导航栏自定义进阶——可拖动图片选项卡

无需多言，直接上网络拾取的代码段：
#import <UIKit/UIKit.h>

#import "math.h"

@interface BrightnessController : UIViewController

{

int brightness;

}

@end

@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

 

@interface SampleAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate>

@end

@implementation SampleAppDelegate

- (void)applicationDidFinishLaunching:(UIApplication *)application {

UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

// Create the array of UIViewControllers

NSMutableArray *controllers = [[NSMutableArray alloc] init]; 

for (int i = 0; i < 11; i++) {

BrightnessController *bControl = [[BrightnessController alloc] initWithBrightness:i];

UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:bControl];

nav.navigationBar.barStyle = UIBarStyleBlackTranslucent;

[controllers addObject:nav];

[bControl release];

[nav release];

}

// Create the toolbar and add the view controllers

UITabBarController *tbarController = [[UITabBarController alloc] init];

tbarController.viewControllers = controllers;

tbarController.customizableViewControllers = controllers;

tbarController.delegate = self; 

// Set up the window

[window addSubview:tbarController.view];

[window makeKeyAndVisible];

[controllers release];

}

@end

int main(int argc, char *argv[])

{

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

int retVal = UIApplicationMain(argc, argv, nil, @"SampleAppDelegate");

[pool release];

return retVal;

}