iPhone 画圆角矩形

 

 

@implementation BrightnessController

// MyCreateBitmapContext: Source based on Apple Sample Code
CGContextRef MyCreateBitmapContext (int pixelsWide,
                                    int pixelsHigh)
{
    CGContextRef    context = NULL;
    CGColorSpaceRef colorSpace;
    void *          bitmapData;
    int             bitmapByteCount;
    int             bitmapBytesPerRow;

    bitmapBytesPerRow   = (pixelsWide * 4);
    bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);

    colorSpace = CGColorSpaceCreateDeviceRGB();
    bitmapData = malloc( bitmapByteCount );
    if (bitmapData == NULL)
    {
        fprintf (stderr, "Memory not allocated!");
        CGColorSpaceRelease( colorSpace );
        return NULL;
    }
    context = CGBitmapContextCreate (bitmapData,
                                     pixelsWide,
                                     pixelsHigh,
                                     8,
                                     bitmapBytesPerRow,
                                     colorSpace,
                                     kCGImageAlphaPremultipliedLast);
    if (context== NULL)
    {
        free (bitmapData);
        fprintf (stderr, "Context not created!");
        return NULL;
    }
    CGColorSpaceRelease( colorSpace );

    return context;
}

// addRoundedRectToPath: Source based on Apple Sample Code
static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth,
                                 float ovalHeight)
{
    float fw, fh;
    if (ovalWidth == 0 || ovalHeight == 0) {
        CGContextAddRect(context, rect);
        return;
    }

    CGContextSaveGState(context);
    CGContextTranslateCTM(context, CGRectGetMinX(rect), CGRectGetMinY(rect));
    CGContextScaleCTM(context, ovalWidth, ovalHeight);
    fw = CGRectGetWidth(rect) / ovalWidth;
    fh = CGRectGetHeight(rect) / ovalHeight;

    CGContextMoveToPoint(context, fw, fh/2);  // Start at lower right corner
    CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);  // Top right corner
    CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1); // Top left corner
    CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1); // Lower left corner
    CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); // Back to lower right

    CGContextClosePath(context);
    CGContextRestoreGState(context);
}

// Build an image tinted at the given percentage
id createImage(float percentage)
{
    CGContextRef context  = MyCreateBitmapContext(30, 30);
    addRoundedRectToPath(context, CGRectMake(0.0f, 0.0f, 30.0f, 30.0f), 4.0f, 4.0f);
    CGFloat gray[4] = {percentage, percentage, percentage, 1.0f};
    CGContextSetFillColor(context, gray);
    CGContextFillPath(context);
    CGImageRef myRef = CGBitmapContextCreateImage (context);
    free(CGBitmapContextGetData(context));
    CGContextRelease(context);
    return [UIImage imageWithCGImage:myRef];
}


#define MAXDEPTH 8

-(BrightnessController *) initWithBrightness: (int) aBrightness
{
    self = [super init];
    brightness = aBrightness;
    self.title = [NSString stringWithFormat:@"%d%%", brightness * 10];
    [self.tabBarItem initWithTitle:self.title image:createImage(((float) brightness / 10.0f)) tag:0];
    return self;
}

- (void)loadView
{
    UIView *contentView = [[UIView alloc] init];
    float percent = brightness * 0.1;
    contentView.backgroundColor = [UIColor colorWithRed:percent green:percent blue:percent alpha:1.0];
    contentView.autoresizesSubviews = YES;
    contentView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
    self.view = contentView;
    [contentView release];
}


@end