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//
// AsyncImageView.m
// Postcard
//
// Created by markj on 2/18/09.
// Copyright 2009 Mark Johnson. You have permission to copy parts of this code into your own projects for any use.
// www.markj.net
//
#import "AsyncImageView.h"
@interface UIImage (Extras)
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;
@end
@implementation UIImage (Extras)
#pragma mark -
#pragma mark Scale and crop image
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (CGSizeEqualToSize(imageSize, targetSize) == NO)
{
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor > heightFactor)
scaleFactor = widthFactor; // scale to fit height
else
scaleFactor = heightFactor; // scale to fit width
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor > heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else
if (widthFactor < heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
UIGraphicsBeginImageContext(targetSize); // this will crop
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
if(newImage == nil)
NSLog(@"could not scale image");
//pop the context to get back to the default
UIGraphicsEndImageContext();
return newImage;
}
@end
// This class demonstrates how the URL loading system can be used to make a UIView subclass
// that can download and display an image asynchronously so that the app doesn't block or freeze
// while the image is downloading. It works fine in a UITableView or other cases where there
// are multiple images being downloaded and displayed all at the same time.
@implementation AsyncImageView
- (void)dealloc {
[connection cancel]; //in case the URL is still downloading
[connection release];
[data release];
[super dealloc];
}
- (void)loadImageFromURL:(NSURL*)url {
NSLog(@"%@",url);
if (connection!=nil) { [connection release]; } //in case we are downloading a 2nd image
if (data!=nil) { [data release]; }
NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; //notice how delegate set to self object
//TODO error handling, what if connection is nil?
}
//the URL connection calls this repeatedly as data arrives
- (void)connection:(NSURLConnection *)theConnection didReceiveData:(NSData *)incrementalData {
if (data==nil) { data = [[NSMutableData alloc] initWithCapacity:2048]; }
[data appendData:incrementalData];
}
//the URL connection calls this once all the data has downloaded
- (void)connectionDidFinishLoading:(NSURLConnection*)theConnection {
//so self data now has the complete image
[connection release];
connection=nil;
if ([[self subviews] count]>0) {
//then this must be another image, the old one is still in subviews
[[[self subviews] objectAtIndex:0] removeFromSuperview]; //so remove it (releases it also)
}
//make an image view for the image
UIImageView* imageView = [[[UIImageView alloc] initWithImage:[[UIImage imageWithData:data] imageByScalingAndCroppingForSize:CGSizeMake(100,100)]] autorelease];
//make sizing choices based on your needs, experiment with these. maybe not all the calls below are needed.
imageView.contentMode = UIViewContentModeScaleAspectFill;
imageView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth || UIViewAutoresizingFlexibleHeight );
[self addSubview:imageView];
imageView.frame = self.bounds;
[imageView setNeedsLayout];
[self setNeedsLayout];
[data release]; //don't need this any more, its in the UIImageView now
data=nil;
}
//just in case you want to get the image directly, here it is in subviews
- (UIImage*) image {
UIImageView* iv = [[self subviews] objectAtIndex:0];
return [iv image];
}
@end
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