Modify dialogs to allow for async usage.

examples/dialogs/dialogs/app.py

@@ -1,5 +1,7 @@
-import toga
+import traceback
 from pathlib import Path
+
+import toga
 from toga.constants import COLUMN
 from toga.style import Pack
 
@@ -9,127 +11,139 @@ class ExampledialogsApp(toga.App):
     def do_clear(self, widget, **kwargs):
         self.label.text = "Ready."
 
-    def action_info_dialog(self, widget):
-        self.main_window.info_dialog('Toga', 'THIS! IS! TOGA!!')
+    async def action_info_dialog(self, widget):
+        await self.main_window.info_dialog('Toga', 'THIS! IS! TOGA!!')
         self.label.text = 'Information was provided.'
 
-    def action_question_dialog(self, widget):
-        if self.main_window.question_dialog('Toga', 'Is this cool or what?'):
+    async def action_question_dialog(self, widget):
+        if await self.main_window.question_dialog('Toga', 'Is this cool or what?'):
             self.label.text = 'User said yes!'
-            self.main_window.info_dialog('Happiness', 'I know, right! :-)')
+            await self.main_window.info_dialog('Happiness', 'I know, right! :-)')
         else:
             self.label.text = 'User says no...'
-            self.main_window.info_dialog('Shucks...', "Well aren't you a spoilsport... :-(")
+            await self.main_window.info_dialog('Shucks...', "Well aren't you a spoilsport... :-(")
 
-    def action_confirm_dialog(self, widget):
-        if self.main_window.question_dialog('Toga', 'Are you sure you want to?'):
+    async def action_confirm_dialog(self, widget):
+        if await self.main_window.question_dialog('Toga', 'Are you sure you want to?'):
             self.label.text = 'Lets do it!'
         else:
             self.label.text = "Left it as it was."
 
-    def action_error_dialog(self, widget):
-        self.main_window.error_dialog('Toga', "Well that didn't work... or did it?")
+    async def action_error_dialog(self, widget):
+        await self.main_window.error_dialog('Toga', "Well that didn't work... or did it?")
         self.label.text = 'Oh noes...'
 
-    def action_open_file_dialog(self, widget):
+    async def action_stack_trace(self, widget):
+        await self.main_window.stack_trace_dialog(
+            'Toga',
+            "Here's where you were when it went bad:",
+            ''.join(traceback.format_stack())
+        )
+        self.label.text = 'Stack traced...'
+
+    async def action_open_file_dialog(self, widget):
         try:
-            fname = self.main_window.open_file_dialog(
+            fname = await self.main_window.open_file_dialog(
                 title="Open file with Toga",
                 multiselect=False
             )
             if fname is not None:
-                self.label.text = "File to open:" + fname
+                self.label.text = f"File to open: {fname}"
             else:
                 self.label.text = "No file selected!"
         except ValueError:
             self.label.text = "Open file dialog was canceled"
 
-    def action_open_file_filtered_dialog(self, widget):
+    async def action_open_file_filtered_dialog(self, widget):
         try:
-            fname = self.main_window.open_file_dialog(
+            fname = await self.main_window.open_file_dialog(
                 title="Open file with Toga",
                 multiselect=False,
                 file_types=['doc', 'txt'],
             )
             if fname is not None:
-                self.label.text = "File to open:" + fname
+                self.label.text = f"File to open: {fname}"
             else:
                 self.label.text = "No file selected!"
         except ValueError:
             self.label.text = "Open file dialog was canceled"
 
-    def action_open_file_dialog_multi(self, widget):
+    async def action_open_file_dialog_multi(self, widget):
         try:
-            filenames = self.main_window.open_file_dialog(
+            filenames = await self.main_window.open_file_dialog(
                 title="Open file with Toga",
                 multiselect=True
             )
             if filenames is not None:
-                msg = "Files to open: {}".format(', '.join(filenames))
+                msg = f"Files to open: {', '.join(str(f) for f in filenames)}"
                 self.label.text = msg
             else:
                 self.label.text = "No files selected!"
 
         except ValueError:
             self.label.text = "Open file dialog was canceled"
 
-    def action_open_file_dialog_with_inital_folder(self, widget):
+    async def action_open_file_dialog_with_inital_folder(self, widget):
         try:
-            fname = self.main_window.open_file_dialog(
+            fname = await self.main_window.open_file_dialog(
                 title="Open file with Toga in home folder",
                 initial_directory=Path.home(),
                 multiselect=False
             )
             if fname is not None:
-                self.label.text = "File to open:" + fname
+                self.label.text = f"File to open: {fname}"
             else:
                 self.label.text = "No file selected!"
         except ValueError:
             self.label.text = "Open file dialog was canceled"
 
