feat: config.rect/bar.minBandSize

fix #8351

examples/specs/bar_grouped_thin_minBandSize.vl.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
+  "data": {"url": "data/movies.json"},
+  "width": 500,
+  "mark": "bar",
+  "encoding": {
+    "x": {"field": "Director", "type": "nominal"},
+    "xOffset": {"field": "Title", "type": "nominal"},
+    "y": {
+      "aggregate": "mean",
+      "field": "Rotten Tomatoes Rating",
+      "type": "quantitative"
+    },
+    "color": {
+      "condition": {
+        "test": "datum['IMDB Rating'] === null || datum['Rotten Tomatoes Rating'] === null",
+        "value": "#aaa"
+      }
+    }
+  },
+  "config": {"mark": {"invalid": null}, "bar": {"minBandSize": 4}}
+}

src/compile/mark/encode/position-rect.ts

@@ -18,7 +18,7 @@ import * as log from '../../../log';
 import {BandSize, isRelativeBandSize} from '../../../mark';
 import {hasDiscreteDomain} from '../../../scale';
 import {isSignalRef, isVgRangeStep, VgEncodeEntry, VgValueRef} from '../../../vega.schema';
-import {getMarkPropOrConfig, signalOrStringValue, signalOrValueRef} from '../../common';
+import {getMarkConfig, getMarkPropOrConfig, signalOrStringValue, signalOrValueRef} from '../../common';
 import {ScaleComponent} from '../../scale/component';
 import {UnitModel} from '../../unit';
 import {nonPosition} from './nonposition';
@@ -77,7 +77,7 @@ function defaultSizeRef(
   sizeChannel: 'width' | 'height',
   scaleName: string,
   scale: ScaleComponent,
-  config: Config,
+  config: Config<SignalRef>,
   bandSize: BandSize,
   hasFieldDef: boolean,
   mark: Mark
@@ -90,8 +90,8 @@ function defaultSizeRef(
         if (bandSize.band !== 1) {
           bandWidth = `${bandSize.band} * ${bandWidth}`;
         }
-        // TODO(#8351): make 0.25 here configurable
-        return {signal: `max(0.25, ${bandWidth})`};
+        const minBandSize = getMarkConfig('minBandSize', {type: mark}, config);
+        return {signal: `max(${signalOrStringValue(minBandSize)}, ${bandWidth})`};
       } else if (bandSize.band !== 1) {
         log.warn(log.message.cannotUseRelativeBandSizeWithNonBandScale(scaleType));
         bandSize = undefined;
@@ -122,8 +122,6 @@ function defaultSizeRef(
       return {signal: `(1 - (${padding.signal})) * ${sizeChannel}`};
     } else if (isNumber(padding)) {
       return {signal: `${1 - padding} * ${sizeChannel}`};
-    } else if (isExprRef(padding)) {
-      return {signal: `(1 - (${padding.expr})) * ${sizeChannel}`};
     }
   }
   const defaultStep = getViewConfigDiscreteStep(config.view, sizeChannel);

src/mark.ts

@@ -442,6 +442,12 @@ export interface RectConfig<ES extends ExprRef | SignalRef> extends RectBinSpaci
    * @minimum 0
    */
   discreteBandSize?: number | RelativeBandSize;
+
+  /**
+   * The minimum band size for bar and rectangle marks.
+   * __Default value:__ `0.25`
+   */
+  minBandSize?: number | ES;
 }
 
 export type BandSize = number | RelativeBandSize | SignalRef;
@@ -650,12 +656,14 @@ const DEFAULT_RECT_BAND_SIZE = 5;
 export const defaultBarConfig: RectConfig<SignalRef> = {
   binSpacing: 1,
   continuousBandSize: DEFAULT_RECT_BAND_SIZE,
+  minBandSize: 0.25,
   timeUnitBandPosition: 0.5
 };
 
 export const defaultRectConfig: RectConfig<SignalRef> = {
   binSpacing: 0,
   continuousBandSize: DEFAULT_RECT_BAND_SIZE,
+  minBandSize: 0.25,
   timeUnitBandPosition: 0.5
 };