Kingfisher/Sources/SwiftUI/KFImageRenderer.swift

//
//  KFImageRenderer.swift
//  Kingfisher
//
//  Created by onevcat on 2021/05/08.
//
//  Copyright (c) 2021 Wei Wang <onevcat@gmail.com>
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.

#if canImport(SwiftUI) && canImport(Combine)
import SwiftUI
import Combine

/// A Kingfisher compatible SwiftUI `View` to load an image from a `Source`.
/// Declaring a `KFImage` in a `View`'s body to trigger loading from the given `Source`.
@available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *)
struct KFImageRenderer<HoldingView> : View where HoldingView: KFImageHoldingView {
    
    @StateObject var binder: KFImage.ImageBinder = .init()
    let context: KFImage.Context<HoldingView>
    
    var body: some View {
        Group {
            if let image = binder.loadedImage {
                context.configurations
                    .reduce(HoldingView.created(from: image)) {
                        current, config in config(current)
                    }
                    .opacity(binder.loaded ? 1.0 : 0.0)
            } else {
                Group {
                    if let placeholder = context.placeholder, let view = placeholder(binder.progress) {
                        view
                    } else {
                        Color.clear
                    }
                }
                .onAppear { [weak binder = self.binder] in
                    guard let binder = binder else {
                        return
                    }
                    if !binder.loadingOrSucceeded {
                        binder.start(context: context)
                    }
                }
                .onDisappear { [weak binder = self.binder] in
                    guard let binder = binder else {
                        return
                    }
                    if context.cancelOnDisappear {
                        binder.cancel()
                    }
                }
            }
        }
    }
}

@available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *)
extension Image {
    // Creates an Image with either UIImage or NSImage.
    init(crossPlatformImage: KFCrossPlatformImage) {
        #if canImport(UIKit)
        self.init(uiImage: crossPlatformImage)
        #elseif canImport(AppKit)
        self.init(nsImage: crossPlatformImage)
        #endif
    }
}

#if canImport(UIKit)
@available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *)
extension UIImage.Orientation {
    func toSwiftUI() -> Image.Orientation {
        switch self {
        case .down: return .down
        case .up: return .up
        case .left: return .left
        case .right: return .right
        case .upMirrored: return .upMirrored
        case .downMirrored: return .downMirrored
        case .leftMirrored: return .leftMirrored
        case .rightMirrored: return .rightMirrored
        @unknown default: return .up
        }
    }
}
#endif
#endif