IOS,上传图片旋转90°问题出现原因以及解决方法

作者:Sanyu发布时间:2016-06-09

这里小编提出一个项目中遇到的问题,在做个人中心这一块,User的头像需要用户自己传图片上去,要么是相机直接拍照,要么是调用相册中已有的照片,但是图片的大小不同,其中小编在传头像时,较小的图片都能正常上传和请求,但是大一些的图片就会出现没有规律的旋转;
第一,旋转情况的示例:

手机显示样子


(2)
小编在上传图片时图片的位置是正确的,但是上传后图片就会出现如上图的旋转,没有规律,或左或右,这种情况让小编一度很头疼,最后在网上找到了两种解决方法,这里小编就把我知道的方法整合出来,希望大神们的方法,能给遇到类似问题的小伙伴提供帮助(出现这种情况是因为上传的图片大小大于2M,当大于2M时图片就出旋转);
方法一:压缩图片的大小iOS自己也有要锁图片的方法例如UIImageJPEGRepresentation(image,0.1);这个方法不管你后边的倍数写多小,他都会有一个极限,遇到特殊情况,这个方法并不能把图片压倒足够小;小编的压缩方法如下:
-(UIImage )imageByScalingToMaxSize:(UIImage )sourceImage{
if (sourceImage.size.width }
CGFloat btWidth=0.0f;
CGFloat btHeight=0.0f; if (sourceImage.size.width>sourceImage.size.height) {
btHeight=ORIGINAL_MAX_WIDTH;
btWidth=sourceImage.size.width *(ORIGINAL_MAX_WIDTH/sourceImage.size.height);
}else {
btWidth=ORIGINAL_MAX_WIDTH;
btHeight=sourceImage.size.height * (ORIGINAL_MAX_WIDTH / sourceImage.size.width);
}
CGSize targetSize=CGSizeMake(btWidth, btHeight); return [self imageByScalingAndCroppingForSourceImage:sourceImage targetSize:targetSize];}
-(UIImage)imageByScalingAndCroppingForSourceImage:(UIImage )sourceImage targetSize:(CGSize)targetSize{
UIImage *newImage=nil; CGSize imageSize=sourceImage.size; CGFloat width=imageSize.width; CGFloat height=imageSize.height; CGFloat targetWidth=targetSize.width; CGFloat targetHeight=targetSize.height; CGFloat scaleFactor=0.0; CGFloat scaledWidth=targetWidth; CGFloat scaledHeight=targetHeight; CGPoint thumbnailPoint=CGPointMake(0.0, 0.0); if (CGSizeEqualToSize(imageSize, targetSize)==NO) { CGFloat widthFactor=targetWidth / width; CGFloat heightFactor= targetHeight /height; if (widthFactor > heightFactor) {
scaleFactor = widthFactor;
}else{
scaleFactor = heightFactor;
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
} // center the image if (widthFactor > heightFactor) {
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}else if ( widthFactor < heightFactor){ thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
} UIGraphicsBeginImageContext(targetSize); // this will crop CGRect thumbnailRect= CGRectZero ;
thumbnailRect.origin=thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;

[sourceImage drawInRect:thumbnailRect];

newImage = UIGraphicsGetImageFromCurrentImageContext(); if(newImage == nil) NSLog(@"could not scale image"); UIGraphicsEndImageContext(); return newImage;}
这种方法虽然该能解决图片旋转的问题,但是压缩过后的图片会出现严重失真,模糊不清出,小编又找了第二种方法
第二种:对要上传的图片进行位置的调整,在从相机中拿到照片后,对咬传的照片进行调整,如果旋转了就报它在旋转回来方法如下:
+(UIImage )fixOrientation:(UIImage )aImage {
if (aImage.imageOrientation == UIImageOrientationUp) return aImage; CGAffineTransform transform = CGAffineTransformIdentity; switch (aImage.imageOrientation) { case UIImageOrientationDown: case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
transform = CGAffineTransformRotate(transform, M_PI); break; case UIImageOrientationLeft: case UIImageOrientationLeftMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
transform = CGAffineTransformRotate(transform, M_PI_2); break; case UIImageOrientationRight: case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
transform = CGAffineTransformRotate(transform, -M_PI_2); break; default: break;
} switch (aImage.imageOrientation) { case UIImageOrientationUpMirrored: case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
transform = CGAffineTransformScale(transform, -1, 1); break; case UIImageOrientationLeftMirrored: case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);
transform = CGAffineTransformScale(transform, -1, 1); break; default: break;
} CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height, CGImageGetBitsPerComponent(aImage.CGImage), 0, CGImageGetColorSpace(aImage.CGImage), CGImageGetBitmapInfo(aImage.CGImage)); CGContextConcatCTM(ctx, transform); switch (aImage.imageOrientation) { case UIImageOrientationLeft: case UIImageOrientationLeftMirrored: case UIImageOrientationRight: case UIImageOrientationRightMirrored: // Grr... CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage); break; default: CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage); break;
} CGImageRef cgimg = CGBitmapContextCreateImage(ctx); UIImage *img = [UIImage imageWithCGImage:cgimg]; CGContextRelease(ctx); CGImageRelease(cgimg); return img;}
好了以上就是小编的全部方法,如果能帮助你,小编会非常高兴,如有其他方法也欢迎读者指出,小编也非常感谢您的不吝赐教.


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