1、ImageWidget增加placeholder、errorWidget属性

lib/widget/image_widget.dart

@@ -17,6 +17,7 @@ class ImageWidget {
     double? height,
     BoxFit fit = BoxFit.cover,
     Widget? placeholder,
+    Widget? errorWidget,
     bool signature = false,
   }) {
     var domainUrl = domain ?? ImageWidget.domain;
@@ -34,7 +35,8 @@ class ImageWidget {
       // 拼接Random，修复图片地址固定，无法展示最新图片问题
       image: CachedNetworkImageProvider(url!),
       imageBuilder: MyOctoImageTransformer.getOctoImageBuilder(type),
-      errorBuilder: ImageWidget.placeholderBuilder(errorWidget: placeholder),
+      placeholderBuilder: ImageWidget.placeholderBuilder(placeholder: placeholder),
+      errorBuilder: ImageWidget.errorBuilder(errorWidget: placeholder),
       fit: fit,
       width: width,
       height: height,
@@ -101,7 +103,7 @@ class ImageWidget {
     return CachedNetworkImageProvider(url);
   }
 
-  static OctoErrorBuilder placeholderBuilder({
+  static OctoErrorBuilder errorBuilder({
     Widget? errorWidget,
   }) {
     return (context, error, stacktrace) => errorWidget != null
@@ -115,6 +117,18 @@ class ImageWidget {
             color: Colors.grey,
           );
   }
+
+  static OctoPlaceholderBuilder? placeholderBuilder({
+    Widget? placeholder,
+  }) {
+    return placeholder != null
+        ? (context) => SizedBox(
+              width: double.infinity,
+              height: double.infinity,
+              child: placeholder,
+            )
+        : null;
+  }
 }
 
 class MyOctoImageTransformer {