TXTZ Output: Fix cover not being properly identified in the generated TXTZ metadata. Fixes #2038848 [Ebook-viewer: book cover for a TXTZ file is not shown](https://bugs.launchpad.net/calibre/+bug/2038848)

src/calibre/ebooks/conversion/plugins/txt_input.py

@@ -126,21 +126,23 @@ class TXTInput(InputFormatPlugin):
 
     def convert(self, stream, options, file_ext, log,
                 accelerators):
-        from calibre.ebooks.conversion.preprocess import DocAnalysis, Dehyphenator
         from calibre.ebooks.chardet import detect
+        from calibre.ebooks.conversion.preprocess import Dehyphenator, DocAnalysis
+        from calibre.ebooks.txt.processor import (
+            block_to_single_line, convert_basic, convert_markdown_with_metadata,
+            convert_textile, detect_formatting_type, detect_paragraph_type,
+            normalize_line_endings, preserve_spaces, remove_indents,
+            separate_hard_scene_breaks, separate_paragraphs_print_formatted,
+            separate_paragraphs_single_line,
+        )
         from calibre.utils.zipfile import ZipFile
-        from calibre.ebooks.txt.processor import (convert_basic,
-                convert_markdown_with_metadata, separate_paragraphs_single_line,
-                separate_paragraphs_print_formatted, preserve_spaces,
-                detect_paragraph_type, detect_formatting_type,
-                normalize_line_endings, convert_textile, remove_indents,
-                block_to_single_line, separate_hard_scene_breaks)
 
         self.log = log
         txt = b''
         log.debug('Reading text from file...')
         length = 0
         base_dir = self.output_dir = os.getcwd()
+        cover_path = None
 
         # Extract content from zip archive.
         if file_ext == 'txtz':
@@ -171,6 +173,10 @@ class TXTInput(InputFormatPlugin):
                             options.formatting_type = txt_formatting
                             if txt_formatting != 'plain':
                                 options.paragraph_type = 'off'
+                    crelpath = root.find('cover-relpath-from-base')
+                    if crelpath is not None and crelpath.text:
+                        cover_path = os.path.abspath(crelpath.text)
+
             if options.formatting_type == 'auto':
                 if file_ext == 'textile':
                     options.formatting_type = txt_formatting
@@ -250,6 +256,7 @@ class TXTInput(InputFormatPlugin):
             txt = block_to_single_line(txt)
         elif options.paragraph_type == 'unformatted':
             from calibre.ebooks.conversion.utils import HeuristicProcessor
+
             # unwrap lines based on punctuation
             docanalysis = DocAnalysis('txt', txt)
             length = docanalysis.line_length(.5)
@@ -318,9 +325,17 @@ class TXTInput(InputFormatPlugin):
         if input_mi is None:
             from calibre.customize.ui import get_file_type_metadata
             input_mi = get_file_type_metadata(stream, file_ext)
+        from calibre import guess_type
         from calibre.ebooks.oeb.transforms.metadata import meta_info_to_oeb_metadata
         meta_info_to_oeb_metadata(input_mi, oeb.metadata, log)
         self.html_postprocess_title = input_mi.title
+        if cover_path and os.path.exists(cover_path):
+            with open(os.path.join(os.getcwd(), cover_path), 'rb') as cf:
+                cdata = cf.read()
+            cover_name = os.path.basename(cover_path)
+            id, href = oeb.manifest.generate('cover', cover_name)
+            oeb.manifest.add(id, href, guess_type(cover_name)[0], data=cdata)
+            oeb.guide.add('cover', 'Cover', href)
 
         return oeb
 

src/calibre/ebooks/conversion/plugins/txt_output.py

@@ -137,6 +137,11 @@ class TXTZOutput(TXTOutput):
                 shutil.copy(tf, os.path.join(tdir, txt_name))
 
             # Images
+            try:
+                cover_href = oeb_book.guide[oeb_book.metadata.cover[0].term].href
+            except Exception:
+                cover_href = None
+            cover_relhref = None
             for item in oeb_book.manifest:
                 if item.media_type in OEB_IMAGES:
                     if hasattr(self.writer, 'images'):
@@ -148,10 +153,11 @@ class TXTZOutput(TXTOutput):
                     else:
                         path = os.path.join(tdir, os.path.dirname(item.href))
                         href = os.path.basename(item.href)
-                    if not os.path.exists(path):
-                        os.makedirs(path)
+                    os.makedirs(path, exist_ok=True)
                     with open(os.path.join(path, href), 'wb') as imgf:
                         imgf.write(item.data)
+                    if item.href == cover_href:
+                        cover_relhref = os.path.relpath(imgf.name, tdir).replace(os.sep, '/')
 
             # Metadata
             with open(os.path.join(tdir, 'metadata.opf'), 'wb') as mdataf:
@@ -159,6 +165,10 @@ class TXTZOutput(TXTOutput):
                 elem = root.makeelement('text-formatting')
                 elem.text = opts.txt_output_formatting
                 root.append(elem)
+                if cover_relhref:
+                    elem = root.makeelement('cover-relpath-from-base')
+                    elem.text = cover_relhref
+                    root.append(elem)
                 mdataf.write(xml2str(root, pretty_print=True))
 
             txtz = ZipFile(output_path, 'w')

src/calibre/ebooks/metadata/extz.py

@@ -39,6 +39,12 @@ def get_metadata(stream, extract_cover=True):
                             if val.rpartition('.')[2].lower() in {'jpeg', 'jpg', 'png'}:
                                 cover_href = val
                                 break
+                        else:
+                            # txtz files use a special element for cover
+                            for cpath in opf.root.xpath('//cover-relpath-from-base'):
+                                if cpath.text:
+                                    cover_href = cpath.text
+                                    break
                 if cover_href:
                     try:
                         mi.cover_data = (os.path.splitext(cover_href)[1], zf.read(cover_href))