refactor: extract download icon widget to separate method and update icon design

Author: Suyunmeng

android/app/src/main/res/drawable/ic_download.xml

@@ -1,10 +1,5 @@
-<?xml version="1.0" encoding="utf-8"?>
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="24dp"
-    android:height="24dp"
-    android:viewportWidth="24"
-    android:viewportHeight="24">
-    <path
-        android:fillColor="#FF000000"
-        android:pathData="M19,9h-4V3H9v6H5l7,7 7,-7zM5,18v2h14v-2H5z"/>
-</vector>
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="24dp" android:viewportHeight="1024" android:viewportWidth="1024" android:width="24dp">
+      
+    <path android:fillColor="#000000" android:pathData="M853.3,853.3a42.7,42.7 0,0 1,0 85.3H170.7a42.7,42.7 0,0 1,0 -85.3h682.7zM512,85.5a42.7,42.7 0,0 1,42.7 42.7v515.4l204.4,-204.4a42.7,42.7 0,0 1,63.9 56.3l-3.6,4 -277.4,277.5a42.7,42.7 0,0 1,-56.3 3.6l-4,-3.5 -277.1,-276.7a42.7,42.7 0,0 1,56.2 -64l4,3.5L469.3,644.1V128.2a42.7,42.7 0,0 1,42.7 -42.7z"/>
+    
+</vector>

lib/main.dart

@@ -114,38 +114,7 @@ class MyHomePage extends StatelessWidget {
                     label: S.current.appName,
                   ),
                   NavigationDestination(
-                    icon: Obx(() {
-                      int activeCount = DownloadManager.activeTasks.length;
-                      return Stack(
-                        children: [
-                          const Icon(Icons.download),
-                          if (activeCount > 0)
-                            Positioned(
-                              right: 0,
-                              top: 0,
-                              child: Container(
-                                padding: const EdgeInsets.all(2),
-                                decoration: BoxDecoration(
-                                  color: Colors.red,
-                                  borderRadius: BorderRadius.circular(10),
-                                ),
-                                constraints: const BoxConstraints(
-                                  minWidth: 16,
-                                  minHeight: 16,
-                                ),
-                                child: Text(
-                                  '$activeCount',
-                                  style: const TextStyle(
-                                    color: Colors.white,
-                                    fontSize: 10,
-                                  ),
-                                  textAlign: TextAlign.center,
-                                ),
-                              ),
-                            ),
-                        ],
-                      );
-                    }),
+                    icon: _buildDownloadIcon(),
                     label: '下载管理',
                   ),
                   NavigationDestination(
@@ -164,6 +133,41 @@ class MyHomePage extends StatelessWidget {
                   controller.setPageIndex(index);
                 })));
   }
+
+  Widget _buildDownloadIcon() {
+    return Obx(() {
+      int activeCount = DownloadManager.activeTasks.length;
+      return Stack(
+        children: [
+          const Icon(Icons.download),
+          if (activeCount > 0)
+            Positioned(
+              right: 0,
+              top: 0,
+              child: Container(
+                padding: const EdgeInsets.all(2),
+                decoration: BoxDecoration(
+                  color: Colors.red,
+                  borderRadius: BorderRadius.circular(10),
+                ),
+                constraints: const BoxConstraints(
+                  minWidth: 16,
+                  minHeight: 16,
+                ),
+                child: Text(
+                  '$activeCount',
+                  style: const TextStyle(
+                    color: Colors.white,
+                    fontSize: 10,
+                  ),
+                  textAlign: TextAlign.center,
+                ),
+              ),
+            ),
+        ],
+      );
+    });
+  }
 }
 
 class _MainController extends GetxController {