[TOC
126.SDWebImage2——显示gif图片
一、说明
其实我们的 GIF分类就是把我们的 GIF差分为一张一张的图片 ，然后再用 UIImageView 的view动画，来播放这些图片。
二、UIImage+GIF 分类
2.1 UIImage+GIF.h
//
// UIImage+GIF.h
// LBGIFImage
//
// Created by Laurin Brandner on 06.01.12.
// Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//
#import <UIKit/UIKit.h>
@interface UIImage (GIF)
//传入Gif图像的名称，得到一个可动画的图像
+ (UIImage *)sd_animatedGIFNamed:(NSString *)name;
//传入Gif图像的二进制数据，得到一个可动画的图像
+ (UIImage *)sd_animatedGIFWithData:(NSData *)data;
- (UIImage *)sd_animatedImageByScalingAndCroppingToSize:(CGSize)size;
@end2.2 UIImage+GIF.m
//
// UIImage+GIF.m
// LBGIFImage
//
// Created by Laurin Brandner on 06.01.12.
// Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//
#import "UIImage+GIF.h"
#import <ImageIO/ImageIO.h>
@implementation UIImage (GIF)
//把图片的二进制数据转换为图片（GIF）
+ (UIImage *)sd_animatedGIFWithData:(NSData *)data {
//如果传入的二进制数据为空，则直接返回nil
if (!data) {
return nil;
}
// 创建图像源
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
// 获取图片帧数
size_t count = CGImageSourceGetCount(source);
//初始化animatedImage
UIImage *animatedImage;
//如果图片帧数小于等于1，那么就直接把二进制数据转换为图片，并返回图片
if (count <= 1) {
animatedImage = [[UIImage alloc] initWithData:data];
}
else {
//创建可变的空的图片数组
NSMutableArray *images = [NSMutableArray array];
//初始化动画播放时间为0
NSTimeInterval duration = 0.0f;
// 遍历并且提取所有的动画帧
for (size_t i = 0; i < count; i++) {
CGImageRef image = CGImageSourceCreateImageAtIndex(source, i, NULL);
// 累加动画时长
duration += [self sd_frameDurationAtIndex:i source:source];
// 将图像添加到动画数组
[images addObject:[UIImage imageWithCGImage:image scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp]];
//释放操作
CGImageRelease(image);
}
//计算动画时间
if (!duration) {
duration = (1.0f / 10.0f) * count;
}
// 建立可动画图像
animatedImage = [UIImage animatedImageWithImages:images duration:duration];
}
//释放操作
CFRelease(source);
return animatedImage;
}
//获得播放的时间长度
+ (float)sd_frameDurationAtIndex:(NSUInteger)index source:(CGImageSourceRef)source {
float frameDuration = 0.1f;
//获得图像的属性（图像源，索引）
CFDictionaryRef cfFrameProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil);
//桥接转换为NSDictionary类型
NSDictionary *frameProperties = (__bridge NSDictionary *)cfFrameProperties;
//取出图像属性里面kCGImagePropertyGIFDictionary这个KEY对应的值，即GIF属性
NSDictionary *gifProperties = frameProperties[(NSString *)kCGImagePropertyGIFDictionary];
//得到延迟时间
NSNumber *delayTimeUnclampedProp = gifProperties[(NSString *)kCGImagePropertyGIFUnclampedDelayTime];
if (delayTimeUnclampedProp) {
//把延迟时间转换为浮点数类型
frameDuration = [delayTimeUnclampedProp floatValue];
}
else {
//如果上面获得的延迟时间为空，则换另外一种方式获得
NSNumber *delayTimeProp = gifProperties[(NSString *)kCGImagePropertyGIFDelayTime];
if (delayTimeProp) {
frameDuration = [delayTimeProp floatValue];
}
}
// Many annoying ads specify a 0 duration to make an image flash as quickly as possible.
// We follow Firefox's behavior and use a duration of 100 ms for any frames that specify
// a duration of <= 10 ms. See <rdar://problem/7689300> and <http://webkit.org/b/36082>
// for more information.
//处理延迟时间
if (frameDuration < 0.011f) {
frameDuration = 0.100f;
}
//释放操作
CFRelease(cfFrameProperties);
return frameDuration;
}
//处理GIF图片
+ (UIImage *)sd_animatedGIFNamed:(NSString *)name {
//获得scale
CGFloat scale = [UIScreen mainScreen].scale;
if (scale > 1.0f) {
//根据图片的名称拼接bundle全路径
NSString *retinaPath = [[NSBundle mainBundle] pathForResource:[name stringByAppendingString:@"@2x"] ofType:@"gif"];
//加载指定路径的图片（二进制数据）
NSData *data = [NSData dataWithContentsOfFile:retinaPath];
//如果data不为空，则直接调用sd_animatedGIFWithData返回一张可动画的图片
if (data) {
return [UIImage sd_animatedGIFWithData:data];
}
//下面的处理和上面一样
NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"gif"];
data = [NSData dataWithContentsOfFile:path];
if (data) {
return [UIImage sd_animatedGIFWithData:data];
}
return [UIImage imageNamed:name];
}
else {
NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"gif"];
NSData *data = [NSData dataWithContentsOfFile:path];
if (data) {
return [UIImage sd_animatedGIFWithData:data];
}
return [UIImage imageNamed:name];
}
}
//缩放|裁剪...
- (UIImage *)sd_animatedImageByScalingAndCroppingToSize:(CGSize)size {
//如果尺寸相等或者是为0则直接返回
if (CGSizeEqualToSize(self.size, size) || CGSizeEqualToSize(size, CGSizeZero)) {
return self;
}
CGSize scaledSize = size;
CGPoint thumbnailPoint = CGPointZero;
CGFloat widthFactor = size.width / self.size.width;
CGFloat heightFactor = size.height / self.size.height;
CGFloat scaleFactor = (widthFactor > heightFactor) ? widthFactor : heightFactor;
scaledSize.width = self.size.width * scaleFactor;
scaledSize.height = self.size.height * scaleFactor;
if (widthFactor > heightFactor) {
thumbnailPoint.y = (size.height - scaledSize.height) * 0.5;
}
else if (widthFactor < heightFactor) {
thumbnailPoint.x = (size.width - scaledSize.width) * 0.5;
}
//初始化可变的缩放图像数组
NSMutableArray *scaledImages = [NSMutableArray array];
//遍历图片
for (UIImage *image in self.images) {
//开启图像上下文
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
//画图，把image绘制到指定的位置
[image drawInRect:CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledSize.width, scaledSize.height)];
//根据当前图形上下文获得一张新的图片
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
//把新图片添加到图像数组
[scaledImages addObject:newImage];
//关闭图形上下文
UIGraphicsEndImageContext();
}
//建立可动画的图像并返回
return [UIImage animatedImageWithImages:scaledImages duration:self.duration];
}
@end三、示例代码
/*gif图片显示*/
-(void)gif{
UIImage *image = [UIImage sd_animatedGIFNamed:@"20140310135421_BJ4UP"];
self.imageView.image =image;
}–
四、图示
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