zxing/iphone/Classes/Decoder.m

//
//  Decoder.m
//  ZXing
//
//  Created by Christian Brunschen on 31/03/2008.
//
/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import "Decoder.h"
#import "TwoDDecoderResult.h"

#include <zxing/qrcode/QRCodeReader.h>
#include <zxing/BinaryBitmap.h>
#include <zxing/ReaderException.h>
#include <zxing/common/IllegalArgumentException.h>
#include <zxing/common/GlobalHistogramBinarizer.h>
#include "GrayBytesMonochromeBitmapSource.h"

using namespace zxing;
using namespace zxing::qrcode;

@implementation Decoder

@synthesize image;
@synthesize cropRect;
@synthesize subsetImage;
@synthesize subsetData;
@synthesize subsetWidth;
@synthesize subsetHeight;
@synthesize subsetBytesPerRow;
@synthesize delegate;

- (void)willDecodeImage {
	[self.delegate decoder:self willDecodeImage:self.image usingSubset:self.subsetImage];
}

- (void)progressDecodingImage:(NSString *)progress {
	[self.delegate decoder:self 
	 decodingImage:self.image 
	 usingSubset:self.subsetImage
	 progress:progress];
}

- (void)didDecodeImage:(TwoDDecoderResult *)result {
	[self.delegate decoder:self didDecodeImage:self.image usingSubset:self.subsetImage withResult:result];
}

- (void)failedToDecodeImage:(NSString *)reason {
	[self.delegate decoder:self failedToDecodeImage:self.image usingSubset:self.subsetImage reason:reason];
}

#define SUBSET_SIZE 320.0
- (void) prepareSubset {
	CGSize size = [image size];
#ifdef DEBUG
	NSLog(@"decoding: image is (%.1f x %.1f), cropRect is (%.1f,%.1f)x(%.1f,%.1f)", size.width, size.height,
		  cropRect.origin.x, cropRect.origin.y, cropRect.size.width, cropRect.size.height);
#endif
	float scale = fminf(1.0f, fmaxf(SUBSET_SIZE / cropRect.size.width, SUBSET_SIZE / cropRect.size.height));
	CGPoint offset = CGPointMake(-cropRect.origin.x, -cropRect.origin.y);
#ifdef DEBUG
	NSLog(@"  offset = (%.1f, %.1f), scale = %.3f", offset.x, offset.y, scale);
#endif
	
	subsetWidth = cropRect.size.width * scale;
	subsetHeight = cropRect.size.height * scale;
	
	subsetBytesPerRow = ((subsetWidth + 0xf) >> 4) << 4;
#ifdef DEBUG
	NSLog(@"decoding: image to decode is (%d x %d) (%d bytes/row)", subsetWidth, subsetHeight, subsetBytesPerRow);
#endif
	
	subsetData = (unsigned char *)malloc(subsetBytesPerRow * subsetHeight);
#ifdef DEBUG
	NSLog(@"allocated %d bytes of memory", subsetBytesPerRow * subsetHeight);
#endif
	
	CGColorSpaceRef grayColorSpace = CGColorSpaceCreateDeviceGray();
	
	CGContextRef ctx = 
	CGBitmapContextCreate(subsetData, subsetWidth, subsetHeight, 
						  8, subsetBytesPerRow, grayColorSpace, 
						  kCGImageAlphaNone);
	CGColorSpaceRelease(grayColorSpace);
	CGContextSetInterpolationQuality(ctx, kCGInterpolationNone);
	CGContextSetAllowsAntialiasing(ctx, false);
	// adjust the coordinate system
	CGContextTranslateCTM(ctx, 0.0, subsetHeight);
	CGContextScaleCTM(ctx, 1.0, -1.0);	
	
#ifdef DEBUG
	NSLog(@"created %dx%d bitmap context", subsetWidth, subsetHeight);
#endif
	
	UIGraphicsPushContext(ctx);
	CGRect rect = CGRectMake(offset.x * scale, offset.y * scale, scale * size.width, scale * size.height);
#ifdef DEBUG
	NSLog(@"rect for image = (%.1f,%.1f)x(%.1f,%.1f)", rect.origin.x, rect.origin.y, rect.size.width, rect.size.height);
#endif
	[image drawInRect:rect];
	UIGraphicsPopContext();
	
#ifdef DEBUG
	NSLog(@"drew image into %d(%d)x%d  bitmap context", subsetWidth, subsetBytesPerRow, subsetHeight);
#endif
	CGContextFlush(ctx);
#ifdef DEBUG
	NSLog(@"flushed context");
#endif
    
