[file_selector] Migrate FileSelectorApi to Dart

packages/file_selector/file_selector_windows/lib/src/file_selector_api.dart

@@ -0,0 +1,92 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/cupertino.dart';
+import 'package:win32/win32.dart';
+
+import 'file_selector_dart/dialog_mode.dart';
+import 'file_selector_dart/dialog_wrapper.dart';
+import 'file_selector_dart/dialog_wrapper_factory.dart';
+import 'file_selector_dart/selection_options.dart';
+
+/// File dialog handling for Open and Save operations.
+class FileSelectorApi {
+  /// Creates a new instance of [FileSelectorApi].
+  /// Allows Dependency Injection of a [DialogWrapperFactory] to handle dialog creation.
+  FileSelectorApi(this._dialogWrapperFactory)
+      : _foregroundWindow = GetForegroundWindow();
+
+  /// Creates a fake instance of [FileSelectorApi] for testing purpose where the [_foregroundWindow] handle is set
+  /// from the outside.
+  @visibleForTesting
+  FileSelectorApi.useFakeForegroundWindow(
+      this._dialogWrapperFactory, this._foregroundWindow);
+
+  final DialogWrapperFactory _dialogWrapperFactory;
+
+  final int _foregroundWindow;
+
+  /// Displays a dialog window to open one or more files.
+  List<String?> showOpenDialog(
+    SelectionOptions options,
+    String? initialDirectory,
+    String? confirmButtonText,
+  ) =>
+      _showDialog(_foregroundWindow, DialogMode.Open, options, initialDirectory,
+          null, confirmButtonText);
+
+  /// Displays a dialog used to save a file.
+  List<String?> showSaveDialog(
+    SelectionOptions options,
+    String? initialDirectory,
+    String? suggestedName,
+    String? confirmButtonText,
+  ) =>
+      _showDialog(_foregroundWindow, DialogMode.Save, options, initialDirectory,
+          suggestedName, confirmButtonText);
+
+  List<String?> _showDialog(
+      int parentWindow,
+      DialogMode mode,
+      SelectionOptions options,
+      String? initialDirectory,
+      String? suggestedName,
+      String? confirmLabel) {
+    final DialogWrapper dialogWrapper =
+        _dialogWrapperFactory.createInstance(mode);
+    if (!SUCCEEDED(dialogWrapper.lastResult)) {
+      throw WindowsException(E_FAIL);
+    }
+    int dialogOptions = 0;
+    if (options.selectFolders) {
+      dialogOptions |= FILEOPENDIALOGOPTIONS.FOS_PICKFOLDERS;
+    }
+    if (options.allowMultiple) {
+      dialogOptions |= FILEOPENDIALOGOPTIONS.FOS_ALLOWMULTISELECT;
+    }
+    if (dialogOptions != 0) {
+      dialogWrapper.addOptions(dialogOptions);
+    }
+
+    if (initialDirectory != null) {
+      dialogWrapper.setFolder(initialDirectory);
+    }
+    if (suggestedName != null) {
+      dialogWrapper.setFileName(suggestedName);
+    }
+    if (confirmLabel != null) {
+      dialogWrapper.setOkButtonLabel(confirmLabel);
+    }
+
+    if (options.allowedTypes.isNotEmpty) {
+      dialogWrapper.setFileTypeFilters(options.allowedTypes);
+    }
+
+    final List<String?>? files = dialogWrapper.show(parentWindow);
+    if (files != null) {
+      return files;
+    }
+    throw WindowsException(E_FAIL);
+  }
+}

packages/file_selector/file_selector_windows/lib/src/file_selector_dart/dialog_mode.dart

@@ -0,0 +1,12 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// The kind of file dialog to show.
+enum DialogMode {
+  /// Used for chosing files.
+  Open,
+
+  /// Used for chosing a directory to save a file.
+  Save
+}

packages/file_selector/file_selector_windows/lib/src/file_selector_dart/dialog_wrapper.dart

