#import "UIImage+Placeholder.h"
#import "MyCommon.h"
#define SCLoading @"SCLoading"
static NSMutableDictionary *mutableImageDic;
@implementation UIImage (Placeholder)
+ (UIImage *)loadingImage:(CGSize)size{
//初始化
if (!mutableImageDic) {
mutableImageDic = [NSMutableDictionary new];
[mutableImageDic setObject:[UIImage imageNamed:SCLoading] forKey:SCLoading];
}
if (CGSizeEqualToSize(size, CGSizeZero)) {//如果是自动布局没有size，则三倍面积
UIImage *img = (UIImage *)[mutableImageDic objectForKey:SCLoading];
size = CGSizeMake(img.size.width * 3, img.size.height * 3);
}
//如果缓存里面，马上返回
NSString *imageSizeKey = NSStringFromCGSize(size);
UIImage *cacheImage = [mutableImageDic objectForKey:imageSizeKey];
if (cacheImage) {
return cacheImage;
}
//没有就绘制
UIImage *img = [mutableImageDic objectForKey:SCLoading];
UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, UIColorFromRGB(0xDBDBDB).CGColor);
CGContextFillRect(context, CGRectMake(0, 0, size.width, size.height));
if (size.width < img.size.width || size.height < img.size.height) {
[img drawInRect:CGRectMake(0, 0, size.width, size.height)];
}else{
[img drawInRect:CGRectMake((size.width - img.size.width)/2, (size.height - img.size.height)/2, img.size.width, img.size.height)];
}
UIImage* retImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//绘制后添加到到字典内
[mutableImageDic setObject:retImage forKey:imageSizeKey];
return retImage;
}
@end
