Allow web favicon to be built from a different source image file

README.md

@@ -123,6 +123,7 @@ foreground of the Android 13+ themed icon. For more information see [Android Ada
 - `web`: Add web related configs
   - `generate`: Specifies whether to generate icons for this platform or not
   - `image_path`: Path to web icon.png
+  - `image_path_favicon`: The location of the icon image file used to generate the favicon (optional - if not defined then falls back to using the web image_path then the global image_path)
   - `background_color`: Updates *background_color* in `web/manifest.json`
   - `theme_color`: Updates *theme_color* in `web/manifest.json`
 

bin/generate.dart

@@ -100,6 +100,7 @@ flutter_launcher_icons:
   web:
     generate: true
     image_path: "path/to/image.png"
+    # image_path_favicon: "assets/icon/icon-favicon.png"
     background_color: "#hexcode"
     theme_color: "#hexcode"
 

lib/config/web_config.dart

@@ -15,6 +15,10 @@ class WebConfig {
   @JsonKey(name: 'image_path')
   final String? imagePath;
 
+  /// Override image path for favicon
+  @JsonKey(name: 'image_path_favicon')
+  final String? imagePathFavicon;
+
   /// manifest.json's background_color
   @JsonKey(name: 'background_color')
   final String? backgroundColor;
@@ -27,6 +31,7 @@ class WebConfig {
   const WebConfig({
     this.generate = false,
     this.imagePath,
+    this.imagePathFavicon,
     this.backgroundColor,
     this.themeColor,
   });

lib/web/web_icon_generator.dart

@@ -53,6 +53,7 @@ class WebIconGenerator extends IconGenerator {
       context.webConfig!.imagePath ?? context.config.imagePath!,
     );
 
+    // load and decode the image file
     context.logger
         .verbose('Decoding and loading image file at $imgFilePath...');
     final imgFile = utils.decodeImageFile(imgFilePath);
@@ -61,9 +62,31 @@ class WebIconGenerator extends IconGenerator {
       throw FileNotFoundException(imgFilePath);
     }
 
+    // resolve the favicon image path and file, which is either one explicitly
+    // provided or the same as the image file loaded above
+    late final String faviconImgFilePath;
+    late final Image faviconImgFile;
+    final faviconImgFileOverride = context.webConfig!.imagePathFavicon;
+    if (faviconImgFileOverride != null) {
+      // favicon override was specified, construct the full path and decode
+      faviconImgFilePath =
+          path.join(context.prefixPath, faviconImgFileOverride);
+      final imgFile = utils.decodeImageFile(faviconImgFilePath);
+      if (imgFile == null) {
+        context.logger
+            .error('Image File not found at give path $faviconImgFilePath...');
+        throw FileNotFoundException(faviconImgFilePath);
+      }
+      faviconImgFile = imgFile;
+    } else {
+      // no favicon override, use the fallback image file
+      faviconImgFilePath = imgFilePath;
+      faviconImgFile = imgFile;
+    }
+
     // generate favicon in web/favicon.png
-    context.logger.verbose('Generating favicon from $imgFilePath...');
-    _generateFavicon(imgFile);
+    context.logger.verbose('Generating favicon from $faviconImgFilePath...');
+    _generateFavicon(faviconImgFile);
 
     // generate icons in web/icons/
     context.logger.verbose('Generating icons from $imgFilePath...');

test/config_test.dart

@@ -47,6 +47,7 @@ void main() {
           equals(<String, dynamic>{
             'generate': true,
             'image_path': 'app_icon.png',
+            'image_path_favicon': null,
             'background_color': '#0175C2',
             'theme_color': '#0175C2',
           }),
@@ -155,6 +156,7 @@ void main() {
           equals(<String, dynamic>{
             'generate': true,
             'image_path': 'app_icon.png',
+            'image_path_favicon': 'app_icon.png',
             'background_color': '#0175C2',
             'theme_color': '#0175C2',
           }),
@@ -238,6 +240,7 @@ void main() {
           equals(<String, dynamic>{
             'generate': true,
             'image_path': 'app_icon.png',
+            'image_path_favicon': null,
             'background_color': '#0175C2',
             'theme_color': '#0175C2',
           }),

test/templates.dart

@@ -119,6 +119,7 @@ flutter_launcher_icons:
   web:
     generate: true
     image_path: "app_icon.png" # filepath
+    image_path_favicon: "app_icon.png" # filepath
     background_color: "#0175C2" # hex_color
     theme_color: "#0175C2" # hex_color
     apple_mobile_web_app_title: "demo"

test/web/web_icon_generator_test.dart

@@ -30,6 +30,7 @@ void main() {
         d.file('flutter_launcher_icons.yaml', templates.fliWebConfig),
         d.file('pubspec.yaml', templates.pubspecTemplate),
         d.file('app_icon.png', imageFile.readAsBytesSync()),
+        d.file('app_icon_favicon.png', imageFile.readAsBytesSync()),
       ]).create();
       prefixPath = path.join(d.sandbox, 'fli_test');
       config = Config.loadConfigFromPath(