Fix errors in tkinter_.py example on Mac (#306, #308).

Fix tkinter error on Mac "unrecognized selector sent to instance"
(Issue #306"). CEF must be initialized after Tk.

Fix error with winfo_id() returning a negative value (Issue #308).
This was resolved by obtaining NSView pointer using PyObjC
package.

There is yet another error "Segmentation fault: 11" which
crashes app often, however it's hard to debug it (Issue #309).

docs/Knowledge-Base.md

@@ -69,7 +69,7 @@ settings:
 ```
 cefpython_package/
     cefpython_py27.so
-        rpath=@loader_path
+        rpath=@loader_path/
         load:@rpath/Chromium Embedded Framework.framework/Chromium Embedded Framework
     Chromium Embedded Framework.framework/
         Chromium Embedded Framework
@@ -117,7 +117,8 @@ release perform the following steps:
    (http://opensource.spotify.com/cefbuilds/index.html)
    and download latest CEF for your platform. Choose "Standard
    Distribution" binaries.
-3. Follow the instructions in `CMakeLists.txt` file
+3. Follow the instructions in `CMakeLists.txt` file, choose steps
+   for building using Ninja
 4. Run either cefclient or cefsimple to test features
 
 

examples/tkinter_.py

@@ -1,10 +1,12 @@
 # Example of embedding CEF Python browser using Tkinter toolkit.
 # This example has two widgets: a navigation bar and a browser.
 #
-# NOTE: This example doesn't work on Mac, details in Issue #306.
+# NOTE: This example often crashes on Mac (Tk 8.5) during initial
+#       app loading with such message: "Segmentation fault: 11".
+#       Reported as Issue #309.
 #
 # Tested configurations:
-# - Tk 8.5 on Windows
+# - Tk 8.5 on Windows/Mac
 # - Tk 8.6 on Linux
 # - CEF Python v55.3+
 #
@@ -32,8 +34,10 @@
 
 # Globals
 logger = _logging.getLogger("tkinter_.py")
-# Python 2.7 on Windows comes with Tk 8.5 which doesn't support PNG images
-IMAGE_EXT = ".gif" if WINDOWS else ".png"
+
+# Constants
+# Tk 8.5 doesn't support png images
+IMAGE_EXT = ".png" if tk.TkVersion > 8.5 else ".gif"
 
 
 def main():
@@ -47,25 +51,27 @@ def main():
     logger.info("Tk {ver}".format(ver=tk.Tcl().eval('info patchlevel')))
     assert cef.__version__ >= "55.3", "CEF Python v55.3+ required to run this"
     sys.excepthook = cef.ExceptHook  # To shutdown all CEF processes on error
+    root = tk.Tk()
+    app = MainFrame(root)
+    # Tk must be initialized before CEF otherwise fatal error (Issue #306)
     cef.Initialize()
-    app = MainFrame(tk.Tk())
     app.mainloop()
     cef.Shutdown()
 
 
 class MainFrame(tk.Frame):
 
-    def __init__(self, master):
+    def __init__(self, root):
         self.browser_frame = None
         self.navigation_bar = None
 
         # Root
-        master.geometry("800x600")
-        tk.Grid.rowconfigure(master, 0, weight=1)
-        tk.Grid.columnconfigure(master, 0, weight=1)
+        root.geometry("800x600")
+        tk.Grid.rowconfigure(root, 0, weight=1)
+        tk.Grid.columnconfigure(root, 0, weight=1)
 
         # MainFrame
-        tk.Frame.__init__(self, master)
+        tk.Frame.__init__(self, root)
         self.master.title("Tkinter example")
         self.master.protocol("WM_DELETE_WINDOW", self.on_close)
         self.master.bind("<Configure>", self.on_root_configure)
@@ -135,6 +141,119 @@ def setup_icon(self):
             self.master.call("wm", "iconphoto", self.master._w, self.icon)
 
 
+class BrowserFrame(tk.Frame):
+
+    def __init__(self, master, navigation_bar=None):
+        self.navigation_bar = navigation_bar
+        self.closing = False
+        self.browser = None
+        tk.Frame.__init__(self, master)
+        self.bind("<FocusIn>", self.on_focus_in)
+        self.bind("<FocusOut>", self.on_focus_out)
+        self.bind("<Configure>", self.on_configure)
+        self.focus_set()
+
