Question

我目前正在使用不模糊的代码，但它只是削减了一块，如果我尝试在线使用不同的代码，它会削减一块，它也变得模糊。我需要做什么，图片是512x512，试图将其降低到100x100，这是一个jpg。

以下是我现在使用的代码：

//setting up each cell
    -(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                     cellForItemAtIndexPath:(NSIndexPath *)indexPath
    {
        CollectionGridCell *myCell = [collectionView
                                        dequeueReusableCellWithReuseIdentifier:@"GridCell"
                                        forIndexPath:indexPath];


        long row = [indexPath row];

           NSURL *baseUrl = [NSURL URLWithString:@"http://example.com/"];

    NSString *imageItemName = [homeImages objectAtIndex:row];
    NSURL *url = [NSURL URLWithString:imageItemName relativeToURL:baseUrl];

   // NSURL *url = /* prepare a url... see note below */
    [myCell.homeImage setImageWithURL:url
                     placeholderImage:[UIImage imageNamed:@"menuButton.png"]
                            completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) {
                                // inspect cacheType here to make sure it's cached as you want it
                               myCell.homeImage.image = [self resizeImage:image newSize:CGSizeMake(75,75)];

                            }];

    return myCell;

}


- (UIImage *)resizeImage:(UIImage*)image newSize:(CGSize)newSize {
    CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
    CGImageRef imageRef = image.CGImage;

    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();

    // Set the quality level to use when rescaling
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height);

    CGContextConcatCTM(context, flipVertical);
    // Draw into the context; this scales the image
    CGContextDrawImage(context, newRect, imageRef);

    // Get the resized image from the context and a UIImage
    CGImageRef newImageRef = CGBitmapContextCreateImage(context);
    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];

    CGImageRelease(newImageRef);
    UIGraphicsEndImageContext();

    return newImage;

}

更新：到目前为止，我尝试过的每种方法都会导致中间的裁剪。我是否必须在我的代码中指定其他内容，是否有东西要求它裁剪出来？

这是我的网格单元.h文件：

#import <UIKit/UIKit.h>

@interface CollectionGridCell : UICollectionViewCell
@property (weak, nonatomic) IBOutlet UIImageView *homeImage;

@end

这是我的网格单元.m文件：

#import "CollectionGridCell.h"

@implementation CollectionGridCell

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

@end

Answer 1

无需重新调整图像大小。只需在属性下方设置图片视图即可。

 [myCell.homeImage setImageWithURL:url
                     placeholderImage:[UIImage imageNamed:@"menuButton.png"]
                            completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) {
                                // inspect cacheType here to make sure it's cached as you want it
                               myCell.homeImage.image = image;
                               myCell.homeImage.contentMode = UIViewContentModeScaleAspectFit;
                            }];

Answer 2

这是一个简单的解决方案：

- (UIImage *)resizeImage:(UIImage*)image newSize:(CGSize)newSize {
    CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
    CGImageRef imageRef = image.CGImage;

    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();

    // Set the quality level to use when rescaling
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height);

    CGContextConcatCTM(context, flipVertical);  
    // Draw into the context; this scales the image
    CGContextDrawImage(context, newRect, imageRef);

    // Get the resized image from the context and a UIImage
    CGImageRef newImageRef = CGBitmapContextCreateImage(context);
    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];

    CGImageRelease(newImageRef);
    UIGraphicsEndImageContext();    

    return newImage;
}

从此链接引用： -

http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/

How to scale down a UIImage and make it crispy / sharp at the same time instead of blurry?

Answer 3

方法：

CGRect rect = CGRectMake(0,0,100,100);
UIGraphicsBeginImageContext(rect.size );
[yourCurrentOriginalImage drawInRect:rect];
UIImage *picture1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

NSData *imageData = UIImagePNGRepresentation(picture1);
UIImage *img=[UIImage imageWithData:imageData];

方法2：

CGSize newSize = CGSizeMake(100, 100);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)]; //image => Your imageName
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
UIGraphicsEndImageContext();

ImageView.contentMode = UIViewContentModeScaleAspectFit;

如何调整图像大小并避免模糊？

3 个答案: