Checking HasNext on Tesseract API to avoid getting error when there is no item in the iterator.

[Kurniawan Kurniawan]

* **Tesseract Version**: 3.5.0 and 4.0

* **Platform**: mac & ubuntu 18.04

I am iterating over recognize api as suggested here. "Result iterator example"

https://github.com/tesseract-ocr/tesseract/wiki/APIExample

Pix *image = pixRead("/usr/src/tesseract/testing/phototest.tif");
  tesseract::TessBaseAPI *api = new tesseract::TessBaseAPI();
  api->Init(NULL, "eng");
  api->SetImage(image);
  api->Recognize(0);
  tesseract::ResultIterator* ri = api->GetIterator();
  tesseract::PageIteratorLevel level = tesseract::RIL_WORD;
  if (ri != 0) {
    do {
      const char* word = ri->GetUTF8Text(level);
      float conf = ri->Confidence(level);
      int x1, y1, x2, y2;
      ri->BoundingBox(level, &x1, &y1, &x2, &y2);
      printf("word: '%s';  \tconf: %.2f; BoundingBox: %d,%d,%d,%d;\n",
               word, conf, x1, y1, x2, y2);
      delete[] word;
    } while (ri->Next(level));
  }

it seems we do before calling next. If I am calling next first, it will skip over the first detections.

Unfortunately when I get this error, 

**'NoneType' object is not iterable issue**

When there is no detection.

Here is the code in python-tesserocr

 if (iterator != None):

        next = True

        while (next):

            x,y,right,bottom = iterator.BoundingBox(level)

                        

            next = iterator.Next(level)

it throws an error on iterator.BoundingBox saying that the iterator is empty.

If I call "next = iterator.Next(level)" first, it avoids that error, but it also skip over the first detection

Here is the image, just the whitespace image


Is there any API to check the hasNext()?

Thanks

[Zdenko Podobny]

No there is not such function. there is IsAtBeginningOf (TessPageIteratorIsAtBeginningOf) and  IsAtFinalElement (TessPageIteratorIsAtFinalElement).

If you are interesting in BoundingBoxes you can check this "Getting the bounding box of the recognized words using python-tesseract".

If you are interesting at handling of tesseract iterator in python than you can find some inspiration in pyocr code, or nidaba.

Zdenko

pi 21. 9. 2018 o 6:42 Kurniawan Kurniawan <kku...@gmail.com> napísal(a):

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