Tokamak/Sources/TokamakCore/PreviewProvider.swift

68 lines
1.7 KiB
Swift

// Copyright 2020-2021 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.
import Foundation
/// This protocol has no functionality currently, and is only provided for compatibility purposes.
public protocol PreviewProvider {
associatedtype Previews: View
@ViewBuilder
static var previews: Previews { get }
}
public struct PreviewDevice: RawRepresentable, ExpressibleByStringLiteral {
public let rawValue: String
public init(rawValue: String) {
self.rawValue = rawValue
}
public init(stringLiteral: String) {
rawValue = stringLiteral
}
}
public protocol PreviewContextKey {
associatedtype Value
static var defaultValue: Self.Value { get }
}
public protocol PreviewContext {
subscript<Key>(key: Key.Type) -> Key.Value where Key: PreviewContextKey { get }
}
public enum PreviewLayout {
case device
case sizeThatFits
case fixed(width: CGFloat, height: CGFloat)
}
public extension View {
func previewDevice(_ value: PreviewDevice?) -> some View {
self
}
func previewLayout(_ value: PreviewLayout) -> some View {
self
}
func previewDisplayName(_ value: String?) -> some View {
self
}
func previewContext<C>(_ value: C) -> some View where C: PreviewContext {
self
}
}