如何让制作一个可以保持圆角的CCSprite

原文

@interface StretchableSprite : CCSprite {}+(id)spriteWithFile:(NSString*)file size:(CGSize)size leftCap:(NSInteger)leftcap topCap:(NSInteger)topcap;-(id)initWithFile:(NSString*)file size:(CGSize)size leftCap:(NSInteger)leftcap topCap:(NSInteger)topcap;@end@implementation StretchableSprite+(id)spriteWithFile:(NSString*)file size:(CGSize)size leftCap:(NSInteger)leftcap topCap:(NSInteger)topcap{    return [[[self alloc] initWithFile:file size:size leftCap:leftcap topCap:topcap] autorelease];}-(id)initWithFile:(NSString*)file size:(CGSize)size leftCap:(NSInteger)leftcap topCap:(NSInteger)topcap{    UIImage* image = [UIImage imageNamed:file];    CGImageRef base = image.CGImage;     CGContextRef context = CGBitmapContextCreate(nil,                                                 size.width,                                                  size.height,                                                  CGImageGetBitsPerComponent(base),                                                  4 * size.width,                                                 CGImageGetColorSpace(base),                                                  kCGImageAlphaPremultipliedLast | kCGBitmapByteOrderDefault);    float BASE_COL_WIDTH[] = {leftcap,1,image.size.width - leftcap -1};    float BASE_ROW_HEIGHT[] = {topcap,1,image.size.height - topcap -1};    float BASE_COL_X[] = {0,leftcap,leftcap + 1};    float BASE_ROW_Y[] = {0,topcap,topcap +1};        float TARGET_COL_WIDTH[] = {BASE_COL_WIDTH[0], size.width - BASE_COL_WIDTH[0] - BASE_COL_WIDTH[2], BASE_COL_WIDTH[2]};    float TARGET_ROW_HEIGHT[] = {BASE_ROW_HEIGHT[0], size.height - BASE_ROW_HEIGHT[0] - BASE_ROW_HEIGHT[2], BASE_ROW_HEIGHT[2]};    float TARGET_COL_X[] = {0,TARGET_COL_WIDTH[0],TARGET_COL_WIDTH[0]+TARGET_COL_WIDTH[1]};    float TARGET_ROW_Y[] = {size.height - TARGET_ROW_HEIGHT[0],        size.height - TARGET_ROW_HEIGHT[0] - TARGET_ROW_HEIGHT[1],        size.height - TARGET_ROW_HEIGHT[0] - TARGET_ROW_HEIGHT[1] - TARGET_ROW_HEIGHT[2]};        for (int row=0; row<3; row++) {        for (int col=0; col<3; col++) {            CGRect source = CGRectMake(BASE_COL_X[col], BASE_ROW_Y[row], BASE_COL_WIDTH[col], BASE_ROW_HEIGHT[row]);            CGRect target = CGRectMake(TARGET_COL_X[col], TARGET_ROW_Y[row], TARGET_COL_WIDTH[col], TARGET_ROW_HEIGHT[row]);            CGImageRef ref = CGImageCreateWithImageInRect(base, source);            CGContextDrawImage(context, target, ref);            CFRelease(ref);        }    }         CGImageRef final = CGBitmapContextCreateImage(context);     CGContextRelease(context);    return [super initWithCGImage:final key:@"stretchable"];}@end