[image_picker] Add desktop support

CODEOWNERS

@@ -83,12 +83,14 @@ packages/webview_flutter/webview_flutter_wkwebview/**    @cyanglaz
 
 # - Linux
 packages/file_selector/file_selector_linux/**            @cbracken
+packages/image_picker/image_picker_linux/**              @cbracken
 packages/path_provider/path_provider_linux/**            @cbracken
 packages/shared_preferences/shared_preferences_linux/**  @cbracken
 packages/url_launcher/url_launcher_linux/**              @cbracken
 
 # - macOS
 packages/file_selector/file_selector_macos/**            @cbracken
+packages/image_picker/image_picker_macos/**              @cbracken
 packages/url_launcher/url_launcher_macos/**              @cbracken
 
 # - Windows

packages/image_picker/image_picker/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 0.8.8
+
+* Adds initial support for Windows, macOS, and Linux.
+    * See README for current desktop limitations.
+* Adds `supportsImageSource` to allow runtime checks for whether a given source
+  is supported by the current platform's implementation.
+
 ## 0.8.7+5
 
 * Fixes `BuildContext` handling in example.

packages/image_picker/image_picker/README.md

@@ -6,9 +6,9 @@
 A Flutter plugin for iOS and Android for picking images from the image library,
 and taking new pictures with the camera.
 
-|             | Android | iOS     | Web                             |
-|-------------|---------|---------|---------------------------------|
-| **Support** | SDK 21+ | iOS 11+ | [See `image_picker_for_web`][1] |
+|             | Android | iOS     | Linux | macOS  | Web                             | Windows     |
+|-------------|---------|---------|-------|--------|---------------------------------|-------------|
+| **Support** | SDK 21+ | iOS 11+ | Any   | 10.14+ | [See `image_picker_for_web`][1] | Windows 10+ |
 
 ## Installation
 
@@ -109,6 +109,61 @@ As activities cannot communicate between tasks, the image picker activity cannot
 send back its eventual result to the calling activity.
 To work around this problem, consider using `launchMode: singleTask` instead.
 
+### Windows, macOS, and Linux
+
+This plugin currently has limited support for the three desktop platforms,
+serving as a wrapper around the [`file_selector`](https://pub.dev/packages/file_selector)
+plugin with appropriate file type filters set. Selection modification options,
+such as max width and height, are not yet supported.
+
+By default, `ImageSource.camera` is not supported, since unlike on Android and
+iOS there is no system-provided UI for taking photos. However, the desktop
+implementations allow delegating to a camera handler by setting a
+`cameraDelegate` before using `image_picker`, such as in `main()`:
+
+<?code-excerpt "readme_excerpts.dart (CameraDelegate)"?>
+``` dart
+import 'package:image_picker_platform_interface/image_picker_platform_interface.dart';
+// ···
+class MyCameraDelegate extends ImagePickerCameraDelegate {
+  @override
+  Future<XFile?> takePhoto(
+      {ImagePickerCameraDelegateOptions options =
+          const ImagePickerCameraDelegateOptions()}) async {
+    return _takeAPhoto(options.preferredCameraDevice);
+  }
+
+  @override
+  Future<XFile?> takeVideo(
+      {ImagePickerCameraDelegateOptions options =
+          const ImagePickerCameraDelegateOptions()}) async {
+    return _takeAVideo(options.preferredCameraDevice);
+  }
+}
+// ···
+void setUpCameraDelegate() {
+  final ImagePickerPlatform instance = ImagePickerPlatform.instance;
+  if (instance is CameraDelegatingImagePickerPlatform) {
+    instance.cameraDelegate = MyCameraDelegate();
+  }
+}
+```
+
+Once you have set a `cameraDelegate`, `image_picker` calls with
+`ImageSource.camera` will work as normal, calling your provided delegate. We
+encourage the community to build packages that implement
+`ImagePickerCameraDelegate`, to provide options for desktop camera UI.
+
+#### macOS installation
+
+Since the macOS implementation uses `file_selector`, you will need to
+add a filesystem access
+[entitlement][https://docs.flutter.dev/platform-integration/macos/building#entitlements-and-the-app-sandbox]:
+```xml
+  <key>com.apple.security.files.user-selected.read-only</key>
+  <true/>
+```
+
 ### Example
 
