BlockBackground.m

//
//  BlockBackground.m
//  arrived
//
//  Created by Gustavo Ambrozio on 29/11/11.
//  Copyright (c) 2011 N/A. All rights reserved.
//
 
#import "BlockBackground.h"
 
@implementation BlockBackground
 
@synthesize backgroundImage = _backgroundImage;
@synthesize vignetteBackground = _vignetteBackground;
 
static BlockBackground *_sharedInstance = nil;
 
+ (BlockBackground *)sharedInstance
{
  if (_sharedInstance != nil)
  {
    return _sharedInstance;
  }
 
  @synchronized(self)
  {
    if (_sharedInstance == nil)
    {
      [[[self alloc] init] autorelease];
    }
  }
 
  return _sharedInstance;
}
 
+ (id)allocWithZone:(NSZone *)zone
{
  @synchronized(self)
  {
    if (_sharedInstance == nil)
    {
      _sharedInstance = [super allocWithZone:zone];
      return _sharedInstance;
    }
  }
  NSAssert(NO, @ "[BlockBackground alloc] explicitly called on singleton class.");
  return nil;
}
 
- (id)copyWithZone:(NSZone *)zone
{
  return self;
}
 
- (id)retain
{
  return self;
}
 
- (unsigned)retainCount
{
  return UINT_MAX;
}
 
- (oneway void)release
{
}
 
- (id)autorelease
{
  return self;
}
 
- (void)setRotation:(NSNotification *)notification
{
  UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
 
  CGRect orientationFrame = [UIScreen mainScreen].bounds;
 
  if ((UIInterfaceOrientationIsLandscape(orientation) &&
       orientationFrame.size.height > orientationFrame.size.width) ||
      (UIInterfaceOrientationIsPortrait(orientation) &&
       orientationFrame.size.width > orientationFrame.size.height))
  {
    float temp = orientationFrame.size.width;
    orientationFrame.size.width = orientationFrame.size.height;
    orientationFrame.size.height = temp;
  }
 
  self.transform = CGAffineTransformIdentity;
  self.frame = orientationFrame;
 
  CGFloat posY = orientationFrame.size.height / 2;
  CGFloat posX = orientationFrame.size.width / 2;
 
  CGPoint newCenter;
  CGFloat rotateAngle;
 
  switch (orientation)
  {
    case UIInterfaceOrientationPortraitUpsideDown:
      rotateAngle = M_PI;
      newCenter = CGPointMake(posX, orientationFrame.size.height - posY);
      break;
    case UIInterfaceOrientationLandscapeLeft:
      rotateAngle = -M_PI / 2.0f;
      newCenter = CGPointMake(posY, posX);
      break;
    case UIInterfaceOrientationLandscapeRight:
      rotateAngle = M_PI / 2.0f;
      newCenter = CGPointMake(orientationFrame.size.height - posY, posX);
      break;
    default: // UIInterfaceOrientationPortrait
      rotateAngle = 0.0;
      newCenter = CGPointMake(posX, posY);
      break;
  }
 
  self.transform = CGAffineTransformMakeRotation(rotateAngle);
  self.center = newCenter;
 
  [self setNeedsLayout];
  [self layoutSubviews];
}
 
- (id)init
{
  self = [super initWithFrame:[[UIScreen mainScreen] bounds]];
  if (self)
  {
    self.windowLevel = UIWindowLevelStatusBar;
    self.hidden = YES;
    self.userInteractionEnabled = NO;
    self.backgroundColor = [UIColor colorWithWhite:0.4 alpha:0.5f];
    self.vignetteBackground = NO;
 
    [[NSNotificationCenter defaultCenter]
        addObserver:self
           selector:@selector(setRotation:)
               name:UIApplicationDidChangeStatusBarOrientationNotification
             object:nil];
    [self setRotation:nil];
  }
  return self;
}
 
- (void)addToMainWindow:(UIView *)view
{
  [self setRotation:nil];
 
  if ([self.subviews containsObject:view])
    return;
 
  if (self.hidden)
  {
    _previousKeyWindow = [[[UIApplication sharedApplication] keyWindow] retain];
    self.alpha = 0.0f;
    self.hidden = NO;
    self.userInteractionEnabled = YES;
    [self makeKeyWindow];
  }
 
  if (self.subviews.count > 0)
  {
    ((UIView *)[self.subviews lastObject]).userInteractionEnabled = NO;
  }
 
  if (_backgroundImage)
  {
    UIImageView *backgroundView = [[UIImageView alloc] initWithImage:_backgroundImage];
    backgroundView.frame = self.bounds;
    backgroundView.contentMode = UIViewContentModeScaleToFill;
    [self addSubview:backgroundView];
    [backgroundView release];
    [_backgroundImage release];
    _backgroundImage = nil;
  }
 
  [self addSubview:view];
}
 
- (void)reduceAlphaIfEmpty
{
  if (self.subviews.count == 1 ||
      (self.subviews.count == 2 &&
       [[self.subviews objectAtIndex:0] isKindOfClass:[UIImageView class]]))
  {
    self.alpha = 0.0f;
    self.userInteractionEnabled = NO;
  }
}
 
- (void)removeView:(UIView *)view
{
  [view removeFromSuperview];
 
  UIView *topView = [self.subviews lastObject];
  if ([topView isKindOfClass:[UIImageView class]])
  {
    // It's a background. Remove it too
    [topView removeFromSuperview];
  }
 
  if (self.subviews.count == 0)
  {
    self.hidden = YES;
    [_previousKeyWindow makeKeyWindow];
    [_previousKeyWindow release];
    _previousKeyWindow = nil;
  }
  else
  {
    ((UIView *)[self.subviews lastObject]).userInteractionEnabled = YES;
  }
}
 
- (void)drawRect:(CGRect)rect
{
  if (_backgroundImage || !_vignetteBackground)
    return;
  CGContextRef context = UIGraphicsGetCurrentContext();
 
  size_t locationsCount = 2;
  CGFloat locations[2] = { 0.0f, 1.0f };
  CGFloat colors[8] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.75f };
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
  CGGradientRef gradient =
      CGGradientCreateWithColorComponents(colorSpace, colors, locations, locationsCount);
  CGColorSpaceRelease(colorSpace);
 
  CGPoint center = CGPointMake(self.bounds.size.width / 2, self.bounds.size.height / 2);
  float radius = MIN(self.bounds.size.width, self.bounds.size.height);
  CGContextDrawRadialGradient(context, gradient, center, 0, center, radius,
                              kCGGradientDrawsAfterEndLocation);
  CGGradientRelease(gradient);
}
 
@end