tesseract/unittest/pagesegmode_test.cc

// (C) Copyright 2017, Google Inc.
// 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.

#if defined(_WIN32)
#  include <io.h> // for _access
#else
#  include <unistd.h> // for access
#endif
#include <allheaders.h>
#include <tesseract/baseapi.h>
#include <string>
#include "helpers.h"
#include "include_gunit.h"
#include "image.h"
#include "log.h"

namespace tesseract {

// Replacement for std::filesystem::exists (C++-17)
static bool file_exists(const char *filename) {
#if defined(_WIN32)
  return _access(filename, 0) == 0;
#else
  return access(filename, 0) == 0;
#endif
}

// The fixture for testing Tesseract.
class PageSegModeTest : public testing::Test {
protected:
  PageSegModeTest() = default;
  ~PageSegModeTest() override {
    src_pix_.destroy();
  }

  void SetUp() override {
    static std::locale system_locale("");
    std::locale::global(system_locale);
  }

  void SetImage(const char *filename) {
    src_pix_.destroy();
    src_pix_ = pixRead(filename);
    api_.Init(TESSDATA_DIR, "eng", tesseract::OEM_TESSERACT_ONLY);
    api_.SetImage(src_pix_);
  }

  // Tests that the given rectangle produces exactly the given text in the
  // given segmentation mode (after chopping off the last 2 newlines.)
  void VerifyRectText(tesseract::PageSegMode mode, const char *str, int left, int top, int width,
                      int height) {
    api_.SetPageSegMode(mode);
    api_.SetRectangle(left, top, width, height);
    char *result = api_.GetUTF8Text();
    chomp_string(result);
    chomp_string(result);
    EXPECT_STREQ(str, result);
    delete[] result;
  }

  // Tests that the given rectangle does NOT produce the given text in the
  // given segmentation mode.
  void NotRectText(tesseract::PageSegMode mode, const char *str, int left, int top, int width,
                   int height) {
    api_.SetPageSegMode(mode);
    api_.SetRectangle(left, top, width, height);
    char *result = api_.GetUTF8Text();
    EXPECT_STRNE(str, result);
    delete[] result;
  }

  Image src_pix_ = nullptr;
  std::string ocr_text_;
  tesseract::TessBaseAPI api_;
};

// Tests the single-word segmentation mode, and that it performs correctly
// and differently to line and block mode.
TEST_F(PageSegModeTest, WordTest) {
  std::string filename = file::JoinPath(TESTING_DIR, "segmodeimg.tif");
  if (!file_exists(filename.c_str())) {
    LOG(INFO) << "Skip test because of missing " << filename << '\n';
    GTEST_SKIP();
  } else {
    SetImage(filename.c_str());
    // Test various rectangles around the inverse page number.
    VerifyRectText(tesseract::PSM_SINGLE_WORD, "183", 1419, 264, 69, 34);
    VerifyRectText(tesseract::PSM_SINGLE_WORD, "183", 1411, 252, 78, 62);
    VerifyRectText(tesseract::PSM_SINGLE_WORD, "183", 1396, 218, 114, 102);
    // Test a random pair of words as a line
    VerifyRectText(tesseract::PSM_SINGLE_LINE, "What should", 237, 393, 256, 36);
  #ifdef DISABLED_LEGACY_ENGINE
    // Skip check as LSTM mode adds a space.
    LOG(INFO) << "Skip `Whatshould` test in LSTM Mode\n";
  #else
    // Test a random pair of words as a word
    VerifyRectText(tesseract::PSM_SINGLE_WORD, "Whatshould", 237, 393, 256, 36);
  #endif
    // Test single block mode.
    VerifyRectText(tesseract::PSM_SINGLE_BLOCK, "both the\nfrom the", 237, 450, 172, 94);
    // But doesn't work in line or word mode.
    NotRectText(tesseract::PSM_SINGLE_LINE, "both the\nfrom the", 237, 450, 172, 94);
    NotRectText(tesseract::PSM_SINGLE_WORD, "both the\nfrom the", 237, 450, 172, 94);
  }
}

} // namespace tesseract