Filter.swift
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//
// Filter.swift
// Kingfisher
//
// Created by Wei Wang on 2016/08/31.
//
// Copyright (c) 2018 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.
import CoreImage
import Accelerate
// Reuse the same CI Context for all CI drawing.
private let ciContext = CIContext(options: nil)
/// Transformer method which will be used in to provide a `Filter`.
public typealias Transformer = (CIImage) -> CIImage?
/// Supply a filter to create an `ImageProcessor`.
public protocol CIImageProcessor: ImageProcessor {
var filter: Filter { get }
}
extension CIImageProcessor {
public func process(item: ImageProcessItem, options: KingfisherOptionsInfo) -> Image? {
switch item {
case .image(let image):
return image.kf.apply(filter)
case .data(_):
return (DefaultImageProcessor.default >> self).process(item: item, options: options)
}
}
}
/// Wrapper for a `Transformer` of CIImage filters.
public struct Filter {
let transform: Transformer
public init(transform: @escaping Transformer) {
self.transform = transform
}
/// Tint filter which will apply a tint color to images.
public static var tint: (Color) -> Filter = {
color in
Filter(transform: { input in
let colorFilter = CIFilter(name: "CIConstantColorGenerator")!
colorFilter.setValue(CIColor(color: color), forKey: kCIInputColorKey)
let colorImage = colorFilter.outputImage
let filter = CIFilter(name: "CISourceOverCompositing")!
filter.setValue(colorImage, forKey: kCIInputImageKey)
filter.setValue(input, forKey: kCIInputBackgroundImageKey)
#if swift(>=4.0)
return filter.outputImage?.cropped(to: input.extent)
#else
return filter.outputImage?.cropping(to: input.extent)
#endif
})
}
public typealias ColorElement = (CGFloat, CGFloat, CGFloat, CGFloat)
/// Color control filter which will apply color control change to images.
public static var colorControl: (ColorElement) -> Filter = { arg -> Filter in
let (brightness, contrast, saturation, inputEV) = arg
return Filter(transform: { input in
let paramsColor = [kCIInputBrightnessKey: brightness,
kCIInputContrastKey: contrast,
kCIInputSaturationKey: saturation]
let paramsExposure = [kCIInputEVKey: inputEV]
#if swift(>=4.0)
let blackAndWhite = input.applyingFilter("CIColorControls", parameters: paramsColor)
return blackAndWhite.applyingFilter("CIExposureAdjust", parameters: paramsExposure)
#else
let blackAndWhite = input.applyingFilter("CIColorControls", withInputParameters: paramsColor)
return blackAndWhite.applyingFilter("CIExposureAdjust", withInputParameters: paramsExposure)
#endif
})
}
}
// MARK: - Deprecated
extension Filter {
@available(*, deprecated, message: "Use init(transform:) instead.", renamed: "init(transform:)")
public init(tranform: @escaping Transformer) {
self.transform = tranform
}
}
extension Kingfisher where Base: Image {
/// Apply a `Filter` containing `CIImage` transformer to `self`.
///
/// - parameter filter: The filter used to transform `self`.
///
/// - returns: A transformed image by input `Filter`.
///
/// - Note: Only CG-based images are supported. If any error happens during transforming, `self` will be returned.
public func apply(_ filter: Filter) -> Image {
guard let cgImage = cgImage else {
assertionFailure("[Kingfisher] Tint image only works for CG-based image.")
return base
}
let inputImage = CIImage(cgImage: cgImage)
guard let outputImage = filter.transform(inputImage) else {
return base
}
guard let result = ciContext.createCGImage(outputImage, from: outputImage.extent) else {
assertionFailure("[Kingfisher] Can not make an tint image within context.")
return base
}
#if os(macOS)
return fixedForRetinaPixel(cgImage: result, to: size)
#else
return Image(cgImage: result, scale: base.scale, orientation: base.imageOrientation)
#endif
}
}