feat: add legend in graph.

Author: CorvusYe

CHANGELOG.md

@@ -1,6 +1,10 @@
+## 0.0.1+9
+- feat: create random color for tag.
+
 ## 0.0.1+8
 - feat(convert): cache the edge names and vertex tags in graph.
 - feat: support customize background.
+- feat(options style): support assigning colors to vertexes through tags (name or index).
 
 ## 0.0.1+7
 - feat: supported customize vertex ui.

lib/core/options/style/graph_style.dart

@@ -46,14 +46,7 @@ class GraphStyle {
     List<Color> colors = [];
 
     for (var tag in tags) {
-      Color? color;
-      if (tagColor != null) {
-        color = tagColor![tag];
-      }
-      if (color == null) {
-        var idx = allTags.indexOf(tag);
-        if (idx < tagColorByIndex.length) color = tagColorByIndex[idx];
-      }
+      Color? color = colorByTag(tag, allTags);
       if (color != null) {
         colors.add(color);
       }
@@ -65,6 +58,18 @@ class GraphStyle {
     return colors;
   }
 
+  Color? colorByTag(String tag, List<String> allTags) {
+    Color? color;
+    if (tagColor != null) {
+      color = tagColor![tag];
+    }
+    if (color == null) {
+      var idx = allTags.indexOf(tag);
+      if (idx < tagColorByIndex.length) color = tagColorByIndex[idx];
+    }
+    return color;
+  }
+
   /// when there is not color matched in [tagColor] on [tagColorByIndex], return random color.
   ///
   /// 当在 [tagColor] 与 [tagColorByIndex] 中匹配不到颜色时，返回随机颜色