feat: Create sphinx extension for integrating Flutter apps into the d…

…ocumentation site (#1393)

doc/_sphinx/conf.py

@@ -5,6 +5,9 @@
 # https://www.sphinx-doc.org/en/master/usage/configuration.html
 import docutils
 import os
+import sys
+sys.path.insert(0, os.path.abspath('.'))
+
 
 # -- Project information -----------------------------------------------------
 
@@ -22,6 +25,7 @@
 extensions = [
     'myst_parser',  # Markdown support
     'sphinxcontrib.mermaid',
+    'extensions.flutter_app',
 ]
 
 # Configuration options for MyST:

doc/_sphinx/extensions/flutter_app.css

@@ -0,0 +1,85 @@
+
+button.flutter-app-button {
+  background: #e2a73c;
+  border: none;
+  border-radius: 6px;
+  box-shadow: 2px 2px 6px 0 black;
+  color: black;
+  cursor: pointer;
+  font-family: var(--font-sans);
+  font-size: 1.1em;
+  font-weight: bold;
+  line-height: 1em;
+  min-height: 26pt;
+  min-width: 120pt;
+}
+
+button.flutter-app-button:hover {
+  background: #f3dc38;
+}
+
+button.flutter-app-button:active {
+  background: white;
+  left: 1px;
+  position: relative;
+  top: 1px;
+}
+
+button.flutter-app-button:after {
+  content: '\f0da';
+  font-family: var(--font-awesome);
+  margin-left: 4px;
+  position: relative;
+  top: 1px;
+}
+
+#flutter-app-overlay {
+  background: #00000050;
+  display: none;
+  height: 100vh;
+  left: 0;
+  position: fixed;
+  top: 0;
+  width: 100vw;
+  z-index: 10000;
+}
+
+#flutter-app-overlay.active {
+  display: initial;
+}
+
+#flutter-app-overlay.active iframe {
+  border: none;
+  box-shadow: 0px 0px 9px 3px black;
+  display: none;
+  left: 50%;
+  position: absolute;
+  top: 50%;
+  transform: translate(-50%, -50%);
+}
+
+#flutter-app-overlay.active iframe.active {
+  display: initial;
+}
+
+#flutter-app-close-button {
+  background: white;
+  border: 1px solid black;
+  border-radius: 50%;
+  color: black;
+  cursor: pointer;
+  font-size: 20px;
+  height: 30px;
+  left: 90%;
+  margin-left: -15px;
+  margin-top: -15px;
+  position: absolute;
+  text-align: center;
+  top: 10%;
+  width: 30px;
+}
+
+#flutter-app-close-button:hover {
+  background: #e38f13;
+  color: white;
+}

doc/_sphinx/extensions/flutter_app.js

@@ -0,0 +1,37 @@
+'use strict';
+
+/// Create an overlay with an iframe, the iframe's source is [url]. This also
+/// creates an (x) button to hide the overlay.
+function run_flutter_app(url) {
+  let id = compute_iframe_id(url);
+  if (!$('#flutter-app-overlay').length) {
+    $('body').append($(`
+      <div id="flutter-app-overlay">
+        <button id="flutter-app-close-button" onclick="close_flutter_app()">✖</button>
+      </div>`
+    ));
+  }
+  if (!$('#' + id).length) {
+    $('#flutter-app-overlay').append($(
+      `<iframe id="${id}" class="flutter-app" src="${url}"></iframe>`
+    ));
+  }
+  $('#flutter-app-overlay').addClass('active');
+  $('#' + id).addClass('active');
+}
+
+/// Handler for the (x) close button on an app iframe.
+function close_flutter_app() {
+  $('#flutter-app-overlay iframe').removeClass('active');
+  $('#flutter-app-overlay').removeClass('active');
+}
+
+/// Convert a URL such as '_static/app/tutorial1/index.html?page1' into a string
+/// that can be used as an id: 'app-tutorial1-index-html-page1'.
+function compute_iframe_id(url) {
+  if (url.startsWith('_static/')) {
+    url = url.substr(8);
+  }
+  let matches = url.matchAll(new RegExp('\\w+', 'g'));
+  return Array.from(matches, m => m[0]).join('-');
+}

