Step8/ImageView.m

/*
 
 File: ImageView.m
 
 Abstract: ImageView 
 
 Version: 1.0
 
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 */ 
 
#import "ImageView.h"
 
#define kMargin 10.f
 
@implementation ImageView
// simple image view to display a given file
// uses ImageIO to open the image file
// handles image dpi and EXIF orientation...
 
// ---------------------------------------------------------------------------------------------------------------------
- (id)initWithFrame: (NSRect)frameRect
{
    // initialize
    if ((self = [super initWithFrame: frameRect]) != nil)
    {
    }
    return self;
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (void) dealloc
{
    if (mImage)
        CGImageRelease(mImage);
    [mMeta release];
    [super dealloc];
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (void) setImagePath: (NSString *)path
{
    // use ImageIO to get a CGImageRef for a file at a given path
    NSURL * url = [NSURL fileURLWithPath: path];
 
    // create the CGImageSourceRef
    CGImageSourceRef isr = CGImageSourceCreateWithURL((CFURLRef)url, NULL);
    
    if (isr)
    {
        // options for getting image and meta data
        // - create a 'cached' image
        // - allow float pixel data
        NSDictionary* options = [NSDictionary dictionaryWithObjectsAndKeys:
            (id)kCFBooleanTrue, (id)kCGImageSourceShouldCache,
            (id)kCFBooleanTrue, (id)kCGImageSourceShouldAllowFloat,
            NULL];
        
        // create image at index 0 (note that ImageIO supports multi-page TIFFs, GIFs, ...)
        CGImageRef image = CGImageSourceCreateImageAtIndex(isr, 0, (CFDictionaryRef)options);
        
        // get the meta data for the image at index 0
        NSDictionary* meta = (NSDictionary*)CGImageSourceCopyPropertiesAtIndex(isr, 0, (CFDictionaryRef)options);
        
        // keep image and meta-data
        [self setImage: image
          withMetadata: meta];
        
        CFRelease (isr);
    }
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (void) setImage: (CGImageRef)image 
     withMetadata: (NSDictionary *)meta
{
    CGImageRetain(image);
    if (mImage)
        CGImageRelease(mImage);
    mImage = image;
    
    if (meta)
        [meta retain];
    [mMeta release];
    mMeta = meta;
 
    // update display
    [self setNeedsDisplay:YES];
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (BOOL) isOpaque
{
    return YES;
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (float) dpiWidth
{
    NSNumber*   val = [mMeta objectForKey:(id)kCGImagePropertyDPIWidth];
    float       dpi = [val floatValue];
    return (0 == dpi ? 72. : dpi);
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (float) dpiHeight
{
    NSNumber*   val = [mMeta objectForKey: (id)kCGImagePropertyDPIHeight];
    float       dpi = [val floatValue];
    return (0 == dpi ? 72 : dpi);
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (int) orientation
{
    NSNumber*   val = [mMeta objectForKey: (id)kCGImagePropertyOrientation];
    int orient = [val intValue];
    if (orient < 1 || orient > 8)
        orient = 1;
    return orient;
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (CGAffineTransform) imageTransform
{
    // determine the image transform:
    // this honors: EXIF orientation, non-square-pixel dpi, ...
    float xdpi = [self dpiWidth];
    float ydpi = [self dpiHeight];
    int orient = [self orientation];
    
    float x = (ydpi > xdpi) ? ydpi/xdpi : 1;
    float y = (xdpi > ydpi) ? xdpi/ydpi : 1;
    float w = x * CGImageGetWidth(mImage);
    float h = y * CGImageGetHeight(mImage);
    
    CGAffineTransform ctms[8] = {
    { x, 0, 0, y, 0, 0},  //  1 =  row 0 top, col 0 lhs  =  normal
    {-x, 0, 0, y, w, 0},  //  2 =  row 0 top, col 0 rhs  =  flip horizontal
    {-x, 0, 0,-y, w, h},  //  3 =  row 0 bot, col 0 rhs  =  rotate 180
    { x, 0, 0,-y, 0, h},  //  4 =  row 0 bot, col 0 lhs  =  flip vertical
    { 0,-x,-y, 0, h, w},  //  5 =  row 0 lhs, col 0 top  =  rot -90, flip vert
    { 0,-x, y, 0, 0, w},  //  6 =  row 0 rhs, col 0 top  =  rot 90
    { 0, x, y, 0, 0, 0},  //  7 =  row 0 rhs, col 0 bot  =  rot 90, flip vert
    { 0, x,-y, 0, h, 0}   //  8 =  row 0 lhs, col 0 bot  =  rotate -90
    };
    
    return ctms[orient-1];
}
 
 
// ---------------------------------------------------------------------------------------------------------------------
- (CGAffineTransform) imageTransformToFitView
{
    // make sure the entire image fits...
    
    CGRect imageRect = CGRectMake(0., 0., CGImageGetWidth(mImage), CGImageGetHeight(mImage));
    
    CGAffineTransform ctm = [self imageTransform];
    
    CGSize ctmdSize = CGRectApplyAffineTransform(imageRect, ctm).size;
    
    // keep a small border
    NSSize destSize = NSInsetRect([self bounds], kMargin, kMargin).size;
    
    // scale to fit in view rect
    float scale = MIN(destSize.width / ctmdSize.width, destSize.height / ctmdSize.height);
    ctm = CGAffineTransformConcat(ctm, CGAffineTransformMakeScale(scale, scale));
    
    return ctm;
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (void) drawRect: (NSRect)rect
{
    // draw the background...
    [[NSColor colorWithCalibratedRed: 0.75 
                               green: 0.75
                                blue: 0.75
                               alpha: 1.0] set];
    [NSBezierPath fillRect: [self bounds]];
    
    // ... and the image
    if (mImage)
    {
        CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
        if (context)
        {
            CGContextSaveGState(context);
 
            NSRect viewBounds = [self bounds];
            size_t width  = CGImageGetWidth(mImage);
            size_t height = CGImageGetHeight(mImage);
            CGRect imageRect = {{0,0}, {width,height}};
            
            // determine transform - fit to view,  EXIF orientation, non-square-pixel dpi, ...
            CGAffineTransform ctm = [self imageTransformToFitView];
            
            // center in view rect
            CGSize ctmdSize = CGRectApplyAffineTransform(imageRect, ctm).size;
            ctm.tx += viewBounds.origin.x + (viewBounds.size.width  - ctmdSize.width)/2;
            ctm.ty += viewBounds.origin.y + (viewBounds.size.height - ctmdSize.height)/2;
            
            CGContextConcatCTM(context, ctm);
            
            // want faster resizing?
            // if we are in live-resizing we use a faster image scaling (kCGInterpolationNone)
            if (mLiveResizing)
            {
                CGInterpolationQuality qual = CGContextGetInterpolationQuality(context);
                
                CGContextSetInterpolationQuality(context, kCGInterpolationNone);
                
                CGContextDrawImage (context, imageRect, mImage );
                
                CGContextSetInterpolationQuality(context, qual);
 
            } else
            {
                // use default interpolation quality 
                CGContextDrawImage(context, imageRect, mImage);
            }
            
            CGContextRestoreGState(context);
        }
    }
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (void)viewWillStartLiveResize
{
    mLiveResizing = YES;
}
 
// ---------------------------------------------------------------------------------------------------------------------
- (void)viewDidEndLiveResize
{
    mLiveResizing = NO;
    
    // at the end of a live resize - redraw. This time it will be in higher quality
    [self display];
}
 
@end


Copyright © 2005 Apple Computer, Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2005-06-01