Start work on porting live css

src/calibre/gui2/tweak_book/live_css.py

@@ -5,8 +5,6 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 __license__ = 'GPL v3'
 __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import json
-
 from PyQt5.Qt import (
     QWidget, QTimer, QStackedLayout, QLabel, QScrollArea, QVBoxLayout,
     QPainter, Qt, QPalette, QRect, QSize, QSizePolicy, pyqtSignal,
@@ -382,6 +380,7 @@ class LiveCSS(QWidget):
     def __init__(self, preview, parent=None):
         QWidget.__init__(self, parent)
         self.preview = preview
+        preview.live_css_data.connect(self.got_live_css_data)
         self.preview_is_refreshing = False
         self.refresh_needed = False
         preview.refresh_starting.connect(self.preview_refresh_starting)
@@ -417,8 +416,6 @@ class LiveCSS(QWidget):
 
     def preview_refreshed(self):
         self.preview_is_refreshing = False
-        # We must let the event loop run otherwise the webview will return
-        # stale data in read_data()
         self.refresh_needed = True
         self.start_update_timer()
 
@@ -448,53 +445,46 @@ class LiveCSS(QWidget):
         if sourceline is None:
             self.clear()
         else:
+            self.preview.request_live_css_data(editor_name, sourceline, tags)
+
+    def got_live_css_data(self, result):
+        maximum_specificities = {}
+        for node in result['nodes']:
+            is_ancestor = node['is_ancestor']
+            for rule in node['css']:
+                self.process_rule(rule, is_ancestor, maximum_specificities)
+        for node in result['nodes']:
+            for rule in node['css']:
+                for prop in rule['properties']:
+                    if prop.specificity < maximum_specificities[prop.name]:
+                        prop.is_overriden = True
+        self.display_received_live_css_data(result)
+
+    def display_received_live_css_data(self, data):
+        editor_name = data['editor_name']
+        sourceline = data['sourceline']
+        tags = data['tags']
+        if data is None or len(data['computed_css']) < 1:
+            if editor_name == self.current_name and (editor_name, sourceline, tags) == self.now_showing:
+                # Try again in a little while in case there was a transient
+                # error in the web view
+                self.start_update_timer()
+                return
+            if self.now_showing == (None, None, None) or self.now_showing[0] != self.current_name:
+                self.clear()
+                return
+            # Try to refresh the data for the currently shown tag instead
+            # of clearing
+            editor_name, sourceline, tags = self.now_showing
             data = self.read_data(sourceline, tags)
             if data is None or len(data['computed_css']) < 1:
-                if editor_name == self.current_name and (editor_name, sourceline, tags) == self.now_showing:
+                self.clear()
-                    # Try again in a little while in case there was a transient
+                return
-                    # error in the web view
+        self.now_showing = (editor_name, sourceline, tags)
-                    self.start_update_timer()
+        data['html_name'] = editor_name
-                    return
+        self.box.show_data(data)
-                if self.now_showing == (None, None, None) or self.now_showing[0] != self.current_name:
+        self.refresh_needed = False
-                    self.clear()
+        self.stack.setCurrentIndex(1)
-                    return
-                # Try to refresh the data for the currently shown tag instead
-                # of clearing
-                editor_name, sourceline, tags = self.now_showing
-                data = self.read_data(sourceline, tags)
-                if data is None or len(data['computed_css']) < 1:
-                    self.clear()
-                    return
-            self.now_showing = (editor_name, sourceline, tags)
-            data['html_name'] = editor_name
-            self.box.show_data(data)
-            self.refresh_needed = False
-            self.stack.setCurrentIndex(1)
-
-    def read_data(self, sourceline, tags):
-        return None  # TODO: Implement this
-        mf = self.preview.view.page().mainFrame()
-        tags = [x.lower() for x in tags]
-        result = unicode_type(mf.evaluateJavaScript(
-            'window.calibre_preview_integration.live_css(%s, %s)' % (
-                json.dumps(sourceline), json.dumps(tags))) or '')
-        try:
-            result = json.loads(result)
-        except ValueError:
-            result = None
-        if result is not None:
-            maximum_specificities = {}
-            for node in result['nodes']:
-                is_ancestor = node['is_ancestor']
-                for rule in node['css']:
-                    self.process_rule(rule, is_ancestor, maximum_specificities)
-            for node in result['nodes']:
-                for rule in node['css']:
-                    for prop in rule['properties']:
-                        if prop.specificity < maximum_specificities[prop.name]:
-                            prop.is_overriden = True
-
-        return result
 
