Add support for searching via the calibre:// URL scheme

manual/url_scheme.rst

@@ -27,7 +27,7 @@ The URL syntax is::
 
 Library names are the folder name of the library with spaces replaced by
 underscores. The special value ``_`` means the current library. You can also
-use hex encoding for the library names, useful if the library names have
+use :ref:`hex encoding <hex_encoding>` for the library names, useful if the library names have
 special characters that would otherwise require URL encoding. Hex encoded
 library names look like::
 
@@ -62,3 +62,28 @@ Here, ``book_format`` is the format of the book, for example, ``EPUB`` or
 easiest way to get these links is to open a book in the viewer, then in the
 viewer controls select :guilabel:`Go to->Location` and there such a link
 will be given that you can copy/paste elsewhere.
+
+
+Searching for books
+------------------------------
+
+The URL syntax is::
+
+    calibre://search/Library_Name?q=query
+    calibre://search/Library_Name?eq=hex_encoded_query
+
+Here query is any valid :ref:`search expression <search_interface>`. If the
+search expression is complicated, :ref:`encode it as a hex string <hex_encoding>`
+and use ``eq`` instead. Leaving out the query will cause the current search to
+be cleared.
+
+
+.. _hex_encoding:
+
+Hex encoding of URL parameters
+----------------------------------
+
+Hex encoding of URL parameters is done by first encoding the parameter as UTF-8
+bytes, and then replacing each byte by two hexadecimal characters representing
+the byte. For example, the string ``abc`` is the bytes ``0x61 0x62 and 0x63`` in
+UTF-8, so the encoded version is the string: ``616263``.

src/calibre/gui2/ui.py

@@ -707,6 +707,24 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
             else:
                 doit()
 
+        elif action == 'search':
+            parts = tuple(filter(None, path.split('/')))
+            if len(parts) != 1:
+                return
+            library_id = decode_library_id(parts[0])
+            library_path = self.library_broker.path_for_library_id(library_id)
+            if library_path is None:
+                return
+            sq = query.get('eq')
+            if sq:
+                sq = bytes.fromhex(sq[0]).decode('utf-8')
+            else:
+                sq = query.get('q')
+                if sq:
+                    sq = sq[0]
+            sq = sq or ''
+            self.search.set_search_string(sq)
+
     def message_from_another_instance(self, msg):
         if isinstance(msg, bytes):
             msg = msg.decode('utf-8', 'replace')