Support align

app/assets/sample_data.json

@@ -199,5 +199,32 @@
    },
    {
       "insert":"\n"
+   },
+   {
+      "insert":"\nCenter Align"
+   },
+   {
+      "attributes":{
+         "align":"center"
+      },
+      "insert":"\n"
+   },
+   {
+      "insert":"Right Align"
+   },
+   {
+      "attributes":{
+         "align":"right"
+      },
+      "insert":"\n"
+   },
+   {
+      "insert":"Justify Align"
+   },
+   {
+      "attributes":{
+         "align":"justify"
+      },
+      "insert":"\n"
    }
 ]

lib/models/documents/attribute.dart

@@ -23,6 +23,7 @@ class Attribute<T> {
     Attribute.background.key: Attribute.background,
     Attribute.header.key: Attribute.header,
     Attribute.indent.key: Attribute.indent,
+    Attribute.align.key: Attribute.align,
     Attribute.list.key: Attribute.list,
     Attribute.codeBlock.key: Attribute.codeBlock,
     Attribute.blockQuote.key: Attribute.blockQuote,
@@ -46,6 +47,8 @@ class Attribute<T> {
 
   static final IndentAttribute indent = IndentAttribute();
 
+  static final AlignAttribute align = AlignAttribute(null);
+
   static final ListAttribute list = ListAttribute(null);
 
   static final CodeBlockAttribute codeBlock = CodeBlockAttribute();
@@ -65,6 +68,7 @@ class Attribute<T> {
   static final Set<String> blockKeys = {
     Attribute.header.key,
     Attribute.indent.key,
+    Attribute.align.key,
     Attribute.list.key,
     Attribute.codeBlock.key,
     Attribute.blockQuote.key,
@@ -73,6 +77,7 @@ class Attribute<T> {
   static final Set<String> blockKeysExceptHeader = {
     Attribute.list.key,
     Attribute.indent.key,
+    Attribute.align.key,
     Attribute.codeBlock.key,
     Attribute.blockQuote.key,
   };
@@ -83,6 +88,18 @@ class Attribute<T> {
 
   static Attribute<int> get h3 => HeaderAttribute(level: 3);
 
+  // "attributes":{"align":"left"}
+  static Attribute<String> get leftAlignment => AlignAttribute('left');
+
+  // "attributes":{"align":"center"}
+  static Attribute<String> get centerAlignment => AlignAttribute('center');
+
+  // "attributes":{"align":"right"}
+  static Attribute<String> get rightAlignment => AlignAttribute('right');
+
+  // "attributes":{"align":"justify"}
+  static Attribute<String> get justifyAlignment => AlignAttribute('justify');
+
   // "attributes":{"list":"bullet"}
   static Attribute<String> get ul => ListAttribute('bullet');
 
@@ -164,6 +181,10 @@ class IndentAttribute extends Attribute<int> {
   IndentAttribute({int level}) : super('indent', AttributeScope.BLOCK, level);
 }
 
+class AlignAttribute extends Attribute<String> {
+  AlignAttribute(String val) : super('align', AttributeScope.BLOCK, val);
+}
+
 class ListAttribute extends Attribute<String> {
   ListAttribute(String val) : super('list', AttributeScope.BLOCK, val);
 }

lib/widgets/default_styles.dart

@@ -55,6 +55,7 @@ class DefaultStyles {
   final DefaultTextBlockStyle quote;
   final DefaultTextBlockStyle code;
   final DefaultTextBlockStyle indent;
+  final DefaultTextBlockStyle align;
 
   DefaultStyles(
       this.h1,
@@ -69,7 +70,8 @@ class DefaultStyles {
       this.lists,
       this.quote,
       this.code,
-      this.indent);
+      this.indent,
+      this.align);
 
   static DefaultStyles getInstance(BuildContext context) {
     ThemeData themeData = Theme.of(context);
@@ -158,6 +160,7 @@ class DefaultStyles {
               color: Colors.grey.shade50,
               borderRadius: BorderRadius.circular(2),
             )),
+        DefaultTextBlockStyle(baseStyle, Tuple2(0.0, 0.0), Tuple2(0.0, 0.0), null),
         DefaultTextBlockStyle(baseStyle, Tuple2(0.0, 0.0), Tuple2(0.0, 0.0), null));
   }
 
@@ -175,6 +178,7 @@ class DefaultStyles {
         other.lists ?? this.lists,
         other.quote ?? this.quote,
         other.code ?? this.code,
-        other.indent ?? this.indent);
+        other.indent ?? this.indent,
+        other.align ?? this.align);
   }
 }

lib/widgets/proxy.dart

@@ -128,6 +128,7 @@ class RenderEmbedProxy extends RenderProxyBox implements RenderContentProxyBox {
 
 class RichTextProxy extends SingleChildRenderObjectWidget {
   final TextStyle textStyle;
+  final TextAlign textAlign;
   final TextDirection textDirection;
   final double textScaleFactor;
   final Locale locale;
@@ -137,13 +138,22 @@ class RichTextProxy extends SingleChildRenderObjectWidget {
 