	CGImageRef subsetImageRef = CGBitmapContextCreateImage(ctx);
#ifdef DEBUG
	NSLog(@"created CGImage from context");
#endif
	
	self.subsetImage = [UIImage imageWithCGImage:subsetImageRef];
	CGImageRelease(subsetImageRef);
	
	CGContextRelease(ctx);
#ifdef DEBUG
	NSLog(@"released context");  
#endif
}  

- (void)decode:(id)arg {
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	{ 
		QRCodeReader reader;
#ifdef DEBUG
		NSLog(@"created QRCoreReader");
#endif
		
		Ref<LuminanceSource> source (new GrayBytesMonochromeBitmapSource(subsetData, subsetWidth, subsetHeight, subsetBytesPerRow));
		
		Ref<Binarizer> binarizer (new GlobalHistogramBinarizer(source));
		Ref<BinaryBitmap> grayImage (new BinaryBitmap(binarizer));
#ifdef DEBUG
		NSLog(@"created GrayBytesMonochromeBitmapSource", subsetWidth, subsetHeight);
		NSLog(@"grayImage count = %d", grayImage->count());
#endif
		
		TwoDDecoderResult *decoderResult = nil;
		
#ifdef TRY_ROTATIONS
		for (int i = 0; !decoderResult && i < 4; i++) {
#endif
			
			try {
#ifdef DEBUG
				NSLog(@"decoding gray image");
#endif
				Ref<Result> result(reader.decode(grayImage));
#ifdef DEBUG
				NSLog(@"gray image decoded");
#endif
				
				Ref<String> resultText(result->getText());
				const char *cString = resultText->getText().c_str();
				std::vector<Ref<ResultPoint> > resultPoints = result->getResultPoints();
				NSMutableArray *points = 
				[NSMutableArray arrayWithCapacity:resultPoints.size()];
				
				for (size_t i = 0; i < resultPoints.size(); i++) {
					Ref<ResultPoint> rp(resultPoints[i]);
					CGPoint p = CGPointMake(rp->getX(), rp->getY());
					[points addObject:[NSValue valueWithCGPoint:p]];
				}
				
				NSString *resultString = [NSString stringWithCString:cString
															encoding:NSUTF8StringEncoding];
				
				decoderResult = [TwoDDecoderResult resultWithText:resultString
														   points:points];
			} catch (ReaderException rex) {
				NSLog(@"failed to decode, caught ReaderException '%s'",
					  rex.what());
			} catch (IllegalArgumentException iex) {
				NSLog(@"failed to decode, caught IllegalArgumentException '%s'", 
					  iex.what());
			} catch (...) {
				NSLog(@"Caught unknown exception!");
			}
			
#ifdef TRY_ROTATIONS
			if (!decoderResult) {
#ifdef DEBUG
				NSLog(@"rotating gray image");
#endif
				grayImage = grayImage->rotateCounterClockwise();
#ifdef DEBUG
				NSLog(@"gray image rotated");
#endif
			}
		}
#endif
		
		if (decoderResult) {
			[self performSelectorOnMainThread:@selector(didDecodeImage:)
								   withObject:decoderResult
								waitUntilDone:NO];
		} else {
			[self performSelectorOnMainThread:@selector(failedToDecodeImage:)
								   withObject:NSLocalizedString(@"Decoder BarcodeDetectionFailure", @"No barcode detected.")
								waitUntilDone:NO];
		}
		
		free(subsetData);
		self.subsetData = NULL;
	}
	[pool release];
#ifdef DEBUG
	NSLog(@"finished decoding.");
#endif
	
	// if this is not the main thread, then we end it
	if (![NSThread isMainThread]) {
		[NSThread exit];
	}
}

- (void) decodeImage:(UIImage *)i {
	[self decodeImage:i cropRect:CGRectMake(0.0f, 0.0f, image.size.width, image.size.height)];
}

- (void) decodeImage:(UIImage *)i cropRect:(CGRect)cr {
	self.image = i;
	self.cropRect = cr;
	
	[self prepareSubset];
	[self.delegate decoder:self willDecodeImage:i usingSubset:self.subsetImage];
	
	
	[self performSelectorOnMainThread:@selector(progressDecodingImage:)
						   withObject:NSLocalizedString(@"Decoder MessageWhileDecoding", @"Decoding ...")
						waitUntilDone:NO];  
	
	[NSThread detachNewThreadSelector:@selector(decode:) 
							 toTarget:self 
						   withObject:nil];
}

- (void) dealloc {
	[image release];
	[subsetImage release];
	if (subsetData) free(subsetData);
	[super dealloc];
}

@end