Add an implementation of Camera for Android.

android/src/toga_android/app.py

@@ -1,5 +1,6 @@
 import asyncio
 import sys
+import warnings
 
 from android.graphics.drawable import BitmapDrawable
 from android.media import RingtoneManager
@@ -18,10 +19,9 @@ class MainWindow(Window):
 
 
 class TogaApp(dynamic_proxy(IPythonApp)):
-    last_intent_requestcode = (
-        -1
-    )  # always increment before using it for invoking new Intents
+    last_requestcode = -1  # A unique ID for native background requests
     running_intents = {}  # dictionary for currently running Intents
+    permission_requests = {}  # dictionary for outstanding permission requests
     menuitem_mapping = {}  # dictionary for mapping menuitems to commands
 
     def __init__(self, app):
@@ -52,28 +52,33 @@ def onDestroy(self):
     def onRestart(self):
         print("Toga app: onRestart")  # pragma: no cover
 
-    # TODO #1798: document and test this somehow
-    def onActivityResult(self, requestCode, resultCode, resultData):  # pragma: no cover
-        """Callback method, called from MainActivity when an Intent ends.
-
-        :param int requestCode: The integer request code originally supplied to startActivityForResult(),
-                                allowing you to identify who this result came from.
-        :param int resultCode: The integer result code returned by the child activity through its setResult().
-        :param Intent resultData: An Intent, which can return result data to the caller (various data can be attached
-                                  to Intent "extras").
-        """
+    def onActivityResult(self, requestCode, resultCode, resultData):
+        print(f"Toga app: onActivityResult {requestCode=} {resultCode=} {resultData=}")
+        try:
+            # Retrieve the completion callback; if non-none, invoke it.
+            callback = self.running_intents.pop(requestCode)
+            # In theory, the callback can be empty; however, we don't
+            # have any practical use for this at present, so the branch
+            # is marked no-cover
+            if callback:  # pragma: no branch
+                callback(resultCode, resultData)
+        except KeyError:  # pragma: no cover
+            # This shouldn't happen; we shouldn't get notified of an
+            # intent that we didn't start
+            print(f"No intent matching request code {requestCode}")
+
+    def onRequestPermissionsResult(self, requestCode, permissions, grantResults):
         print(
-            f"Toga app: onActivityResult, requestCode={requestCode}, resultData={resultData}"
+            f"Toga app: onRequestPermissionsResult {requestCode=} {permissions=} {grantResults=}"
         )
         try:
-            # remove Intent from the list of running Intents,
-            # and set the result of the intent.
-            result_future = self.running_intents.pop(requestCode)
-            result_future.set_result(
-                {"resultCode": resultCode, "resultData": resultData}
-            )
-        except KeyError:
-            print("No intent matching request code {requestCode}")
+            # Retrieve the completion callback and invoke it.
+            callback = self.permission_requests.pop(requestCode)
+            callback(permissions, grantResults)
+        except KeyError:  # pragma: no cover
+            # This shouldn't happen; we shouldn't get notified of an
+            # permission that we didn't request.
+            print(f"No permission request matching request code {requestCode}")
 
     def onConfigurationChanged(self, new_config):
         pass  # pragma: no cover
@@ -250,27 +255,65 @@ def set_current_window(self, window):
 
     # TODO #1798: document and test this somehow
     async def intent_result(self, intent):  # pragma: no cover
-        """Calls an Intent and waits for its result.
-
-        A RuntimeError will be raised when the Intent cannot be invoked.
-
-        :param Intent intent: The Intent to call
-        :returns: A Dictionary containing "resultCode" (int) and "resultData" (Intent or None)
-        :rtype: dict
-        """
+        warnings.warn(
+            "intent_result has been deprecated; use start_activity",
+            DeprecationWarning,
+        )
         try:
-            self._listener.last_intent_requestcode += 1
-            code = self._listener.last_intent_requestcode
-
             result_future = asyncio.Future()
-            self._listener.running_intents[code] = result_future
 
-            self.native.startActivityForResult(intent, code)
+            def complete_handler(code, data):
+                result_future.set_result({"resultCode": code, "resultData": data})
+
+            self.start_activity(intent, on_complete=complete_handler)
+
             await result_future
             return result_future.result()
         except AttributeError:
             raise RuntimeError("No appropriate Activity found to handle this intent.")
 
+    def _native_startActivityForResult(
+        self, activity, code, *options
+    ):  # pragma: no cover
+        # A wrapper around the native method so that it can be mocked during testing.
+        self.native.startActivityForResult(activity, code, *options)
+
+    def start_activity(self, activity, *options, on_complete=None):
+        """Start a native Android activity.
+
+        :param activity: The Intent/Activity to start
+        :param options: Any additional arguments to pass to the native
+            ``startActivityForResult`` call.
+        :param on_complete: The callback to invoke when the activity
+            completes. The callback will be invoked with 2 arguments:
+            the result code, and the result data.
+        """
+        self._listener.last_requestcode += 1
+        code = self._listener.last_requestcode
+
+        self._listener.running_intents[code] = on_complete
+
+        self._native_startActivityForResult(activity, code, *options)
+
+    def _native_requestPermissions(self, permissions, code):  # pragma: no cover
+        # A wrapper around the native method so that it can be mocked during testing.
+        self.native.requestPermissions(permissions, code)
+
+    def request_permissions(self, permissions, on_complete):
+        """Request a set of permissions from the user.
+
+        :param permissions: The list of permissions to request.
+        :param on_complete: The callback to invoke when the permission request
+            completes. The callback will be invoked with 2 arguments: the list of
+            permissions that were processed, and a second list of the same size,
+            containing the grant status of each of those permissions.
+        """
+        self._listener.last_requestcode += 1
+        code = self._listener.last_requestcode
+
+        self._listener.permission_requests[code] = on_complete
+        self._native_requestPermissions(permissions, code)
+
     def enter_full_screen(self, windows):
         pass
 