 <?code-excerpt "readme_excerpts.dart (Pick)"?>

packages/image_picker/image_picker/example/lib/main.dart

@@ -316,18 +316,19 @@ class _MyHomePageState extends State<MyHomePage> {
               child: const Icon(Icons.photo_library),
             ),
           ),
-          Padding(
-            padding: const EdgeInsets.only(top: 16.0),
-            child: FloatingActionButton(
-              onPressed: () {
-                isVideo = false;
-                _onImageButtonPressed(ImageSource.camera, context: context);
-              },
-              heroTag: 'image2',
-              tooltip: 'Take a Photo',
-              child: const Icon(Icons.camera_alt),
+          if (_picker.supportsImageSource(ImageSource.camera))
+            Padding(
+              padding: const EdgeInsets.only(top: 16.0),
+              child: FloatingActionButton(
+                onPressed: () {
+                  isVideo = false;
+                  _onImageButtonPressed(ImageSource.camera, context: context);
+                },
+                heroTag: 'image2',
+                tooltip: 'Take a Photo',
+                child: const Icon(Icons.camera_alt),
+              ),
             ),
-          ),
           Padding(
             padding: const EdgeInsets.only(top: 16.0),
             child: FloatingActionButton(
@@ -341,19 +342,20 @@ class _MyHomePageState extends State<MyHomePage> {
               child: const Icon(Icons.video_library),
             ),
           ),
-          Padding(
-            padding: const EdgeInsets.only(top: 16.0),
-            child: FloatingActionButton(
-              backgroundColor: Colors.red,
-              onPressed: () {
-                isVideo = true;
-                _onImageButtonPressed(ImageSource.camera, context: context);
-              },
-              heroTag: 'video1',
-              tooltip: 'Take a Video',
-              child: const Icon(Icons.videocam),
+          if (_picker.supportsImageSource(ImageSource.camera))
+            Padding(
+              padding: const EdgeInsets.only(top: 16.0),
+              child: FloatingActionButton(
+                backgroundColor: Colors.red,
+                onPressed: () {
+                  isVideo = true;
+                  _onImageButtonPressed(ImageSource.camera, context: context);
+                },
+                heroTag: 'video1',
+                tooltip: 'Take a Video',
+                child: const Icon(Icons.videocam),
+              ),
             ),
-          ),
         ],
       ),
     );

packages/image_picker/image_picker/example/lib/readme_excerpts.dart

@@ -4,6 +4,28 @@
 
 import 'package:flutter/services.dart';
 import 'package:image_picker/image_picker.dart';
+// #docregion CameraDelegate
+import 'package:image_picker_platform_interface/image_picker_platform_interface.dart';
+// #enddocregion CameraDelegate
+
+/// Example of a camera delegate
+// #docregion CameraDelegate
+class MyCameraDelegate extends ImagePickerCameraDelegate {
+  @override
+  Future<XFile?> takePhoto(
+      {ImagePickerCameraDelegateOptions options =
+          const ImagePickerCameraDelegateOptions()}) async {
+    return _takeAPhoto(options.preferredCameraDevice);
+  }
+
+  @override
+  Future<XFile?> takeVideo(
+      {ImagePickerCameraDelegateOptions options =
+          const ImagePickerCameraDelegateOptions()}) async {
+    return _takeAVideo(options.preferredCameraDevice);
+  }
+}
+// #enddocregion CameraDelegate
 
 /// Example function for README demonstration of various pick* calls.
 Future<List<XFile?>> readmePickExample() async {
@@ -49,6 +71,20 @@ Future<void> getLostData() async {
 }
 // #enddocregion LostData
 
+/// Example of camera delegate setup.
+// #docregion CameraDelegate
+void setUpCameraDelegate() {
+  final ImagePickerPlatform instance = ImagePickerPlatform.instance;
+  if (instance is CameraDelegatingImagePickerPlatform) {
+    instance.cameraDelegate = MyCameraDelegate();
+  }
+}
+// #enddocregion CameraDelegate
+
 // Stubs for the getLostData function.
 void _handleLostFiles(List<XFile> file) {}
 void _handleError(PlatformException? exception) {}
+
+// Stubs for MyCameraDelegate.
+Future<XFile?> _takeAPhoto(CameraDevice device) async => null;
+Future<XFile?> _takeAVideo(CameraDevice device) async => null;

