add helpers to work with many locis

- StructureElement.Loci.getPrincipalAxesMany
- structureElementLociLabelMany

src/mol-model/structure/structure/element/loci.ts

@@ -582,6 +582,20 @@ export namespace Loci {
         return PrincipalAxes.ofPositions(positions);
     }
 
+    export function getPrincipalAxesMany(locis: Loci[]): PrincipalAxes {
+        let elementCount = 0;
+        locis.forEach(l => {
+            elementCount += size(l);
+        });
+        const positions = new Float32Array(3 * elementCount);
+        let offset = 0;
+        locis.forEach(l => {
+            toPositionsArray(l, positions, offset);
+            offset += size(l) * 3;
+        });
+        return PrincipalAxes.ofPositions(positions);
+    }
+
     function sourceIndex(unit: Unit, element: ElementIndex) {
         return Unit.isAtomic(unit)
             ? unit.model.atomicHierarchy.atomSourceIndex.value(element)

src/mol-plugin-state/manager/structure/selection.ts

@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2019-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2019-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author David Sehnal <david.sehnal@gmail.com>
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
@@ -22,6 +22,7 @@ import { PluginStateObject as PSO } from '../../objects';
 import { UUID } from '../../../mol-util';
 import { StructureRef } from './hierarchy-state';
 import { Boundary } from '../../../mol-math/geometry/boundary';
+import { iterableToArray } from '../../../mol-data/util';
 
 interface StructureSelectionManagerState {
     entries: Map<string, SelectionEntry>,
@@ -405,14 +406,8 @@ export class StructureSelectionManager extends StatefulPluginComponent<Structure
     }
 
     getPrincipalAxes(): PrincipalAxes {
-        const elementCount = this.elementCount();
-        const positions = new Float32Array(3 * elementCount);
-        let offset = 0;
-        this.entries.forEach(v => {
-            StructureElement.Loci.toPositionsArray(v.selection, positions, offset);
-            offset += StructureElement.Loci.size(v.selection) * 3;
-        });
-        return PrincipalAxes.ofPositions(positions);
+        const values = iterableToArray(this.entries.values());
+        return StructureElement.Loci.getPrincipalAxesMany(values.map(v => v.selection));
     }
 
     modify(modifier: StructureSelectionModifier, loci: Loci) {

src/mol-theme/label.ts

@@ -92,6 +92,14 @@ export function structureElementStatsLabel(stats: StructureElement.Stats, option
     return o.htmlStyling ? label : stripTags(label);
 }
 
+export function structureElementLociLabelMany(locis: StructureElement.Loci[], options: Partial<LabelOptions> = {}): string {
+    const stats = StructureElement.Stats.create();
+    for (const l of locis) {
+        StructureElement.Stats.add(stats, stats, StructureElement.Stats.ofLoci(l));
+    }
+    return structureElementStatsLabel(stats, options);
+}
+
 function _structureElementStatsLabel(stats: StructureElement.Stats, countsOnly = false, hidePrefix = false, condensed = false, reverse = false): string {
     const { structureCount, chainCount, residueCount, conformationCount, elementCount } = stats;