android/src/toga_android/factory.py

@@ -2,6 +2,7 @@
 from .app import App, MainWindow
 from .command import Command
 from .fonts import Font
+from .hardware.camera import Camera
 from .icons import Icon
 from .images import Image
 from .paths import Paths
@@ -44,6 +45,8 @@ def not_implemented(feature):
     "Icon",
     "Image",
     "Paths",
+    # Hardware
+    "Camera",
     # Widgets
     # ActivityIndicator
     "Box",

android/src/toga_android/hardware/camera.py

@@ -0,0 +1,115 @@
+import warnings
+from pathlib import Path
+
+from android.content import Context, Intent
+from android.content.pm import PackageManager
+from android.hardware.camera2 import CameraCharacteristics
+from android.provider import MediaStore
+from androidx.core.content import ContextCompat, FileProvider
+from java.io import File
+
+import toga
+
+
+class CameraDevice:
+    def __init__(self, manager, id):
+        self._manager = manager
+        self._id = id
+
+    def id(self):
+        return self._id
+
+    def name(self):
+        return f"Camera {self._id}"
+
+    def has_flash(self):
+        characteristics = self._manager.getCameraCharacteristics(self._id)
+        return characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE)
+
+
+class Camera:
+    CAMERA_PERMISSION = "android.permission.CAMERA"
+
+    def __init__(self, interface):
+        self.interface = interface
+
+        # Does the device have a camera?
+        self.context = self.interface.app._impl.native.getApplicationContext()
+        self.has_camera = self.context.getPackageManager().hasSystemFeature(
+            PackageManager.FEATURE_CAMERA
+        )
+
+    def _native_checkSelfPermission(self, context, permission):  # pragma: no cover
+        # A wrapper around the native call so it can be mocked.
+        return ContextCompat.checkSelfPermission(context, Camera.CAMERA_PERMISSION)
+
+    def has_permission(self):
+        result = self._native_checkSelfPermission(
+            self.context, Camera.CAMERA_PERMISSION
+        )
+        return result == PackageManager.PERMISSION_GRANTED
+
+    def request_permission(self, future):
+        def request_complete(permissions, results):
+            # Map the permissions to their result
+            perms = dict(zip(permissions, results))
+            try:
+                result = (
+                    perms[Camera.CAMERA_PERMISSION] == PackageManager.PERMISSION_GRANTED
+                )
+            except KeyError:  # pragma: no cover
+                # This shouldn't ever happen - we shouldn't get a completion of a camera
+                # permission request that doesn't include the camera permission - but
+                # just in case, we'll assume if it's not there, it failed.
+                result = False
+            future.set_result(result)
+
+        self.interface.app._impl.request_permissions(
+            [Camera.CAMERA_PERMISSION],
+            on_complete=request_complete,
+        )
+
+    def get_devices(self):
+        manager = self.interface.app._impl.native.getSystemService(
+            Context.CAMERA_SERVICE
+        )
+
+        return [
+            CameraDevice(manager=manager, id=ident)
+            for ident in manager.getCameraIdList()
+        ]
+
+    def take_photo(self, result, device, flash):
+        if not self.has_camera:
+            warnings.warn("No camera is available")
+            result.set_result(None)
+        elif self.has_permission():
+            # We have permission; go directly to taking the photo.
+            # The "shared" subfolder of the app's cache folder is
+            # marked as a file provider. Ensure the folder exists.
+            shared_folder = File(self.context.getCacheDir(), "shared")
+            if not shared_folder.exists():
+                shared_folder.mkdirs()
+
+            # Create a temporary file in the shared folder,
+            # and convert it to a URI using the app's fileprovider.
+            photo_file = File.createTempFile("camera", ".jpg", shared_folder)
+            photo_uri = FileProvider.getUriForFile(
+                self.context,
+                f"{self.interface.app.app_id}.fileprovider",
+                photo_file,
+            )
+
+            def photo_taken(code, data):
+                # Activity.RESULT_CANCELED == 0
+                if code:
+                    photo = toga.Image(Path(photo_file.getAbsolutePath()))
+                    result.set_result(photo)
+                else:
+                    result.set_result(None)
+
+            intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
+            intent.putExtra(MediaStore.EXTRA_OUTPUT, photo_uri)
+            self.interface.app._impl.start_activity(intent, on_complete=photo_taken)
+        else:
+            raise PermissionError("App does not have permission to take photos")