Merge pull request r0x0r#843 from r0x0r/evaluate_js_async

r0x0r · web-flow · commit e6bc4b587418 · 2022-02-15T10:14:22.000+02:00
r0x0r#801 Evaluate js async
diff --git a/docs/guide/api.md b/docs/guide/api.md
@@ -171,10 +171,10 @@ Destroy the window.
 ## evaluate_js
 
 ``` python
-window.evaluate_js(script)
+window.evaluate_js(script, callback=None)
 ```
 
-Execute Javascript code. The last evaluated expression is returned. Javascript types are converted to Python types, eg. JS objects to dicts, arrays to lists, undefined to None. Note that due implementation limitations the string 'null' will be evaluated to None.
+Execute Javascript code. The last evaluated expression is returned. Promises are resolved and callback function is called with the result. Javascript types are converted to Python types, eg. JS objects to dicts, arrays to lists, undefined to None. Note that due implementation limitations the string 'null' will be evaluated to None.
 You must escape \n and \r among other escape sequences if they present in Javascript code. Otherwise they get parsed by Python. r'strings' is a recommended way to load Javascript. For GTK WebKit2 versions older than 2.22, there is a limit of about ~900 characters for a value returned by `evaluate_js`.
 
 ## get_current_url
diff --git a/examples/evaluate_js_async.py b/examples/evaluate_js_async.py
@@ -0,0 +1,23 @@
+import webview
+
+"""
+This example demonstrates evaluating async JavaScript
+"""
+
+def callback(result):
+    print(result)
+
+def evaluate_js_async(window):
+    window.evaluate_js(
+        """
+        new Promise((resolve, reject) => {
+            setTimeout(() => {
+                resolve('Whaddup!');
+            }, 300);
+        });
+        """, callback)
+
+
+if __name__ == '__main__':
+    window = webview.create_window('Run custom JavaScript', html='<html><body></body></html>')
+    webview.start(evaluate_js_async, window, debug=True)
diff --git a/webview/js/api.py b/webview/js/api.py
@@ -69,7 +69,13 @@
          }, 100)
     },
 
-    _returnValues: {}
+    _returnValues: {},
+    _asyncCallback: function(result, id) {
+        window.pywebview._bridge.call('asyncCallback', result, id)
+    },
+    _isPromise: function (obj) {
+        return !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';
+    }
 }
 window.pywebview._createApi(%s);
 
diff --git a/webview/platforms/cef.py b/webview/platforms/cef.py
@@ -117,26 +117,17 @@ def resize(self, width, height):
                                    0x0002 | 0x0004 | 0x0010)
         self.browser.NotifyMoveOrResizeStarted()
 
-    def evaluate_js(self, code):
+    def evaluate_js(self, code, unique_id):
         self.loaded.wait()
-        eval_script = """
-            try {{
-                window.external.return_result({0}, '{1}');
-            }} catch(e) {{
-                console.error(e.stack);
-                window.external.return_result(null, '{1}');
-            }}
-        """
 
-        id_ = uuid1().hex[:8]
-        self.eval_events[id_] = Event()
-        self.browser.ExecuteJavascript(eval_script.format(code, id_))
-        self.eval_events[id_].wait()  # result is obtained via JSBridge.return_result
+        self.eval_events[unique_id] = Event()
+        result = self.browser.ExecuteJavascript(code)
+        self.eval_events[unique_id].wait()  # result is obtained via JSBridge.return_result
 
-        result = copy(self.js_bridge.results[id_])
+        result = copy(self.js_bridge.results[unique_id])
 
-        del self.eval_events[id_]
-        del self.js_bridge.results[id_]
+        del self.eval_events[unique_id]
+        del self.js_bridge.results[unique_id]
 
         return result
 
@@ -191,7 +182,7 @@ def wrapper(*args, **kwargs):
         uid = args[-1]
 
         if uid not in instances:
-            logger.debug('CEF window with uid {0} does not exist'.format(uid))
+            logger.error('CEF window with uid {0} does not exist'.format(uid))
             return
 
         return func(*args, **kwargs)
@@ -278,9 +269,9 @@ def load_url(url, uid):
 
 
 @_cef_call
-def evaluate_js(code, uid):
+def evaluate_js(code, result, uid):
     instance = instances[uid]
-    return instance.evaluate_js(code)
+    return instance.evaluate_js(code, result)
 
