[GitHub] [brooklyn-ui] algairim commented on a change in pull request #232: Draw relationship path labels with textPath, if supplied

[GitBox]

algairim commented on a change in pull request #232:
URL: https://github.com/apache/brooklyn-ui/pull/232#discussion_r656898649



##########
File path: ui-modules/blueprint-composer/app/components/util/d3-blueprint.js
##########
@@ -776,11 +776,39 @@ export function D3Blueprint(container, options) {
         let relationData = _relationGroup.selectAll('.relation')
             .data(_d3DataHolder.visible.relationships, (d)=>(d.source._id + 
'_related_to_' + d.target._id));
 
-        relationData.enter().insert('path')
+        let relationDataEntered = relationData.enter();
+
+        // Draw the relationship path
+        relationDataEntered.insert('path')
             .attr('class', 'relation')
+            .attr('id', (d)=>(d.source._id + '-' + d.target._id))
             .attr('opacity', 0)
             .attr('from', (d)=>(d.source._id))
             .attr('to', (d)=>(d.target._id));
+
+        // Draw the relationship label that follows the path, somewhere in the 
middle.
+        // NOTE `textPath` DECREASES THE UI PERFORMANCE, USE LABELS WITH 
CAUTION.
+        relationDataEntered.insert('text') // Add text layer of '█'s to 
erase the area on the path.
+            .attr('dominant-baseline', 'middle')
+            .attr('text-anchor', 'middle')
+            .attr('font-family', 'monospace')
+            .attr('fill', '#f5f6fa')
+                .insert('textPath')
+                .attr('hidden', (d) => (d.label ? null : ''))
+                .attr('xlink:href', (d)=>('#' + d.source._id + '-' + 
d.target._id))
+                .attr('startOffset', '59%')
+                .html((d) => (d.label ? '█'.repeat(d.label.length + 2) : 
null));

Review comment:
       This step might look redundant, however, this is how middle part of the 
path is erased for the label text:
   <img width="721" alt="Screenshot 2021-06-23 at 09 55 22" 
src="https://user-images.githubusercontent.com/81319331/123068027-6f2dd180-d409-11eb-9996-6103b17ab9ea.png";>
   




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