doc/_sphinx/extensions/flutter_app.py

@@ -0,0 +1,228 @@
+#!/usr/bin/env python
+import os
+import shutil
+import subprocess
+from docutils import nodes
+from docutils.parsers.rst import directives
+from sphinx.util.docutils import SphinxDirective
+from sphinx.util.logging import getLogger
+
+
+# ------------------------------------------------------------------------------
+# `.. flutter-app::` directive
+# ------------------------------------------------------------------------------
+
+class FlutterAppDirective(SphinxDirective):
+    """
+    Embed Flutter apps into documentation pages.
+
+    This extension allows inserting precompiled Flutter apps into the
+    generated documentation. The app to be inserted has to be configured for
+    compiling in 'web' mode.
+
+    Example of usage in Markdown:
+
+        ```{flutter-app}
+        :sources: ../../tetris-tutorial
+        :page: page3
+        :show: popup
+        ```
+
+    The following arguments are supported:
+      :sources: - the directory where the app is located, i.e. the directory
+        with the pubspec.yaml file of the app. The path should be relative to
+        the `doc/_sphinx` folder.
+
+      :page: - an additional parameter that will be appended to the URL of the
+        app. The app can retrieve this parameter by checking the property
+        `window.location.search` (where `window` is from `dart:html`), and then
+        display the content based on that. Thus, this parameter allows bundling
+        multiple separate Flutter widgets into one compiled app.
+        In addition, the "code" run mode will try to locate a file or a folder
+        with the matching name.
+
+      :show: - a list of one or more run modes, which could include "widget",
+        "popup", and "code". Each of these modes produces a different output:
+          "widget" - an iframe shown directly inside the docs page;
+          "popup" - a [Run] button which opens the app to (almost) fullscreen;
+          "code" - (NYI) opens a popup showing the code that was compiled.
+    """
+    has_content = False
+    required_arguments = 0
+    optional_arguments = 0
+    option_spec = {
+        'sources': directives.unchanged,
+        'page': directives.unchanged,
+        'show': directives.unchanged,
+    }
+    # Static list of targets that were already compiled during the build
+    COMPILED = []
+
+    def __init__(self, *args, **kwds):
+        super().__init__(*args, **kwds)
+        self.modes = None
+        self.logger = None
+        self.app_name = None
+        self.source_dir = None
+        self.source_build_dir = None
+        self.target_dir = None
+        self.html_dir = None
+
+    def run(self):
+        self.logger = getLogger('flutter-app')
+        self._process_show_option()
+        self._process_sources_option()
+        self.source_build_dir = os.path.join(self.source_dir, 'build', 'web')
+        self.app_name = os.path.basename(self.source_dir)
+        self.html_dir = '_static/apps/' + self.app_name
+        self.target_dir = os.path.abspath(
+            os.path.join('..', '_build', 'html', self.html_dir))
+        self._ensure_compiled()
+
+        page = self.options.get('page', '')
+        iframe_url = self.html_dir + '/index.html?' + page
+        result = []
+        if 'popup' in self.modes:
+            result.append(Button(
+                '',
+                nodes.Text('Run'),
+                classes=['flutter-app-button', 'popup'],
+                onclick=f'run_flutter_app("{iframe_url}")',
+            ))
+        if 'code' in self.modes:
+            pass
+        if 'widget' in self.modes:
+            result.append(IFrame(src=iframe_url))
+        return result
+
+    def _process_show_option(self):
+        argument = self.options.get('show')
+        if argument:
+            values = argument.split()
+            for value in values:
+                if value not in ['widget', 'popup', 'code']:
+                    raise self.error('Invalid :show: value ' + value)
+            self.modes = values
+        else:
+            self.modes = ['widget']
+
+    def _process_sources_option(self):
+        argument = self.options.get('sources', '')
+        abspath = os.path.abspath(argument)
