Improve code quality

example/lib/main_screen.dart

@@ -46,8 +46,8 @@ class _MainScreenState extends State<MainScreen> {
             ),
             // size: 320.0,
             embeddedImage: snapshot.data,
-            embeddedImageStyle: QrEmbeddedImageStyle(
-              size: const Size.square(60),
+            embeddedImageStyle: const QrEmbeddedImageStyle(
+              size: Size.square(60),
             ),
           ),
         );

lib/src/paint_cache.dart

@@ -34,11 +34,9 @@ class PaintCache {
   /// Retrieve the first [Paint] object from the paint cache for the provided
   /// element and position.
   Paint? firstPaint(QrCodeElement element, {FinderPatternPosition? position}) {
-    if (element == QrCodeElement.codePixel) {
-      return _pixelPaints.first;
-    } else {
-      return _keyedPaints[_cacheKey(element, position: position)];
-    }
+    return element == QrCodeElement.codePixel
+        ? _pixelPaints.first
+        : _keyedPaints[_cacheKey(element, position: position)];
   }
 
   /// Retrieve all [Paint] objects from the paint cache for the provided
@@ -49,10 +47,8 @@ class PaintCache {
     QrCodeElement element, {
     FinderPatternPosition? position,
   }) {
-    if (element == QrCodeElement.codePixel) {
-      return _pixelPaints;
-    } else {
-      return <Paint?>[_keyedPaints[_cacheKey(element, position: position)]];
-    }
+    return element == QrCodeElement.codePixel
+        ? _pixelPaints
+        : <Paint?>[_keyedPaints[_cacheKey(element, position: position)]];
   }
 }

lib/src/qr_image_view.dart

@@ -44,7 +44,10 @@ class QrImageView extends StatefulWidget {
     this.embeddedImageEmitsError = false,
     @Deprecated('use colors in eyeStyle and dataModuleStyle instead')
     this.foregroundColor,
-  })  : assert(QrVersions.isSupportedVersion(version)),
+  })  : assert(
+          QrVersions.isSupportedVersion(version),
+          'QR code version $version is not supported',
+        ),
         _data = data,
         _qrCode = null;
 
@@ -75,7 +78,10 @@ class QrImageView extends StatefulWidget {
     this.embeddedImageEmitsError = false,
     @Deprecated('use colors in eyeStyle and dataModuleStyle instead')
     this.foregroundColor,
-  })  : assert(QrVersions.isSupportedVersion(version)),
+  })  : assert(
+          QrVersions.isSupportedVersion(version),
+          'QR code version $version is not supported',
+        ),
         _data = null,
         _qrCode = qr;
 
@@ -165,11 +171,7 @@ class _QrImageViewState extends State<QrImageView> {
         version: widget.version,
         errorCorrectionLevel: widget.errorCorrectionLevel,
       );
-      if (_validationResult.isValid) {
-        _qr = _validationResult.qrCode;
-      } else {
-        _qr = null;
-      }
+      _qr = _validationResult.isValid ? _validationResult.qrCode : null;
     } else if (widget._qrCode != null) {
       _qr = widget._qrCode;
       _validationResult =
@@ -192,29 +194,27 @@ class _QrImageViewState extends State<QrImageView> {
             builder: (BuildContext ctx, AsyncSnapshot<ui.Image> snapshot) {
               if (snapshot.error != null) {
                 print('snapshot error: ${snapshot.error}');
-                if (widget.embeddedImageEmitsError) {
-                  return _errorWidget(context, constraints, snapshot.error);
-                } else {
-                  return _qrWidget(context, null, widgetSize);
-                }
+                return widget.embeddedImageEmitsError
+                    ? _errorWidget(context, constraints, snapshot.error)
+                    : _qrWidget(null, widgetSize);
               }
               if (snapshot.hasData) {
                 print('loaded image');
                 final ui.Image? loadedImage = snapshot.data;
-                return _qrWidget(context, loadedImage, widgetSize);
+                return _qrWidget(loadedImage, widgetSize);
               } else {
                 return Container();
               }
             },
           );
         } else {
-          return _qrWidget(context, null, widgetSize);
+          return _qrWidget(null, widgetSize);
         }
       },
     );
   }
 
-  Widget _qrWidget(BuildContext context, ui.Image? image, double edgeLength) {
+  Widget _qrWidget(ui.Image? image, double edgeLength) {
     final QrPainter painter = QrPainter.withQr(
       qr: _qr!,
       color: widget.foregroundColor,

lib/src/qr_painter.dart

@@ -48,7 +48,10 @@ class QrPainter extends CustomPainter {
       'You should use the background color value of your container widget',
     )
     this.emptyColor,
-  }) : assert(QrVersions.isSupportedVersion(version)) {
+  }) : assert(
+          QrVersions.isSupportedVersion(version),
+          'QR code version $version is not supported',
+        ) {
     _init(data);
   }
 
@@ -351,11 +354,7 @@ class QrPainter extends CustomPainter {
       position: position,
     )!;
     outerPaint.strokeWidth = metrics.pixelSize;
-    if (color != null) {
-      outerPaint.color = color!;
-    } else {
-      outerPaint.color = eyeStyle.color!;
-    }
+    outerPaint.color = color != null ? color! : eyeStyle.color!;
 
     final ui.Paint innerPaint = _paintCache
         .firstPaint(QrCodeElement.finderPatternInner, position: position)!;
@@ -477,10 +476,7 @@ class QrPainter extends CustomPainter {
   }
 
   /// Returns the raw QR code [ui.Image] object.
-  Future<ui.Image> toImage(
-    double size, {
-    ui.ImageByteFormat format = ui.ImageByteFormat.png,
-  }) {
+  Future<ui.Image> toImage(double size) {
     return toPicture(size).toImage(size.toInt(), size.toInt());
   }
 
@@ -489,7 +485,7 @@ class QrPainter extends CustomPainter {
     double size, {
     ui.ImageByteFormat format = ui.ImageByteFormat.png,
   }) async {
-    final ui.Image image = await toImage(size, format: format);
+    final ui.Image image = await toImage(size);
     return image.toByteData(format: format);
   }
 }

lib/src/types.dart

@@ -4,8 +4,6 @@
  * See LICENSE for distribution and usage details.
  */
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Represents a specific element / part of a QR code. This is used to isolate
@@ -59,6 +57,7 @@ enum QrDataModuleShape {
 }
 
 /// Styling options for finder pattern eye.
+@immutable
 class QrEyeStyle {
   /// Create a new set of styling options for QR Eye.
   const QrEyeStyle({this.eyeShape, this.color});
@@ -82,6 +81,7 @@ class QrEyeStyle {
 }
 
 /// Styling options for data module.
+@immutable
 class QrDataModuleStyle {
   /// Create a new set of styling options for data modules.
   const QrDataModuleStyle({
@@ -108,9 +108,10 @@ class QrDataModuleStyle {
 }
 
 /// Styling options for any embedded image overlay
+@immutable
 class QrEmbeddedImageStyle {
   /// Create a new set of styling options.
-  QrEmbeddedImageStyle({
+  const QrEmbeddedImageStyle({
     this.size,
     this.color,
   });
@@ -118,10 +119,10 @@ class QrEmbeddedImageStyle {
   /// The size of the image. If one dimension is zero then the other dimension
   /// will be used to scale the zero dimension based on the original image
   /// size.
-  Size? size;
+  final Size? size;
 
   /// Color to tint the image.
-  Color? color;
+  final Color? color;
 
   /// Check to see if the style object has a non-null, non-zero size.
   bool get hasDefinedSize => size != null && size!.longestSide > 0;