MRo Blog

< ![CDATA[ 
#!/usr/bin/env ruby
require 'complex'
 
class Array
	# DFT and inverse.
	# 
	# Algorithm from 
	# 'Meyberg, Vachenauer: Hoehere Mathematik II, Springer Berlin, 1991, page 332'
	#
	# See http://blog.mro.name/2011/04/simple-ruby-fast-fourier-transform/ 
	#
	def fft doinverse = false
		src = self
		# raise ArgumentError.new "Expected array input but was '#{src.class}'" unless src.kind_of? Array
		n = src.length
		nlog2 = Math.log( n ) / Math.log( 2 )
		raise ArgumentError.new "Input array size must be a power of two but was '#{n}'" unless nlog2.floor - nlog2 == 0.0
		n2 = n / 2
		phi = Math::PI / n2
		if doinverse
			phi = -phi
		else
			src.collect!{|c| c /= n.to_f}
		end
 
		# build a sine/cosine table
		wt = Array.new n2
		wt.each_index { |i| wt[i] = Complex.new Math.cos(i * phi), Math.sin(i * phi) }
 
		# bit reordering
		n1 = n - 1
		j = 0
		1.upto(n1) do |i|
			m = n2
			while j >= m
				j -= m
				m /= 2
			end
			j += m
			src[i],src[j] = src[j],src[i] if j > i
		end
 
		# 1d(N) Ueberlagerungen
		mm = 1
		begin
			m = mm
			mm *= 2
			0.upto(m - 1) do |k|
				w = wt[ k * n2 ]
				k.step(n1, mm) do |i|
					j = i + m
					src[j] = src[i] - (temp = w * src[j])
					src[i] += temp
				end
			end
			n2 /= 2
		end while mm != n
		src
	end
end
 
class String
	# parse Complex.new.to_s
	def to_c
		m = @@PATTERN.match self
		return nil if m.nil?
		Complex.new m[1].to_f, m[2].to_f
	end
private
	# float_pat = /(-?\d+(?:\.\d+)?(?:e[+-]?\d+)?)/
	@@PATTERN = /^[ \t\r\n]*(-?\d+(?:\.\d+)?(?:e[+-]?\d+)?)?\s*((?:\s+|[+-])\d+(?:\.\d+)?(?:e[+-]?\d+)?i)?[ \t\r\n]*$/
end
 
values = []
$stdin.each_line do |l|
	c = l.to_c
	if c.nil?
		$stderr.puts "unmatched '#{l}'"
	else
		values < < c
	end
end
INVERSE = ARGV[0] == 'inverse'
$stderr.puts INVERSE ? 'inverse' : 'forward'
 
values.fft(INVERSE).each {|i| puts "#{i.real} #{i.image}i"}
]]>

@implementation UIImage (MRORemote)
 
// add the @2x filename suffix
+(NSURL *)url2x:(NSURL *)url
{
  NSString *path = url.path;
  NSAssert(path != nil, @"");
  NSString *last = path.lastPathComponent;
  NSString *ext = path.pathExtension;
  NSAssert(last != nil, @"");
  NSAssert(ext != nil, @"");
  NSString *part = [last substringToIndex:MAX(0, last.length - ext.length - 1)];
  return [NSURL URLWithString:[NSString stringWithFormat:@"%@@2x.%@", part, ext] relativeToURL:[url absoluteURL]];
}
 
+(UIImage *)imageWithContentsOfURL:(NSURL *)url probe2x:(BOOL)probe2x
{
  if ( url == nil )
    return nil;
  UIScreen *screen = [UIScreen mainScreen];
  const CGFloat scale = [screen respondsToSelector:@selector(scale)] ? [screen scale] : 1.0f;
  if ( probe2x && 2.0f == scale && [UIImage respondsToSelector:@selector(imageWithCGImage:scale:orientation:)] ) {
    UIImage *img = nil;
    NSData *raw = [NSData dataWithContentsOfURL:[UIImage url2x:url]];
    if ( raw != nil )
      img = [UIImage imageWithData:raw];
    if ( img != nil )
      img = [UIImage imageWithCGImage:img.CGImage scale:scale orientation:img.imageOrientation];
    if ( img != nil )
      return img;
    NSAssert(raw == nil && img == nil, @"");
  }
  // MRLogD(@"loading %@", [url absoluteURL]);
  NSData *raw = [NSData dataWithContentsOfURL:url];
  if ( raw == nil )
    return nil;
  return [UIImage imageWithData:raw];
}
@end

-(void)drawTextInRect:(CGRect)rect
{
	MRLogD(@"(%f,%f) (%f,%f)", rect.origin.x, rect.origin.y, rect.size.width, rect.size.height);
	if ( _CGFont == NULL ) {
		[super drawTextInRect:rect];
		return;
	}
	NSAssert(_mapping != NULL, @"Mapping function pointer not set.");
 
	// prepare the target graphics context.
	const CGContextRef ctx = UIGraphicsGetCurrentContext();
	CGContextSaveGState(ctx);
	{
		// prepare the glyphs array to draw
		const NSString *txt = self.text;
		const size_t glyphCount = txt.length;
		CGGlyph glyphs[glyphCount];
		{
			// turn the string txt into glyphs (indices into the font):
			// give non-allocating unicode character retrieval a try:
			const UniChar *raw_unichars = CFStringGetCharactersPtr( (CFStringRef)txt );
			const UniChar *unichars = raw_unichars == NULL ? malloc( glyphCount * sizeof(UniChar) ) : raw_unichars;
			NSAssert(unichars != NULL, @"unichars not allocated");
			if ( raw_unichars == NULL )
				CFStringGetCharacters( (CFStringRef)txt, CFRangeMake(0, txt.length), (UniChar *)unichars );
			for ( int i = glyphCount - 1; i >= 0; i-- )
				glyphs[i] = _mapping(unichars[i]);
			if ( raw_unichars == NULL )
				free( (void *)unichars );
		}
 
		CGContextSetFont(ctx, _CGFont);
		CGContextSetFontSize(ctx, self.font.pointSize);
		CGContextSetTextMatrix( ctx, CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, 0.0) );
 
		// first print 'invisible' to measure size:
		CGContextSetTextDrawingMode(ctx, kCGTextInvisible);
		const CGPoint pre = CGContextGetTextPosition(ctx);
		CGContextShowGlyphs(ctx, glyphs, glyphCount);
		const CGPoint post = CGContextGetTextPosition(ctx);
		// restore text position
		CGContextSetTextPosition(ctx, pre.x, pre.y);
 
		// centered horizontal + vertical:
		NSAssert( (int)rect.origin.x == 0, @"origin.x not zero" );
		NSAssert( (int)rect.origin.y == 0, @"origin.y not zero" );
		NSAssert(self.baselineAdjustment == UIBaselineAdjustmentAlignCenters, @"vertical alignment not 'center'");
		NSAssert(self.textAlignment == UITextAlignmentCenter, @"horizontal alignment not 'center'");
		const CGPoint p = CGPointMake( ( rect.size.width - (post.x - pre.x) ) / 2, (rect.size.height + self.font.pointSize + pre.y) / 2 );
 
		// finally render it to the graphics context:
		CGContextSetTextDrawingMode(ctx, kCGTextFill);
		CGContextSetFillColorWithColor(ctx, self.textColor.CGColor);
		CGContextShowGlyphsAtPoint(ctx, p.x, p.y, glyphs, glyphCount);
	}
	CGContextRestoreGState(ctx);
}

CGGlyph unicode2glyphDeutscheDruckschrift(UniChar c)
{
	if ( '0' < = c && c <= '9' )
		return c + (16 - '0');
	if ( 'A' <= c && c <= 'Z' )
		return c + (32 - 'A');
	if ( 'a' <= c && c <= 'z' )
		return c + (58 - 'a');
	return 0;
}
 
-(void)viewDidLoad
{
	[super viewDidLoad];
	...
	[fontLabel setFontFromFile:@"DeutscheDruckschrift" ofType:@"ttf" mapping:unicode2glyphDeutscheDruckschrift];
	...
}