fix clear format button

lib/src/models/documents/document.dart

@@ -119,9 +119,13 @@ class Document {
     return delta;
   }
 
-  Style collectStyle(int index, int len) {
+  Style collectStyle(int index, int len, bool collectAll) {
     final res = queryChild(index);
-    return (res.node as Line).collectStyle(res.offset, len);
+    if (collectAll) {
+      return (res.node as Line).collectAllStyle(res.offset, len);
+    } else {
+      return (res.node as Line).collectStyle(res.offset, len);
+    }
   }
 
   ChildQuery queryChild(int offset) {

lib/src/models/documents/nodes/line.dart

@@ -368,4 +368,37 @@ class Line extends Container<Leaf?> {
 
     return result;
   }
+
+  /// Returns all style for any character within the specified text range.
+  Style collectAllStyle(int offset, int len) {
+    final local = math.min(length - offset, len);
+    var result = Style();
+
+    final data = queryChild(offset, true);
+    var node = data.node as Leaf?;
+    if (node != null) {
+      result = result.mergeAll(node.style);
+      var pos = node.length - data.offset;
+      while (!node!.isLast && pos < local) {
+        node = node.next as Leaf?;
+        result = result.mergeAll(node!.style);
+        pos += node.length;
+      }
+    }
+
+    result = result.mergeAll(style);
+    if (parent is Block) {
+      final block = parent as Block;
+      result = result.mergeAll(block.style);
+    }
+
+    final remaining = len - local;
+    if (remaining > 0) {
+      final rest = nextLine!.collectAllStyle(0, remaining);
+      result = result.mergeAll(rest);
+    }
+
+    return result;
+  }
+
 }

lib/src/widgets/controller.dart

@@ -57,7 +57,13 @@ class QuillController extends ChangeNotifier {
 
   Style getSelectionStyle() {
     return document
-        .collectStyle(selection.start, selection.end - selection.start)
+        .collectStyle(selection.start, selection.end - selection.start, false)
+        .mergeAll(toggledStyle);
+  }
+
+  Style getAllSelectionStyle() {
+    return document
+        .collectStyle(selection.start, selection.end - selection.start, true)
         .mergeAll(toggledStyle);
   }
 

lib/src/widgets/toolbar/clear_format_button.dart

@@ -34,7 +34,7 @@ class _ClearFormatButtonState extends State<ClearFormatButton> {
         fillColor: fillColor,
         onPressed: () {
           for (final k
-              in widget.controller.getSelectionStyle().attributes.values) {
+              in widget.controller.getAllSelectionStyle().attributes.values) {
             widget.controller.formatSelection(Attribute.clone(k, null));
           }
         });