I think the crux of the problem is your attempt to stop the OCR thread at a
random spot in its execution yet expect the state of the Tesseract instance
to be consistent. You are right to want to delete the instance otherwise
you would have a memory leak but it looks like you can't do that after
stopping the OCR thread abnormally. In our own iPhone app (ScanBizCards)
what we do in that case is to let the OCR thread finish its work in the
background even though its results will be ignored and not shown to the
user. The downside is mostly that if the user starts a new scan right after
aborting one we delay the start of the new scan until the previous
(aborted) scan finishes.
On Monday, August 27, 2012 6:43:35 AM UTC-4, fulberto100 wrote:
>
> hi,
> im using tesseract on my iPhone app.
>
> i want to stop/cancel the ocr process. is there a way to do it?
> i wrote in backPressed method:
> tesseract->Clear();
> tesseract->End();
>
> but when the ocr starts and i hit the back button, it crashes, cos it is
> still OCRing.
>
> here is my iOS code:
>
> - (void)processOcrAt:(UIImage *)image
> {
> [self setTesseractImage:image];
>
> //char* utf8Text = tesseract->GetUTF8Text();
> //[self performSelector:@selector(ocrProcessingFinished:)
> withObject:[NSString stringWithUTF8String:utf8Text]];
> //dispatch_queue_t queue = dispatch_queue_create("com.awesome", 0);
>
> main = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
> dispatch_async(main, ^{
> tesseract->Recognize(NULL);
> char* utf8Text = tesseract->GetUTF8Text();
> [self performSelectorOnMainThread:@selector(ocrProcessingFinished:)
> withObject:[NSString
> stringWithUTF8String:utf8Text]
> waitUntilDone:NO];
> delete [] utf8Text;
> });
>
>
> }
>
> -(IBAction)backPressed:(id)sender{
> dispatch_release(main);
> tesseract->Clear();
> //tesseract->End();
>
> delete tesseract;
> tesseract = nil;
> delete pixels;
> [self.navigationController popViewControllerAnimated:YES];
> }
>
>
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