展示本地gif图片
SDWebImage比较占内存,FLAnimatedImage不怎么占用内存
1.使用SDWebImage
- 导入头文件
#import "UIImage+GIF.h" - 设置gif图
self.imageView.image = [UIImage sd_animatedGIFNamed:@"test"];
也可以通过NSData导入
+ (UIImage *)sd_animatedGIFWithData:(NSData *)data
2.使用FLAnimatedImage
- 导入头文件
#import "FLAnimatedImage.h" - 设置gif图
NSString *path = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"gif"];
NSData *data = [NSData dataWithContentsOfFile:path];
FLAnimatedImage *image = [FLAnimatedImage animatedImageWithGIFData:data];
self.imageView.animatedImage = image;
3.SDWebImage实现原理
使用UIImage + GIF分类
1.将gif图的每一帧导出为一个UIImage,并且算出每一帧的播放时间,将导出的image放入images数组中
2.使用+ animatedImageWithImages: duration: 方法创建image,参数为第一步的images数组和播放总时长
3.设置UIImageView的image时用sd_animatedGIFNamed:方法即可展示gif
方法1: 通过NSData获取gif的UIImage
方法名:+ (UIImage )sd_animatedGIFWithData:(NSData *)data;
- 获取gif数据,及其帧数
- 获取每帧的像素位图,求出每帧的播放时间
- 按照屏幕分辨率生成UIImage并放入数组
- 通过+ animatedImageWithImages: duration:生成UIImage
+ (UIImage *)sd_animatedGIFWithData:(NSData *)data {
if (!data) {
return nil;
}
//通过CFData读取gif文件的数据
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
//获取gif文件的帧数
size_t count = CGImageSourceGetCount(source);
UIImage *animatedImage;
if (count <= 1) {
animatedImage = [[UIImage alloc] initWithData:data];
}
else {//大于一张图片时
NSMutableArray *images = [NSMutableArray array];
//设置gif播放的时间
NSTimeInterval duration = 0.0f;
for (size_t i = 0; i < count; i++) {
//获取gif指定帧的像素位图
CGImageRef image = CGImageSourceCreateImageAtIndex(source, i, NULL);
if (!image) {
continue;
}
//获取每张图的播放时间
duration += [self sd_frameDurationAtIndex:i source:source];
[images addObject:[UIImage imageWithCGImage:image scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp]];
CGImageRelease(image);
}
if (!duration) {//如果播放时间为空
duration = (1.0f / 10.0f) * count;
}
animatedImage = [UIImage animatedImageWithImages:images duration:duration];
}
CFRelease(source);
return animatedImage;
}
方法2:获取指定帧的image的播放时间
方法名:+ (float)sd_frameDurationAtIndex:(NSUInteger)index source:(CGImageSourceRef)source
- 获取指定帧图片的属性字典
- 获取图片的gif属性字典
- 获取每一帧的播放时间(如果小于0.1,设置为0.1)
+ (float)sd_frameDurationAtIndex:(NSUInteger)index source:(CGImageSourceRef)source {
float frameDuration = 0.1f;
//获取这一帧图片的属性字典
CFDictionaryRef cfFrameProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil);
NSDictionary *frameProperties = (__bridge NSDictionary *)cfFrameProperties;
//获取gif属性字典
NSDictionary *gifProperties = frameProperties[(NSString *)kCGImagePropertyGIFDictionary];
//获取这一帧持续的时间
NSNumber *delayTimeUnclampedProp = gifProperties[(NSString *)kCGImagePropertyGIFUnclampedDelayTime];
if (delayTimeUnclampedProp) {
frameDuration = [delayTimeUnclampedProp floatValue];
}
else {
NSNumber *delayTimeProp = gifProperties[(NSString *)kCGImagePropertyGIFDelayTime];
if (delayTimeProp) {
frameDuration = [delayTimeProp floatValue];
}
}
//如果帧数小于0.1,则指定为0.1
if (frameDuration < 0.011f) {
frameDuration = 0.100f;
}
CFRelease(cfFrameProperties);
return frameDuration;
}
方法3:通过图片的Name获取UIImage
方法名:+ (UIImage *)sd_animatedGIFNamed:(NSString *)name;
- 根据屏幕分辨率给图片自动加后缀(@2x)
- 从mainBundle中获取Data数据
- 调用方法 + sd_animatedGIFWithData:
+ (UIImage *)sd_animatedGIFNamed:(NSString *)name {
//判断屏幕分辨率
CGFloat scale = [UIScreen mainScreen].scale;
if (scale > 1.0f) {
NSString *retinaPath = [[NSBundle mainBundle] pathForResource:[name stringByAppendingString:@"@2x"] ofType:@"gif"];
NSData *data = [NSData dataWithContentsOfFile:retinaPath];
if (data) {
return [UIImage sd_animatedGIFWithData:data];
}
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];
}
}
方法4:对gif按比例进行缩放
方法名:- (UIImage *)sd_animatedImageByScalingAndCroppingToSize:(CGSize)size;
- 获取较大的缩放比例值,宽高等比缩放
- 调整位置,使缩放后的图居中
- 遍历self.images, 将图片缩放后导出放入数组
- 通过animatedImageWithImages:duration:返回image
- (UIImage *)sd_animatedImageByScalingAndCroppingToSize:(CGSize)size {
if (CGSizeEqualToSize(self.size, size) || CGSizeEqualToSize(size, CGSizeZero)) {
return self;
}
CGSize scaledSize = size;
CGPoint thumbnailPoint = CGPointZero;
//获取较大的缩放比例值,宽高等比缩放
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;
//调整位置,使缩放后的图居中
if (widthFactor > heightFactor) {
thumbnailPoint.y = (size.height - scaledSize.height) * 0.5;
}
else if (widthFactor < heightFactor) {
thumbnailPoint.x = (size.width - scaledSize.width) * 0.5;
}
//遍历self.images, 将图片缩放后导出放入数组
NSMutableArray *scaledImages = [NSMutableArray array];
for (UIImage *image in self.images) {
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
[image drawInRect:CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledSize.width, scaledSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
[scaledImages addObject:newImage];
UIGraphicsEndImageContext();
}
return [UIImage animatedImageWithImages:scaledImages duration:self.duration];
}
