File: winforms.py

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# -*- coding: utf-8 -*-

"""
(C) 2014-2019 Roman Sirokov and contributors
Licensed under BSD license

http://github.com/r0x0r/pywebview/
"""

import os
import sys
import logging
import json
import shutil
import tempfile
import webbrowser
from threading import Event, Semaphore
from ctypes import windll
from uuid import uuid4

from webview import WebViewException, windows, OPEN_DIALOG, FOLDER_DIALOG, SAVE_DIALOG, _debug, _user_agent
from webview.guilib import forced_gui_
from webview.serving import resolve_url
from webview.util import parse_api_js, interop_dll_path, parse_file_type, inject_base_uri, default_html, js_bridge_call
from webview.js import alert
from webview.js.css import disable_text_select
from webview.localization import localization

import clr

clr.AddReference('System.Windows.Forms')
clr.AddReference('System.Collections')
clr.AddReference('System.Threading')

import System.Windows.Forms as WinForms
from System import IntPtr, Int32, Func, Type, Environment, Uri
from System.Threading import Thread, ThreadStart, ApartmentState
from System.Drawing import Size, Point, Icon, Color, ColorTranslator, SizeF


logger = logging.getLogger('pywebview')

settings = {}

def _is_edge():
    try:
        import _winreg as winreg  # Python 2
    except ImportError:
        import winreg  # Python 3

    try:
        net_key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, r'SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full')
        version, _ = winreg.QueryValueEx(net_key, 'Release')

        windows_key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, r'SOFTWARE\Microsoft\Windows NT\CurrentVersion')
        build, _ = winreg.QueryValueEx(windows_key, 'CurrentBuild')
        build = int(build)

        return version >= 394802 and build >= 17134 # .NET 4.6.2 + Windows 10 1803
    except Exception as e:
        logger.exception(e)
        return False
    finally:
        winreg.CloseKey(net_key)


is_cef = forced_gui_ == 'cef'
is_edge = _is_edge() and forced_gui_ != 'mshtml'


if is_cef:
    from . import cef as CEF
    IWebBrowserInterop = object

    logger.debug('Using WinForms / CEF')
    renderer = 'cef'
elif is_edge:
    clr.AddReference(interop_dll_path('Microsoft.Toolkit.Forms.UI.Controls.WebView.dll'))
    from Microsoft.Toolkit.Forms.UI.Controls import WebView
    from System.ComponentModel import ISupportInitialize
    IWebBrowserInterop = object

    logger.debug('Using WinForms / EdgeHTML')
    renderer = 'edgehtml'
else:
    clr.AddReference(interop_dll_path('WebBrowserInterop.dll'))
    from WebBrowserInterop import IWebBrowserInterop, WebBrowserEx

    logger.debug('Using WinForms / MSHTML')
    renderer = 'mshtml'


class BrowserView:
    instances = {}

    class MSHTML:
        class JSBridge(IWebBrowserInterop):
            __namespace__ = 'BrowserView.MSHTML.JSBridge'
            window = None

            def call(self, func_name, param, value_id):
                return js_bridge_call(self.window, func_name, param, value_id)

            def alert(self, message):
                BrowserView.alert(message)

            def console(self, message):
                print(message)

        def __init__(self, form, window):
            self.pywebview_window = window
            self.web_browser = WebBrowserEx()
            self.web_browser.Dock = WinForms.DockStyle.Fill
            self.web_browser.ScriptErrorsSuppressed = not _debug
            self.web_browser.IsWebBrowserContextMenuEnabled = _debug
            self.web_browser.WebBrowserShortcutsEnabled = False
            self.web_browser.DpiAware = True

            user_agent = _user_agent or settings.get('user_agent')
            if user_agent:
                self.web_browser.ChangeUserAgent(user_agent)

            self.web_browser.ScriptErrorsSuppressed = not _debug
            self.web_browser.IsWebBrowserContextMenuEnabled = _debug

