我试图将图像分割成16个（在矩阵中）。我使用的是swift 2.1。这是代码：
let cellSize = Int(originalImage.size.height) / 4
for i in 0...4 {
for p in 0...4 {
let tmpImgRef: CGImage = originalImage.CGImage!
let rect: CGImage = CGImageCreateWithImageInRect(tmpImgRef, CGRectMake(CGFloat(i * cellSize), CGFloat(p * cellSize), CGFloat(cellSize), CGFloat(cellSize)))!
gameCells.append(cell)
}
}
这有效，但返回的图像只是原始图像的一部分。我一直在搜索，我知道这是因为当我创建一个CGImage时，它的大小与UIImage不同，但我不知道如何解决它。如果我可以使用CGImage的高度而不是UIImage来制作变量cellSize，我想我会修复它，但我无法获得CGImage高度。
感谢您的帮助！
答案 0 :(得分：4)
根本问题是UIImage和CGImage解释其size的方式之间的区别。 UIImage使用“点数”，CGImage使用像素。转换因子是scale。
例如，如果UIImage的{{1}}为3，则scale在任何给定方向上的每个“点”，底层UIImage中的该方向上有三个像素1}}。因此对于CGImage为3和UIImage为100x100点的scale，基础size的大小为300x300像素。
要返回由 n x n 切割的简单图像数组（例如，如果 n 为3，则会有9个图像数组），您可以在Swift 3中执行以下操作：
CGImage或者，在Swift 2.3中：
/// Slice image into array of tiles
///
/// - Parameters:
/// - image: The original image.
/// - howMany: How many rows/columns to slice the image up into.
///
/// - Returns: An array of images.
///
/// - Note: The order of the images that are returned will correspond
/// to the `imageOrientation` of the image. If the image's
/// `imageOrientation` is not `.up`, take care interpreting
/// the order in which the tiled images are returned.
func slice(image: UIImage, into howMany: Int) -> [UIImage] {
let width: CGFloat
let height: CGFloat
switch image.imageOrientation {
case .left, .leftMirrored, .right, .rightMirrored:
width = image.size.height
height = image.size.width
default:
width = image.size.width
height = image.size.height
}
let tileWidth = Int(width / CGFloat(howMany))
let tileHeight = Int(height / CGFloat(howMany))
let scale = Int(image.scale)
var images = [UIImage]()
let cgImage = image.cgImage!
var adjustedHeight = tileHeight
var y = 0
for row in 0 ..< howMany {
if row == (howMany - 1) {
adjustedHeight = Int(height) - y
}
var adjustedWidth = tileWidth
var x = 0
for column in 0 ..< howMany {
if column == (howMany - 1) {
adjustedWidth = Int(width) - x
}
let origin = CGPoint(x: x * scale, y: y * scale)
let size = CGSize(width: adjustedWidth * scale, height: adjustedHeight * scale)
let tileCgImage = cgImage.cropping(to: CGRect(origin: origin, size: size))!
images.append(UIImage(cgImage: tileCgImage, scale: image.scale, orientation: image.imageOrientation))
x += tileWidth
}
y += tileHeight
}
return images
}
这可确保生成的图像位于正确的func slice(image image: UIImage, into howMany: Int) -> [UIImage] {
let width: CGFloat
let height: CGFloat
switch image.imageOrientation {
case .Left, .LeftMirrored, .Right, .RightMirrored:
width = image.size.height
height = image.size.width
default:
width = image.size.width
height = image.size.height
}
let tileWidth = Int(width / CGFloat(howMany))
let tileHeight = Int(height / CGFloat(howMany))
let scale = Int(image.scale)
var images = [UIImage]()
let cgImage = image.CGImage!
var adjustedHeight = tileHeight
var y = 0
for row in 0 ..< howMany {
if row == (howMany - 1) {
adjustedHeight = Int(height) - y
}
var adjustedWidth = tileWidth
var x = 0
for column in 0 ..< howMany {
if column == (howMany - 1) {
adjustedWidth = Int(width) - x
}
let origin = CGPoint(x: x * scale, y: y * scale)
let size = CGSize(width: adjustedWidth * scale, height: adjustedHeight * scale)
let tileCgImage = CGImageCreateWithImageInRect(cgImage, CGRect(origin: origin, size: size))!
