/*
     File: TilingView.m
 Abstract: Handles tile drawing and tile image loading.
  Version: 1.1
 
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#import "TilingView.h"
#import <QuartzCore/CATiledLayer.h>


@implementation TilingView
@synthesize annotates;

+ (Class)layerClass {
	return [CATiledLayer class];
}

- (id)initWithImageName:(NSString *)name size:(CGSize)size
{
    if ((self = [super initWithFrame:CGRectMake(0, 0, size.width, size.height)])) {
        imageName = [name retain];

        CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
        tiledLayer.levelsOfDetail = 4;
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
 	CGContextRef context = UIGraphicsGetCurrentContext();
    
    // get the scale from the context by getting the current transform matrix, then asking for
    // its "a" component, which is one of the two scale components. We could also ask for "d".
    // This assumes (safely) that the view is being scaled equally in both dimensions.
    CGFloat scale = CGContextGetCTM(context).a;
    
    CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
    CGSize tileSize = tiledLayer.tileSize;
    
    // Even at scales lower than 100%, we are drawing into a rect in the coordinate system of the full
    // image. One tile at 50% covers the width (in original image coordinates) of two tiles at 100%. 
    // So at 50% we need to stretch our tiles to double the width and height; at 25% we need to stretch 
    // them to quadruple the width and height; and so on.
    // (Note that this means that we are drawing very blurry images as the scale gets low. At 12.5%, 
    // our lowest scale, we are stretching about 6 small tiles to fill the entire original image area. 
    // But this is okay, because the big blurry image we're drawing here will be scaled way down before 
    // it is displayed.)
    tileSize.width /= scale;
    tileSize.height /= scale;
    
    // calculate the rows and columns of tiles that intersect the rect we have been asked to draw
    int firstCol = floorf(CGRectGetMinX(rect) / tileSize.width);
    int lastCol = floorf((CGRectGetMaxX(rect)-1) / tileSize.width);
    int firstRow = floorf(CGRectGetMinY(rect) / tileSize.height);
    int lastRow = floorf((CGRectGetMaxY(rect)-1) / tileSize.height);

    for (int row = firstRow; row <= lastRow; row++) {
        for (int col = firstCol; col <= lastCol; col++) {
            UIImage *tile = [self tileForScale:scale row:row col:col];
            CGRect tileRect = CGRectMake(tileSize.width * col, tileSize.height * row,
                                         tileSize.width, tileSize.height);

            // if the tile would stick outside of our bounds, we need to truncate it so as to avoid
            // stretching out the partial tiles at the right and bottom edges
            tileRect = CGRectIntersection(self.bounds, tileRect);

            [tile drawInRect:tileRect];
            
            if (self.annotates) {
                [[UIColor whiteColor] set];
                CGContextSetLineWidth(context, 6.0 / scale);
                CGContextStrokeRect(context, tileRect);
            }
        }
    }
}

- (UIImage *)tileForScale:(CGFloat)scale row:(int)row col:(int)col
{
     // we use "imageWithContentsOfFile:" instead of "imageNamed:" here because we don't want UIImage to cache our tiles
    NSString *tileName = [NSString stringWithFormat:@"%@_%d_%d_%d", imageName, (int)(scale * 1000), col, row];
    NSString *path = [[NSBundle mainBundle] pathForResource:tileName ofType:@"png"];
    UIImage *image = [UIImage imageWithContentsOfFile:path];
    return image;
}

@end