            self.js_result_semaphore = Semaphore(0)
            self.js_bridge = BrowserView.MSHTML.JSBridge()
            self.js_bridge.window = window

            self.web_browser.ObjectForScripting = self.js_bridge

            # HACK. Hiding the WebBrowser is needed in order to show a non-default background color. Tweaking the Visible property
            # results in showing a non-responsive control, until it is loaded fully. To avoid this, we need to disable this behaviour
            # for the default background color.
            if window.background_color != '#FFFFFF':
                self.web_browser.Visible = False
                self.first_load = True
            else:
                self.first_load = False

            self.cancel_back = False
            self.web_browser.PreviewKeyDown += self.on_preview_keydown
            self.web_browser.Navigating += self.on_navigating
            self.web_browser.NewWindow3 += self.on_new_window
            self.web_browser.DownloadComplete += self.on_download_complete
            self.web_browser.DocumentCompleted += self.on_document_completed

            if window.real_url:
                self.web_browser.Navigate(window.real_url)
            elif window.html:
                self.web_browser.DocumentText = window.html
            else:
                self.web_browser.DocumentText = default_html

            self.form = form
            form.Controls.Add(self.web_browser)

        def evaluate_js(self, script):
            result = self.web_browser.Document.InvokeScript('eval', (script,))
            self.js_result = None if result is None or result is 'null' else json.loads(result)
            self.js_result_semaphore.release()

        def load_html(self, content, base_uri):
            self.web_browser.DocumentText = inject_base_uri(content, base_uri)
            self.pywebview_window.loaded.clear()

        def load_url(self, url):
            self.web_browser.Navigate(url)

        def on_preview_keydown(self, sender, args):
            if args.KeyCode == WinForms.Keys.Back:
                self.cancel_back = True
            elif args.KeyCode == WinForms.Keys.Delete:
                self.web_browser.Document.ExecCommand('Delete', False, None)
            elif args.Modifiers == WinForms.Keys.Control and args.KeyCode == WinForms.Keys.C:
                self.web_browser.Document.ExecCommand('Copy', False, None)
            elif args.Modifiers == WinForms.Keys.Control and args.KeyCode == WinForms.Keys.X:
                self.web_browser.Document.ExecCommand('Cut', False, None)
            elif args.Modifiers == WinForms.Keys.Control and args.KeyCode == WinForms.Keys.V:
                self.web_browser.Document.ExecCommand('Paste', False, None)
            elif args.Modifiers == WinForms.Keys.Control and args.KeyCode == WinForms.Keys.Z:
                self.web_browser.Document.ExecCommand('Undo', False, None)
            elif args.Modifiers == WinForms.Keys.Control and args.KeyCode == WinForms.Keys.A:
                self.web_browser.Document.ExecCommand('selectAll', False, None)

        def on_new_window(self, sender, args):
            args.Cancel = True
            webbrowser.open(args.Url)

        def on_download_complete(self, sender, args):
            pass

        def on_navigating(self, sender, args):
            if self.cancel_back:
                args.Cancel = True
                self.cancel_back = False

        def on_document_completed(self, sender, args):
            document = self.web_browser.Document
            document.InvokeScript('eval', (alert.src,))

            if _debug:
                document.InvokeScript('eval', ('window.console = { log: function(msg) { window.external.console(JSON.stringify(msg)) }}',))

            if self.first_load:
                self.web_browser.Visible = True
                self.first_load = False

            self.url = None if args.Url.AbsoluteUri == 'about:blank' else str(args.Url.AbsoluteUri)

            document.InvokeScript('eval', (parse_api_js(self.pywebview_window, 'mshtml'),))

            if not self.pywebview_window.text_select:
                document.InvokeScript('eval', (disable_text_select,))
            self.pywebview_window.loaded.set()

            if self.pywebview_window.easy_drag:
                document.MouseMove += self.on_mouse_move

