add markdown support using md4c

crengine/include/bookformats.h

@@ -20,7 +20,8 @@ typedef enum {
     doc_format_pdb,
     doc_format_odt,
     doc_format_svg,
-    doc_format_max = doc_format_svg
+    doc_format_md,
+    doc_format_max = doc_format_md
     // don't forget update getDocFormatName() when changing this enum
 } doc_format_t;
 

crengine/src/lvdocview.cpp

@@ -31,6 +31,7 @@
 #include "../include/fb3fmt.h"
 #include "../include/docxfmt.h"
 #include "../include/odtfmt.h"
+#include "mdfmt.h"
 
 /// to show page bounds rectangles
 //#define SHOW_PAGE_RECT
@@ -4649,6 +4650,37 @@ bool LVDocView::LoadDocument(LVStreamRef stream, bool metadataOnly) {
         }
 #endif
 
+#if (USE_MD4C == 1)
+        if (DetectMarkdownFormat(m_stream, stream->GetName())) {
+            CRLog::info("Markdown format detected");
+            createEmptyDocument();
+            m_doc->setProps(m_doc_props);
+            setRenderProps(0, 0);
+            setDocFormat(doc_format_md);
+            if (m_callback)
+                m_callback->OnLoadFileFormatDetected(doc_format_md);
+            updateDocStyleSheet();
+            bool res = ImportMarkdownDocument(m_stream, stream->GetName(), m_doc, m_callback, this);
+            if (!res) {
+                setDocFormat(doc_format_none);
+                createDefaultDocument(cs32("ERROR: Error reading Markdown format"), cs32("Cannot open document"));
+                if (m_callback) {
+                    m_callback->OnLoadFileError(cs32("Error reading Markdown document"));
+                }
+                return false;
+            } else {
+                setRenderProps(0, 0);
+                REQUEST_RENDER("loadDocument")
+                if (m_callback) {
+                    m_callback->OnLoadFileEnd();
+                    //m_doc->compact();
+                    m_doc->dumpStatistics();
+                }
+                return true;
+            }
+        }
+#endif
+
 		bool repeat_recursively = false;
         m_arc = LVOpenArchieve( m_stream );
 		if (!m_arc.isNull())