   @override
   RenderParagraphProxy createRenderObject(BuildContext context) {
-    return RenderParagraphProxy(null, textStyle, textDirection, textScaleFactor,
-        strutStyle, locale, textWidthBasis, textHeightBehavior);
+    return RenderParagraphProxy(
+        null,
+        textStyle,
+        textAlign,
+        textDirection,
+        textScaleFactor,
+        strutStyle,
+        locale,
+        textWidthBasis,
+        textHeightBehavior);
   }
 
   RichTextProxy(
       RichText child,
       this.textStyle,
+      this.textAlign,
       this.textDirection,
       this.textScaleFactor,
       this.locale,
@@ -152,6 +162,7 @@ class RichTextProxy extends SingleChildRenderObjectWidget {
       this.textHeightBehavior)
       : assert(child != null),
         assert(textStyle != null),
+        assert(textAlign != null),
         assert(textDirection != null),
         assert(locale != null),
         assert(strutStyle != null),
@@ -161,6 +172,7 @@ class RichTextProxy extends SingleChildRenderObjectWidget {
   void updateRenderObject(
       BuildContext context, covariant RenderParagraphProxy renderObject) {
     renderObject.textStyle = textStyle;
+    renderObject.textAlign = textAlign;
     renderObject.textDirection = textDirection;
     renderObject.textScaleFactor = textScaleFactor;
     renderObject.locale = locale;
@@ -175,6 +187,7 @@ class RenderParagraphProxy extends RenderProxyBox
   RenderParagraphProxy(
     RenderParagraph child,
     TextStyle textStyle,
+    TextAlign textAlign,
     TextDirection textDirection,
     double textScaleFactor,
     StrutStyle strutStyle,
@@ -183,7 +196,7 @@ class RenderParagraphProxy extends RenderProxyBox
     TextHeightBehavior textHeightBehavior,
   )   : _prototypePainter = TextPainter(
             text: TextSpan(text: ' ', style: textStyle),
-            textAlign: TextAlign.left,
+            textAlign: textAlign,
             textDirection: textDirection,
             textScaleFactor: textScaleFactor,
             strutStyle: strutStyle,
@@ -203,6 +216,15 @@ class RenderParagraphProxy extends RenderProxyBox
     markNeedsLayout();
   }
 
+  set textAlign(TextAlign value) {
+    assert(value != null);
+    if (_prototypePainter.textAlign == value) {
+      return;
+    }
+    _prototypePainter.textAlign = value;
+    markNeedsLayout();
+  }
+
   set textDirection(TextDirection value) {
     assert(value != null);
     if (_prototypePainter.textDirection == value) {

lib/widgets/text_block.dart

@@ -180,6 +180,8 @@ class EditableTextBlock extends StatelessWidget {
         lineSpacing = defaultStyles.code.lineSpacing;
       } else if (attrs.containsKey(Attribute.indent.key)) {
         lineSpacing = defaultStyles.indent.lineSpacing;
+      } else if (attrs.containsKey(Attribute.align.key)) {
+        lineSpacing = defaultStyles.align.lineSpacing;
       }
       top = lineSpacing.item1;
       bottom = lineSpacing.item2;

lib/widgets/text_line.dart

@@ -42,6 +42,7 @@ class TextLine extends StatelessWidget {
     TextSpan textSpan = _buildTextSpan(context);
     StrutStyle strutStyle =
         StrutStyle.fromTextStyle(textSpan.style, forceStrutHeight: true);
+    final textAlign = _getTextAlign();
     RichText child = RichText(
       text: _buildTextSpan(context),
       textDirection: textDirection,
@@ -51,6 +52,7 @@ class TextLine extends StatelessWidget {
     return RichTextProxy(
         child,
         textSpan.style,
+        textAlign,
         textDirection,
         1.0,
         Localizations.localeOf(context, nullOk: true),
@@ -59,6 +61,20 @@ class TextLine extends StatelessWidget {
         null);
   }
 
+  TextAlign _getTextAlign() {
+    final alignment = line.style.attributes[Attribute.align.key];
+    if (alignment == Attribute.leftAlignment) {
+      return TextAlign.left;
+    } else if (alignment == Attribute.centerAlignment) {
+      return TextAlign.center;
+    } else if (alignment == Attribute.rightAlignment) {
+      return TextAlign.right;
+    } else if (alignment == Attribute.justifyAlignment) {
+      return TextAlign.justify;
+    }
+    return TextAlign.start;
+  }
+
   TextSpan _buildTextSpan(BuildContext context) {
     DefaultStyles defaultStyles = DefaultStyles.getInstance(context);
     List<TextSpan> children = line.children