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