Fix generation for already supported image formats

lib/cli_commands.dart

@@ -284,9 +284,20 @@ String? _checkImageExists({
       exit(1);
     }
 
-    if (p.extension(image).toLowerCase() != '.png') {
+    // https://github.com/brendan-duncan/image#supported-image-formats
+    final List<String> supportedFormats = [
+      "png", "apng", // PNG
+      "jpg", "jpeg", "jpe", "jfif", // JPEG
+      "tga", "tpic", // TGA
+      "gif", // GIF
+      "ico", // ICO
+      "bmp", "dib", // BMP
+    ];
+
+    if (!supportedFormats
+        .any((format) => p.extension(image).toLowerCase() == ".$format")) {
       print(
-        'Unsupported file format: $image  Your image must be a PNG file.',
+        'Unsupported file format: $image  Your image must be in one of the following formats: $supportedFormats',
       );
       exit(1);
     }
@@ -295,6 +306,29 @@ String? _checkImageExists({
   return image == '' ? null : image;
 }
 
+void createBackgroundImage({
+  required String imageDestination,
+  required String imageSource,
+}) {
+  // Copy will not work if the directory does not exist, so createSync
+  // will ensure that the directory exists.
+  File(imageDestination).createSync(recursive: true);
+
+  // If source image is not already png, convert it, otherwise just copy it.
+  if (p.extension(imageSource).toLowerCase() != '.png') {
+    final image = decodeImage(File(imageSource).readAsBytesSync());
+    if (image == null) {
+      print('$imageSource could not be read');
+      exit(1);
+    }
+    File(imageDestination)
+      ..createSync(recursive: true)
+      ..writeAsBytesSync(encodePng(image));
+  } else {
+    File(imageSource).copySync(imageDestination);
+  }
+}
+
 /// Get config from `pubspec.yaml` or `flutter_native_splash.yaml`
 Map<String, dynamic> getConfig({
   required String? configFile,

lib/ios.dart

@@ -433,10 +433,10 @@ void _createBackground({
     file.createSync(recursive: true);
     file.writeAsBytesSync(encodePng(background));
   } else if (backgroundImageSource != null) {
-    // Copy will not work if the directory does not exist, so createSync
-    // will ensure that the directory exists.
-    File(backgroundImageDestination).createSync(recursive: true);
-    File(backgroundImageSource).copySync(backgroundImageDestination);
+    createBackgroundImage(
+      imageDestination: backgroundImageDestination,
+      imageSource: backgroundImageSource,
+    );
   } else {
     throw Exception('No color string or background image!');
   }
@@ -453,10 +453,10 @@ void _createBackground({
     file.createSync(recursive: true);
     file.writeAsBytesSync(encodePng(background));
   } else if (darkBackgroundImageSource != null) {
-    // Copy will not work if the directory does not exist, so createSync
-    // will ensure that the directory exists.
-    File(darkBackgroundImageDestination).createSync(recursive: true);
-    File(darkBackgroundImageSource).copySync(darkBackgroundImageDestination);
+    createBackgroundImage(
+      imageDestination: darkBackgroundImageDestination,
+      imageSource: darkBackgroundImageSource,
+    );
   } else {
     final file = File(darkBackgroundImageDestination);
     if (file.existsSync()) file.deleteSync();

lib/web.dart

@@ -101,27 +101,30 @@ void createBackgroundImages({
   required String? backgroundImage,
   required String? darkBackgroundImage,
 }) {
-  const backgroundDestination = '${_webSplashImagesFolder}light-background.png';
+  print('[Web] Creating background images');
+  _createBackgroundImage(
+    backgroundImage: backgroundImage,
+    fileName: "light-background.png",
+  );
+  _createBackgroundImage(
+    backgroundImage: darkBackgroundImage,
+    fileName: "dark-background.png",
+  );
+}
+
+void _createBackgroundImage({
+  required String? backgroundImage,
+  required String fileName,
+}) {
+  final backgroundDestination = '$_webSplashImagesFolder$fileName';
   if (backgroundImage == null) {
     final file = File(backgroundDestination);
     if (file.existsSync()) file.deleteSync();
   } else {
-    // Copy will not work if the directory does not exist, so createSync
-    // will ensure that the directory exists.
-    File(backgroundDestination).createSync(recursive: true);
-    File(backgroundImage).copySync(backgroundDestination);
-  }
-
-  const darkBackgroundDestination =
-      '${_webSplashImagesFolder}dark-background.png';
-  if (darkBackgroundImage == null) {
-    final file = File(darkBackgroundDestination);
-    if (file.existsSync()) file.deleteSync();
-  } else {
-    // Copy will not work if the directory does not exist, so createSync
-    // will ensure that the directory exists.
-    File(darkBackgroundDestination).createSync(recursive: true);
-    File(darkBackgroundImage).copySync(darkBackgroundDestination);
+    createBackgroundImage(
+      imageDestination: backgroundDestination,
+      imageSource: backgroundImage,
+    );
   }
 }