Add initial projection support for interactors.

packages/plot/src/interactors/Interval1D.js

@@ -6,6 +6,7 @@ import { getField } from './util/get-field.js';
 import { invert } from './util/invert.js';
 import { patchScreenCTM } from './util/patchScreenCTM.js';
 import { sanitizeStyles } from './util/sanitize-styles.js';
+import { getScale } from './util/scale.js';
 
 export class Interval1D {
   constructor(mark, {
@@ -62,11 +63,11 @@ export class Interval1D {
   }
 
   init(svg, root) {
-    const { brush, channel, style } = this;
-    this.scale = svg.scale(channel);
+    const { brush, channel, style, mark: { plot } } = this;
+    this.scale = getScale(svg, channel, plot);
 
-    const rx = svg.scale('x').range;
-    const ry = svg.scale('y').range;
+    const rx = getScale(svg, 'x', plot).range;
+    const ry = getScale(svg, 'y', plot).range;
     brush.extent([[min(rx), min(ry)], [max(rx), max(ry)]]);
 
     const facets = select(svg).selectAll('g[aria-label="facet"]');

packages/plot/src/interactors/Interval2D.js

@@ -6,6 +6,7 @@ import { getField } from './util/get-field.js';
 import { invert } from './util/invert.js';
 import { patchScreenCTM } from './util/patchScreenCTM.js';
 import { sanitizeStyles } from './util/sanitize-styles.js';
+import { getScale } from './util/scale.js';
 
 const asc = (a, b) => a - b;
 
@@ -69,9 +70,9 @@ export class Interval2D {
   }
 
   init(svg) {
-    const { brush, style } = this;
-    const xscale = this.xscale = svg.scale('x');
-    const yscale = this.yscale = svg.scale('y');
+    const { brush, style, mark: { plot } } = this;
+    const xscale = this.xscale = getScale(svg, 'x', plot);
+    const yscale = this.yscale = getScale(svg, 'y', plot);
     const rx = xscale.range;
     const ry = yscale.range;
     brush.extent([[min(rx), min(ry)], [max(rx), max(ry)]]);

packages/plot/src/interactors/Nearest.js

@@ -2,6 +2,7 @@ import { isSelection } from '@uwdata/mosaic-core';
 import { eq, literal } from '@uwdata/mosaic-sql';
 import { select, pointer } from 'd3';
 import { getField } from './util/get-field.js';
+import { getScale } from './util/scale.js';
 
 export class Nearest {
   constructor(mark, {
@@ -36,7 +37,7 @@ export class Nearest {
 
     const facets = select(svg).selectAll('g[aria-label="facet"]');
     const root = facets.size() ? facets : select(svg);
-    const scale = svg.scale(channel);
+    const scale = getScale(svg, channel, mark.plot);
     const param = !isSelection(selection);
 
     root.on('pointerdown pointermove', function(evt) {

packages/plot/src/interactors/util/scale.js

@@ -0,0 +1,45 @@
+export function getScale(fig, channel, plot) {
+  const scale = fig.scale(channel);
+  if (scale) return scale;
+
+  const proj = fig.projection();
+  if (proj && (channel === 'x' || channel === 'y')) {
+    const type = plot.getAttribute('projectionType');
+    return projectionScale(proj, type, channel);
+  }
+}
+
+function projectionScale(proj, type, channel) {
+  const { offset, translate: [tx, ty], scale, width, height } = proj;
+  const planar = type === 'identity' || type === 'reflect-y';
+
+  let range;
+  let apply;
+  let invert;
+
+  if (channel === 'x') {
+    range = [offset[0], offset[0] + width];
+    apply = planar ? x => x * scale + tx
+      : v => proj.stream([v, 0])[0];
+    invert = planar ? x => (x - tx) / scale
+      : proj.invert ? x => proj.invert([(x - tx) / scale, 0])[0]
+      : null;
+  } else {
+    range = [offset[1], offset[1] + height];
+    apply = type === 'identity' ? y => y * scale + ty
+      : type === 'reflect-y' ? y => -y * scale + ty
+      : v => proj.stream([0, v])[1];
+    invert = type === 'identity' ? y => (y - ty) / scale
+      : type === 'reflect-y' ? y => (ty - y) / scale
+      : proj.invert ? y => proj.invert([0, (y - ty) / scale])[1]
+      : null;
+  }
+
+  return {
+    type: planar || type === 'equirectangular' ? 'linear' : `${type}-x`,
+    domain: range.map(v => invert(v)),
+    range,
+    apply,
+    invert
+  };
+}