60 lines
1.9 KiB
Swift
60 lines
1.9 KiB
Swift
// Copyright 2020 Tokamak contributors
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
//
|
|
// Created by Carson Katri on 11/26/20.
|
|
//
|
|
|
|
public struct _PreferenceActionModifier<Key>: _PreferenceWritingModifierProtocol
|
|
where Key: PreferenceKey, Key.Value: Equatable
|
|
{
|
|
public let action: (Key.Value) -> ()
|
|
public init(action: @escaping (Key.Value) -> Swift.Void) {
|
|
self.action = action
|
|
}
|
|
|
|
public func body(_ content: Content, with preferenceStore: inout _PreferenceStore) -> AnyView {
|
|
let value = preferenceStore.value(forKey: Key.self)
|
|
let previousValue = value.reduce((value.storage.valueList as? [Key.Value] ?? []).dropLast())
|
|
if previousValue != value.value {
|
|
action(value.value)
|
|
}
|
|
return content.view
|
|
}
|
|
|
|
public static func _makeView(_ inputs: ViewInputs<Self>) -> ViewOutputs {
|
|
.init(
|
|
inputs: inputs,
|
|
preferenceStore: inputs.preferenceStore ?? .init(),
|
|
preferenceAction: {
|
|
let value = $0.value(forKey: Key.self).value
|
|
let previousValue = $0.previousValue(forKey: Key.self).value
|
|
if value != previousValue {
|
|
inputs.content.action(value)
|
|
}
|
|
}
|
|
)
|
|
}
|
|
}
|
|
|
|
public extension View {
|
|
func onPreferenceChange<K>(
|
|
_ key: K.Type = K.self,
|
|
perform action: @escaping (K.Value) -> ()
|
|
) -> some View
|
|
where K: PreferenceKey, K.Value: Equatable
|
|
{
|
|
modifier(_PreferenceActionModifier<K>(action: action))
|
|
}
|
|
}
|