这里有很多示例代码通过将 UIImage 转换为 JPEG 来压缩 UIImage
像这样
extension UIImage {
func resized(withPercentage percentage: CGFloat, isOpaque: Bool = true) -> UIImage? {
let canvas = CGSize(width: size.width * percentage, height: size.height * percentage)
let format = imageRendererFormat
format.opaque = isOpaque
return UIGraphicsImageRenderer(size: canvas, format: format).image {
_ in draw(in: CGRect(origin: .zero, size: canvas))
}
}
func resized(toWidth width: CGFloat, isOpaque: Bool = true) -> UIImage? {
let canvas = CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))
let format = imageRendererFormat
format.opaque = isOpaque
return UIGraphicsImageRenderer(size: canvas, format: format).image {
_ in draw(in: CGRect(origin: .zero, size: canvas))
}
}
}
例如这段代码,我试过将 isOpaque 设置为 true 和 false,在这两种情况下都不保留透明度。
这里的另一个例子Resize UIImage to 200x200pt/px
extension UIImage {
func scaleImage(toSize newSize: CGSize) -> UIImage? {
var newImage: UIImage?
let newRect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height).integral
UIGraphicsBeginImageContextWithOptions(newSize, false, 0)
if let context = UIGraphicsGetCurrentContext(), let cgImage = self.cgImage {
context.interpolationQuality = .high
let flipVertical = CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: newSize.height)
context.concatenate(flipVertical)
context.draw(cgImage, in: newRect)
if let img = context.makeImage() {
newImage = UIImage(cgImage: img)
}
UIGraphicsEndImageContext()
}
return newImage
}
}
该功能将图像调整为特定分辨率不是大小。
我拥有的是 png 图像,其中我保留了透明度,同时将文件大小保持在 500k 以下(硬限制 - 因为服务器限制它)
我怎样才能快速做到这一点?