[file_selector] Migrate DialogWrapper to Dart.

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/file_dialog_controller.dart

@@ -0,0 +1,91 @@
+// 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:ffi';
+
+import 'package:win32/win32.dart';
+
+import 'ifile_open_dialog_factory.dart';
+
+/// A thin wrapper for IFileDialog to allow for faking and inspection in tests.
+///
+/// Since this class defines the end of what can be unit tested, it should
+/// contain as little logic as possible.
+class FileDialogController {
+  /// Creates a controller managing [IFileDialog](https://pub.dev/documentation/win32/latest/winrt/IFileDialog-class.html).
+  /// It also receives an IFileOpenDialogFactory to construct [IFileOpenDialog]
+  /// instances.
+  FileDialogController(
+      IFileDialog fileDialog, IFileOpenDialogFactory iFileOpenDialogFactory)
+      : _fileDialog = fileDialog,
+        _iFileOpenDialogFactory = iFileOpenDialogFactory;
+
+  /// The [IFileDialog] to work with.
+  final IFileDialog _fileDialog;
+
+  /// The [IFileOpenDialogFactory] to work construc [IFileOpenDialog] instances.
+  final IFileOpenDialogFactory _iFileOpenDialogFactory;
+
+  /// Sets the default folder for the dialog to [path]. It also returns the operation result.
+  int setFolder(Pointer<COMObject> path) {
+    return _fileDialog.setFolder(path);
+  }
+
+  /// Sets the file [name] that is initially shown in the IFileDialog. It also returns the operation result.
+  int setFileName(String name) {
+    return _fileDialog.setFileName(TEXT(name));
+  }
+
+  /// Sets the allowed file type extensions in the IFileOpenDialog. It also returns the operation result.
+  int setFileTypes(int count, Pointer<COMDLG_FILTERSPEC> filters) {
+    return _fileDialog.setFileTypes(count, filters);
+  }
+
+  /// Sets the label of the confirmation button. It also returns the operation result. It also returns the operation result.
+  int setOkButtonLabel(String text) {
+    return _fileDialog.setOkButtonLabel(TEXT(text));
+  }
+
+  /// Gets the IFileDialog's [options](https://pub.dev/documentation/win32/latest/winrt/FILEOPENDIALOGOPTIONS-class.html),
+  /// which is a bitfield. It also returns the operation result.
+  int getOptions(Pointer<Uint32> outOptions) {
+    return _fileDialog.getOptions(outOptions);
+  }
+
+  /// Sets the [options](https://pub.dev/documentation/win32/latest/winrt/FILEOPENDIALOGOPTIONS-class.html),
+  /// which is a bitfield, into the IFileDialog. It also returns the operation result.
+  int setOptions(int options) {
+    return _fileDialog.setOptions(options);
+  }
+
+  /// Shows an IFileDialog using the given parent. It returns the operation result.
+  int show(int parent) {
+    return _fileDialog.show(parent);
+  }
+
+  /// Return results from an IFileDialog. This should be used when selecting
+  /// single items. It also returns the operation result.
+  int getResult(Pointer<Pointer<COMObject>> outItem) {
+    return _fileDialog.getResult(outItem);
+  }
+
+  /// Return results from an IFileOpenDialog. This should be used when selecting
+  /// single items. This function will fail if the IFileDialog* provided to the
+  /// constructor was not an IFileOpenDialog instance, returning an E_FAIL
+  /// error.
+  int getResults(Pointer<Pointer<COMObject>> outItems) {
+    IFileOpenDialog? fileOpenDialog;
+    try {
+      fileOpenDialog = _iFileOpenDialogFactory.from(_fileDialog);
+      return fileOpenDialog.getResults(outItems);
+    } catch (_) {
+      return E_FAIL;
+    } finally {
+      fileOpenDialog?.release();
+      if (fileOpenDialog != null) {
+        free(fileOpenDialog.ptr);
+      }
+    }
+  }
+}

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

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+// 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:win32/win32.dart';
+
+import 'file_dialog_controller.dart';
+import 'ifile_dialog_controller_factory.dart';
+import 'ifile_open_dialog_factory.dart';
+
+/// Implementation of FileDialogControllerFactory that makes standard
+/// FileDialogController instances.
+class FileDialogControllerFactory implements IFileDialogControllerFactory {
+  @override
+  FileDialogController createController(IFileDialog dialog) {
+    return FileDialogController(dialog, IFileOpenDialogFactory());
+  }
+}

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

@@ -0,0 +1,14 @@
+// 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:win32/win32.dart';
+
+import 'file_dialog_controller.dart';
+
+/// Interface for creating FileDialogControllers, to allow for dependency
+/// injection.
+abstract class IFileDialogControllerFactory {
+  /// Returns a FileDialogController to interact with the given [IFileDialog].
+  FileDialogController createController(IFileDialog dialog);
+}

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

@@ -0,0 +1,19 @@
+// 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:win32/win32.dart';
+
+import 'dialog_mode.dart';
+
+/// A factory for [IFileDialog] instances.
+class IFileDialogFactory {
+  /// Creates the corresponding IFileDialog instace. The caller is responsible of releasing the resource.
+  IFileDialog createInstace(DialogMode dialogMode) {
+    if (dialogMode == DialogMode.Open) {
+      return FileOpenDialog.createInstance();
+    }
+
+    return FileSaveDialog.createInstance();
+  }
+}

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

@@ -0,0 +1,13 @@
+// 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:win32/win32.dart';
+
+/// A wrapper of the IFileOpenDialog interface to use its from function.
+class IFileOpenDialogFactory {
+  /// Wraps the IFileOpenDialog from function.
+  IFileOpenDialog from(IFileDialog fileDialog) {
+    return IFileOpenDialog.from(fileDialog);
+  }
+}