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Refactoring and cleaner code
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@onevcat
onevcat committed Mar 12, 2022
1 parent 35101a1 commit 74b5053
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Showing 4 changed files with 159 additions and 170 deletions.
125 changes: 34 additions & 91 deletions Source/APNGKit/APNGDecoder.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,10 @@ class APNGDecoder {
let expectedSequenceNumber: Int
}

let reader: Reader
let options: APNGImage.DecodingOptions
let cachePolicy: APNGImage.CachePolicy

// Called when the first pass is done.
let onFirstPassDone = Delegate<(), Void>()

Expand All @@ -34,27 +38,24 @@ class APNGDecoder {

private let decodingQueue = DispatchQueue(label: "com.onevcat.apngkit.decodingQueue", qos: .userInteractive)

// Holds decoded frame data and chunk info.
private var frames: [APNGFrame?] = []
// Used only when `cachePolicy` is `.cache`.
private(set) var decodedImageCache: [CGImage?]?

var defaultImageChunks: [IDAT] { firstFrameResult?.defaultImageChunks ?? [] }
private(set) var firstFrameResult: FirstFrameResult?

// Used only when `cachePolicy` is `.cache`.
private(set) var decodedImageCache: [CGImage?]?

var canvasFullSize: CGSize { .init(width: imageHeader.width, height: imageHeader.height) }
var canvasFullRect: CGRect { .init(origin: .zero, size: canvasFullSize) }
private var canvasFullSize: CGSize { .init(width: imageHeader.width, height: imageHeader.height) }

// The data chunks shared by all frames: after IHDR and before the actual IDAT or fdAT chunk.
// Use this to revert to a valid PNG for creating a CG data provider.
private(set) var sharedData = Data()
let reader: Reader

// Holds the reader and sequence status after the first frame decoded. When reset, we need to make sure the renderer
// reader is set to this position before starting another read process.
private(set) var resetStatus: ResetStatus!
let options: APNGImage.DecodingOptions
let cachePolicy: APNGImage.CachePolicy

convenience init(data: Data, options: APNGImage.DecodingOptions = []) throws {
let reader = DataReader(data: data)
Expand All @@ -77,6 +78,7 @@ class APNGDecoder {
guard let signature = try reader.read(upToCount: 8),
signature.bytes == Self.pngSignature
else {
// Not a PNG image.
throw APNGKitError.decoderError(.fileFormatError)
}
let ihdr = try reader.readChunk(type: IHDR.self, skipChecksumVerify: skipChecksumVerify)
Expand All @@ -102,7 +104,8 @@ class APNGDecoder {
//
// For now, just hard code a reasonable upper limitation.
if numberOfFrames >= 1024 && !options.contains(.unlimitedFrameCount) {
printLog("The input frame count exceeds the upper limit. Consider to make sure the frame count is correct or set `.unlimitedFrameCount` to allow huge frame count at your risk.")
printLog("The input frame count exceeds the upper limit. Consider to make sure the frame count is correct " +
"or set `.unlimitedFrameCount` to allow huge frame count at your risk.")
throw APNGKitError.decoderError(.invalidNumberOfFrames(value: numberOfFrames))
}
frames = [APNGFrame?](repeating: nil, count: acTLResult.chunk.numberOfFrames)
Expand Down Expand Up @@ -132,7 +135,6 @@ class APNGDecoder {
}

sharedData.append(acTLResult.dataBeforeThunk)

animationControl = acTLResult.chunk
}
}
Expand All @@ -143,7 +145,6 @@ extension APNGDecoder {
guard firstFrameResult == nil else {
return
}

firstFrameResult = frameResult
sharedData.append(contentsOf: frameResult.dataBeforeFirstFrame)
set(frame: frameResult.frame, at: 0)
Expand All @@ -159,33 +160,29 @@ extension APNGDecoder {

// Frame thread safe.
extension APNGDecoder {
func set(frame: APNGFrame, at index: Int) {
decodingQueue.sync { frames[index] = frame }
var framesCount: Int {
decodingQueue.sync { frames.count }
}

func frame(at index: Int) -> APNGFrame? {
decodingQueue.sync { frames[index] }
}

var loadedFrames: [APNGFrame] {
decodingQueue.sync { frames.compactMap { $0 } }
}

var framesCount: Int {
decodingQueue.sync { frames.count }
func set(frame: APNGFrame, at index: Int) {
decodingQueue.sync { frames[index] = frame }
}

func setDecodedImageCache(image: CGImage, at index: Int) {
decodingQueue.sync {
if cachePolicy == .cache {
decodedImageCache?[index] = image
}
func cachedImage(at index: Int) -> CGImage? {
guard cachePolicy == .cache else { return nil }
return decodingQueue.sync {
guard let cache = decodedImageCache else { return nil }
return cache[index]
}
}

var isFirstFrameLoaded: Bool {
decodingQueue.sync {
frames[0] != nil
func setCachedImage(_ image: CGImage, at index: Int) {
if cachePolicy == .cache {
decodingQueue.sync { decodedImageCache?[index] = image }
}
}