        def on_mouse_move(self, sender, e):
            if e.MouseButtonsPressed == WinForms.MouseButtons.Left:
                WebBrowserEx.ReleaseCapture()
                windll.user32.SendMessageW(self.form.Handle.ToInt32(), WebBrowserEx.WM_NCLBUTTONDOWN, WebBrowserEx.HT_CAPTION, 6)

    class EdgeHTML:
        def __init__(self, form, window):
            self.pywebview_window = window
            self.web_view = WebView()

            life = ISupportInitialize(self.web_view)
            life.BeginInit()
            form.Controls.Add(self.web_view)

            self.js_result_semaphore = Semaphore(0)
            self.web_view.Dock = WinForms.DockStyle.Fill
            self.web_view.DpiAware = True
            self.web_view.IsIndexedDBEnabled = True
            self.web_view.IsJavaScriptEnabled = True
            self.web_view.IsScriptNotifyAllowed = True
            self.web_view.IsPrivateNetworkClientServerCapabilityEnabled = True
            self.web_view.DefaultBackgroundColor = form.BackColor

            self.web_view.ScriptNotify += self.on_script_notify
            self.web_view.NewWindowRequested += self.on_new_window_request
            self.web_view.NavigationCompleted += self.on_navigation_completed

            # This must be before loading URL. Otherwise the webview will remain empty
            life.EndInit()

            self.httpd = None # HTTP server for load_html
            self.tmpdir = None
            self.url = None
            self.ishtml = False

            if window.html or 'localhost' in window.real_url or '127.0.0.1' in window.real_url:
                _allow_localhost()

            if window.real_url:
                self.load_url(window.real_url)
            elif window.html:
                self.load_html(window.html, '')
            else:
                self.load_html(default_html, '')

        def evaluate_js(self, script):
            try:
                result = self.web_view.InvokeScript('eval', (script,))
            except Exception as e:
                logger.exception('Error occurred in script')
                result = None

            self.js_result = None if result is None or result == '' else json.loads(result)
            self.js_result_semaphore.release()

        def get_current_url(self):
            return self.url

        def load_html(self, html, base_uri):
            self.tmpdir = tempfile.mkdtemp()
            self.temp_html = os.path.join(self.tmpdir, 'index.html')

            with open(self.temp_html, 'w', encoding='utf-8') as f:
                f.write(inject_base_uri(html, base_uri))

            if self.httpd:
                self.httpd.shutdown()

            url = resolve_url('file://' + self.temp_html, True)
            self.ishtml = True
            self.web_view.Navigate(url)

        def load_url(self, url):
            self.ishtml = False
            
            # WebViewControl as of 5.1.1 crashes on file:// urls. Stupid workaround to make it work
            if url.startswith('file://'):
                url = resolve_url(url, True)

            self.web_view.Navigate(url)

        def on_script_notify(self, _, args):
            try:
                func_name, func_param, value_id = json.loads(args.Value)

                if func_name == 'alert':
                    WinForms.MessageBox.Show(func_param)
                elif func_name == 'console':
                    print(func_param)
                else:
                    js_bridge_call(self.pywebview_window, func_name, func_param, value_id)
            except Exception as e:
                logger.exception('Exception occured during on_script_notify')

        def on_new_window_request(self, _, args):
            webbrowser.open(str(args.get_Uri()))
            args.set_Handled(True)

        def on_navigation_completed(self, _, args):
            try:
                if self.tmpdir and os.path.exists(self.tmpdir):
                    shutil.rmtree(self.tmpdir)
                    self.tmpdir = None
            except Exception as e:
                logger.exception('Failed deleting %s' % self.tmpdir)

            url = str(args.Uri)
            self.url = None if self.ishtml else url
            self.web_view.InvokeScript('eval', ('window.alert = (msg) => window.external.notify(JSON.stringify(["alert", msg+"", ""]))',))

