1 /*
2  * Copyright 2022 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  *      https://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 @file:Suppress("ObjectLiteralToLambda")
18 
19 package com.google.android.horologist.compose.layout
20 
21 import androidx.compose.foundation.layout.Arrangement
22 import androidx.compose.foundation.layout.PaddingValues
23 import androidx.compose.runtime.Composable
24 import androidx.compose.runtime.remember
25 import androidx.compose.ui.Alignment
26 import androidx.compose.ui.platform.LocalConfiguration
27 import androidx.compose.ui.platform.LocalDensity
28 import androidx.compose.ui.unit.Dp
29 import androidx.compose.ui.unit.dp
30 import androidx.wear.compose.foundation.lazy.AutoCenteringParams
31 import androidx.wear.compose.foundation.lazy.ScalingLazyListAnchorType
32 import com.google.android.horologist.annotations.ExperimentalHorologistApi
33 import com.google.android.horologist.compose.layout.ScalingLazyColumnState.RotaryMode
34 
35 /**
36  * Default layouts for ScalingLazyColumnState, based on UX guidance.
37  */
38 public object ScalingLazyColumnDefaults {
39     /**
40      * Layout the first item, directly under the time text.
41      * This is positioned from the top of the screen instead of the
42      * center.
43      */
44     @ExperimentalHorologistApi
belowTimeTextnull45     public fun belowTimeText(
46             rotaryMode: RotaryMode = RotaryMode.Scroll,
47             firstItemIsFullWidth: Boolean = false,
48             verticalArrangement: Arrangement.Vertical =
49                     Arrangement.spacedBy(
50                             space = 4.dp,
51                             alignment = Alignment.Top,
52                     ),
53             horizontalAlignment: Alignment.Horizontal = Alignment.CenterHorizontally,
54             contentPadding: PaddingValues = PaddingValues(horizontal = 10.dp),
55             topPaddingDp: Dp = 32.dp + (if (firstItemIsFullWidth) 20.dp else 0.dp),
56     ): ScalingLazyColumnState.Factory {
57         return object : ScalingLazyColumnState.Factory {
58             @Composable
59             override fun create(): ScalingLazyColumnState {
60                 val density = LocalDensity.current
61                 val configuration = LocalConfiguration.current
62 
63                 return remember {
64                     val screenHeightPx =
65                             with(density) { configuration.screenHeightDp.dp.roundToPx() }
66                     val topPaddingPx = with(density) { topPaddingDp.roundToPx() }
67                     val topScreenOffsetPx = screenHeightPx / 2 - topPaddingPx
68 
69                     ScalingLazyColumnState(
70                             initialScrollPosition = ScalingLazyColumnState.ScrollPosition(
71                                     index = 0,
72                                     offsetPx = topScreenOffsetPx,
73                             ),
74                             anchorType = ScalingLazyListAnchorType.ItemStart,
75                             rotaryMode = rotaryMode,
76                             verticalArrangement = verticalArrangement,
77                             horizontalAlignment = horizontalAlignment,
78                             contentPadding = contentPadding,
79                     )
80                 }
81             }
82         }
83     }
84 
85     /**
86      * Layout the item [initialCenterIndex] at [initialCenterOffset] from the
87      * center of the screen.
88      */
89     @ExperimentalHorologistApi
scalingLazyColumnDefaultsnull90     public fun scalingLazyColumnDefaults(
91             rotaryMode: RotaryMode = RotaryMode.Scroll,
92             initialCenterIndex: Int = 1,
93             initialCenterOffset: Int = 0,
94             verticalArrangement: Arrangement.Vertical =
95                     Arrangement.spacedBy(
96                             space = 4.dp,
97                             alignment = Alignment.Top,
98                     ),
99             horizontalAlignment: Alignment.Horizontal = Alignment.CenterHorizontally,
100             contentPadding: PaddingValues = PaddingValues(horizontal = 10.dp),
101             autoCentering: AutoCenteringParams? = AutoCenteringParams(
102                     initialCenterIndex,
103                     initialCenterOffset,
104             ),
105             anchorType: ScalingLazyListAnchorType = ScalingLazyListAnchorType.ItemCenter,
106             hapticsEnabled: Boolean = true,
107             reverseLayout: Boolean = false,
108     ): ScalingLazyColumnState.Factory {
109         return object : ScalingLazyColumnState.Factory {
110             @Composable
111             override fun create(): ScalingLazyColumnState {
112                 return remember {
113                     ScalingLazyColumnState(
114                             initialScrollPosition = ScalingLazyColumnState.ScrollPosition(
115                                     index = initialCenterIndex,
116                                     offsetPx = initialCenterOffset,
117                             ),
118                             rotaryMode = rotaryMode,
119                             verticalArrangement = verticalArrangement,
120                             horizontalAlignment = horizontalAlignment,
121                             contentPadding = contentPadding,
122                             autoCentering = autoCentering,
123                             anchorType = anchorType,
124                             hapticsEnabled = hapticsEnabled,
125                             reverseLayout = reverseLayout,
126                     )
127                 }
128             }
129         }
130     }
131 }
132