added example code from tesseract-ocr#4070 : GetGradient()

src/examples/get-page-gradient.cpp

@@ -0,0 +1,58 @@
+// example as part of https://github.com/tesseract-ocr/tesseract/pull/4070
+
+#include <allheaders.h>
+#include <tesseract/baseapi.h>
+
+
+#if defined(BUILD_MONOLITHIC)
+# define main tesseract_get_page_gradient_main
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+int main(int argc, const char **argv);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif
+
+int main(int argc, const char **argv) {
+ tesseract::TessBaseAPI *api = new tesseract::TessBaseAPI();
+ // Initialize tesseract-ocr with English, without specifying tessdata path
+ if (api->InitSimple(NULL, "eng")) {
+ fprintf(stderr, "Could not initialize tesseract.\n");
+ return 1;
+ }
+
+ // Open input image with leptonica library
+ std::string filepath;
+ if (argc > 1 && argv[1] != nullptr) {
+ filepath = argv[1];
+ }
+ if (filepath.empty()) {
+ filepath = "rotate_image.png";
+ }
+ Pix *image = pixRead(filepath.c_str());
+ if (!image) {
+ fprintf(stderr, "Could not open image file: %s\n", filepath.c_str());
+ return 1;
+ }
+
+ api->SetImage(image);
+
+ // Find lines, get average gradient
+ api->AnalyseLayout();
+ float gradient = api->GetGradient();
+
+ printf("Average Gradient: %f\n", gradient);
+
+ // Destroy used object and release memory
+ api->End();
+ delete api;
+ pixDestroy(&image);
+
+ return 0;
+}