Expand All @@ -195,26 +192,23 @@ extension APNGDecoder {
}
}

func cachedImage(at index: Int) -> CGImage? {
decodingQueue.sync {
guard cachePolicy == .cache else { return nil }
guard let cache = decodedImageCache else { return nil }
return cache[index]
}
var loadedFrames: [APNGFrame] {
decodingQueue.sync { frames.compactMap { $0 } }
}

var allFramesCached: Bool {
var isFirstFrameLoaded: Bool {
decodingQueue.sync { frames[0] != nil }
}

var isAllFramesCached: Bool {
decodingQueue.sync {
guard let cache = decodedImageCache else { return false }
return cache.allSatisfy { $0 != nil }
}
}

var firstPass: Bool {
decodingQueue.sync {
let loadedFrameCount = frames.firstIndex { $0 == nil } ?? frames.count
return loadedFrameCount < frames.count
}
var isDuringFirstPass: Bool {
decodingQueue.sync { frames.contains { $0 == nil } }
}
}

Expand All @@ -236,9 +230,7 @@ extension APNGDecoder {
}

private func generateImageData(width: Int, height: Int, data: Data) throws -> Data {
let ihdr = try imageHeader.updated(
width: width, height: height
).encode()
let ihdr = try imageHeader.updated(width: width, height: height).encode()
let idat = IDAT.encode(data: data)
return Self.pngSignature + ihdr + sharedData + idat + Self.IENDBytes
}
Expand All @@ -250,9 +242,7 @@ extension APNGDecoder {
let payload = try defaultImageChunks.map { idat in
try idat.loadData(with: self.reader)
}.joined()
let data = try generateImageData(
width: imageHeader.width, height: imageHeader.height, data: Data(payload)
)
let data = try generateImageData(width: imageHeader.width, height: imageHeader.height, data: Data(payload))
return data
}
}
Expand All @@ -277,48 +267,6 @@ public struct APNGFrame {
}
}

// Drawing properties for IHDR.
extension IHDR {
var colorSpace: CGColorSpace {
switch colorType {
case .greyscale, .greyscaleWithAlpha: return .deviceGray
case .trueColor, .trueColorWithAlpha: return .deviceRGB
case .indexedColor: return .deviceRGB
}
}

var bitmapInfo: CGBitmapInfo {
switch colorType {
case .greyscale, .trueColor:
return CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue)
case .greyscaleWithAlpha, .trueColorWithAlpha, .indexedColor:
return CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
}
}

var bitDepthPerComponent: Int {
// The sample depth is the same as the bit depth except in the case of
// indexed-colour PNG images (colour type 3), in which the sample depth is always 8 bits.
Int(colorType == .indexedColor ? 8 : bitDepth)
}

var bitsPerPixel: UInt32 {
let componentsPerPixel =
colorType == .indexedColor ? 4 /* Draw indexed color as true color with alpha in CG world. */
: colorType.componentsPerPixel
return UInt32(componentsPerPixel * bitDepthPerComponent)
}

var bytesPerPixel: UInt32 {
bitsPerPixel / 8
}

var bytesPerRow: Int {
width * Int(bytesPerPixel)
}

}

extension fcTL {
func normalizedRect(fullHeight: Int) -> CGRect {
.init(x: xOffset, y: fullHeight - yOffset - height, width: width, height: height)
Expand All @@ -328,8 +276,3 @@ extension fcTL {
.init(x: xOffset, y: yOffset, width: width, height: height)
}
}

extension CGColorSpace {
static let deviceRGB = CGColorSpaceCreateDeviceRGB()
static let deviceGray = CGColorSpaceCreateDeviceGray()
}
4 changes: 2 additions & 2 deletions Source/APNGKit/APNGImage.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ import Delegate
/// ```
public class APNGImage {

/// The maximum size in memory which determines whether the decoded images should be cached or not.
/// The maximum byte size in memory which determines whether the decoded images should be cached or not.
///
/// If a cache policy is not specified in `DecodingOptions`, APNGKit will decide if the decoded images should be
/// cached or not by checking its loop number and the estimated size. Enlarge this number to allow bigger images
Expand Down Expand Up @@ -120,7 +120,7 @@ public class APNGImage {
// If you need to know the full duration before the first pass, use `DecodingOptions.fullFirstPass` to
// initialize the image object.
let knownDuration = decoder.loadedFrames.reduce(0.0) { $0 + ($1.frameControl.duration) }
return decoder.firstPass ? .loadedPartial(knownDuration) : .full(knownDuration)
return decoder.isDuringFirstPass ? .loadedPartial(knownDuration) : .full(knownDuration)
}

/// The cache policy used by this image for the image data of decoded frames.
Expand Down
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