            if _debug:
                self.web_view.InvokeScript('eval', ('window.console = { log: (msg) => window.external.notify(JSON.stringify(["console", msg+"", ""]))}',))

            self.web_view.InvokeScript('eval', (parse_api_js(self.pywebview_window, 'edgehtml'),))

            if not self.pywebview_window.text_select:
                self.web_view.InvokeScript('eval', (disable_text_select,))

            self.pywebview_window.loaded.set()

    class BrowserForm(WinForms.Form):
        def __init__(self, window):
            self.uid = window.uid
            self.pywebview_window = window
            self.real_url = None
            self.Text = window.title
            self.Size = Size(window.initial_width, window.initial_height)
            self.MinimumSize = Size(window.min_size[0], window.min_size[1])

            if window.transparent: # window transparency is not supported, as webviews are not transparent.
                self.BackColor = Color.LimeGreen
                self.TransparencyKey = Color.LimeGreen
                self.SetStyle(WinForms.ControlStyles.SupportsTransparentBackColor, True)
            else:
                self.BackColor = ColorTranslator.FromHtml(window.background_color)

            if window.initial_x is not None and window.initial_y is not None:
                self.move(window.initial_x, window.initial_y)
            else:
                self.StartPosition = WinForms.FormStartPosition.CenterScreen

            self.AutoScaleDimensions = SizeF(96.0, 96.0)
            self.AutoScaleMode = WinForms.AutoScaleMode.Dpi

            if not window.resizable:
                self.FormBorderStyle = WinForms.FormBorderStyle.FixedSingle
                self.MaximizeBox = False

            if window.minimized:
                self.WindowState = WinForms.FormWindowState.Minimized

            # Application icon
            handle = windll.kernel32.GetModuleHandleW(None)
            icon_handle = windll.shell32.ExtractIconW(handle, sys.executable, 0)

            if icon_handle != 0:
                self.Icon = Icon.FromHandle(IntPtr.op_Explicit(Int32(icon_handle))).Clone()

            windll.user32.DestroyIcon(icon_handle)

            self.closed = window.closed
            self.closing = window.closing
            self.shown = window.shown
            self.loaded = window.loaded
            self.url = window.real_url
            self.text_select = window.text_select
            self.on_top = window.on_top

            self.is_fullscreen = False
            if window.fullscreen:
                self.toggle_fullscreen()

            if window.frameless:
                self.frameless = window.frameless
                self.FormBorderStyle = 0
            if is_cef:
                CEF.create_browser(window, self.Handle.ToInt32(), BrowserView.alert)
            elif is_edge:
                self.browser = BrowserView.EdgeHTML(self, window)
            else:
                self.browser = BrowserView.MSHTML(self, window)

            self.Shown += self.on_shown
            self.FormClosed += self.on_close
            self.FormClosing += self.on_closing

            if is_cef:
                self.Resize += self.on_resize

        def on_shown(self, sender, args):
            if not is_cef:
                self.shown.set()

        def on_close(self, sender, args):
            def _shutdown():
                if is_cef:
                    CEF.shutdown()
                WinForms.Application.Exit()

            if is_cef:
                CEF.close_window(self.uid)

            del BrowserView.instances[self.uid]

            # during tests windows is empty for some reason. no idea why.
            if self.pywebview_window in windows:
                windows.remove(self.pywebview_window)

            self.closed.set()

            if len(BrowserView.instances) == 0:
                self.Invoke(Func[Type](_shutdown))

        def on_closing(self, sender, args):
            if self.pywebview_window.confirm_close:
                result = WinForms.MessageBox.Show(localization['global.quitConfirmation'], self.Text,
                                                WinForms.MessageBoxButtons.OKCancel, WinForms.MessageBoxIcon.Asterisk)

                if result == WinForms.DialogResult.Cancel:
                    args.Cancel = True

            if not args.Cancel:
                self.closing.set()