packages/image_picker/image_picker/example/linux/.gitignore

@@ -0,0 +1 @@
+flutter/ephemeral

packages/image_picker/image_picker/example/linux/CMakeLists.txt

@@ -0,0 +1,138 @@
+# Project-level configuration.
+cmake_minimum_required(VERSION 3.10)
+project(runner LANGUAGES CXX)
+
+# The name of the executable created for the application. Change this to change
+# the on-disk name of your application.
+set(BINARY_NAME "image_picker_example")
+# The unique GTK application identifier for this application. See:
+# https://wiki.gnome.org/HowDoI/ChooseApplicationID
+set(APPLICATION_ID "dev.flutter.plugins.image_picker_example")
+
+# Explicitly opt in to modern CMake behaviors to avoid warnings with recent
+# versions of CMake.
+cmake_policy(SET CMP0063 NEW)
+
+# Load bundled libraries from the lib/ directory relative to the binary.
+set(CMAKE_INSTALL_RPATH "$ORIGIN/lib")
+
+# Root filesystem for cross-building.
+if(FLUTTER_TARGET_PLATFORM_SYSROOT)
+  set(CMAKE_SYSROOT ${FLUTTER_TARGET_PLATFORM_SYSROOT})
+  set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})
+  set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+  set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endif()
+
+# Define build configuration options.
+if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+  set(CMAKE_BUILD_TYPE "Debug" CACHE
+    STRING "Flutter build mode" FORCE)
+  set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
+    "Debug" "Profile" "Release")
+endif()
+
+# Compilation settings that should be applied to most targets.
+#
+# Be cautious about adding new options here, as plugins use this function by
+# default. In most cases, you should add new options to specific targets instead
+# of modifying this function.
+function(APPLY_STANDARD_SETTINGS TARGET)
+  target_compile_features(${TARGET} PUBLIC cxx_std_14)
+  target_compile_options(${TARGET} PRIVATE -Wall -Werror)
+  target_compile_options(${TARGET} PRIVATE "$<$<NOT:$<CONFIG:Debug>>:-O3>")
+  target_compile_definitions(${TARGET} PRIVATE "$<$<NOT:$<CONFIG:Debug>>:NDEBUG>")
+endfunction()
+
+# Flutter library and tool build rules.
+set(FLUTTER_MANAGED_DIR "${CMAKE_CURRENT_SOURCE_DIR}/flutter")
+add_subdirectory(${FLUTTER_MANAGED_DIR})
+
+# System-level dependencies.
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(GTK REQUIRED IMPORTED_TARGET gtk+-3.0)
+
+add_definitions(-DAPPLICATION_ID="${APPLICATION_ID}")
+
+# Define the application target. To change its name, change BINARY_NAME above,
+# not the value here, or `flutter run` will no longer work.
+#
+# Any new source files that you add to the application should be added here.
+add_executable(${BINARY_NAME}
+  "main.cc"
+  "my_application.cc"
+  "${FLUTTER_MANAGED_DIR}/generated_plugin_registrant.cc"
+)
+
+# Apply the standard set of build settings. This can be removed for applications
+# that need different build settings.
+apply_standard_settings(${BINARY_NAME})
+
+# Add dependency libraries. Add any application-specific dependencies here.
+target_link_libraries(${BINARY_NAME} PRIVATE flutter)
+target_link_libraries(${BINARY_NAME} PRIVATE PkgConfig::GTK)
+
+# Run the Flutter tool portions of the build. This must not be removed.
+add_dependencies(${BINARY_NAME} flutter_assemble)
+
+# Only the install-generated bundle's copy of the executable will launch
+# correctly, since the resources must in the right relative locations. To avoid
+# people trying to run the unbundled copy, put it in a subdirectory instead of
+# the default top-level location.
+set_target_properties(${BINARY_NAME}
+  PROPERTIES
+  RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/intermediates_do_not_run"
+)
+
+# Generated plugin build rules, which manage building the plugins and adding
+# them to the application.
+include(flutter/generated_plugins.cmake)
+
+
+# === Installation ===
+# By default, "installing" just makes a relocatable bundle in the build
+# directory.
+set(BUILD_BUNDLE_DIR "${PROJECT_BINARY_DIR}/bundle")
+if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+  set(CMAKE_INSTALL_PREFIX "${BUILD_BUNDLE_DIR}" CACHE PATH "..." FORCE)
+endif()
+
+# Start with a clean build bundle directory every time.
+install(CODE "
+  file(REMOVE_RECURSE \"${BUILD_BUNDLE_DIR}/\")
+  " COMPONENT Runtime)
+
+set(INSTALL_BUNDLE_DATA_DIR "${CMAKE_INSTALL_PREFIX}/data")
+set(INSTALL_BUNDLE_LIB_DIR "${CMAKE_INSTALL_PREFIX}/lib")
+
+install(TARGETS ${BINARY_NAME} RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}"
+  COMPONENT Runtime)
+
+install(FILES "${FLUTTER_ICU_DATA_FILE}" DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
+  COMPONENT Runtime)
+
+install(FILES "${FLUTTER_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+  COMPONENT Runtime)
+
+foreach(bundled_library ${PLUGIN_BUNDLED_LIBRARIES})
+  install(FILES "${bundled_library}"
+    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endforeach(bundled_library)
+
+# Fully re-copy the assets directory on each build to avoid having stale files
+# from a previous install.
+set(FLUTTER_ASSET_DIR_NAME "flutter_assets")
+install(CODE "
+  file(REMOVE_RECURSE \"${INSTALL_BUNDLE_DATA_DIR}/${FLUTTER_ASSET_DIR_NAME}\")
+  " COMPONENT Runtime)
+install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
+  DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)
+
+# Install the AOT library on non-Debug builds only.
+if(NOT CMAKE_BUILD_TYPE MATCHES "Debug")
+  install(FILES "${AOT_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endif()