Question

I’m following the instructions outlined in this answer to fill a layer with a pattern in Core Graphics. When the layer is a CALayer subclass, the drawing works fine. However, when the layer is a CATiledLayer subclass, I get an EXC_BAD_ACCESS error at runtime.

static void drawPatternImage (void *info, CGContextRef ctx)
{
    CGImageRef image = (CGImageRef) info;
    CGContextDrawImage(ctx, 
                       CGRectMake(0,0, CGImageGetWidth(image),CGImageGetHeight(image)),
                       image); // EXC_BAD_ACCESS here :(
}

static void releasePatternImage( void *info )
{
    CGImageRelease((CGImageRef)info);
}

// pattern creation
int width = CGImageGetWidth(image);
int height = CGImageGetHeight(image);
static const CGPatternCallbacks callbacks = {0, &drawPatternImage, &releasePatternImage};
CGPatternRef pattern = CGPatternCreate (image,
                        CGRectMake (0, 0, width, height),
                        CGAffineTransformMake (1, 0, 0, 1, 0, 0),
                        width,
                        height,
                        kCGPatternTilingConstantSpacing,
                        true,
                        &callbacks);
CGColorSpaceRef space = CGColorSpaceCreatePattern(NULL);
CGFloat components[1] = {1.0};
CGColorRef color = CGColorCreateWithPattern(space, pattern, components);
CGColorSpaceRelease(space);
CGPatternRelease(pattern);
theLayer.backgroundColor = color;
CGColorRelease(color);

What do I need to do to draw a patterned image in a CATiledLayer subclass?

Answer 1

i use “CGContextDrawTiledImage” in the “drawLayer” method for a CATiledLayer class:

in .h:

@interface StarView : UIView {
    UIImage *imgTextureCarta;
}

in .m

- (id)initWithFrame:(CGRect)frame {
    NSString* imagePath = [ [ NSBundle mainBundle] pathForResource:@"aTexture" ofType:@"png"];
    imgTextureCarta = [UIImage imageWithContentsOfFile: imagePath];
    [imgTextureCarta retain];
    CGImageRef texureCarta;
    texureCarta = (imgTextureCarta.CGImage);
}



-(void)drawLayer:(CALayer *)layer inContext:(CGContextRef)context{
    CGImageRef texureCarta;
    texureCarta = (imgTextureCarta.CGImage);
    CGRect bounds = layer.bounds;
    CGContextSetBlendMode (context, 0);
    CGContextClipToRect(context, layer.bounds);
    CGContextDrawTiledImage(context, CGRectMake(0,0, 128, 120), texureCarta);
}

- (void)dealloc {
    [imgTextureCarta release];
    [super dealloc];
}