fix: smoothen value gradient for var param -> point selection

vega · Feb 5, 2021 · 20a36c1 · 20a36c1
1 parent e7af254
commit 20a36c1
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Showing 3 changed files with 63 additions and 20 deletions.
diff --git a/src/compile/selection/project.ts b/src/compile/selection/project.ts
@@ -63,39 +63,44 @@ const project: SelectionCompiler = {
     };
 
     const type = selCmpt.type;
+    const cfg = model.config.selection[type];
     const init =
       selDef.value !== undefined
         ? (array(selDef.value as any) as SelectionInitMapping[] | SelectionInitIntervalMapping[])
         : null;
 
     // If no explicit projection (either fields or encodings) is specified, set some defaults.
     // If an initial value is set, try to infer projections.
-    // Otherwise, use the default configuration.
     let {fields, encodings} = isObject(selDef.select) ? selDef.select : ({} as BaseSelectionConfig);
-    if (!fields && !encodings) {
-      const cfg = model.config.selection[type];
+    if (!fields && !encodings && init) {
+      for (const initVal of init) {
+        // initVal may be a scalar value to smoothen varParam -> pointSelection gradient.
+        if (!isObject(initVal)) {
+          continue;
+        }
 
-      if (init) {
-        for (const initVal of init) {
-          for (const key of keys(initVal)) {
-            if (isSingleDefUnitChannel(key)) {
-              (encodings || (encodings = [])).push(key as SingleDefUnitChannel);
+        for (const key of keys(initVal)) {
+          if (isSingleDefUnitChannel(key)) {
+            (encodings || (encodings = [])).push(key as SingleDefUnitChannel);
+          } else {
+            if (type === 'interval') {
+              log.warn(log.message.INTERVAL_INITIALIZED_WITH_X_Y);
+              encodings = cfg.encodings;
             } else {
-              if (type === 'interval') {
-                log.warn(log.message.INTERVAL_INITIALIZED_WITH_X_Y);
-                encodings = cfg.encodings;
-              } else {
-                (fields || (fields = [])).push(key);
-              }
+              (fields || (fields = [])).push(key);
             }
           }
         }
-      } else {
-        encodings = cfg.encodings;
-        fields = cfg.fields;
       }
     }
 
+    // We break this out as a separate if block (instead of an else condition)
+    // to account for unprojected point selections that have scalar initial values
+    if (!fields && !encodings) {
+      encodings = cfg.encodings;
+      fields = cfg.fields;
+    }
+
     for (const channel of encodings ?? []) {
       const fieldDef = model.fieldDef(channel);
       if (fieldDef) {
@@ -161,7 +166,9 @@ const project: SelectionCompiler = {
 
     if (init) {
       selCmpt.init = (init as any).map((v: SelectionInitMapping | SelectionInitIntervalMapping) => {
-        return proj.items.map(p => (v[p.channel] !== undefined ? v[p.channel] : v[p.field]));
+        // Selections can be initialized either with a full object that maps projections to values
+        // or scalar values to smoothen the abstraction gradient from variable params to point selections.
+        return proj.items.map(p => (isObject(v) ? (v[p.channel] !== undefined ? v[p.channel] : v[p.field]) : v));
       });
     }
 

diff --git a/src/selection.ts b/src/selection.ts
@@ -194,7 +194,11 @@ export interface SelectionParameter<T extends SelectionType = SelectionType> {
    *
    * __See also:__ [`init`](https://vega.github.io/vega-lite/docs/init.html) documentation.
    */
-  value?: T extends 'point' ? SelectionInitMapping[] : T extends 'interval' ? SelectionInitIntervalMapping : never;
+  value?: T extends 'point'
+    ? SelectionInit | SelectionInitMapping[]
+    : T extends 'interval'
+    ? SelectionInitIntervalMapping
+    : never;
 
   /**
    * When set, a selection is populated by input elements (also known as dynamic query widgets)

diff --git a/test/compile/selection/point.test.ts b/test/compile/selection/point.test.ts
@@ -78,6 +78,18 @@ describe('Multi Selection', () => {
         fields: ['nested.a', 'nested.b'],
         clear: false
       }
+    },
+    // Seven ensures a smooth abstraction gradient for "value" var params -> point selections
+    {
+      name: 'seven',
+      value: 50,
+      select: {type: 'point', fields: ['Horsepower']}
+    },
+    // Eight ensures this smooth "value" gradient logic doesn't kick in on unprojected point selections
+    {
+      name: 'eight',
+      value: 75,
+      select: 'point'
     }
   ]));
 
@@ -271,7 +283,27 @@ describe('Multi Selection', () => {
           }
         ]
       },
-      {name: 'six_store'}
+      {name: 'six_store'},
+      {
+        name: 'seven_store',
+        values: [
+          {
+            unit: '',
+            fields: [{type: 'E', field: 'Horsepower'}],
+            values: [50]
+          }
+        ]
+      },
+      {
+        name: 'eight_store',
+        values: [
+          {
+            unit: '',
+            fields: [{type: 'E', field: '_vgsid_'}],
+            values: [75]
+          }
+        ]
+      }
     ]);
   });