Initial commit

lib/pages/chat/image_edit_geometry.dart

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+// SPDX-FileCopyrightText: 2019-Present Christian Kußowski
+// SPDX-FileCopyrightText: 2019-Present Contributors to FluffyChat
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import 'dart:ui';
+
+import 'package:crop_image/crop_image.dart';
+
+/// Pure coordinate/rotation helpers for the image editor in
+/// `send_file_dialog.dart`. Kept dependency-free (only `dart:ui` and
+/// `crop_image`) so they can be unit-tested without spinning up the app.
+
+/// Maps a quarter-turn count (positive = clockwise) to the [CropRotation] used
+/// when baking the final image, so the on-screen `RotatedBox` preview and the
+/// saved result always rotate the same way.
+CropRotation imageEditorRotationForQuarterTurns(int quarterTurns) {
+  switch (((quarterTurns % 4) + 4) % 4) {
+    case 1:
+      return CropRotation.right;
+    case 2:
+      return CropRotation.down;
+    case 3:
+      return CropRotation.left;
+    default:
+      return CropRotation.up;
+  }
+}
+
+/// Maps a pointer position on the draw surface (logical pixels) to a coordinate
+/// in the source image's pixel space, given the currently shown crop region
+/// [cropPx] displayed at [displaySize]. The mapping is a uniform scale plus
+/// translation because the draw surface preserves the crop's aspect ratio.
+Offset imageEditorLocalToImagePx(Offset local, Size displaySize, Rect cropPx) {
+  final scale = cropPx.width / displaySize.width;
+  return Offset(cropPx.left + local.dx * scale, cropPx.top + local.dy * scale);
+}