48 lines
1.5 KiB
Swift
48 lines
1.5 KiB
Swift
// Copyright 2020 Tokamak contributors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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protocol AppearanceActionType {
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var appear: (() -> ())? { get }
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var disappear: (() -> ())? { get }
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}
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/// Underscore is present in the name for SwiftUI compatibility.
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struct _AppearanceActionModifier: ViewModifier {
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var appear: (() -> ())?
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var disappear: (() -> ())?
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init(appear: (() -> ())? = nil, disappear: (() -> ())? = nil) {
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self.appear = appear
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self.disappear = disappear
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}
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typealias Body = Never
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}
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extension ModifiedContent: AppearanceActionType
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where Content: View, Modifier == _AppearanceActionModifier
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{
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var appear: (() -> ())? { modifier.appear }
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var disappear: (() -> ())? { modifier.disappear }
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}
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extension View {
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public func onAppear(perform action: (() -> ())? = nil) -> some View {
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modifier(_AppearanceActionModifier(appear: action))
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}
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public func onDisappear(perform action: (() -> ())? = nil) -> some View {
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modifier(_AppearanceActionModifier(disappear: action))
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}
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}
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