我使用以下函数创建图像的缩略图:
func scaleImage(image: UIImage, toSize newSize: CGSize) -> (UIImage) {
let newRect = CGRectIntegral(CGRectMake(0,0, newSize.width, newSize.height))
UIGraphicsBeginImageContextWithOptions(newSize, false, 0)
let context = UIGraphicsGetCurrentContext()
CGContextSetInterpolationQuality(context, .High)
let flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height)
CGContextConcatCTM(context, flipVertical)
CGContextDrawImage(context, newRect, image.CGImage)
let newImage = UIImage(CGImage: CGBitmapContextCreateImage(context)!)
UIGraphicsEndImageContext()
return newImage
}
我用以下方式调用它:
let imageThumb = self.scaleImage(currImage, toSize: CGSizeMake(currImage.size.width/4, currImage.size.height/4))
然后我使用以下函数对imageThumb进行编码:
func compressImage(image:UIImage) -> NSData {
// Reducing file size to a 10th
var actualHeight : CGFloat = image.size.height
var actualWidth : CGFloat = image.size.width
let maxHeight : CGFloat = 1136.0
let maxWidth : CGFloat = 640.0
var imgRatio : CGFloat = actualWidth/actualHeight
let maxRatio : CGFloat = maxWidth/maxHeight
var compressionQuality : CGFloat = 0.5
if (actualHeight > maxHeight || actualWidth > maxWidth){
if(imgRatio < maxRatio){
//adjust width according to maxHeight
imgRatio = maxHeight / actualHeight;
actualWidth = imgRatio * actualWidth;
actualHeight = maxHeight;
}
else if(imgRatio > maxRatio){
//adjust height according to maxWidth
imgRatio = maxWidth / actualWidth;
actualHeight = imgRatio * actualHeight;
actualWidth = maxWidth;
}
else{
actualHeight = maxHeight;
actualWidth = maxWidth;
compressionQuality = 1;
}
}
let rect = CGRectMake(0.0, 0.0, actualWidth, actualHeight);
UIGraphicsBeginImageContext(rect.size);
image.drawInRect(rect)
let img = UIGraphicsGetImageFromCurrentImageContext();
let imageData = UIImageJPEGRepresentation(img, compressionQuality);
UIGraphicsEndImageContext();
return imageData!;
}
最后,我将其编码为base64
并将其存储在我的数据库中。然后我检索它,解码它并在ImageView中显示。问题是我以纵向模式拍摄的所有照片最终都会以横向显示。我不确定方向丢失的方向。