-    def action_select_folder_dialog(self, widget):
+    async def action_select_folder_dialog(self, widget):
         try:
-            path_names = self.main_window.select_folder_dialog(
+            path_name = await self.main_window.select_folder_dialog(
                 title="Select folder with Toga"
             )
-            if path_names is not None:
-                self.label.text = "Folder selected:" + ','.join([path for path in path_names])
+            if path_name is not None:
+                self.label.text = f"Folder selected: {path_name}"
             else:
                 self.label.text = "No folder selected!"
         except ValueError:
             self.label.text = "Folder select dialog was canceled"
 
-    def action_select_folder_dialog_multi(self, widget):
+    async def action_select_folder_dialog_multi(self, widget):
         try:
-            path_names = self.main_window.select_folder_dialog(
+            path_names = await self.main_window.select_folder_dialog(
                 title="Select multiple folders with Toga",
                 multiselect=True
             )
-            self.label.text = "Folders selected:" + ','.join([path for path in path_names])
+            if path_names is not None:
+                self.label.text = f"Folders selected: {','.join([str(p) for p in path_names])}"
+            else:
+                self.label.text = "No fodlers selected!"
         except ValueError:
             self.label.text = "Folders select dialog was canceled"
 
-    def action_select_folder_dialog_with_initial_folder(self, widget):
+    async def action_select_folder_dialog_with_initial_folder(self, widget):
         try:
-            path_names = self.main_window.select_folder_dialog(
+            path_name = await self.main_window.select_folder_dialog(
                 title="Select folder with Toga in current folder",
                 initial_directory=Path.cwd(),
             )
-            self.label.text = "Folder selected:" + ','.join([path for path in path_names])
+            self.label.text = f"Folder selected: {path_name}"
         except ValueError:
             self.label.text = "Folder select dialog was canceled"
 
-    def action_save_file_dialog(self, widget):
+    async def action_save_file_dialog(self, widget):
         fname = 'Toga_file.txt'
         try:
-            save_path = self.main_window.save_file_dialog(
+            save_path = await self.main_window.save_file_dialog(
                 "Save file with Toga",
-                suggested_filename=fname
+                suggested_filename=fname,
             )
             if save_path is not None:
-                self.label.text = "File saved with Toga:" + save_path
+                self.label.text = f"File saved with Toga: {save_path}"
             else:
                 self.label.text = "Save file dialog was canceled"
+
         except ValueError:
             self.label.text = "Save file dialog was canceled"
 
@@ -148,7 +162,7 @@ async def window_close_handler(self, window):
             self.set_window_label_text(len(self.windows) - 2)
             return True
         else:
-            window.info_dialog(f'Abort {window.title}!', 'Maybe try that again...')
+            await window.info_dialog(f'Abort {window.title}!', 'Maybe try that again...')
             self.close_attempts.add(window)
             return False
 
@@ -181,7 +195,7 @@ def action_close_secondary_windows(self, widget):
 
     async def exit_handler(self, app):
         # Return True if app should close, and False if it should remain open
-        if self.main_window.confirm_dialog('Toga', 'Are you sure you want to quit?'):
+        if await self.main_window.confirm_dialog('Toga', 'Are you sure you want to quit?'):
             print(f"Label text was '{self.label.text}' when you quit the app")
             return True
         else:
@@ -209,6 +223,7 @@ def startup(self):
         btn_question = toga.Button('Question', on_press=self.action_question_dialog, style=btn_style)
         btn_confirm = toga.Button('Confirm', on_press=self.action_confirm_dialog, style=btn_style)
         btn_error = toga.Button('Error', on_press=self.action_error_dialog, style=btn_style)
+        btn_stack_trace = toga.Button('Stack Trace', on_press=self.action_stack_trace, style=btn_style)
         btn_open = toga.Button('Open File', on_press=self.action_open_file_dialog, style=btn_style)
         btn_open_filtered = toga.Button(
             'Open File (Filtered)',
@@ -221,7 +236,7 @@ def startup(self):
             style=btn_style
         )
         btn_open_init_folder = toga.Button(
-            'Open File In Current Folder',
+            'Open File In Home Folder',
             on_press=self.action_open_file_dialog_with_inital_folder,
         )
 
@@ -258,6 +273,7 @@ def startup(self):
                 btn_question,
                 btn_confirm,
                 btn_error,
+                btn_stack_trace,
                 btn_open,
                 btn_open_filtered,
                 btn_open_multi,

src/android/toga_android/dialogs.py

@@ -1,35 +1,118 @@
+import asyncio
+
+from .libs.android import R__drawable
 from .libs.android.app import AlertDialog__Builder
 from .libs.android.content import DialogInterface__OnClickListener
 
