feat(meter): scaffold 2nd-gen meter (setup, API, a11y, styling) — SWC-2008..2011

2nd-gen/packages/core/components/meter/Meter.base.ts

@@ -0,0 +1,84 @@
+/**
+ * Copyright 2026 Adobe. All rights reserved.
+ * This file is licensed to you under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under
+ * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+
+import { PropertyValues } from 'lit';
+import { property } from 'lit/decorators.js';
+
+import { SpectrumElement } from '@spectrum-web-components/core/element/index.js';
+import {
+  LINEAR_PROGRESS_VALID_SIZES,
+  LinearProgressMixin,
+  SizedMixin,
+} from '@spectrum-web-components/core/mixins/index.js';
+
+import { METER_VARIANTS, type MeterVariant } from './Meter.types.js';
+
+/**
+ * A non-focusable, read-only bar that shows a value inside a fixed range.
+ * Implements the WAI-ARIA `meter` role on the shadow `.swc-Meter` element
+ * (the host carries no ARIA).
+ *
+ * @attribute {ElementSize} size - The size of the meter.
+ */
+export abstract class MeterBase extends LinearProgressMixin(
+  SizedMixin(SpectrumElement, {
+    validSizes: LINEAR_PROGRESS_VALID_SIZES,
+    defaultSize: 'm',
+  })
+) {
+  /**
+   * The size of the meter.
+   *
+   * @default m
+   */
+  declare public size: (typeof LINEAR_PROGRESS_VALID_SIZES)[number];
+
+  // ─────────────────────────
+  //     API TO OVERRIDE
+  // ─────────────────────────
+
+  /**
+   * @internal
+   *
+   * A readonly array of all valid variants for the meter. Concrete
+   * subclasses re-declare with their own valid set so validation logic
+   * resolves against `(this.constructor as typeof MeterBase).VARIANTS`.
+   */
+  static readonly VARIANTS: readonly string[] = METER_VARIANTS;
+
+  /**
+   * The variant of the meter. Drives the bar fill color.
+   */
+  @property({ type: String, reflect: true })
+  public variant: MeterVariant = 'informative';
+
+  // ──────────────────────
+  //     IMPLEMENTATION
+  // ──────────────────────
+
+  protected override update(changes: PropertyValues): void {
+    if (window.__swc?.DEBUG) {
+      const constructor = this.constructor as typeof MeterBase;
+      if (!constructor.VARIANTS.includes(this.variant)) {
+        window.__swc.warn(
+          this,
+          `<${this.localName}> element expects the "variant" attribute to be one of the following:`,
+          'https://opensource.adobe.com/spectrum-web-components/components/meter/#variants',
+          {
+            issues: [...constructor.VARIANTS],
+          }
+        );
+      }
+    }
+    super.update(changes);
+  }
+}

2nd-gen/packages/core/components/meter/Meter.types.ts

@@ -0,0 +1,19 @@
+/**
+ * Copyright 2026 Adobe. All rights reserved.
+ * This file is licensed to you under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under
+ * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+
+export const METER_VARIANTS = [
+  'informative',
+  'positive',
+  'notice',
+  'negative',
+] as const;
+export type MeterVariant = (typeof METER_VARIANTS)[number];

2nd-gen/packages/core/components/meter/index.ts

@@ -0,0 +1,13 @@
+/**
+ * Copyright 2026 Adobe. All rights reserved.
+ * This file is licensed to you under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under
+ * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+export * from './Meter.base.js';
+export * from './Meter.types.js';

2nd-gen/packages/core/mixins/index.ts

@@ -11,6 +11,16 @@
  */
 
 export { DisabledMixin, type DisabledInterface } from './disabled-mixin.js';
+export {
+  LINEAR_PROGRESS_LABEL_POSITIONS,
+  LINEAR_PROGRESS_STATIC_COLORS,
+  LINEAR_PROGRESS_VALID_SIZES,
+  LinearProgressMixin,
+  type LinearProgressInterface,
+  type LinearProgressLabelPosition,
+  type LinearProgressSize,
+  type LinearProgressStaticColor,
+} from './linear-progress-mixin.js';
 export {
   ObserveSlotPresence,
   type SlotPresenceObservingInterface,