Add support for ALTO output

CMakeLists.txt

@@ -215,6 +215,7 @@ set(tesseract_src ${tesseract_src}
     src/api/capi.cpp
     src/api/renderer.cpp
     src/api/pdfrenderer.cpp
+    src/api/altorenderer.cpp
 )
 
 if (WIN32)
@@ -223,7 +224,7 @@ if (WIN32)
         set(tesseract_hdr
             ${tesseract_hdr}
             ${CMAKE_CURRENT_SOURCE_DIR}/src/vs2010/tesseract/resource.h)
-        set(tesseract_rsc ${CMAKE_CURRENT_BINARY_DIR}/vs2010/tesseract/libtesseract.rc)
+        set(tesseract_rsc ${CMAKE_CURRENT_BINARY_DIR}/vs2010/tesseract/libtesseract.rc src/api/altorenderer.cpp)
         set_source_files_properties(
             ${CMAKE_CURRENT_SOURCE_DIR}/src/arch/dotproductsse.cpp
             PROPERTIES COMPILE_DEFINITIONS __SSE4_1__)

android/jni/Android.mk

@@ -31,6 +31,7 @@ LOCAL_SRC_FILES := $(wildcard $(LOCAL_PATH)/../../api/*.cpp $(LOCAL_PATH)/../../
 
 EXPLICIT_SRC_EXCLUDES := \
   $(LOCAL_PATH)/../../api/pdfrenderer.cpp \
+  $(LOCAL_PATH)/../../api/altorenderer.cpp \
   $(LOCAL_PATH)/../../api/tesseractmain.cpp \
 
 LOCAL_SRC_FILES := $(filter-out $(EXPLICIT_SRC_EXCLUDES), $(LOCAL_SRC_FILES))

src/api/Makefile.am

@@ -32,7 +32,7 @@ libtesseract_api_la_CPPFLAGS = $(AM_CPPFLAGS)
 if VISIBILITY
 libtesseract_api_la_CPPFLAGS += -DTESS_EXPORTS
 endif
-libtesseract_api_la_SOURCES = baseapi.cpp capi.cpp renderer.cpp pdfrenderer.cpp
+libtesseract_api_la_SOURCES = baseapi.cpp capi.cpp renderer.cpp pdfrenderer.cpp altorenderer.cpp
 
 lib_LTLIBRARIES += libtesseract.la
 libtesseract_la_LDFLAGS = $(LEPTONICA_LIBS) $(OPENCL_LDFLAGS)