 
-class NoOpListener(DialogInterface__OnClickListener):
-    def onClick(self, dialog, which):
-        pass
+class OnClickListener(DialogInterface__OnClickListener):
+    def __init__(self, fn=None, value=None):
+        super().__init__()
+        self._fn = fn
+        self._value = value
+
+    def onClick(self, _dialog, _which):
+        if self._fn:
+            self._fn(self._value)
+
+
+class BaseDialog:
+    def __init__(self):
+        loop = asyncio.get_event_loop()
+        self.future = loop.create_future()
+        # self.future = asyncio.create_future()
+
+    def __eq__(self, other):
+        raise RuntimeError("Can't check dialog result directly; use await or an on_result handler")
+
+    def __bool__(self):
+        raise RuntimeError("Can't check dialog result directly; use await or an on_result handler")
+
+    def __await__(self):
+        return self.future.__await__()
+
+
+class TextDialog(BaseDialog):
+    def __init__(self, window, title, message, positive_text, negative_text=None, icon=None, on_result=None):
+        """Create Android textual dialog.
+
+        - window: Toga Window
+        - title: Title of dialog
+        - message: Message of dialog
+        - positive_text: Button label where clicking it returns True (or None to skip)
+        - negative_text: Button label where clicking it returns False (or None to skip)
+        - icon: Integer used as an Android resource ID number for dialog icon (or None to skip)
+        """
+        super().__init__()
 
+        builder = AlertDialog__Builder(window.app.native)
+        builder.setCancelable(False)
+        builder.setTitle(title)
+        builder.setMessage(message)
+        if icon is not None:
+            builder.setIcon(icon)
 
-def info(window, title, message):
-    builder = AlertDialog__Builder(window.app.native)
-    builder.setTitle(title)
-    builder.setMessage(message)
-    builder.setPositiveButton("OK", NoOpListener())
-    builder.show()
+        if positive_text is not None:
+            builder.setPositiveButton(
+                positive_text,
+                OnClickListener(self.completion_handler, True)
+            )
+        if negative_text is not None:
+            builder.setNegativeButton(
+                negative_text,
+                OnClickListener(self.completion_handler, False)
+            )
+        builder.show()
 
+    def completion_handler(self, return_value: bool) -> None:
+        if self.on_result:
+            self.on_result(self, return_value)
 
-def question(window, title, message):
-    window.platform.not_implemented("dialogs.question()")
+        self.future.set_result(return_value)
 
 
-def confirm(window, title, message):
-    window.platform.not_implemented("dialogs.confirm()")
+class InfoDialog(TextDialog):
+    def __init__(self, window, title, message, on_result=None):
+        super().__init__(
+            window=window,
+            title=title,
+            message=message,
+            positive_text="OK",
+            on_result=on_result,
+        )
 
 
-def error(window, title, message):
-    window.platform.not_implemented("dialogs.error()")
+class QuestionDialog(TextDialog):
+    def __init__(self, window, title, message, on_result=None):
+        super().__init__(
+            window=window,
+            title=title,
+            message=message,
+            positive_text="Yes",
+            negative_text="No",
+            on_result=on_result,
+        )
 
 
-def stack_trace(window, title, message, content, retry=False):
-    window.platform.not_implemented("dialogs.stack_trace()")
+class ConfirmDialog(TextDialog):
+    def __init__(self, window, title, message, on_result=None):
+        super().__init__(
+            window=window,
+            title=title,
+            message=message,
+            positive_text="OK",
+            negative_text="Cancel",
+            on_result=on_result,
+        )
 
 
-def save_file(window, title, suggested_filename, file_types):
-    window.platform.not_implemented("dialogs.save_file()")
+class ErrorDialog(TextDialog):
+    def __init__(self, window, title, message, on_result=None):
+        super().__init__(
+            window=window,
+            title=title,
+            message=message,
+            positive_text="OK",
+            icon=R__drawable.ic_dialog_alert,
+            on_result=on_result,
+        )

src/android/toga_android/window.py

@@ -103,16 +103,16 @@ def set_full_screen(self, is_full_screen):
         self.interface.factory.not_implemented('Window.set_full_screen()')
 
     def info_dialog(self, title, message):
-        dialogs.info(self, title, message)
+        return dialogs.InfoDialog(self, title, message)
 
     def question_dialog(self, title, message):
-        self.interface.factory.not_implemented('Window.question_dialog()')
+        return dialogs.QuestionDialog(self, title, message)
 
     def confirm_dialog(self, title, message):
-        self.interface.factory.not_implemented('Window.confirm_dialog()')
+        return dialogs.ConfirmDialog(self, title, message)
 
     def error_dialog(self, title, message):
-        self.interface.factory.not_implemented('Window.error_dialog()')
+        return dialogs.ErrorDialog(self, title, message)
 
     def stack_trace_dialog(self, title, message, content, retry=False):
         self.interface.factory.not_implemented('Window.stack_trace_dialog()')