+    def embed_browser(self):
+        window_info = cef.WindowInfo()
+        rect = [0, 0, self.winfo_width(), self.winfo_height()]
+        window_info.SetAsChild(self.get_window_handle(), rect)
+        self.browser = cef.CreateBrowserSync(window_info,
+                                             url="https://www.google.com/")
+        assert self.browser
+        self.browser.SetClientHandler(LoadHandler(self))
+        self.browser.SetClientHandler(FocusHandler(self))
+        self.message_loop_work()
+
+    def get_window_handle(self):
+        if self.winfo_id() > 0:
+            return self.winfo_id()
+        elif MAC:
+            # On Mac window id is an invalid negative value (Issue #308).
+            # This is kind of a dirty hack to get window handle using
+            # PyObjC package. If you change structure of windows then you
+            # need to do modifications here as well.
+            # noinspection PyUnresolvedReferences
+            from AppKit import NSApp
+            # noinspection PyUnresolvedReferences
+            import objc
+            # Sometimes there is more than one window, when application
+            # didn't close cleanly last time Python displays an NSAlert
+            # window asking whether to Reopen that window.
+            # noinspection PyUnresolvedReferences
+            return objc.pyobjc_id(NSApp.windows()[-1].contentView())
+        else:
+            raise Exception("Couldn't obtain window handle")
+
+    def message_loop_work(self):
+        cef.MessageLoopWork()
+        self.after(10, self.message_loop_work)
+
+    def on_configure(self, _):
+        if not self.browser:
+            self.embed_browser()
+
+    def on_root_configure(self):
+        # Root <Configure> event will be called when top window is moved
+        if self.browser:
+            self.browser.NotifyMoveOrResizeStarted()
+
+    def on_mainframe_configure(self, width, height):
+        if self.browser:
+            if WINDOWS:
+                WindowUtils.OnSize(self.get_window_handle(), 0, 0, 0)
+            elif LINUX:
+                self.browser.SetBounds(0, 0, width, height)
+            self.browser.NotifyMoveOrResizeStarted()
+
+    def on_focus_in(self, _):
+        logger.debug("BrowserFrame.on_focus_in")
+        if self.browser:
+            self.browser.SetFocus(True)
+
+    def on_focus_out(self, _):
+        logger.debug("BrowserFrame.on_focus_out")
+        if self.browser:
+            self.browser.SetFocus(False)
+
+    def on_root_close(self):
+        if self.browser:
+            # Close browser and free reference by setting to None
+            self.browser.CloseBrowser(True)
+            self.browser = None
+        self.destroy()
+
+
+class LoadHandler(object):
+
+    def __init__(self, browser_frame):
+        self.browser_frame = browser_frame
+
+    def OnLoadStart(self, browser, **_):
+        if self.browser_frame.master.navigation_bar:
+            self.browser_frame.master.navigation_bar.set_url(browser.GetUrl())
+
+
+class FocusHandler(object):
+
+    def __init__(self, browser_frame):
+        self.browser_frame = browser_frame
+
+    def OnTakeFocus(self, next_component, **_):
+        logger.debug("FocusHandler.OnTakeFocus, next={next}"
+                     .format(next=next_component))
+
+    def OnSetFocus(self, source, **_):
+        logger.debug("FocusHandler.OnSetFocus, source={source}"
+                     .format(source=source))
+        return False
+
+    def OnGotFocus(self, **_):
+        """Fix CEF focus issues (#255). Call browser frame's focus_set
+           to get rid of type cursor in url entry widget."""
+        logger.debug("FocusHandler.OnGotFocus")
+        self.browser_frame.focus_set()
+
+
 class NavigationBar(tk.Frame):
 