        def on_resize(self, sender, args):
            CEF.resize(self.Width, self.Height, self.uid)

        def evaluate_js(self, script):
            def _evaluate_js():
                self.browser.evaluate_js(script)

            self.loaded.wait()
            self.Invoke(Func[Type](_evaluate_js))
            self.browser.js_result_semaphore.acquire()

            return self.browser.js_result

        def load_html(self, content, base_uri):
            def _load_html():
                 self.browser.load_html(content, base_uri)

            self.Invoke(Func[Type](_load_html))

        def load_url(self, url):
            def _load_url():
                self.browser.load_url(url)

            self.Invoke(Func[Type](_load_url))

        def get_current_url(self):
            return self.browser.get_current_url

        def hide(self):
            self.Invoke(Func[Type](self.Hide))

        def show(self):
            self.Invoke(Func[Type](self.Show))

        def toggle_fullscreen(self):
            def _toggle():
                screen = WinForms.Screen.FromControl(self)

                if not self.is_fullscreen:
                    self.old_size = self.Size
                    self.old_state = self.WindowState
                    self.old_style = self.FormBorderStyle
                    self.old_location = self.Location
                    self.FormBorderStyle = 0  # FormBorderStyle.None
                    self.Bounds = WinForms.Screen.PrimaryScreen.Bounds
                    self.WindowState = WinForms.FormWindowState.Maximized
                    self.is_fullscreen = True
                    windll.user32.SetWindowPos(self.Handle.ToInt32(), None, screen.Bounds.X, screen.Bounds.Y,
                                            screen.Bounds.Width, screen.Bounds.Height, 64)
                else:
                    self.Size = self.old_size
                    self.WindowState = self.old_state
                    self.FormBorderStyle = self.old_style
                    self.Location = self.old_location
                    self.is_fullscreen = False

            if self.InvokeRequired:
                self.Invoke(Func[Type](_toggle))
            else:
                _toggle()

        @property
        def on_top(self):
            return self.on_top

        @on_top.setter
        def on_top(self, on_top):
            def _set():
                z_order = -1 if on_top is True else -2
                SWP_NOSIZE = 0x0001  # Retains the current size
                windll.user32.SetWindowPos(self.Handle.ToInt32(), z_order, self.Location.X, self.Location.Y, None, None, SWP_NOSIZE)
            if self.InvokeRequired:
                self.Invoke(Func[Type](_set))
            else:
                _set()

        def resize(self, width, height):
            windll.user32.SetWindowPos(self.Handle.ToInt32(), None, self.Location.X, self.Location.Y,
                width, height, 64)

        def move(self, x, y):
            SWP_NOSIZE = 0x0001  # Retains the current size
            SWP_NOZORDER = 0x0004  # Retains the current Z order
            SWP_SHOWWINDOW = 0x0040  # Displays the window
            windll.user32.SetWindowPos(self.Handle.ToInt32(), None, x, y, None, None,
                                       SWP_NOSIZE|SWP_NOZORDER|SWP_SHOWWINDOW)

        def minimize(self):
            def _minimize():
                self.WindowState = WinForms.FormWindowState.Minimized

            self.Invoke(Func[Type](_minimize))

        def restore(self):
            def _restore():
                self.WindowState = WinForms.FormWindowState.Normal

            self.Invoke(Func[Type](_restore))



    @staticmethod
    def alert(message):
        WinForms.MessageBox.Show(message)


def _set_ie_mode():
    """
    By default hosted IE control emulates IE7 regardless which version of IE is installed. To fix this, a proper value
    must be set for the executable.
    See http://msdn.microsoft.com/en-us/library/ee330730%28v=vs.85%29.aspx#browser_emulation for details on this
    behaviour.
    """

    try:
        import _winreg as winreg  # Python 2
    except ImportError:
        import winreg  # Python 3

