iOS 图片背景模糊效果
1.使用CoreImage中的模糊滤镜
原始效果图如下:
CoreImage的实现:
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UIImage * image = [UIImage imageNamed:@"icon"];
/*..CoreImage中的模糊效果滤镜..*/
//CIImage,相当于UIImage,作用为获取图片资源
CIImage * ciImage = [[CIImage alloc]initWithImage:image
];
//CIFilter,高斯模糊滤镜
CIFilter * blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"];
//将图片输入到滤镜中
[blurFilter setValue:ciImage forKey:kCIInputImageKey];
//用来查询滤镜可以设置的参数以及一些相关的信息
NSLog(@"%@",[blurFilter attributes]);
//设置模糊程度,默认为10,取值范围(0-100)
[blurFilter setValue:@(20) forKey:@"inputRadius"];
//将处理好的图片输出
CIImage * outCiImage = [blurFilter valueForKey:kCIOutputImageKey];
//CIContext
CIContext * context = [CIContext contextWithOptions:nil];
//获取CGImage句柄,也就是从数据流中取出图片
CGImageRef outCGImage = [context createCGImage:outCiImage fromRect:[outCiImage extent]];
//最终获取到图片
UIImage * blurImage = [UIImage imageWithCGImage:outCGImage];
//释放CGImage句柄
CGImageRelease(outCGImage);
UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds];
imageView.image = blurImage;
[self.view addSubview:imageView];
}
[blurFilter attributes]打印结果如下:
//参数以及一些相关的信息,如果不做任何的设置,默认程度为10( CIAttributeDefault = 10);
{
"CIAttributeFilterAvailable_Mac" = "10.4";
"CIAttributeFilterAvailable_iOS" = 6;
CIAttributeFilterCategories = (
CICategoryBlur,
CICategoryStillImage,
CICategoryVideo,
CICategoryBuiltIn
);
CIAttributeFilterDisplayName = "Gaussian Blur";
CIAttributeFilterName = CIGaussianBlur;
CIAttributeReferenceDocumentation = "http://developer.apple.com/cgi-bin/apple_ref.cgi?apple_ref=//apple_ref/doc/filter/ci/CIGaussianBlur";
inputImage = {
CIAttributeClass = CIImage;
CIAttributeDescription = "The image to use as an input image. For filters that also use a background image, this is the foreground image.";
CIAttributeDisplayName = Image;
CIAttributeType = CIAttributeTypeImage;
};
inputRadius = {
CIAttributeClass = NSNumber;
CIAttributeDefault = 10;
CIAttributeDescription = "The radius determines how many pixels are used to create the blur. The larger the radius, the blurrier the result.";
CIAttributeDisplayName = Radius;
CIAttributeIdentity = 0;
CIAttributeMin = 0;
CIAttributeSliderMax = 100;
CIAttributeSliderMin = 0;
CIAttributeType = CIAttributeTypeScalar;
};
}
默认程度为10效果图如下: 
默认程度为50效果图如下:
2.使用UIImage+ImageEffects
到该地址下载:https://github.com/YouXianMing/UIImageBlur,里面还有很多好东西,值得关注;
导入UIImage+ImageEffects文件到工程中即可使用;
UIImage+ImageEffects的实现:
UIImage * image = [UIImage imageNamed:@"icon"];
//模糊效果渲染耗费时间,建议在子线程中渲染
//对图片进行模糊
UIImage * blurImage = [image blurImage];
//设置模糊度
UIImage * blurImage1 = [image blurImageWithRadius:10];
//设置局部模糊度
UIImage * blurImage2 = [image blurImageAtFrame:CGRectMake(0, 0, image.size.width, image.size.height/2)];
//灰度效果
UIImage * blurImage3 = [image grayScale];
/*其他的一些方法,可以自己尝试使用
//固定宽度与固定高度
- (UIImage *)scaleWithFixedWidth:(CGFloat)width;
- (UIImage *)scaleWithFixedHeight:(CGFloat)height;
//平均的颜色
- (UIColor *)averageColor;
//裁剪图片的一部分
- (UIImage *)croppedImageAtFrame:(CGRect)frame;
*/
UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds];
imageView.image = blurImage;
[self.view addSubview:imageView];
效果图分别如下:
//局部模糊
//灰色
3.使用UIVisualEffectView
注意:UIVisualEffectView只适用用户iOS 8或以上,才可以使用8以下则不能使用;
UIVisualEffectView的实现:
1.直接将文本内容加在effectView(该情况下的文本内容不能与背景相符应);
UIImage * image = [UIImage imageNamed:@"icon"];
UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds];
imageView.image = image;
[self.view addSubview:imageView];
UIBlurEffect * blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
//创建模糊view
UIVisualEffectView * effectView = [[UIVisualEffectView alloc]initWithEffect:blur];
