Created
July 15, 2016 07:42
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autocrop UIImage from http://stackoverflow.com/questions/9061800/how-do-i-autocrop-a-uiimage
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func cropRect() -> CGRect { | |
let cgImage = self.CGImage! | |
let context = createARGBBitmapContextFromImage(cgImage) | |
if context == nil { | |
return CGRectZero | |
} | |
let height = CGFloat(CGImageGetHeight(cgImage)) | |
let width = CGFloat(CGImageGetWidth(cgImage)) | |
let rect = CGRectMake(0, 0, width, height) | |
CGContextDrawImage(context, rect, cgImage) | |
let data = UnsafePointer<CUnsignedChar>(CGBitmapContextGetData(context)) | |
if data == nil { | |
return CGRectZero | |
} | |
var lowX = width | |
var lowY = height | |
var highX: CGFloat = 0 | |
var highY: CGFloat = 0 | |
//Filter through data and look for non-transparent pixels. | |
for (var y: CGFloat = 0 ; y < height ; y++) { | |
for (var x: CGFloat = 0; x < width ; x++) { | |
let pixelIndex = (width * y + x) * 4 /* 4 for A, R, G, B */ | |
if data[Int(pixelIndex)] != 0 { //Alpha value is not zero pixel is not transparent. | |
if (x < lowX) { | |
lowX = x | |
} | |
if (x > highX) { | |
highX = x | |
} | |
if (y < lowY) { | |
lowY = y | |
} | |
if (y > highY) { | |
highY = y | |
} | |
} | |
} | |
} | |
return CGRectMake(lowX, lowY, highX-lowX, highY-lowY) | |
} | |
// The method to create the Bitmap Context: | |
func createARGBBitmapContextFromImage(inImage: CGImageRef) -> CGContextRef? { | |
let width = CGImageGetWidth(inImage) | |
let height = CGImageGetHeight(inImage) | |
let bitmapBytesPerRow = width * 4 | |
let bitmapByteCount = bitmapBytesPerRow * height | |
let colorSpace = CGColorSpaceCreateDeviceRGB() | |
if colorSpace == nil { | |
return nil | |
} | |
let bitmapData = malloc(bitmapByteCount) | |
if bitmapData == nil { | |
return nil | |
} | |
let context = CGBitmapContextCreate (bitmapData, | |
width, | |
height, | |
8, // bits per component | |
bitmapBytesPerRow, | |
colorSpace, | |
CGImageAlphaInfo.PremultipliedFirst.rawValue) | |
return context | |
} | |
// example | |
let image = // UIImage Source | |
let newRect = image.cropRect() | |
if let imageRef = CGImageCreateWithImageInRect(image.CGImage!, newRect) { | |
let newImage = UIImage(CGImage: imageRef) | |
// Use this new Image | |
} |
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