feat(docs): add Chinese translation (jump link) (#5839)

Co-authored-by: YobeZhou <smilezyb@163.com>

docs/_ext/link_roles.py

@@ -0,0 +1,58 @@
+# based on http://protips.readthedocs.io/link-roles.html
+
+#from __future__ import print_function, unicode_literals
+
+import os
+import re
+import subprocess
+from collections import namedtuple
+
+from docutils import nodes
+from sphinx.transforms.post_transforms import SphinxPostTransform
+
+URL_BASE = {
+    "zh_CN": "https://lvgl.100ask.net/"
+}
+
+class translation_link(nodes.Element):
+    """Node for "link_to_translation" role."""
+
+
+# Linking to translation is done at the "writing" stage to avoid issues with the info being cached between builders
+def link_to_translation(name, rawtext, text, lineno, inliner, options={}, content=[]):
+    node = translation_link()
+    node['expr'] = (rawtext, text, options)
+    return [node], []
+
+
+class TranslationLinkNodeTransform(SphinxPostTransform):
+    # Transform needs to happen early to ensure the new reference node is also transformed
+    default_priority = 0
+
+    def run(self, **kwargs):
+        # Only output relative links if building HTML
+        for node in self.document.traverse(translation_link):
+            if 'html' in self.app.builder.name:
+                rawtext, text, options = node['expr']
+                (language, link_text) = text.split(':')
+                env = self.document.settings.env
+                docname = env.docname
+                #doc_path = env.doc2path(docname, False)
+                urlpath = os.environ['LVGL_URLPATH']+'/'
+                return_path = URL_BASE.get(language, "") + urlpath
+                
+                url = '{}.html'.format(os.path.join(return_path, docname))
+
+                node.replace_self(nodes.reference(rawtext, link_text, refuri=url, **options))
+            else:
+                node.replace_self([])
+
+
+def setup(app):
+
+    # link to the current documentation file in specific language version
+    app.add_role('link_to_translation', link_to_translation)
+    app.add_node(translation_link)
+    app.add_post_transform(TranslationLinkNodeTransform)
+
+    return {'parallel_read_safe': True, 'parallel_write_safe': True, 'version': '0.5'}