    def get_ie_mode():
        """
        Get the installed version of IE
        :return:
        """
        ie_key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, r"Software\Microsoft\Internet Explorer")
        try:
            version, type = winreg.QueryValueEx(ie_key, "svcVersion")
        except:
            version, type = winreg.QueryValueEx(ie_key, "Version")

        winreg.CloseKey(ie_key)

        if version.startswith("11"):
            value = 0x2AF9
        elif version.startswith("10"):
            value = 0x2711
        elif version.startswith("9"):
            value = 0x270F
        elif version.startswith("8"):
            value = 0x22B8
        else:
            value = 0x2AF9  # Set IE11 as default

        return value

    try:
        browser_emulation = winreg.OpenKey(winreg.HKEY_CURRENT_USER,
                                           r"Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION",
                                           0, winreg.KEY_ALL_ACCESS)
    except WindowsError:
        browser_emulation = winreg.CreateKeyEx(winreg.HKEY_CURRENT_USER,
                                               r"Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION",
                                               0, winreg.KEY_ALL_ACCESS)

    try:
        dpi_support = winreg.OpenKey(winreg.HKEY_CURRENT_USER,
                                     r"Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_96DPI_PIXEL",
                                     0, winreg.KEY_ALL_ACCESS)
    except WindowsError:
        dpi_support = winreg.CreateKeyEx(winreg.HKEY_CURRENT_USER,
                                               r"Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_96DPI_PIXEL",
                                               0, winreg.KEY_ALL_ACCESS)

    mode = get_ie_mode()
    executable_name = sys.executable.split("\\")[-1]
    winreg.SetValueEx(browser_emulation, executable_name, 0, winreg.REG_DWORD, mode)
    winreg.CloseKey(browser_emulation)

    winreg.SetValueEx(dpi_support, executable_name, 0, winreg.REG_DWORD, 1)
    winreg.CloseKey(dpi_support)


def _allow_localhost():
    import subprocess

    # lifted from https://github.com/pyinstaller/pyinstaller/wiki/Recipe-subprocess
    def subprocess_args(include_stdout=True):
        if hasattr(subprocess, 'STARTUPINFO'):
            si = subprocess.STARTUPINFO()
            si.dwFlags |= subprocess.STARTF_USESHOWWINDOW
            env = os.environ
        else:
            si = None
            env = None

        if include_stdout:
            ret = {'stdout': subprocess.PIPE}
        else:
            ret = {}

        ret.update({'stdin': subprocess.PIPE,
                    'stderr': subprocess.PIPE,
                    'startupinfo': si,
                    'env': env })
        return ret

    output = subprocess.check_output('checknetisolation LoopbackExempt -s', **subprocess_args(False))

    if 'cw5n1h2txyewy' not in str(output):
        windll.shell32.ShellExecuteW(None, 'runas', 'checknetisolation', 'LoopbackExempt -a -n=\"Microsoft.Win32WebViewHost_cw5n1h2txyewy\"', None, 1)


_main_window_created = Event()
_main_window_created.clear()

def create_window(window):
    def create():
        browser = BrowserView.BrowserForm(window)
        BrowserView.instances[window.uid] = browser

        if not window.hidden:
            browser.Show()

        _main_window_created.set()

        if window.uid == 'master':
            app.Run()

    app = WinForms.Application

    if window.uid == 'master':
        if not is_edge and not is_cef:
            _set_ie_mode()

        if sys.getwindowsversion().major >= 6:
            windll.user32.SetProcessDPIAware()

        if is_cef:
            CEF.init(window)

        app.EnableVisualStyles()
        app.SetCompatibleTextRenderingDefault(False)
        thread = Thread(ThreadStart(create))
        thread.SetApartmentState(ApartmentState.STA)
        thread.Start()
        thread.Join()

    else:
        _main_window_created.wait()
        i = list(BrowserView.instances.values())[0]     # arbitrary instance
        i.Invoke(Func[Type](create))