     def __init__(self, master):
@@ -254,97 +373,5 @@ def __init__(self):
         # TODO: implement tabs
 
 
-class BrowserFrame(tk.Frame):
-
-    def __init__(self, master, navigation_bar=None):
-        self.navigation_bar = navigation_bar
-        self.closing = False
-        self.browser = None
-        tk.Frame.__init__(self, master)
-        self.bind("<FocusIn>", self.on_focus_in)
-        self.bind("<FocusOut>", self.on_focus_out)
-        self.bind("<Configure>", self.on_configure)
-        self.focus_set()
-
-    def embed_browser(self):
-        window_info = cef.WindowInfo()
-        window_info.SetAsChild(self.winfo_id())
-        self.browser = cef.CreateBrowserSync(window_info,
-                                             url="https://www.google.com/")
-        assert self.browser
-        self.browser.SetClientHandler(LoadHandler(self))
-        self.browser.SetClientHandler(FocusHandler(self))
-        self.message_loop_work()
-
-    def message_loop_work(self):
-        cef.MessageLoopWork()
-        self.after(10, self.message_loop_work)
-
-    def on_configure(self, _):
-        if not self.browser:
-            self.embed_browser()
-
-    def on_root_configure(self):
-        # Root <Configure> event will be called when top window is moved
-        if self.browser:
-            self.browser.NotifyMoveOrResizeStarted()
-
-    def on_mainframe_configure(self, width, height):
-        if self.browser:
-            if WINDOWS:
-                WindowUtils.OnSize(self.winfo_id(), 0, 0, 0)
-            elif LINUX:
-                self.browser.SetBounds(0, 0, width, height)
-            self.browser.NotifyMoveOrResizeStarted()
-
-    def on_focus_in(self, _):
-        logger.debug("BrowserFrame.on_focus_in")
-        if self.browser:
-            self.browser.SetFocus(True)
-
-    def on_focus_out(self, _):
-        logger.debug("BrowserFrame.on_focus_out")
-        if self.browser:
-            self.browser.SetFocus(False)
-
-    def on_root_close(self):
-        if self.browser:
-            # Close browser and free reference by setting to None
-            self.browser.CloseBrowser(True)
-            self.browser = None
-        self.destroy()
-
-
-class LoadHandler(object):
-
-    def __init__(self, browser_frame):
-        self.browser_frame = browser_frame
-
-    def OnLoadStart(self, browser, **_):
-        if self.browser_frame.master.navigation_bar:
-            self.browser_frame.master.navigation_bar.set_url(browser.GetUrl())
-
-
-class FocusHandler(object):
-
-    def __init__(self, browser_frame):
-        self.browser_frame = browser_frame
-
-    def OnTakeFocus(self, next_component, **_):
-        logger.debug("FocusHandler.OnTakeFocus, next={next}"
-                     .format(next=next_component))
-
-    def OnSetFocus(self, source, **_):
-        logger.debug("FocusHandler.OnSetFocus, source={source}"
-                     .format(source=source))
-        return False
-
-    def OnGotFocus(self, **_):
-        """Fix CEF focus issues (#255). Call browser frame's focus_set
-           to get rid of type cursor in url entry widget."""
-        logger.debug("FocusHandler.OnGotFocus")
-        self.browser_frame.focus_set()
-
-
 if __name__ == '__main__':
     main()

tools/run_examples.py

@@ -65,8 +65,9 @@ def main():
         print("[run_examples.py] PASS: qt.py pyside (PySide not installed)")
         passed.append("qt.py pyside")
 
-    # tkinter
-    if packages["tkinter"] or packages["Tkinter"]:
+    # tkinter.
+    # This example often crashes on Mac (Issue #309), so don't run it.
+    if not MAC and (packages["tkinter"] or packages["Tkinter"]):
         examples.append("tkinter_.py")
     else:
         print(["run_examples.py] PASS: tkinter_.py (tkinter not installed)"])