/* |
File: MakeThumbnailOperation.m |
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Contains: An NSOperation subclass that creates a thumbnail from image data. |
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Written by: DTS |
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Copyright: Copyright (c) 2010 Apple Inc. All Rights Reserved. |
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Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc. |
("Apple") in consideration of your agreement to the following |
terms, and your use, installation, modification or |
redistribution of this Apple software constitutes acceptance of |
these terms. If you do not agree with these terms, please do |
not use, install, modify or redistribute this Apple software. |
|
In consideration of your agreement to abide by the following |
terms, and subject to these terms, Apple grants you a personal, |
non-exclusive license, under Apple's copyrights in this |
original Apple software (the "Apple Software"), to use, |
reproduce, modify and redistribute the Apple Software, with or |
without modifications, in source and/or binary forms; provided |
that if you redistribute the Apple Software in its entirety and |
without modifications, you must retain this notice and the |
following text and disclaimers in all such redistributions of |
the Apple Software. Neither the name, trademarks, service marks |
or logos of Apple Inc. may be used to endorse or promote |
products derived from the Apple Software without specific prior |
written permission from Apple. Except as expressly stated in |
this notice, no other rights or licenses, express or implied, |
are granted by Apple herein, including but not limited to any |
patent rights that may be infringed by your derivative works or |
by other works in which the Apple Software may be incorporated. |
|
The Apple Software is provided by Apple on an "AS IS" basis. |
APPLE MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING |
WITHOUT LIMITATION THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, |
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING |
THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN |
COMBINATION WITH YOUR PRODUCTS. |
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IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, |
INCIDENTAL OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED |
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) ARISING IN ANY WAY |
OUT OF THE USE, REPRODUCTION, MODIFICATION AND/OR DISTRIBUTION |
OF THE APPLE SOFTWARE, HOWEVER CAUSED AND WHETHER UNDER THEORY |
OF CONTRACT, TORT (INCLUDING NEGLIGENCE), STRICT LIABILITY OR |
OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE POSSIBILITY OF |
SUCH DAMAGE. |
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*/ |
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#import "MakeThumbnailOperation.h" |
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@implementation MakeThumbnailOperation |
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- (id)initWithImageData:(NSData *)imageData MIMEType:(NSString *)MIMEType |
// See comment in header. |
{ |
assert(imageData != nil); |
assert(MIMEType != nil); |
self = [super init]; |
if (self != nil) { |
self->_imageData = [imageData copy]; |
self->_MIMEType = [MIMEType copy]; |
self->_thumbnailSize = 32.0f; |
} |
return self; |
} |
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- (void)dealloc |
{ |
CGImageRelease(self->_thumbnail); |
[self->_MIMEType release]; |
[self->_imageData release]; |
[super dealloc]; |
} |
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@synthesize imageData = _imageData; |
@synthesize MIMEType = _MIMEType; |
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@synthesize thumbnailSize = _thumbnailSize; |
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@synthesize thumbnail = _thumbnail; |
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- (void)main |
{ |
CGDataProviderRef provider; |
CGImageRef sourceImage; |
CGFloat thumbnailSize; |
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// Latch thumbnailSize for performance, and also to prevent it changing out from underneath us. |
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thumbnailSize = self.thumbnailSize; |
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assert(self.imageData != nil); |
assert(self.MIMEType != nil); |
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// Set up the source CGImage. |
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provider = CGDataProviderCreateWithCFData( (CFDataRef) self.imageData); |
assert(provider != NULL); |
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if ( [self.MIMEType isEqual:@"image/jpeg"] ) { |
sourceImage = CGImageCreateWithJPEGDataProvider(provider, NULL, true, kCGRenderingIntentDefault); |
} else if ( [self.MIMEType isEqual:@"image/png"] ) { |
sourceImage = CGImageCreateWithPNGDataProvider(provider, NULL, true, kCGRenderingIntentDefault); |
} else { |
sourceImage = NULL; |
} |
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// Render it to a bitmap context and then create an image from that context. |
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if (sourceImage != NULL) { |
static const CGFloat kWhite[4] = {0.0f, 0.0f, 0.0f, 1.0f}; |
CGColorRef white; |
CGContextRef context; |
CGColorSpaceRef space; |
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space = CGColorSpaceCreateDeviceRGB(); |
assert(space != NULL); |
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white = CGColorCreate(space, kWhite); |
assert(white != NULL); |
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// Create the context that's thumbnailSize x thumbnailSize. |
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context = CGBitmapContextCreate(NULL, thumbnailSize, thumbnailSize, 8, 0, space, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); |
if (context != NULL) { |
CGRect r; |
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// Make sure anything we don't cover comes out white. While the next |
// steps ensures that we cover the entire image, there's a possibility |
// that we're dealing with a transparent PNG. |
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CGContextSetFillColorWithColor(context, white); |
CGContextFillRect(context, CGRectMake(0.0f, 0.0f, thumbnailSize, thumbnailSize)); |
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// Calculate the drawing rectangle so that the image fills the entire |
// thumbnail. That is, for a tall image, we scale it so that the |
// width matches thumbnailSize and the it's centred vertically. |
// Similarly for a wide image. |
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r = CGRectZero; |
r.size.width = CGImageGetWidth(sourceImage); |
r.size.height = CGImageGetWidth(sourceImage); |
if (r.size.height > r.size.width) { |
// tall image |
r.size.height = (r.size.height / r.size.width) * thumbnailSize; |
r.size.width = thumbnailSize; |
r.origin.y = - ((r.size.height - thumbnailSize) / 2); |
} else { |
// wide image |
r.size.width = (r.size.width / r.size.height) * thumbnailSize; |
r.size.height = thumbnailSize; |
r.origin.x = - ((r.size.width - thumbnailSize) / 2); |
} |
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// Draw the source image and get then create the thumbnail from the |
// context. |
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CGContextDrawImage(context, r, sourceImage); |
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self->_thumbnail = CGBitmapContextCreateImage(context); |
assert(self->_thumbnail != NULL); |
} |
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CGContextRelease(context); |
CGColorSpaceRelease(space); |
CGColorRelease(white); |
} |
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CGImageRelease(sourceImage); |
CGDataProviderRelease(provider); |
} |
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@end |
