Work on dialog to display category notes

src/calibre/db/cache.py

@@ -2464,6 +2464,18 @@ class Cache:
         vm = table.id_map
         return {vm.get(fid):v for fid,v in lm.items() if v}
 
+    @read_api
+    def link_for(self, field, item_id):
+        '''
+        Return the link, if any, for the specified item or None if no link is found
+        '''
+        f = self.fields.get(field)
+        if f is not None:
+            table = f.table
+            lm = getattr(table, 'link_map', None)
+            if lm is not None:
+                return lm.get(item_id)
+
     @read_api
     def get_all_link_maps_for_book(self, book_id):
         '''

src/calibre/ebooks/metadata/book/render.py

@@ -89,6 +89,18 @@ def author_search_href(which, title=None, author=None):
     return func(key, title=title, author=author), tt
 
 
+def render_author_link(default_author_link, author, book_title=None, author_sort=None):
+    book_title = book_title or ''
+    if default_author_link.startswith('search-'):
+        which_src = default_author_link.partition('-')[2]
+        link, lt = author_search_href(which_src, title=book_title, author=author)
+    else:
+        formatter = EvalFormatter()
+        vals = {'author': qquote(author), 'title': qquote(book_title), 'author_sort': qquote(author_sort or author)}
+        link = lt = formatter.safe_format(default_author_link, vals, '', vals)
+    return link, lt
+
+
 def mi_to_html(
         mi,
         field_list=None, default_author_link=None, use_roman_numbers=True,
@@ -270,21 +282,11 @@ def mi_to_html(
                 ans.append((field, row % (_('Ids')+title_sep, links)))
         elif field == 'authors':
             authors = []
-            formatter = EvalFormatter()
             for aut in mi.authors:
                 link = ''
                 if show_links:
                     if default_author_link:
-                        if default_author_link.startswith('search-'):
-                            which_src = default_author_link.partition('-')[2]
-                            link, lt = author_search_href(which_src, title=mi.title, author=aut)
-                        else:
-                            vals = {'author': qquote(aut), 'title': qquote(mi.title)}
-                            try:
-                                vals['author_sort'] =  qquote(mi.author_sort_map[aut])
-                            except KeyError:
-                                vals['author_sort'] = qquote(aut)
-                            link = lt = formatter.safe_format(default_author_link, vals, '', vals)
+                        link, lt = render_author_link(default_author_link, aut, mi.title, mi.author_sort_map.get(aut) or aut)
                     else:
                         aut = p(aut)
                 if link:

src/calibre/gui2/dialogs/show_category_note.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python
+# License: GPLv3 Copyright: 2023, Kovid Goyal <kovid at kovidgoyal.net>
+
+import os
+from qt.core import (
+    QByteArray, QDialogButtonBox, QIcon, QSize, Qt, QTextDocument, QVBoxLayout,
+)
+
+from calibre.db.constants import RESOURCE_URL_SCHEME
+from calibre.ebooks.metadata.book.render import render_author_link
+from calibre.gui2 import Application, default_author_link
+from calibre.gui2.book_details import resolved_css
+from calibre.gui2.widgets2 import Dialog, HTMLDisplay
+
+
+class Display(HTMLDisplay):
+    notes_resource_scheme = RESOURCE_URL_SCHEME
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.document().setDefaultStyleSheet(resolved_css() + '\n\nli { margin-top: 0.5ex; margin-bottom: 0.5ex; }')
+        self.setFocusPolicy(Qt.FocusPolicy.NoFocus)
+
+    def loadResource(self, rtype, qurl):
+        if qurl.scheme() == RESOURCE_URL_SCHEME and int(rtype) == int(QTextDocument.ResourceType.ImageResource):
+            db = self.parent().db
+            resource = db.get_notes_resource(f'{qurl.host()}:{qurl.path()[1:]}')
+            if resource is not None:
+                return QByteArray(resource['data'])
+            return
+        return super().loadResource(rtype, qurl)
+
+
+class ShowNoteDialog(Dialog):
+
+    def __init__(self, field, item_id, db, parent=None):
+        self.db = db.new_api
+        self.item_val = self.db.get_item_name(field, item_id)
+        self.has_links = self.db.has_link_map(field)
+        self.item_link = (self.db.link_for(field, item_id) or '') if self.has_links else ''
+        self.author_search_link = self.author_search_tooltip = ''
+        if field == 'authors':
+            lk = default_author_link()
+            if lk != 'calibre':
+                self.author_search_link, self.author_search_tooltip = render_author_link(lk, self.item_val)
+        self.field, self.item_id = field, item_id
+        super().__init__(self.item_val, 'show-notes-for-category', parent=parent)
+        self.setWindowIcon(QIcon.ic('tag.png'))
+        self.display.setHtml(self.db.notes_for(self.field, self.item_id))
+
+    def setup_ui(self):
+        self.l = l = QVBoxLayout(self)
+
+        self.display = d = Display(self)
+        l.addWidget(d)
+
+        self.bb.clear()
+        self.bb.addButton(QDialogButtonBox.StandardButton.Close)
+        l.addWidget(self.bb)
+
+    def sizeHint(self):
+        return QSize(800, 620)
+
+
+def develop_show_note():
+    from calibre.library import db as dbc
+    app = Application([])
+    d = ShowNoteDialog('authors', 1, dbc(os.path.expanduser('~/test library')))
+    d.exec()
+    del d, app
+
+
+if __name__ == '__main__':
+    develop_show_note()