def set_title(title, uid):
    def _set_title():
        window.Text = title

    window = BrowserView.instances[uid]
    if window.InvokeRequired:
        window.Invoke(Func[Type](_set_title))
    else:
        _set_title()


def create_file_dialog(dialog_type, directory, allow_multiple, save_filename, file_types, uid):
    window = BrowserView.instances[uid]

    if not directory:
        directory = os.environ['HOMEPATH']

    try:
        if dialog_type == FOLDER_DIALOG:
            dialog = WinForms.FolderBrowserDialog()
            dialog.RestoreDirectory = True

            if directory:
                dialog.SelectedPath = directory

            result = dialog.ShowDialog(window)
            if result == WinForms.DialogResult.OK:
                file_path = (dialog.SelectedPath,)
            else:
                file_path = None
        elif dialog_type == OPEN_DIALOG:
            dialog = WinForms.OpenFileDialog()

            dialog.Multiselect = allow_multiple
            dialog.InitialDirectory = directory

            if len(file_types) > 0:
                dialog.Filter = '|'.join(['{0} ({1})|{1}'.format(*parse_file_type(f)) for f in file_types])
            else:
                dialog.Filter = localization['windows.fileFilter.allFiles'] + ' (*.*)|*.*'
            dialog.RestoreDirectory = True

            result = dialog.ShowDialog(window)
            if result == WinForms.DialogResult.OK:
                file_path = tuple(dialog.FileNames)
            else:
                file_path = None

        elif dialog_type == SAVE_DIALOG:
            dialog = WinForms.SaveFileDialog()
            dialog.Filter = localization['windows.fileFilter.allFiles'] + ' (*.*)|'
            dialog.InitialDirectory = directory
            dialog.RestoreDirectory = True
            dialog.FileName = save_filename

            result = dialog.ShowDialog(window)
            if result == WinForms.DialogResult.OK:
                file_path = dialog.FileName
            else:
                file_path = None

        return file_path
    except:
        logger.exception('Error invoking {0} dialog'.format(dialog_type))
        return None


def get_current_url(uid):
    if is_cef:
        return CEF.get_current_url(uid)
    else:
        window = BrowserView.instances[uid]
        window.loaded.wait()
        return window.browser.url


def load_url(url, uid):
    window = BrowserView.instances[uid]
    window.loaded.clear()

    if is_cef:
        CEF.load_url(url, uid)
    else:
        window.load_url(url)


def load_html(content, base_uri, uid):
    if is_cef:
        CEF.load_html(inject_base_uri(content, base_uri), uid)
        return
    else:
        BrowserView.instances[uid].load_html(content, base_uri)


def show(uid):
    window = BrowserView.instances[uid]
    window.show()


def hide(uid):
    window = BrowserView.instances[uid]
    window.hide()


def toggle_fullscreen(uid):
    window = BrowserView.instances[uid]
    window.toggle_fullscreen()


def set_on_top(uid, on_top):
    window = BrowserView.instances[uid]
    window.on_top = on_top


def resize(width, height, uid):
    window = BrowserView.instances[uid]
    window.resize(width, height)


def move(x, y, uid):
    window = BrowserView.instances[uid]
    window.move(x, y)


def minimize(uid):
    window = BrowserView.instances[uid]
    window.minimize()


def restore(uid):
    window = BrowserView.instances[uid]
    window.restore()


def destroy_window(uid):
    def _close():
        window.Close()

    window = BrowserView.instances[uid]
    window.Invoke(Func[Type](_close))

    if not is_cef:
        window.browser.js_result_semaphore.release()


def evaluate_js(script, uid):
    if is_cef:
        return CEF.evaluate_js(script, uid)
    else:
        return BrowserView.instances[uid].evaluate_js(script)


def get_position(uid):
    return BrowserView.instances[uid].Left, BrowserView.instances[uid].Top


def get_size(uid):
    size = BrowserView.instances[uid].Size
    return size.Width, size.Height