 
 @_cef_call
diff --git a/webview/platforms/cocoa.py b/webview/platforms/cocoa.py
@@ -557,7 +557,7 @@ def eval():
             self.webkit.evaluateJavaScript_completionHandler_(script, handler)
 
         def handler(result, error):
-            JSResult.result = None if result is None or result == 'null' else json.loads(result)
+            JSResult.result = None if result is None else json.loads(result)
             JSResult.result_semaphore.release()
 
         class JSResult:
diff --git a/webview/platforms/edgechromium.py b/webview/platforms/edgechromium.py
@@ -117,8 +117,8 @@ def load_url(self, url):
 
     def on_script_notify(self, _, args):
         try:
-            func_name, func_param, value_id = json.loads(args.get_WebMessageAsJson())
-
+            return_value = args.get_WebMessageAsJson()
+            func_name, func_param, value_id = json.loads(return_value)
             if func_name == 'alert':
                 WinForms.MessageBox.Show(func_param)
             elif func_name == 'console':
diff --git a/webview/platforms/winforms.py b/webview/platforms/winforms.py
@@ -206,7 +206,7 @@ def __init__(self, window):
 
             if window.frameless:
                 self.frameless = window.frameless
-                self.FormBorderStyle = 0
+                self.FormBorderStyle = getattr(WinForms.FormBorderStyle, 'None')
             if is_cef:
                 CEF.create_browser(window, self.Handle.ToInt32(), BrowserView.alert)
             elif is_chromium:
@@ -339,7 +339,7 @@ def _toggle():
                     self.old_state = self.WindowState
                     self.old_style = self.FormBorderStyle
                     self.old_location = self.Location
-                    self.FormBorderStyle = 0  # FormBorderStyle.None
+                    self.FormBorderStyle = getattr(WinForms.FormBorderStyle, 'None')
                     self.Bounds = WinForms.Screen.PrimaryScreen.Bounds
                     self.WindowState = WinForms.FormWindowState.Maximized
                     self.is_fullscreen = True
@@ -406,7 +406,7 @@ def _restore():
 
     @staticmethod
     def alert(message):
-        WinForms.MessageBox.Show(message)
+        WinForms.MessageBox.Show(str(message))
 
 
 def _set_ie_mode():
@@ -664,9 +664,9 @@ def _close():
         window.browser.js_result_semaphore.release()
 
 
-def evaluate_js(script, uid):
+def evaluate_js(script, uid, result_id=None):
     if is_cef:
-        return CEF.evaluate_js(script, uid)
+        return CEF.evaluate_js(script, result_id, uid)
     else:
         return BrowserView.instances[uid].evaluate_js(script)
 
diff --git a/webview/util.py b/webview/util.py
@@ -153,6 +153,17 @@ def _call():
         window.move(*param)
         return
 
+    if func_name == 'asyncCallback':
+        value = json.loads(param) if param is not None else None
+
+        if callable(window._callbacks[value_id]):
+            window._callbacks[value_id](value)
+        else:
+            logger.error('Async function executed and callback is not callable. Returned value {0}'.format(value))
+
+        del window._callbacks[value_id]
+        return
+
     func = window._functions.get(func_name) or getattr(window._js_api, func_name, None)
 
     if func is not None:
diff --git a/webview/window.py b/webview/window.py
@@ -3,6 +3,7 @@
 import os
 from enum import Flag, auto
 from functools import wraps
+from uuid import uuid1
 
 from webview.event import Event
 from webview.localization import original_localization
@@ -24,7 +25,7 @@ def wrapper(*args, **kwargs):
         event = args[0].loaded if event_type == 'loaded' else args[0].shown
 
         try:
-            if not event.wait(15):
+            if not event.wait(20):
                 raise WebViewException('Main window failed to start')
 
             if args[0].gui is None:
@@ -81,6 +82,7 @@ def __init__(self, uid, title, url, html, width, height, x, y, resizable, fullsc
 
         self._js_api = js_api
         self._functions = {}
+        self._callbacks = {}
 
         self.closed = Event()
         self.closing = Event(True)
@@ -293,14 +295,42 @@ def move(self, x, y):
         self.gui.move(x, y, self.uid)
 
     @_loaded_call
-    def evaluate_js(self, script):
+    def evaluate_js(self, script, callback=None):
         """
         Evaluate given JavaScript code and return the result
         :param script: The JavaScript code to be evaluated
         :return: Return value of the evaluated code
+        :callback: Optional callback function that will be called for resolved promises
         """
-        escaped_script = 'JSON.stringify(eval("{0}"))'.format(escape_string(script))
-        return self.gui.evaluate_js(escaped_script, self.uid)
+        unique_id = uuid1().hex
+        self._callbacks[unique_id] = callback
+
+        if self.gui.renderer == 'cef':
+            sync_eval = 'window.external.return_result(JSON.stringify(value), "{0}");'.format(unique_id,)
+        else:
+            sync_eval = 'JSON.stringify(value);'
+
+
+        if callback:
+            escaped_script = """
+                var value = eval("{0}");
+                if (pywebview._isPromise(value)) {{
+                    value.then(function evaluate_async(result) {{
+                        pywebview._asyncCallback(JSON.stringify(result), "{1}")
+                    }});
+                    true;
+                }} else {{ {2} }}
+            """.format(escape_string(script), unique_id, sync_eval)
+        else:
+            escaped_script = """
+                var value = eval("{0}");
+                {1};
+            """.format(escape_string(script), sync_eval)
+
+        if self.gui.renderer == 'cef':
+            return self.gui.evaluate_js(escaped_script, self.uid, unique_id)
+        else:
+            return self.gui.evaluate_js(escaped_script, self.uid)
 
     @_shown_call
     def create_file_dialog(self, dialog_type=10, directory='', allow_multiple=False, save_filename='', file_types=()):
