support custom width for text bolck

lib/flutter_quill.dart

@@ -1 +1,2 @@
 library flutter_quill;
+export 'package:tuple/tuple.dart';

lib/widgets/default_styles.dart

@@ -59,9 +59,9 @@ class DefaultStyles {
   final DefaultTextBlockStyle code;
   final DefaultTextBlockStyle indent;
   final DefaultTextBlockStyle align;
-
+  final DefaultTextBlockStyle textBlockStyle;
-  DefaultStyles(
+  DefaultStyles({
-      {this.h1,
+    this.h1,
     this.h2,
     this.h3,
     this.paragraph,
@@ -77,7 +77,9 @@ class DefaultStyles {
     this.align,
     this.sizeSmall,
     this.sizeLarge,
-      this.sizeHuge});
+    this.sizeHuge,
+    this.textBlockStyle,
+  });
 
   static DefaultStyles getInstance(BuildContext context) {
     ThemeData themeData = Theme.of(context);
@@ -174,7 +176,9 @@ class DefaultStyles {
             baseStyle, Tuple2(0.0, 0.0), Tuple2(0.0, 0.0), null),
         sizeSmall: TextStyle(fontSize: 10.0),
         sizeLarge: TextStyle(fontSize: 18.0),
-        sizeHuge: TextStyle(fontSize: 22.0));
+        sizeHuge: TextStyle(fontSize: 22.0),
+        textBlockStyle: DefaultTextBlockStyle(baseStyle,  Tuple2(0.0, 0.0), Tuple2(32.0, 0.0), null)
+        );
   }
 
   DefaultStyles merge(DefaultStyles other) {
@@ -195,6 +199,8 @@ class DefaultStyles {
         align: other.align ?? this.align,
         sizeSmall: other.sizeSmall ?? this.sizeSmall,
         sizeLarge: other.sizeLarge ?? this.sizeLarge,
-        sizeHuge: other.sizeHuge ?? this.sizeHuge);
+        sizeHuge: other.sizeHuge ?? this.sizeHuge,
+        textBlockStyle: other.textBlockStyle??this.textBlockStyle,
+        );
   }
 }

lib/widgets/raw_editor.dart

@@ -604,7 +604,9 @@ class RawEditorState extends EditorState
                 : null,
             widget.embedBuilder,
             _cursorCont,
-            indentLevelCounts);
+            indentLevelCounts,
+            widget.styleBuilder,
+            );
         result.add(editableTextBlock);
       } else {
         throw StateError('Unreachable.');

lib/widgets/text_block.dart

@@ -58,6 +58,7 @@ class EditableTextBlock extends StatelessWidget {
   final bool hasFocus;
   final EdgeInsets contentPadding;
   final EmbedBuilder embedBuilder;
+  final StyleBuilder styleBuilder;
   final CursorCont cursorCont;
   final Map<int, int> indentLevelCounts;
 
@@ -73,7 +74,7 @@ class EditableTextBlock extends StatelessWidget {
       this.contentPadding,
       this.embedBuilder,
       this.cursorCont,
-      this.indentLevelCounts)
+      this.indentLevelCounts, this.styleBuilder)
       : assert(hasFocus != null),
         assert(embedBuilder != null),
         assert(cursorCont != null);
@@ -114,14 +115,15 @@ class EditableTextBlock extends StatelessWidget {
       index++;
       EditableTextLine editableTextLine = EditableTextLine(
           line,
-          _buildLeading(context, line, index, indentLevelCounts, count),
+          Center(child: _buildLeading(context, line, index, indentLevelCounts, count)),
           TextLine(
             line: line,
             textDirection: textDirection,
             embedBuilder: embedBuilder,
+            styleBuilder:styleBuilder,
             styles: styles,
           ),
-          _getIndentWidth(),
+          _getIndentWidth(defaultStyles),
           _getSpacingForLine(line, index, count, defaultStyles),
           textDirection,
           textSelection,
@@ -185,9 +187,9 @@ class EditableTextBlock extends StatelessWidget {
     return null;
   }
 
-  double _getIndentWidth() {
+  double _getIndentWidth(DefaultStyles defaultStyles) {
     Map<String, Attribute> attrs = block.style.attributes;
-
+    double minimumIndent = defaultStyles?.textBlockStyle?.lineSpacing?.item1??0;
     Attribute indent = attrs[Attribute.indent.key];
     double extraIndent = 0.0;
     if (indent != null && indent.value != null) {
@@ -195,10 +197,10 @@ class EditableTextBlock extends StatelessWidget {
     }
 
     if (attrs.containsKey(Attribute.blockQuote.key)) {
-      return 16.0 + extraIndent;
+      return minimumIndent + extraIndent;
     }
 
-    return 32.0 + extraIndent;
+    return minimumIndent + extraIndent;
   }
 
   Tuple2 _getSpacingForLine(