Add click-to-select support to splom [1852]

Author: rmoestl

src/traces/splom/index.js

@@ -221,7 +221,9 @@ function plotOne(gd, cd0) {
         scene.matrix = createMatrix(regl);
     }
 
-    var selectMode = dragmode === 'lasso' || dragmode === 'select' || !!trace.selectedpoints;
+    var clickSelectEnabled = fullLayout.clickmode.indexOf('select') > -1;
+    var selectMode = dragmode === 'lasso' || dragmode === 'select' ||
+      !!trace.selectedpoints || clickSelectEnabled;
     scene.selectBatch = null;
     scene.unselectBatch = null;
 
@@ -372,7 +374,7 @@ function selectPoints(searchInfo, polygon) {
     if(polygon !== false && !polygon.degenerate) {
         els = [], unels = [];
         for(i = 0; i < x.length; i++) {
-            if(polygon.contains([xpx[i], ypx[i]])) {
+            if(polygon.contains([xpx[i], ypx[i]], null, i, searchInfo)) {
                 els.push(i);
                 selection.push({
                     pointNumber: i,

test/jasmine/tests/select_test.js

@@ -630,7 +630,8 @@ describe('@flaky Click-to-select', function() {
             testCase('scatterpolar', require('@mocks/polar_scatter.json'), 130, 290,
               [[], [], [], [19], [], []], { dragmode: 'zoom' }),
             testCase('scatterpolargl', require('@mocks/glpolar_scatter.json'), 130, 290,
-              [[], [], [], [19], [], []], { dragmode: 'zoom' })
+              [[], [], [], [19], [], []], { dragmode: 'zoom' }),
+            testCase('splom', require('@mocks/splom_lower.json'), 427, 400, [[], [7], []])
         ]
           .forEach(function(testCase) {
               it('trace type ' + testCase.traceType, function(done) {