (mStickyRect.contains(ev.getX(), ev.getY())) {
103            ev.offsetLocation(-mStickyRect.left, -mStickyRect.top);
104            return mStickyContainer.dispatchTouchEvent(ev);
105        } else {
106            return super.dispatchTouchEvent(ev);
107        }
108    }
109
110    @Override
111    public void draw(Canvas canvas) {
112        super.draw(canvas);
113        if (mSticky != null) {
114            final int saveCount = canvas.save();
115            // The view to draw when sticking to the top
116            final View drawTarget = mStickyContainer != null ? mStickyContainer : mSticky;
117            // The offset to draw the view at when sticky
118            final int drawOffset = mStickyContainer != null ? mSticky.getTop() : 0;
119            // Position of the draw target, relative to the outside of the scrollView
120            final int drawTop = drawTarget.getTop();
121            if (drawTop + drawOffset < mStatusBarInset || !drawTarget.isShown()) {
122                // ListView does not translate the canvas, so we can simply draw at the top
123                mStickyRect.set(0, -drawOffset + mStatusBarInset, drawTarget.getWidth(),
124                        drawTarget.getHeight() - drawOffset + mStatusBarInset);
125                canvas.translate(0, mStickyRect.top);
126                canvas.clipRect(0, 0, drawTarget.getWidth(), drawTarget.getHeight());
127                drawTarget.draw(canvas);
128            } else {
129                mStickyRect.setEmpty();
130            }
131            canvas.restoreToCount(saveCount);
132        }
133    }
134
135    @Override
136    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
137    public WindowInsets onApplyWindowInsets(WindowInsets insets) {
138        if (getFitsSystemWindows()) {
139            mStatusBarInset = insets.getSystemWindowInsetTop();
140            insets.replaceSystemWindowInsets(
141                    insets.getSystemWindowInsetLeft(),
142                    0, /* top */
143                    insets.getSystemWindowInsetRight(),
144                    insets.getSystemWindowInsetBottom()
145            );
146        }
147        return insets;
148    }
149
150    @Override
151    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
152        super.onInitializeAccessibilityEvent(event);
153
154        // Decoration-only headers should not count as an item for accessibility, adjust the
155        // accessibility event to account for that.
156        final int numberOfHeaders = mSticky != null ? 1 : 0;
157        event.setItemCount(event.getItemCount() - numberOfHeaders);
158        event.setFromIndex(Math.max(event.getFromIndex() - numberOfHeaders, 0));
159        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
160            event.setToIndex(Math.max(event.getToIndex() - numberOfHeaders, 0));
161        }
162    }
163}
164