src/api/altorenderer.cpp

@@ -0,0 +1,252 @@
+// File:        altorenderer.cpp
+// Description: ALTO rendering interface
+// Author:      Jake Sebright
+
+// (C) Copyright 2018
+// 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.
+
+#include "baseapi.h"
+#include <memory>
+#include "renderer.h"
+
+namespace tesseract {
+
+    ///
+    /// Add coordinates to specified TextBlock, TextLine, or String bounding box
+    /// Add word confidence if adding to a String bounding box
+    ///
+    static void AddBoxToAlto(const ResultIterator *it, PageIteratorLevel level,
+                             STRING *alto_str) {
+        int left, top, right, bottom;
+        it->BoundingBox(level, &left, &top, &right, &bottom);
+
+        int hpos = left;
+        int vpos = top;
+        int height = bottom - top;
+        int width = right - left;
+
+        *alto_str += " HPOS=\"";
+        alto_str->add_str_int("", hpos);
+        *alto_str += "\"";
+        *alto_str += " VPOS=\"";
+        alto_str->add_str_int("", vpos);
+        *alto_str += "\"";
+        *alto_str += " WIDTH=\"";
+        alto_str->add_str_int("", width);
+        *alto_str += "\"";
+        *alto_str += " HEIGHT=\"";
+        alto_str->add_str_int("", height);
+        *alto_str += "\"";
+
+        if (level == RIL_WORD) {
+            int wc = it->Confidence(RIL_WORD);
+            *alto_str += " WC=\"0.";
+            alto_str->add_str_int("", wc);
+            *alto_str += "\"";
+        }
+        if (level != RIL_WORD) {
+
+            *alto_str += ">";
+        }
+    }
+
+    ///
+    /// Add a unique ID to an ALTO element
+    ///
+    static void AddIdToAlto(STRING *alto_str, const std::string base, int num1) {
+        const size_t BUFSIZE = 64;
+        char id_buffer[BUFSIZE];
+        snprintf(id_buffer, BUFSIZE - 1, "%s_%d", base.c_str(), num1);
+        id_buffer[BUFSIZE - 1] = '\0';
+        *alto_str += " ID=\"";
+        *alto_str += id_buffer;
+        *alto_str += "\"";
+    }
+
+    ///
+    /// Append the ALTO XML for the beginning of the document
+    ///
+    bool TessAltoRenderer::BeginDocumentHandler() {
+        AppendString(
+        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+        "<alto xmlns=\"http://www.loc.gov/standards/alto/ns-v3#\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://www.loc.gov/standards/alto/ns-v3# http://www.loc.gov/alto/v3/alto-3-0.xsd\">\n"
+        "\t<Description>\n"
+        "\t\t<MeasurementUnit>pixel</MeasurementUnit>\n"
+        "\t\t<sourceImageInformation>\n"
+        "\t\t\t<fileName>");
+
+        AppendString(title());
+
+        AppendString("\t\t\t</fileName>\n"
+        "\t\t</sourceImageInformation>\n"
+        "\t\t<OCRProcessing ID=\"OCR_0\">\n"
+        "\t\t\t<ocrProcessingStep>\n"
+        "\t\t\t\t<processingSoftware>\n"
+        "\t\t\t\t\t<softwareName>tesseract ");
+        AppendString(TessBaseAPI::Version());
+        AppendString("</softwareName>\n"
+        "\t\t\t\t</processingSoftware>\n"
+        "\t\t\t</ocrProcessingStep>\n"
+        "\t\t</OCRProcessing>\n"
+        "\t</Description>\n"
+        "\t<Layout>\n");
+
+        return true;
+    }
+
+    ///
+    /// Append the ALTO XML for the layout of the image
+    ///
+    bool TessAltoRenderer::AddImageHandler(TessBaseAPI* api) {
+        const std::unique_ptr<const char[]> hocr(api->GetAltoText(imagenum()));
+        if (hocr == nullptr) return false;
+
+        AppendString(hocr.get());
+
+        return true;
+    }
+
+    ///
+    /// Append the ALTO XML for the end of the document
+    ///
+    bool TessAltoRenderer::EndDocumentHandler() {
+        AppendString("\t</Layout>\n</alto>\n");
+
+        return true;
+    }
+
+    TessAltoRenderer::TessAltoRenderer(const char *outputbase)
+        : TessResultRenderer(outputbase, "xml") {
+    }
+
+    ///
+    /// Make an XML-formatted string with ALTO markup from the internal
+    /// data structures.
+    ///
+    char *TessBaseAPI::GetAltoText(int page_number) {
+        return GetAltoText(nullptr, page_number);
+    }
+
+    ///
+    /// Make an XML-formatted string with ALTO markup from the internal
+    /// data structures.
+    ///
+    char *TessBaseAPI::GetAltoText(ETEXT_DESC *monitor, int page_number) {