crengine/src/mdfmt.cpp

@@ -0,0 +1,130 @@
+/***************************************************************************
+ *   crengine-ng                                                           *
+ *   Copyright (C) 2022,2024 Aleksey Chernov <[email protected]>          *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU General Public License           *
+ *   as published by the Free Software Foundation; either version 2        *
+ *   of the License, or (at your option) any later version.                *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the Free Software           *
+ *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,            *
+ *   MA 02110-1301, USA.                                                   *
+ ***************************************************************************/
+
+#include "mdfmt.h"
+
+#if (USE_MD4C == 1)
+
+#include <lvtinydom.h>
+
+#include <string.h>
+
+#include <md4c-html.h>
+
+#define TEXT_PARSER_CHUNK_SIZE 16384
+
+bool DetectMarkdownFormat(LVStreamRef stream, const lString32& fileName) {
+    // Check file extension
+    lString32 nm = fileName;
+    nm = nm.lowercase();
+    if (!nm.endsWith(".md"))
+        return false;
+    // Check file size
+    lvsize_t sz = stream->GetSize();
+    if (sz < 5 || sz > MARKDOWN_MAX_FILE_SIZE)
+        return false;
+    // Checking for compliance with the text format
+    LVTextParser textParser(stream, NULL, true);
+    bool res = textParser.CheckFormat();
+    stream->SetPos(0);
+    return res;
+}
+
+typedef struct cre_md4c_parse_data_tag
+{
+    lString8* htmlData;
+} cre_md4c_parse_data;
+
+static void my_md4c_process_output(const MD_CHAR* chunk, MD_SIZE sz, void* userData) {
+    cre_md4c_parse_data* data = (cre_md4c_parse_data*)userData;
+    data->htmlData->append(chunk, sz);
+}
+
+bool ImportMarkdownDocument(LVStreamRef stream, const lString32& fileName, ldomDocument* doc, LVDocViewCallback* progressCallback, CacheLoadingCallback* formatCallback) {
+    if (doc->openFromCache(formatCallback)) {
+        if (progressCallback) {
+            progressCallback->OnLoadFileEnd();
+        }
+        return true;
+    }
+    bool res = false;
+    // Read stream
+    lString8 rawData;
+    lString8 htmlData;
+    char buffer[TEXT_PARSER_CHUNK_SIZE];
+    lvsize_t bytesRead = 0;
+    stream->SetPos(0);
+    while (stream->Read(buffer, TEXT_PARSER_CHUNK_SIZE, &bytesRead) == LVERR_OK) {
+        rawData.append(buffer, bytesRead);
+        if (bytesRead < TEXT_PARSER_CHUNK_SIZE)
+            break;
+    }
+    // Parse and convert to html
+    cre_md4c_parse_data parseData;
+    parseData.htmlData = &htmlData;
+    int parse_res = md_html(rawData.c_str(), rawData.length(), my_md4c_process_output, (void*)&parseData,
+                            MD_FLAG_COLLAPSEWHITESPACE | MD_FLAG_TABLES | MD_FLAG_TASKLISTS |
+                                    MD_FLAG_STRIKETHROUGH | MD_FLAG_PERMISSIVEURLAUTOLINKS |
+                                    MD_FLAG_PERMISSIVEEMAILAUTOLINKS | MD_FLAG_PERMISSIVEWWWAUTOLINKS |
+                                    MD_FLAG_LATEXMATHSPANS,
+                            0);
+    rawData.clear();
+    if (0 != parse_res) {
+        // Parse failed
+        CRLog::error("MD4C: Failed to parse Markdown document!");
+        return res;
+    }
+    // Write document content to stream to parse them
+    lvsize_t result_len = htmlData.length();
+    lString32 title = LVExtractFilenameWithoutExtension(fileName);
+    lString8 gen_preamble = cs8("<html><head><title>") + UnicodeToUtf8(title) + cs8("</title></head><body>");
+    lString8 gen_tail = cs8("</body></html>");
+    lvsize_t dw;
+    LVStreamRef memStream = LVCreateMemoryStream();
+    res = !memStream.isNull();
+    if (res)
+        res = LVERR_OK == memStream->Write(gen_preamble.c_str(), gen_preamble.length(), &dw);
+    if (res)
+        res = dw == (lvsize_t)gen_preamble.length();
+    if (res) {
+        res = LVERR_OK == memStream->Write(htmlData.data(), result_len, &dw);
+    }
+    htmlData.clear();
+    if (res)
+        res = dw == result_len;
+    if (res)
+        res = LVERR_OK == memStream->Write(gen_tail.c_str(), gen_tail.length(), &dw);
+    if (res)
+        res = dw == (lvsize_t)gen_tail.length();
+    if (res) {
+        // Parse stream to document
+        ldomDocumentWriter writer(doc);
+        LVHTMLParser parser(memStream, &writer);
+        parser.setProgressCallback(progressCallback);
+        res = parser.CheckFormat() && parser.Parse();
+    }
+    if (res) {
+        doc->getProps()->setString(DOC_PROP_TITLE, title);
+        doc->buildTocFromHeadings();
+    }
+    return res;
+}
+
+#endif

crengine/src/mdfmt.h

@@ -0,0 +1,42 @@
+/***************************************************************************
+ *   crengine-ng                                                           *
+ *   Copyright (C) 2022,2024 Aleksey Chernov <[email protected]>          *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU General Public License           *
+ *   as published by the Free Software Foundation; either version 2        *
+ *   of the License, or (at your option) any later version.                *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the Free Software           *
+ *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,            *
+ *   MA 02110-1301, USA.                                                   *
+ ***************************************************************************/
+
+#ifndef __MDFMT_H_INCLUDED__
+#define __MDFMT_H_INCLUDED__
+
+#include <crsetup.h>
+
+#if (USE_MD4C == 1)
+
+#include <lvstream.h>
+#include <lvstring.h>
+
+class ldomDocument;
+class LVDocViewCallback;
+class CacheLoadingCallback;
+
+#define MARKDOWN_MAX_FILE_SIZE 10 * 1024 * 1024 // 10M
+
+bool DetectMarkdownFormat(LVStreamRef stream, const lString32& fileName);
+bool ImportMarkdownDocument(LVStreamRef stream, const lString32& fileName, ldomDocument* doc, LVDocViewCallback* progressCallback, CacheLoadingCallback* formatCallback);
+
+#endif
+
+#endif // __MDFMT_H_INCLUDED__