+        if not argument:
+            raise self.error('Missing required argument :sources:')
+        if not os.path.isdir(abspath):
+            raise self.error(
+                f'sources=`{abspath}` does not exist or is not a directory')
+        assert not abspath.endswith('/')
+        self.source_dir = abspath
+
+    def _ensure_compiled(self):
+        need_compiling = (
+            ('popup' in self.modes or 'widget' in self.modes) and
+            self.source_dir not in FlutterAppDirective.COMPILED
+        )
+        if not need_compiling:
+            return
+        self.logger.info('Compiling Flutter app ' + self.app_name)
+        self._compile_source()
+        self._copy_compiled()
+        self._create_index()
+        self.logger.info('  + copied into ' + self.target_dir)
+        assert os.path.isfile(self.target_dir + '/main.dart.js')
+        assert os.path.isfile(self.target_dir + '/index.html')
+        FlutterAppDirective.COMPILED.append(self.source_dir)
+
+    def _compile_source(self):
+        try:
+            subprocess.run(
+                ['flutter', 'build', 'web', '--web-renderer', 'html'],
+                stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT,
+                cwd=self.source_dir,
+                check=True,
+            )
+        except subprocess.CalledProcessError as e:
+            cmd = e.cmd.join(' ')
+            raise self.severe(
+                f'Command `{cmd}` returned with exit status {e.returncode}\n' +
+                e.output.decode('utf-8'),
+            )
+
+    def _copy_compiled(self):
+        assert os.path.isdir(self.source_build_dir)
+        main_js = os.path.join(self.source_build_dir, 'main.dart.js')
+        assets_dir = os.path.join(self.source_build_dir, 'assets')
+        os.makedirs(self.target_dir, exist_ok=True)
+        shutil.copy2(main_js, self.target_dir)
+        if os.path.exists(assets_dir):
+            shutil.copytree(
+                src=assets_dir,
+                dst=os.path.join(self.target_dir, 'assets'),
+                dirs_exist_ok=True,
+            )
+
+    def _create_index(self):
+        target_file = os.path.join(self.target_dir, 'index.html')
+        with open(target_file, 'wt') as out:
+            out.write('<!DOCTYPE html>\n')
+            out.write('<html>\n<head>\n')
+            out.write('<base href="/%s/">\n' % self.html_dir)
+            out.write('<title>%s</title>\n' % self.app_name)
+            out.write('</head>\n<body>\n')
+            out.write('<script src="main.dart.js"></script>\n')
+            out.write('</body>\n</html>\n')
+
+
+# ------------------------------------------------------------------------------
+# Nodes
+# ------------------------------------------------------------------------------
+
+class IFrame(nodes.Element, nodes.General):
+    pass
+
+
+def visit_iframe(self, node):
+    self.body.append(self.starttag(node, 'iframe', src=node.attributes['src']))
+
+
+def depart_iframe(self, _):
+    self.body.append('</iframe>')
+
+
+class Button(nodes.Element, nodes.General):
+    pass
+
+
+def visit_button(self, node):
+    attrs = {}
+    if 'onclick' in node.attributes:
+        attrs['onclick'] = node.attributes['onclick']
+    self.body.append(self.starttag(node, 'button', **attrs).strip())
+
+
+def depart_button(self, _):
+    self.body.append('</button>')
+
+
+# ------------------------------------------------------------------------------
+# Extension setup
+# ------------------------------------------------------------------------------
+
+def setup(app):
+    base_dir = os.path.dirname(__file__)
+    target_dir = os.path.abspath('../_build/html/_static/')
+    os.makedirs(target_dir, exist_ok=True)
+    shutil.copy(os.path.join(base_dir, 'flutter_app.js'), target_dir)
+    shutil.copy(os.path.join(base_dir, 'flutter_app.css'), target_dir)
+
+    app.add_node(IFrame, html=(visit_iframe, depart_iframe))
+    app.add_node(Button, html=(visit_button, depart_button))
+    app.add_directive('flutter-app', FlutterAppDirective)
+    app.add_js_file('flutter_app.js')
+    app.add_css_file('flutter_app.css')
+    return {
+        'parallel_read_safe': False,
+        'parallel_write_safe': False,
+        'env_version': 1,
+    }