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:
上传前相册图片样子
上传后手机应用显示样子(1)
(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<ORIGINAL_MAX_WIDTH) {
return sourceImage;
}
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(这个方法我用了类别,写成➕方法来用,加号没识别出来,变成了黑点):
- (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.
