1 /*
2  * Copyright (C) 2024 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 
17 package com.android.intentresolver.widget
18 
19 import android.content.Context
20 import android.util.AttributeSet
21 import android.view.View
22 import android.widget.LinearLayout
23 import androidx.core.view.ScrollingView
24 import androidx.core.view.marginBottom
25 import androidx.core.view.marginLeft
26 import androidx.core.view.marginRight
27 import androidx.core.view.marginTop
28 import androidx.core.widget.NestedScrollView
29 
30 /**
31  * A narrowly tailored [NestedScrollView] to be used inside [ResolverDrawerLayout] and help to
32  * orchestrate content preview scrolling. It expects one [LinearLayout] child with
33  * [LinearLayout.VERTICAL] orientation. If the child has more than one child, the first its child
34  * will be made scrollable (it is expected to be a content preview view).
35  */
36 class ChooserNestedScrollView : NestedScrollView {
37     constructor(context: Context) : super(context)
38     constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)
39     constructor(
40         context: Context,
41         attrs: AttributeSet?,
42         defStyleAttr: Int
43     ) : super(context, attrs, defStyleAttr)
44 
onMeasurenull45     override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
46         val content =
47             getChildAt(0) as? LinearLayout ?: error("Exactly one child, LinerLayout, is expected")
48         require(content.orientation == LinearLayout.VERTICAL) { "VERTICAL orientation is expected" }
49         require(MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY) {
50             "Expected to have an exact width"
51         }
52 
53         val lp = content.layoutParams ?: error("LayoutParams is missing")
54         val contentWidthSpec =
55             getChildMeasureSpec(
56                 widthMeasureSpec,
57                 paddingLeft + content.marginLeft + content.marginRight + paddingRight,
58                 lp.width
59             )
60         val contentHeightSpec =
61             getChildMeasureSpec(
62                 heightMeasureSpec,
63                 paddingTop + content.marginTop + content.marginBottom + paddingBottom,
64                 lp.height
65             )
66         content.measure(contentWidthSpec, contentHeightSpec)
67 
68         if (content.childCount > 1) {
69             // We expect that the first child should be scrollable up
70             val child = content.getChildAt(0)
71             val height =
72                 MeasureSpec.getSize(heightMeasureSpec) +
73                     child.measuredHeight +
74                     child.marginTop +
75                     child.marginBottom
76 
77             content.measure(
78                 contentWidthSpec,
79                 MeasureSpec.makeMeasureSpec(height, MeasureSpec.getMode(heightMeasureSpec))
80             )
81         }
82         setMeasuredDimension(
83             MeasureSpec.getSize(widthMeasureSpec),
84             minOf(
85                 MeasureSpec.getSize(heightMeasureSpec),
86                 paddingTop +
87                     content.marginTop +
88                     content.measuredHeight +
89                     content.marginBottom +
90                     paddingBottom
91             )
92         )
93     }
94 
onNestedPreScrollnull95     override fun onNestedPreScroll(target: View, dx: Int, dy: Int, consumed: IntArray, type: Int) {
96         // let the parent scroll
97         super.onNestedPreScroll(target, dx, dy, consumed, type)
98         // scroll ourselves, if recycler has not scrolled
99         val delta = dy - consumed[1]
100         if (delta > 0 && target is ScrollingView && !target.canScrollVertically(-1)) {
101             val preScrollY = scrollY
102             scrollBy(0, delta)
103             consumed[1] += scrollY - preScrollY
104         }
105     }
106 }
107