images.append(UIImage(CGImage: tileCgImage, scale: image.scale, orientation: image.imageOrientation))
x += tileWidth
}
y += tileHeight
}
return images
}
中（这就是为什么上面的图像在“点”中跨越图像并且乘以获得scale中的正确像素）。同样，如果尺寸（以“点”为单位）不能被 n 整除，则它将分别构成该行或列的最后一个图像的差异。例如。当你为一个高度为736点的图像制作三个图块时，前两个将是245个点，但最后一个将是246个点。
有一个例外，它没有（完全）优雅地处理。也就是说，如果CGImage的{{1}}不是UIImage，则检索图像的顺序对应于该方向，而不是您查看时图像的左上角它
答案 1 :(得分：3)
您可以将图像纵向和横向分成两部分，然后根据需要进行子分割：
extension UIImage {
var topHalf: UIImage? {
guard let cgImage = cgImage, let image = cgImage.cropping(to: CGRect(origin: .zero, size: CGSize(width: size.width, height: size.height/2))) else { return nil }
return UIImage(cgImage: image, scale: scale, orientation: imageOrientation)
}
var bottomHalf: UIImage? {
guard let cgImage = cgImage, let image = cgImage.cropping(to: CGRect(origin: CGPoint(x: 0, y: CGFloat(Int(size.height)-Int(size.height/2))), size: CGSize(width: size.width, height: CGFloat(Int(size.height) - Int(size.height/2))))) else { return nil }
return UIImage(cgImage: image, scale: scale, orientation: imageOrientation)
}
var leftHalf: UIImage? {
guard let cgImage = cgImage, let image = cgImage.cropping(to: CGRect(origin: .zero, size: CGSize(width: size.width/2, height: size.height))) else { return nil }
return UIImage(cgImage: image, scale: scale, orientation: imageOrientation)
}
var rightHalf: UIImage? {
guard let cgImage = cgImage, let image = cgImage.cropping(to: CGRect(origin: CGPoint(x: CGFloat(Int(size.width)-Int((size.width/2))), y: 0), size: CGSize(width: CGFloat(Int(size.width)-Int((size.width/2))), height: size.height)))
else { return nil }
return UIImage(cgImage: image, scale: scale, orientation: imageOrientation)
}
var splitedInFourParts: [UIImage] {
guard case let topHalf = topHalf,
case let bottomHalf = bottomHalf,
let topLeft = topHalf?.leftHalf,
let topRight = topHalf?.rightHalf,
let bottomLeft = bottomHalf?.leftHalf,
let bottomRight = bottomHalf?.rightHalf else{ return [] }
return [topLeft, topRight, bottomLeft, bottomRight]
}
var splitedInSixteenParts: [UIImage] {
var array = splitedInFourParts.flatMap({$0.splitedInFourParts})
// if you need it in reading order you need to swap some image positions
swap(&array[2], &array[4])
swap(&array[3], &array[5])
swap(&array[10], &array[12])
swap(&array[11], &array[13])
return array
}
}
按列和行拆分图像：
extension UIImage {
func matrix(_ rows: Int, _ columns: Int) -> [UIImage] {
let y = (size.height / CGFloat(rows)).rounded()
let x = (size.width / CGFloat(columns)).rounded()
var images: [UIImage] = []
images.reserveCapacity(rows * columns)
guard let cgImage = cgImage else { return [] }
(0..<rows).forEach { row in
(0..<columns).forEach { column in
var width = Int(x)
var height = Int(y)
if row == rows-1 && size.height.truncatingRemainder(dividingBy: CGFloat(rows)) != 0 {
height = Int(size.height - size.height / CGFloat(rows) * (CGFloat(rows)-1))
}
if column == columns-1 && size.width.truncatingRemainder(dividingBy: CGFloat(columns)) != 0 {
width = Int(size.width - (size.width / CGFloat(columns) * (CGFloat(columns)-1)))
}
if let image = cgImage.cropping(to: CGRect(origin: CGPoint(x: column * Int(x), y: row * Int(x)), size: CGSize(width: width, height: height))) {
images.append(UIImage(cgImage: image, scale: scale, orientation: imageOrientation))
}
}
}
return images
}
}
let myPicture = UIImage(data: try! Data(contentsOf: URL(string:"https://i.stack.imgur.com/Xs4RX.jpg")!))!
let images = myPicture.matrix(4, 4)
images.count // 16
答案 2 :(得分：0)
我用它将图像切割成矩阵。矩阵表示为一维数组。
func snapshotImage(image: UIImage, rect: CGRect) -> UIImage {
var imageRect: CGRect! = rect
if image.scale > 1.0 {
imageRect = CGRect(origin: CGPoint(x: rect.origin.x * image.scale, y: rect.origin.y * image.scale), size: CGSize(width: rect.size.width * image.scale, height: rect.size.height * image.scale))
}
let imageRef: CGImage = image.cgImage!.cropping(to: imageRect)!
let result: UIImage = UIImage(cgImage: imageRef, scale: image.scale, orientation: image.imageOrientation)
return result
}
func sliceImage(image: UIImage, size: CGSize) -> [UIImage] {
var slices: [UIImage] = [UIImage]()
var rect = CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height)
var y: Float = 0.0
let width: Int = Int(image.size.width / size.width)
let height: Int = Int(image.size.height / size.height)
for _ in 0...height {
var x: Float = 0.0
for _ in 0...width {
rect.origin.x = CGFloat(x);
slices.append(self.snapshotImage(image: image, rect: rect))
x += Float(size.width)
}
y += Float(size.height)
rect.origin.y = CGFloat(y)
}
return slices
}