fix(label): fix label rich style does not inherit the plain label style & add new option richInheritPlainLabel to control this behavior.

Author: plainheart

src/label/labelStyle.ts

@@ -395,15 +395,18 @@ function setTextStyleCommon(
     let richResult: TextStyleProps['rich'];
     if (richItemNames) {
         richResult = {};
+        const richInheritPlainLabel = textStyleModel.get('richInheritPlainLabel') !== false;
         for (const name in richItemNames) {
             if (richItemNames.hasOwnProperty(name)) {
                 // Cascade is supported in rich.
-                const richTextStyle = textStyleModel.getModel(['rich', name]);
+                const richTextStyle = textStyleModel.getModel(['rich', name], richInheritPlainLabel && textStyleModel);
                 // In rich, never `disableBox`.
-                // FIXME: consider `label: {formatter: '{a|xx}', color: 'blue', rich: {a: {}}}`,
+                // consider `label: {formatter: '{a|xx}', color: 'blue', rich: {a: {}}}`,
                 // the default color `'blue'` will not be adopted if no color declared in `rich`.
                 // That might confuses users. So probably we should put `textStyleModel` as the
                 // root ancestor of the `richTextStyle`. But that would be a break change.
+                // Since v6, the rich style inherits plain label by default
+                // but this behavior can be disabled by setting `richInheritPlainLabel` to `false`.
                 setTokenTextStyle(
                     richResult[name] = {}, richTextStyle, globalTextStyle, opt, isNotNormal, isAttached, false, true
                 );