+        if (tesseract_ == nullptr || (page_res_ == nullptr && Recognize(monitor) < 0))
+            return nullptr;
+
+        int lcnt = 0, bcnt = 0, wcnt = 0;
+        int page_id = page_number;
+
+        STRING alto_str("");
+
+        if (input_file_ == nullptr)
+            SetInputName(nullptr);
+
+        #ifdef _WIN32
+                // convert input name from ANSI encoding to utf-8
+              int str16_len =
+                  MultiByteToWideChar(CP_ACP, 0, input_file_->string(), -1, nullptr, 0);
+              wchar_t *uni16_str = new WCHAR[str16_len];
+              str16_len = MultiByteToWideChar(CP_ACP, 0, input_file_->string(), -1,
+                                              uni16_str, str16_len);
+              int utf8_len = WideCharToMultiByte(CP_UTF8, 0, uni16_str, str16_len, nullptr, 0,
+                                                 nullptr, nullptr);
+              char *utf8_str = new char[utf8_len];
+              WideCharToMultiByte(CP_UTF8, 0, uni16_str, str16_len, utf8_str,
+                                  utf8_len, nullptr, nullptr);
+              *input_file_ = utf8_str;
+              delete[] uni16_str;
+              delete[] utf8_str;
+        #endif
+
+            alto_str += "\t\t<Page WIDTH=\"";
+            alto_str.add_str_int("", rect_width_);
+            alto_str += "\" HEIGHT=\"";
+            alto_str.add_str_int("", rect_height_);
+            alto_str += "\" PHYSICAL_IMG_NR=\"";
+            alto_str.add_str_int("", rect_height_);
+            alto_str += "\"";
+            AddIdToAlto(&alto_str, "page", page_id);
+            alto_str += ">\n";
+            alto_str += ("\t\t\t<PrintSpace HPOS=\"0\" "
+                         "VPOS=\"0\""
+                         " WIDTH=\"");
+            alto_str.add_str_int("", rect_width_);
+            alto_str += "\" HEIGHT=\"";
+            alto_str.add_str_int("", rect_height_);
+            alto_str += "\">\n";
+
+            ResultIterator *res_it = GetIterator();
+            while (!res_it->Empty(RIL_BLOCK)) {
+                if (res_it->Empty(RIL_WORD)) {
+                    res_it->Next(RIL_WORD);
+                    continue;
+                }
+
+                if (res_it->IsAtBeginningOf(RIL_BLOCK)) {
+                    alto_str += "\t\t\t\t<TextBlock ";
+                    AddIdToAlto(&alto_str, "block", bcnt);
+                    AddBoxToAlto(res_it, RIL_BLOCK, &alto_str);
+                    alto_str += "\n";
+                }
+
+                if (res_it->IsAtBeginningOf(RIL_TEXTLINE)) {
+
+                    alto_str += "\t\t\t\t\t<TextLine ";
+                    AddIdToAlto(&alto_str, "line", lcnt);
+                    AddBoxToAlto(res_it, RIL_TEXTLINE, &alto_str);
+                    alto_str += "\n";
+                }
+
+                alto_str += "\t\t\t\t\t\t<String ";
+                AddIdToAlto(&alto_str, "string", wcnt);
+                AddBoxToAlto(res_it, RIL_WORD, &alto_str);
+                alto_str += " CONTENT=\"";
+
+
+                bool last_word_in_line = res_it->IsAtFinalElement(RIL_TEXTLINE, RIL_WORD);
+                bool last_word_in_block = res_it->IsAtFinalElement(RIL_BLOCK, RIL_WORD);
+
+                do {
+                    const std::unique_ptr<const char[]> grapheme(
+                            res_it->GetUTF8Text(RIL_SYMBOL));
+                    if (grapheme && grapheme[0] != 0) {
+                        alto_str += HOcrEscape(grapheme.get());
+                    }
+                    res_it->Next(RIL_SYMBOL);
+                } while (!res_it->Empty(RIL_BLOCK) && !res_it->IsAtBeginningOf(RIL_WORD));
+
+                alto_str += "\"/>\n";
+
+                wcnt++;
+
+                if (last_word_in_line) {
+                    alto_str += "\t\t\t\t\t</TextLine>\n";
+                    lcnt++;
+                }
+
+                if (last_word_in_block) {
+                    alto_str += "\t\t\t\t</TextBlock>\n";
+                    bcnt++;
+                }
+            }
+
+            alto_str += "\t\t\t</PrintSpace>\n";
+            alto_str += "\t\t</Page>\n";
+
+            char *ret = new char[alto_str.length() + 1];
+            strcpy(ret, alto_str.string());
+            delete res_it;
+            return ret;
+    }
+
+}