effectView.frame = CGRectMake(0, 250, imageView.frame.size.width, 200);
[imageView addSubview:effectView];
//添加显示文本
UILabel * lable = [[UILabel alloc]initWithFrame:effectView.bounds];
lable.text = @"哈哈哈哈哈";
lable.textAlignment = NSTextAlignmentCenter;
lable.font = [UIFont systemFontOfSize:24];
[effectView.contentView addSubview:lable];
效果图如下:
2.加在effectView的子view中使文本与背景相符应;
UIImage * image = [UIImage imageNamed:@"icon"];
UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds];
imageView.image = image;
[self.view addSubview:imageView];
UIBlurEffect * blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
//创建模糊view
UIVisualEffectView * effectView = [[UIVisualEffectView alloc]initWithEffect:blur];
effectView.frame = CGRectMake(0, 250, imageView.frame.size.width, 200);
[imageView addSubview:effectView];
//添加显示文本
UILabel * lable = [[UILabel alloc]initWithFrame:effectView.bounds];
lable.text = @"哈哈哈哈哈";
lable.textAlignment = NSTextAlignmentCenter;
lable.font = [UIFont systemFontOfSize:24];
//创建模糊子view的UIVisualEffectView
//1.创建出子模糊view
UIVisualEffectView * subEffectView = [[UIVisualEffectView alloc]initWithEffect:[UIVibrancyEffect effectForBlurEffect:(UIBlurEffect *)effectView.effect]];
//2.设定尺寸
subEffectView.frame = effectView.bounds;
//3.将子模糊view添加到effectView的contentView才能够生效
[effectView.contentView addSubview:subEffectView];
//4.添加要显示的view来达到特殊的效果
[subEffectView.contentView addSubview:lable];
效果图如下:
4.下载图片后自动模糊效果
在项目中导入UIImage+ImageEffects和GCD文件;
UIImage+ImageEffects地址:https://github.com/YouXianMing/UIImageBlur;
GCD地址:https://github.com/YouXianMing/GCD-Program;
代码的实现:
创建一个UIView的子类,命名为BlurDownloadPicView;
BlurDownloadPicView.h的里面内容:
#import <UIKit/UIKit.h>
@interface BlurDownloadPicView : UIView
//图片下载地址
@property (nonatomic, strong)NSString * picUrl;
//图片显示的方式
@property (nonatomic)UIViewContentMode contentMode;
//开始执行
- (void)startProgress;
@end
BlurDownloadPicView.m的里面内容:
#import "BlurDownloadPicView.h"
#import "GCD.h"
#import "UIImage+ImageEffects.h"
@interface BlurDownloadPicView ()
@property (nonatomic, strong)UIImageView * imageView;
@end
@implementation BlurDownloadPicView
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self loadSubViews];
}
return self;
}
- (void)loadSubViews
{
self.imageView = [[UIImageView alloc]initWithFrame:self.bounds];
self.imageView.alpha = 0;
[self addSubview:self.imageView];
}
- (void)startProgress
{
if (self.picUrl) {
[GCDQueue executeInGlobalQueue:^{
//创建请求
NSURLRequest * request = [NSURLRequest requestWithURL:[NSURL URLWithString:self.picUrl]];
//因为是同步请求,会阻塞主线程(mainQueue)
NSData * data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
//获取图片
UIImage * image = [[UIImage alloc]initWithData:data];
//对图片进行模糊,会阻塞主线程(mainQueue)
UIImage * blurImage = [image blurImage];
[GCDQueue executeInMainQueue:^{
//加载图片
self.imageView.image = blurImage;
[UIView animateWithDuration:1 animations:^{
self.imageView.alpha = 1;
}];
}];
}];
}
}
//重写set,get方法
-(void)setContentMode:(UIViewContentMode)contentMode
{
self.contentMode = contentMode;
self.imageView.contentMode = contentMode;
}
- (UIViewContentMode)contentMode
{
return self.contentMode;
}在ViewController.m里面的实现;
引入#import “BlurDownloadPicView.h”头文件
在viewDidLoad里面的代码实现
- (void)viewDidLoad {
[super viewDidLoad];
NSString * picUrl = @"http://i4.download.fd.pchome.net/g1/M00/0D/1C/oYYBAFTEeAmIWRXgAAKhY5iKdP8AACP_QP4y0IAAqF7878.jpg";
BlurDownloadPicView * blurPicView = [[BlurDownloadPicView alloc]initWithFrame:self.view.bounds];
[self.view addSubview:blurPicView];
blurPicView.picUrl = picUrl;
[blurPicView startProgress];
}效果图如下:
