The document discusses tiling and zooming images on iOS. It provides code samples for adding a scroll view and image view to tile and zoom an image. It also describes handling pinch gestures to zoom and double tap gestures to further zoom an image. The document raises questions about displaying different image tiles at different zoom levels and generating ASCII art from images.

1. Tiling and Zooming
ASCII Art
iOS SOHO!
June 9th, 2014
Daniel Doubrovkine
@dblockdotorg

2. Francisco De Goya Y Lucientes, Señora Sabasa Garcia, ca. 1806/1811
https://artsy.net/artwork/francisco-jose-de-goya-y-lucientes-senora-sabasa-garcia
courtesy of the National Gallery of Art, Washington D.C.

4. UIScrollView + UIImageView
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:scrollView];
!
UIImage *image = [UIImage imageNamed:@"boy.jpg"];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
[scrollView addSubview:imageView];
!
scrollView.contentSize = image.size;

5. CenterOnPoint
- (void)centerOnPoint:(CGPoint)point
{
CGFloat x = point.x - (self.view.frame.size.width / 2.0f);
CGFloat y = point.y - (self.view.frame.size.height / 2.0f);
[self.scrollView setContentOffset:CGPointMake(round(x), round(y));
}
!
!
{
[self centerOnPoint:CGPointMake(image.size.width / 2, image.size.height / 2)];
}

6. Zoom on Tap
!
{
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(handleDoubleTap:)];
[doubleTap setNumberOfTapsRequired:2];
[self.view addGestureRecognizer:doubleTap];
}
!
- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer
{
[UIView animateWithDuration:0.3 animations:^{
self.imageView.frame = CGRectMake(0, 0,
self.imageView.frame.size.width + 100,
self.imageView.frame.size.height + 100);
self.scrollView.contentSize = self.imageView.frame.size;
}];
}

7. Pinch Zoom
{
scrollView.delegate = self;
scrollView.minimumZoomScale = 0.5;
scrollView.maximumZoomScale = 2;
}
!
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
self.imageView.frame = CGRectMake(0, 0,
self.image.size.width * self.scrollView.zoomScale,
self.image.size.height * self.scrollView.zoomScale);
self.scrollView.contentSize = self.imageView.frame.size;
}
!
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}

8. Different Images at Different Zoom Levels?

9. ARTiledImageDataSource
- (UIImage *)imageTileForLevel:(NSInteger)level x:(NSInteger)x y:(NSInteger)y;
- (CGSize)tileSize;
- (CGSize)imageSize;
- (NSInteger)minimumImageZoomLevel;
- (NSInteger)maximumImageZoomLevel;

10. - (void)drawRect:(CGRect)rect
• Translate the CGRect into the tile coordinate system at this scale.
!
NSInteger firstCol = floor(CGRectGetMinX(rect) / tileSize.width);
…
!
for (NSInteger row = firstRow; row <= lastRow; row++) {
for (NSInteger col = firstCol; col <= lastCol; col++) {
!
• Fetch each tile & draw with drawInRect:blendMode.

11. ARTiledImageView
ARTiledImageScrollView
https://github.com/dblock/ARTiledImageView
+ All The Size Maths
+ Scroll & Zoom Gestures
+ In-Memory Tile Cache
+ Local vs. Remote Tiles

12. WHERE’S THE
ASCII ART?
seriously …

13. UIImage to Text to UIImage
static const NSString * UIImageViewASCII_CharacterMap = @" .,;_-`*”;
!
…
!
int r = rawData[byteIndex] & 0xff;
int g = (rawData[byteIndex] >> 8) & 0xff;
int b = (rawData[byteIndex] >> 16) & 0xff;
!
NSInteger characterIndex = 7 - (((int)(r + g + b)/3) >> 5) & 0x7;
!
[UIImageViewASCII_CharacterMap characterAtIndex:characterIndex];

14. //
// UIImage+ASCII.h
// Pods
//
// Created by Daniel Doubrovkine on 3/23/14.
//
//
!
#import <UIKit/UIKit.h>
!
@interface UIImage (ASCII)
!
/**
* Convert an image to ASCII.
*
* @param font ASCII font.
* @param color Text color.
*
* @return Returns an image with the ASCII text.
*/
- (UIImage *)asciiImage:(UIFont *)font color:(UIColor *)color;
!
/**
* Convert an image to ASCII.
*
* @return Returns the ASCII text.
*/
- (NSString *)asciiText;
!
@end

15. Zoom Tiled ASCII Art?
Daniel Doubrovkine
@dblockdotorg!
dblock@dblock.org!
!
http://iphone.artsy.net

16. https://github.com/dblock/ARImageViewInsideScrollView!
https://github.com/dblock/ARTiledImageView!
https://github.com/dblock/ARASCIISwizzle!
https://github.com/objectiveSee/DRKonamiCode