iphone - tesseract OCRing 时如何停止？

Question

我在我的 iPhone 应用程序中使用 tesseract 进行图像 OCRing。 我想在运行时停止所有 OCR 进程。

这是我的代码:

在.h文件中:

dispatch_queue_t main;
tesseract::TessBaseAPI *tesseract;
uint32_t *pixels;

在.m文件中:

- (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];
}

当我在 ocr 运行时点击后退按钮时，它会崩溃。因为 ocr 仍在运行。我怎样才能阻止它？我在 tesseract 中找不到任何方法。

Answer 1

Recognize() 函数中的 ETEXT_DESC 参数怎么样？ (不确定您写答案 fulberto100 时是否存在)。它是一个监视器，用于跟踪进度以及取消进度。它在 TessBaseAPI::ProcessPage 中使用。不过我自己还没试过。

ETEXT_DESC monitor;
monitor.cancel = NULL;
monitor.cancel_this = NULL;
monitor.set_deadline_msecs(timeout_millisec);
// Now run the main recognition.
failed = Recognize(&monitor) < 0;