Frontend first draft

frontend/pshared/lib/utils/image/conversion.dart

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+import 'package:image/image.dart' as img;
+
+import 'package:share_plus/share_plus.dart';
+
+import 'package:pshared/api/errors/failed_to_read_image.dart';
+import 'package:pshared/config/constants.dart';
+import 'package:pshared/utils/image/transformed.dart';
+
+
+bool _imageTooBig(img.Image image, int maxDimension) {
+  return image.width > maxDimension && image.height > maxDimension;
+}
+
+bool _imageTooSmall(img.Image image, int maxDimension) {
+  return image.width < maxDimension && image.height < maxDimension;
+}
+
+TransformedImage _getImageBytes(img.Image image, int maxDimension) {
+  List<int> imageBytes;
+
+  if (_imageTooBig(image, maxDimension) || _imageTooSmall(image, maxDimension)) {
+    final double scale = image.width < image.height
+        ? maxDimension / image.width
+        : maxDimension / image.height;
+    
+    int newWidth = (image.width * scale).toInt();
+    int newHeight = (image.height * scale).toInt();
+
+    final img.Image resizedImage = img.copyResize(image, width: newWidth, height: newHeight);
+    image = resizedImage;
+  }
+
+  imageBytes = img.encodePng(image);
+  return TransformedImage(imageBytes, 'image/png');
+}
+
+Future<TransformedImage> defaultTransformImage(XFile file, {int? maxDimension}) async {
+  maxDimension = maxDimension ?? Constants.defaultDimensionLength;
+  img.Image? image = img.decodeImage(await file.readAsBytes());
+  if (image == null) {
+    throw ErrorFailedToReadImage();
+  }
+
+  return _getImageBytes(image, maxDimension);
+}

frontend/pshared/lib/utils/image/transformed.dart

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+class TransformedImage {
+  final List<int> bytes;
+  final String imageType;
+
+  TransformedImage(this.bytes, this.imageType);
+}