Load entire image and use CATiledLayer - iphone

Question

I'm not sure I did understand that very well in the Apple doc. I'm considering using CATiledLayer to display a JPEG image. However, I only have an entire JPEG file at my disposal and no small tiles. Is it still possible to use a CATiledLayer and let it "tile" the JPEG?
Thanks!

Answer 1

No. You will have to tile them yourself, unfortunately. The WWDC 2010 videos on Core Animation discuss how to do this and in their sample code, they demonstrate how to use a CATileLayer when the tiles already exist.
Correction
I meant to say watch the Scroll View session. It's session 104 "Designing Apps with Scroll Views"

Answer 2

You may use This for making CATileLayer with image and Zoom functionality in scrollview.
- (void)viewDidLoad
{
[super viewDidLoad];
// You do not need to and must not autorelease [NSBundle mainBundle]
NSString *path = [[NSBundle mainBundle] pathForResource:#"img" ofType:#"jpg"];
NSData *data = [NSData dataWithContentsOfFile:path];
image = [UIImage imageWithData:data];
// CGRect pageRect = CGRectMake(0, 0, 1600, 2400);
CGRect pageRect = CGRectMake(0.0, 0.0, image.size.width, image.size.height);
CATiledLayer *tiledLayer = [CATiledLayer layer];
tiledLayer.delegate = self;
tiledLayer.tileSize = CGSizeMake(256.0, 256.0);
tiledLayer.levelsOfDetail = 5; // was 1000, which makes no sense. Each level of detail is a power of 2.
tiledLayer.levelsOfDetailBias = 5; // was 1000, which also makes no sense.
// Do not change the tiledLayer.frame.
tiledLayer.bounds = pageRect; // I think you meant bounds instead of frame.
// Flip the image vertically.
tiledLayer.transform = CATransform3DMakeScale(1.0f, -1.0F, 1.0f);
myContentView = [[UIView alloc] initWithFrame:CGRectMake(500,400,image.size.width,image.size.height)];
[myContentView.layer addSublayer:tiledLayer];
// UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
scrollView=[[UIScrollView alloc]initWithFrame:CGRectMake(10, 10, 300, 400)];
scrollView.backgroundColor = [UIColor whiteColor];
// [scrollView setContentSize:CGSizeMake(image.size.width,image.size.height)];
[scrollView setContentSize:image.size];
scrollView.maximumZoomScale = 32; // = 2 ^ 5
scrollView.delegate = self;
// scrollView.contentSize = pageRect.size;
[scrollView addSubview:myContentView];
[self.view addSubview:scrollView];
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return myContentView;
}
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)context
{
NSString *path = [[NSBundle mainBundle] pathForResource:#"img" ofType:#"jpg"];
NSData *data = [NSData dataWithContentsOfFile:path];
image = [UIImage imageWithData:data];
CGRect imageRect = CGRectMake (0.0, 0.0, image.size.width, image.size.height);
CGContextDrawImage (context, imageRect, [image CGImage]);
}

Answer 3

The easier way is to just downscale the image until it fits (I think devices support up to 2044x2044 or so). You can create subimages of a CGImage with CGImageCreateWithImageInRect()