@@ -0,0 +1,197 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:core';
+import 'dart:ffi';
+
+import 'package:ffi/ffi.dart';
+import 'package:file_selector_platform_interface/file_selector_platform_interface.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:win32/win32.dart';
+
+import 'dialog_mode.dart';
+import 'file_dialog_controller.dart';
+import 'ifile_dialog_controller_factory.dart';
+import 'ifile_dialog_factory.dart';
+import 'shell_win32_api.dart';
+
+/// Wraps an IFileDialog, managing object lifetime as a scoped object and
+/// providing a simplified API for interacting with it as needed for the plugin.
+class DialogWrapper {
+  /// Creates a DialogWrapper using a [IFileDialogControllerFactory] and a [DialogMode].
+  /// It is also responsible of creating a [IFileDialog].
+  DialogWrapper(IFileDialogControllerFactory fileDialogControllerFactory,
+      IFileDialogFactory fileDialogFactory, this._dialogMode)
+      : _isOpenDialog = _dialogMode == DialogMode.Open {
+    try {
+      final IFileDialog dialog = fileDialogFactory.createInstace(_dialogMode);
+      _dialogController = fileDialogControllerFactory.createController(dialog);
+      _shellWin32Api = ShellWin32Api();
+    } catch (ex) {
+      if (ex is WindowsException) {
+        _lastResult = ex.hr;
+      }
+    }
+  }
+
+  /// Creates a DialogWrapper for testing purposes.
+  @visibleForTesting
+  DialogWrapper.withFakeDependencies(FileDialogController dialogController,
+      this._dialogMode, this._shellWin32Api)
+      : _isOpenDialog = _dialogMode == DialogMode.Open,
+        _dialogController = dialogController;
+
+  int _lastResult = S_OK;
+
+  final DialogMode _dialogMode;
+
+  final bool _isOpenDialog;
+
+  final String _allowAnyValue = 'Any';
+
+  final String _allowAnyExtension = '*.*';
+
+  late FileDialogController _dialogController;
+
+  late ShellWin32Api _shellWin32Api;
+
+  /// Returns the result of the last Win32 API call related to this object.
+  int get lastResult => _lastResult;
+
+  /// Attempts to set the default folder for the dialog to [path], if it exists.
+  void setFolder(String path) {
+    if (path == null || path.isEmpty) {
+      return;
+    }
+
+    using((Arena arena) {
+      final Pointer<GUID> ptrGuid = GUIDFromString(IID_IShellItem);
+      final Pointer<Pointer<COMObject>> ptrPath = arena<Pointer<COMObject>>();
+      _lastResult =
+          _shellWin32Api.createItemFromParsingName(path, ptrGuid, ptrPath);
+
+      if (!SUCCEEDED(_lastResult)) {
+        return;
+      }
+
+      _dialogController.setFolder(ptrPath.value);
+    });
+  }
+
+  /// Sets the file name that is initially shown in the dialog.
+  void setFileName(String name) {
+    _dialogController.setFileName(name);
+  }
+
+  /// Sets the label of the confirmation button.
+  void setOkButtonLabel(String label) {
+    _dialogController.setOkButtonLabel(label);
+  }
+
+  /// Adds the given options to the dialog's current [options](https://pub.dev/documentation/win32/latest/winrt/FILEOPENDIALOGOPTIONS-class.html).
+  /// Both are bitfields.
+  void addOptions(int newOptions) {
+    using((Arena arena) {
+      final Pointer<Uint32> currentOptions = arena<Uint32>();
+      _lastResult = _dialogController.getOptions(currentOptions);
+      if (!SUCCEEDED(_lastResult)) {
+        return;
+      }
+      currentOptions.value |= newOptions;
+      _lastResult = _dialogController.setOptions(currentOptions.value);
+    });
+  }
+
+  /// Sets the filters for allowed file types to select.
+  /// filters -> std::optional<EncodableList>
+  void setFileTypeFilters(List<XTypeGroup> filters) {
+    final Map<String, String> filterSpecification = <String, String>{};
+
+    if (filters.isEmpty) {
+      filterSpecification[_allowAnyValue] = _allowAnyExtension;
+    } else {
+      for (final XTypeGroup option in filters) {
+        final String? label = option.label;
