图像阵列中的快速分割
图像阵列中的快速分割
提问于 2017-03-24 19:56:05
我试图把一个图像分割出来(在一个矩阵中)，创建16个图像。我用的是斯威夫特2.1。下面是代码：
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)
}
}这是可行的，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，但我不知道如何修复它。如果我能够使变量cellSize与CGImage的高度而不是UIImage的高度相对应，我想我会修复它，但不能得到CGImage的高度。
谢谢你的帮助！
回答 3
Stack Overflow用户
回答已采纳
发布于 2017-03-24 22:18:25
根本的问题是UIImage和CGImage如何解释他们的size之间的区别。UIImage使用“点”，CGImage使用像素。转换因子是scale。
例如，如果UIImage的scale为3，任何给定方向的“点”-- UIImage --都有三个像素在基础CGImage中。因此，对于UIImage的scale为3，size为100 x100点，底层CGImage的大小为300×300像素。
若要返回由n切片的图像的简单数组(例如，如果n为3，数组中将有9幅图像)，您可以在Swift 3中执行如下操作：
/// 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
}或者，在Swift 2.3中：
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
}这确保了生成的图像在正确的scale中(这就是为什么上面的图像在“点”中跨出并乘以在CGImage中获得正确的像素)。这也是，如果以“点”为单位的尺寸不能被n整除，它将分别弥补该行或列的最后图像中的差异。例如，当你为一个高度为736点的图像制作三个瓷砖时，前两个是245个点，而最后一个是246个点)。
有一个例外，这不能(完全)优雅地处理。也就是说，如果UIImage的imageOrientation不是.up，那么检索图像的顺序对应于该方向，而不是在您查看图像的左上角。
Stack Overflow用户
发布于 2017-03-24 20:55:39
您可以将图像分割为垂直和水平两部分，并根据需要将结果拆分：
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
}
}将图像按列和行拆分：
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 // 16Stack Overflow用户
发布于 2017-03-24 20:35:28
我用这个把图像分割成矩阵。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
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/43008098
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