     def process_rule(self, rule, is_ancestor, maximum_specificities):
         selector = rule['selector']

src/calibre/gui2/tweak_book/preview.py

@@ -280,13 +280,12 @@ class PreviewBridge(Bridge):
 
     request_sync = from_js(object, object, object)
     request_split = from_js(object, object)
+    live_css_data = from_js(object)
 
     go_to_sourceline_address = to_js()
     go_to_anchor = to_js()
     set_split_mode = to_js()
-
+    live_css = to_js()
-    def __init__(self, parent=None):
-        Bridge.__init__(self, parent)
 
 
 class WebPage(QWebEnginePage):
@@ -423,6 +422,7 @@ class Preview(QWidget):
     link_clicked = pyqtSignal(object, object)
     refresh_starting = pyqtSignal()
     refreshed = pyqtSignal()
+    live_css_data = pyqtSignal(object)
     render_process_restarted = pyqtSignal()
 
     def __init__(self, parent=None):
@@ -433,6 +433,7 @@ class Preview(QWidget):
         self.view = WebView(self)
         self.view._page.bridge.request_sync.connect(self.request_sync)
         self.view._page.bridge.request_split.connect(self.request_split)
+        self.view._page.bridge.live_css_data.connect(self.live_css_data)
         self.view._page.loadFinished.connect(self.load_finished)
         self.view.render_process_restarted.connect(self.render_process_restarted)
         self.pending_go_to_anchor = None
@@ -645,6 +646,9 @@ class Preview(QWidget):
             else:
                 self.stop_split()
 
+    def request_live_css_data(self, editor_name, sourceline, tags):
+        self.view._page.bridge.live_css(editor_name, sourceline, tags)
+
     def apply_settings(self):
         s = self.view.settings()
         s.setFontSize(s.DefaultFontSize, tprefs['preview_base_font_size'])

src/pyj/editor.pyj

@@ -336,19 +336,21 @@ def go_to_anchor(anchor):
         address = get_sourceline_address(elem)
         to_python.request_sync('', '', address)
 
-def live_css(sourceline, tags):
+@from_python
+def live_css(editor_name, sourceline, tags):
+    all_properties = {}
+    ans = {'nodes':v'[]', 'computed_css':all_properties, 'editor_name': editor_name, 'sourceline': sourceline, 'tags': tags}
     target = None
     i = 0
     for node in document.querySelectorAll(f'[data-lnum="{sourceline}"]'):
         tn = node.tagName.toLowerCase() if node.tagName else ''
         if tn is not tags[i]:
-            return JSON.stringify(None)
+            to_python.live_css_data(ans)
+            return
         i += 1
         target = node
         if i >= tags.length:
             break
-    all_properties = {}
-    ans = {'nodes':v'[]', 'computed_css':all_properties}
     is_ancestor = False
     while target and target.ownerDocument:
         css = get_matched_css(target, is_ancestor, all_properties)
@@ -362,7 +364,8 @@ def live_css(sourceline, tags):
             })
         target = target.parentNode
         is_ancestor = True
-    return JSON.stringify(ans)
+    to_python.live_css_data(ans)
+
 
 document.body.addEventListener('click', onclick, True)
 document.documentElement.appendChild(E.style(