src/api/baseapi.h

@@ -594,6 +594,19 @@ class TESS_API TessBaseAPI {
    */
   char* GetHOCRText(int page_number);
 
+  /**
+   * Make an XML-formatted string with Alto markup from the internal
+   * data structures.
+   */
+  char* GetAltoText(ETEXT_DESC* monitor, int page_number);
+
+
+  /**
+   * Make an XML-formatted string with Alto markup from the internal
+   * data structures.
+   */
+  char* GetAltoText(int page_number);
+
   /**
    * Make a TSV-formatted string from the internal data structures.
    * page_number is 0-based but will appear in the output as 1-based.

src/api/capi.cpp

@@ -66,6 +66,11 @@ TESS_API TessResultRenderer* TESS_CALL TessHOcrRendererCreate2(const char* outpu
     return new TessHOcrRenderer(outputbase, font_info);
 }
 
+TESS_API TessResultRenderer* TESS_CALL TessAltoRendererCreate(const char* outputbase)
+{
+    return new TessAltoRenderer(outputbase);
+}
+
 TESS_API TessResultRenderer* TESS_CALL TessPDFRendererCreate(const char* outputbase, const char* datadir,
                                                              BOOL textonly)
 {

src/api/capi.h

@@ -56,6 +56,7 @@ extern "C" {
 typedef tesseract::TessResultRenderer TessResultRenderer;
 typedef tesseract::TessTextRenderer TessTextRenderer;
 typedef tesseract::TessHOcrRenderer TessHOcrRenderer;
+typedef tesseract::TessAltoRenderer TessAltoRenderer;
 typedef tesseract::TessPDFRenderer TessPDFRenderer;
 typedef tesseract::TessUnlvRenderer TessUnlvRenderer;
 typedef tesseract::TessBoxTextRenderer TessBoxTextRenderer;
@@ -126,6 +127,7 @@ TESS_API void  TESS_CALL TessDeleteIntArray(int* arr);
 TESS_API TessResultRenderer* TESS_CALL TessTextRendererCreate(const char* outputbase);
 TESS_API TessResultRenderer* TESS_CALL TessHOcrRendererCreate(const char* outputbase);
 TESS_API TessResultRenderer* TESS_CALL TessHOcrRendererCreate2(const char* outputbase, BOOL font_info);
+TESS_API TessResultRenderer* TESS_CALL TessAltoRendererCreate(const char* outputbase);
 TESS_API TessResultRenderer* TESS_CALL TessPDFRendererCreate(const char* outputbase, const char* datadir,
                                                              BOOL textonly);
 TESS_API TessResultRenderer* TESS_CALL TessUnlvRendererCreate(const char* outputbase);
@@ -277,6 +279,8 @@ TESS_API TessMutableIterator*
 TESS_API char* TESS_CALL TessBaseAPIGetUTF8Text(TessBaseAPI* handle);
 TESS_API char* TESS_CALL TessBaseAPIGetHOCRText(TessBaseAPI* handle, int page_number);
 
+TESS_API char* TESS_CALL TessBaseAPIGetAltoText(TessBaseAPI* handle, int page_number);
+
 TESS_API char* TESS_CALL TessBaseAPIGetBoxText(TessBaseAPI* handle, int page_number);
 
 TESS_API char* TESS_CALL TessBaseAPIGetUNLVText(TessBaseAPI* handle);

src/api/renderer.h

@@ -166,6 +166,20 @@ class TESS_API TessHOcrRenderer : public TessResultRenderer {
   bool font_info_;  // whether to print font information
 };
 
+/**
+ * Renders tesseract output into an alto text string
+ */
+    class TESS_API TessAltoRenderer : public TessResultRenderer {
+    public:
+        explicit TessAltoRenderer(const char *outputbase);
+
+    protected:
+        virtual bool BeginDocumentHandler();
+        virtual bool AddImageHandler(TessBaseAPI* api);
+        virtual bool EndDocumentHandler();
+
+    };
+
 /**
  * Renders Tesseract output into a TSV string
  */

src/api/tesseractmain.cpp

@@ -419,6 +419,19 @@ static void PreloadRenderers(
       }
     }
 
+    api->GetBoolVariable("tessedit_create_alto", &b);
+    if (b) {
+        tesseract::TessAltoRenderer* renderer =
+                new tesseract::TessAltoRenderer(outputbase);
+        if (renderer->happy()) {
+            renderers->push_back(renderer);
+        } else {
+            delete renderer;
+            tprintf("Error, could not create ALTO output file: %s\n",
+                    strerror(errno));
+        }
+    }
+
     api->GetBoolVariable("tessedit_create_tsv", &b);
     if (b) {
       bool font_info;

src/ccmain/tesseractclass.cpp

@@ -387,6 +387,8 @@ Tesseract::Tesseract()
                   this->params()),
       BOOL_MEMBER(tessedit_create_hocr, false, "Write .html hOCR output file",
                   this->params()),
+      BOOL_MEMBER(tessedit_create_alto, false, "Write .xml ALTO file",
+                  this->params()),
       BOOL_MEMBER(tessedit_create_tsv, false, "Write .tsv output file",
                   this->params()),
       BOOL_MEMBER(tessedit_create_pdf, false, "Write .pdf output file",