ZoomingPDFViewer/TiledPDFView.m

/*
     File: TiledPDFView.m
 Abstract: This view is backed by a CATiledLayer into which the PDF page is rendered into.
  Version: 3.1
 
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 */
 
#import "TiledPDFView.h"
#import <QuartzCore/QuartzCore.h>
 
@implementation TiledPDFView
 
 
// Create a new TiledPDFView with the desired frame and scale.
- (id)initWithFrame:(CGRect)frame scale:(CGFloat)scale
{
    self = [super initWithFrame:frame];
    if (self) {
        
        CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
        /*
         levelsOfDetail and levelsOfDetailBias determine how the layer is rendered at different zoom levels. This only matters while the view is zooming, because once the the view is done zooming a new TiledPDFView is created at the correct size and scale.
         */
        tiledLayer.levelsOfDetail = 4;
        tiledLayer.levelsOfDetailBias = 3;
        tiledLayer.tileSize = CGSizeMake(512.0, 512.0);
        self.myScale = scale;
        self.layer.borderColor = [UIColor lightGrayColor].CGColor;
        self.layer.borderWidth = 5;
    }
    return self;
}
 
 
// The layer's class should be CATiledLayer.
+ (Class)layerClass
{
    return [CATiledLayer class];
}
 
 
// Set the CGPDFPageRef for the view.
- (void)setPage:(CGPDFPageRef)newPage {
    if( self.pdfPage != NULL ) CGPDFPageRelease( self.pdfPage );
    if( newPage != NULL ) self.pdfPage = CGPDFPageRetain( newPage );
}
 
// Draw the CGPDFPageRef into the layer at the correct scale.
-(void)drawLayer:(CALayer*)layer inContext:(CGContextRef)context {
    
    NSLog(@"%s myScale:%f",__PRETTY_FUNCTION__,self.myScale);
    
    // Fill the background with white.
    CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
    CGContextFillRect(context, self.bounds);
 
    // Print a blank page and return if our page is null.
    if( _pdfPage == NULL ) return;
    
    CGContextSaveGState(context);
    // Flip the context so that the PDF page is rendered right side up.
    CGContextTranslateCTM(context, 0.0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    
    // Scale the context so that the PDF page is rendered at the correct size for the zoom level.
    CGContextScaleCTM(context, self.myScale, self.myScale);
//    NSLog(@"%s myScale: %f, layer.bounds=%@",__PRETTY_FUNCTION__,self.myScale,NSStringFromCGRect(self.layer.bounds));
    CGContextDrawPDFPage(context, self.pdfPage);
    CGContextRestoreGState(context);
}
 
 
// Clean up.
- (void)dealloc {
    if( self.pdfPage != NULL ) CGPDFPageRelease( self.pdfPage );
}
 
 
@end