+        if (option.allowsAny || option.extensions!.isEmpty) {
+          filterSpecification[label ?? _allowAnyValue] = _allowAnyExtension;
+        } else {
+          final String extensionsForLabel = option.extensions!
+              .map((String extension) => '*.$extension')
+              .join(';');
+          filterSpecification[label ?? extensionsForLabel] = extensionsForLabel;
+        }
+      }
+    }
+
+    using((Arena arena) {
+      final Pointer<COMDLG_FILTERSPEC> registerFilterSpecification =
+          arena<COMDLG_FILTERSPEC>(filterSpecification.length);
+
+      int index = 0;
+      for (final String key in filterSpecification.keys) {
+        registerFilterSpecification[index]
+          ..pszName = TEXT(key)
+          ..pszSpec = TEXT(filterSpecification[key]!);
+        index++;
+      }
+
+      _lastResult = _dialogController.setFileTypes(
+          filterSpecification.length, registerFilterSpecification);
+    });
+  }
+
+  /// Displays the dialog, and returns the selected files, or null on error.
+  List<String?>? show(int parentWindow) {
+    _lastResult = _dialogController.show(parentWindow);
+    if (!SUCCEEDED(_lastResult)) {
+      return null;
+    }
+    late List<String>? files;
+
+    using((Arena arena) {
+      final Pointer<Pointer<COMObject>> shellItemArrayPtr =
+          arena<Pointer<COMObject>>();
+      final Pointer<Uint32> shellItemCountPtr = arena<Uint32>();
+      final Pointer<Pointer<COMObject>> shellItemPtr =
+          arena<Pointer<COMObject>>();
+
+      files =
+          _getFilePathList(shellItemArrayPtr, shellItemCountPtr, shellItemPtr);
+    });
+    return files;
+  }
+
+  List<String>? _getFilePathList(
+      Pointer<Pointer<COMObject>> shellItemArrayPtr,
+      Pointer<Uint32> shellItemCountPtr,
+      Pointer<Pointer<COMObject>> shellItemPtr) {
+    final List<String> files = <String>[];
+    if (_isOpenDialog) {
+      _lastResult = _dialogController.getResults(shellItemArrayPtr);
+      if (!SUCCEEDED(_lastResult)) {
+        return null;
+      }
+
+      final IShellItemArray shellItemResources =
+          IShellItemArray(shellItemArrayPtr.cast());
+      _lastResult = shellItemResources.getCount(shellItemCountPtr);
+      if (!SUCCEEDED(_lastResult)) {
+        return null;
+      }
+      for (int index = 0; index < shellItemCountPtr.value; index++) {
+        shellItemResources.getItemAt(index, shellItemPtr);
+        final IShellItem shellItem = IShellItem(shellItemPtr.cast());
+        files.add(_shellWin32Api.getPathForShellItem(shellItem));
+      }
+    } else {
+      _lastResult = _dialogController.getResult(shellItemPtr);
+      if (!SUCCEEDED(_lastResult)) {
+        return null;
+      }
+      final IShellItem shellItem = IShellItem(shellItemPtr.cast());
+      files.add(_shellWin32Api.getPathForShellItem(shellItem));
+    }
+    return files;
+  }
+}

packages/file_selector/file_selector_windows/lib/src/file_selector_dart/dialog_wrapper_factory.dart

@@ -0,0 +1,26 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dialog_mode.dart';
+import 'dialog_wrapper.dart';
+import 'ifile_dialog_controller_factory.dart';
+import 'ifile_dialog_factory.dart';
+
+/// Implementation of DialogWrapperFactory that provides [DialogWrapper] instances.
+class DialogWrapperFactory {
+  /// Creates a [DialogWrapperFactory] that makes use of [IFileDialogControllerFactory] and [IFileDialogFactory]
+  /// to create [DialogWrapper] instances.
+  DialogWrapperFactory(
+      this._fileDialogControllerFactory, this._fileDialogFactory);
+
+  final IFileDialogControllerFactory _fileDialogControllerFactory;
+
+  final IFileDialogFactory _fileDialogFactory;
+
+  /// Creates a [DialogWrapper] based on [dialogMode].
+  DialogWrapper createInstance(DialogMode dialogMode) {
+    return DialogWrapper(
+        _fileDialogControllerFactory, _fileDialogFactory, dialogMode);
+  }
+}