Arrays Swift:由于某种原因导致代码崩溃
我是Swift的新手,我正在网上学习一门课程,但不幸的是他们没有回答我的问题。我相信答案很简单,但因为我是初学者,我希望这里的人能回答我Arrays Swift:由于某种原因导致代码崩溃,arrays,swift,uiimage,unsafemutablepointer,Arrays,Swift,Uiimage,Unsafemutablepointer,我是Swift的新手,我正在网上学习一门课程,但不幸的是他们没有回答我的问题。我相信答案很简单,但因为我是初学者,我希望这里的人能回答我 import UIKit public struct Pixel { public var value: UInt32 = 0 public init() { } public var red: UInt8 { get { return UInt8(value & 0xFF)
import UIKit
public struct Pixel {
public var value: UInt32 = 0
public init() { }
public var red: UInt8 {
get {
return UInt8(value & 0xFF)
}
set {
value = UInt32(newValue) | (value & 0xFFFFFF00)
}
}
public var green: UInt8 {
get {
return UInt8((value >> 8) & 0xFF)
}
set {
value = (UInt32(newValue) << 8) | (value & 0xFFFF00FF)
}
}
public var blue: UInt8 {
get {
return UInt8((value >> 16) & 0xFF)
}
set {
value = (UInt32(newValue) << 16) | (value & 0xFF00FFFF)
}
}
public var alpha: UInt8 {
get {
return UInt8((value >> 24) & 0xFF)
}
set {
value = (UInt32(newValue) << 24) | (value & 0x00FFFFFF)
}
}
}
public class RGBAImage
{
public var pixels: [Pixel]
public var width: Int
public var height: Int
private var imageData: UnsafeMutablePointer<Pixel>
public init?(image: UIImage) {
guard let cgImage = image.cgImage else { return nil }
// Redraw image for correct pixel format
let colorSpace = CGColorSpaceCreateDeviceRGB()
var bitmapInfo: UInt32 = CGBitmapInfo.byteOrder32Big.rawValue
bitmapInfo |= CGImageAlphaInfo.premultipliedLast.rawValue & CGBitmapInfo.alphaInfoMask.rawValue
width = Int(image.size.width)
height = Int(image.size.height)
let bytesPerRow = width * 4
imageData = UnsafeMutablePointer<Pixel>.allocate(capacity: width * height)
guard let imageContext = CGContext.init(data: imageData, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo) else { return nil }
imageContext.draw(cgImage, in: CGRect(origin: CGPoint.zero, size: image.size))
let bufferPointer = UnsafeMutableBufferPointer<Pixel>(start: imageData, count: width * height)
pixels = Array(bufferPointer) // <-- is this creating a copy of that bufferPointer contents or a reference?
imageData.deinitialize(count: width * height) // <-- I tried commenting out this code, so not to free the memory but to no avail. I am not sure if the previous line copied the buffer or kept a reference to it
}
public func toUIImage() -> UIImage? {
let colorSpace = CGColorSpaceCreateDeviceRGB()
var bitmapInfo: UInt32 = CGBitmapInfo.byteOrder32Big.rawValue
bitmapInfo |= CGImageAlphaInfo.premultipliedLast.rawValue & CGBitmapInfo.alphaInfoMask.rawValue
let bytesPerRow = width * 4
let imageDataReference = UnsafeMutablePointer<Pixel>(mutating: pixels)
defer {
imageDataReference.deinitialize(count: width * height)
}
let imageContext = CGContext(data: imageDataReference, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo, releaseCallback: nil, releaseInfo: nil)
guard let cgImage = imageContext!.makeImage() else {return nil}
let image = UIImage(cgImage: cgImage)
return image
}
}
// Pixel visitor callback
public typealias PixelVisitor = (_ pixel: inout Pixel, _ args: AnyObject?) -> Void
public class ImageProcessor
{
private var rgb_img: RGBAImage
public init(img: UIImage) {
rgb_img = RGBAImage(image: img)!
}
public func Pixels() -> [Pixel] {
return rgb_img.pixels
}
public var width: Int {
get {
return rgb_img.width
}
}
public var height: Int {
get {
return rgb_img.height
}
}
public func visitPixels(_ callback: PixelVisitor, _ args: AnyObject?) {
for y in 0..<self.rgb_img.height {
let base = y * rgb_img.width
for x in 0..<self.rgb_img.width {
let index = base + x;
var pixel = rgb_img.pixels[index]
pixel.value += 0x202020 // <--- causing crash at index == 8?!
//callback(&pixel, args)
}
}
}
public func toUIImage() -> UIImage? {
return self.rgb_img.toUIImage()
}
}
我做错了什么?避免溢出的最简单方法是允许swift这么做
let res = pixel.value.addingReportingOverflow(0x202020)
pixel.value = res.partialValue
而不是你的崩溃线
如果您想处理溢出,并在这种情况下使像素为白色/黑色/红色/其他任何颜色-在我的示例中,您可以通过res上的溢出属性来检查它 它崩溃的错误消息是什么?可能是整数溢出。在添加
0x202020
并崩溃之前,什么是pixel.value
?对我来说很好,有一张200x200的图像。@MartinR你会将value
从aUInt32
更改为UInt64
?@Adrian:pixel.value
是一个32位整数,每个颜色分量(r,g,b,a)有一个字节,并直接对应于位图的内存表示。更改类型没有帮助,必须以某种方式处理溢出。如果您不关心溢出标志值,为什么不使用运算符呢?它也短路了。
let res = pixel.value.addingReportingOverflow(0x202020)
pixel.value = res.partialValue