Gradient Editor `<mv-gradient-editor>`

フォームに関連付けられる CSS グラデーションエディター（linear、radial、conic）：カラーストップはリアルタイムのバー上のキーボード対応スライダーで、クリック、Enter、+ で追加し、バーの外へドラッグするか Delete で削除します。各ストップにカラーピッカーと位置フィールドが付きます。

カテゴリー	フォーム
タイプ	Web Component（`<mv-gradient-editor>`）
ステータス	安定版
同時にインストールされるもの	color-picker, tooltip, segmented
Keywords	gradient, color-stops, linear-gradient, conic, radial, angle, inspector, form-associated, editor, safe-rewrite

When to use

A theme or design tool lets users build linear, radial or conic CSS gradients with draggable stops
A form must submit a CSS gradient string edited visually with per-stop colors and an angle

Avoid when

Only one flat color is needed → use Color Picker instead
Users pick among a few predefined gradients rather than editing stops → use Swatch instead

インストール

node scripts/add.mjs gradient-editor --out ./src/marvelous

Marvelous UI の MCP サーバーを使う AI エージェント：install_components({ slugs: ["gradient-editor"], target_dir: "<absolute path>/src/marvelous", framework: "react" })。

コピーされるファイル（依存関係を含む）：tokens/tokens.css, core/base.css, core/canvas.js, core/dom.js, core/element.js, core/focus.js, core/form.js, core/position.js, components/color-picker/color-picker.js, components/color-picker/color-picker.css, components/tooltip/tooltip.js, components/tooltip/tooltip.css, components/segmented/segmented.js, components/segmented/segmented.css, components/gradient-editor/gradient-editor.js, components/gradient-editor/gradient-editor.css。

使い方

クイックスタート、動作する最小限のマークアップ：

<mv-gradient-editor name="background" value="linear-gradient(90deg, #7C3AED 0%, #F472B6 100%)"></mv-gradient-editor>

基本となるマークアップです。ここから属性、data-*、CSS 変数でカスタマイズしてください：

<div id="ge-demo">
  <style>
    #ge-demo { display: flex; flex-wrap: wrap; gap: 1.5rem; align-items: center; justify-content: center; width: 100%; }
    #ge-demo .ge-art { display: grid; gap: .75rem; width: 17rem; }
    #ge-demo .ge-stage { display: grid; place-items: center; height: 15rem; border-radius: var(--mv-radius-xl); border: 1px solid var(--mv-border); background: var(--mv-bg-muted); }
    #ge-demo .ge-ticket { display: grid; align-content: space-between; width: 12rem; height: 12rem; padding: 1rem; border-radius: 1.25rem; color: #fff; text-shadow: 0 1px 6px oklch(0 0 0 / .3); box-shadow: 0 18px 40px -18px oklch(0.25 0.12 280 / .75); }
    #ge-demo .ge-ticket small { font: 600 .65rem var(--mv-font-sans); letter-spacing: .08em; text-transform: uppercase; opacity: .85; }
    #ge-demo .ge-ticket strong { font: 700 1.35rem/1.1 var(--mv-font-sans); }
    #ge-demo .ge-css { margin: 0; padding: .6rem .75rem; border-radius: var(--mv-radius-md); border: 1px solid var(--mv-border); background: var(--mv-surface); color: var(--mv-fg-muted); font: 500 .68rem/1.5 var(--mv-font-mono); overflow-wrap: anywhere; }
    #ge-demo form { display: grid; gap: .75rem; width: 18rem; padding: .875rem; border: 1px solid var(--mv-border); border-radius: var(--mv-radius-lg); background: var(--mv-surface); box-shadow: var(--mv-shadow-sm); }
    #ge-demo .ge-title { margin: 0; font: 600 .8rem var(--mv-font-sans); color: var(--mv-fg); }
  </style>
  <div class="ge-art">
    <div class="ge-stage">
      <div class="ge-ticket" id="ge-demo-ticket"><small>Pass · Sep 24</small><strong>Lisbon Design Week</strong></div>
    </div>
    <p class="ge-css" id="ge-demo-css"></p>
  </div>
  <form id="ge-demo-form" aria-labelledby="ge-demo-title">
    <p class="ge-title" id="ge-demo-title">Ticket background</p>
    <mv-gradient-editor id="ge-demo-editor" name="background" label="Ticket background" value="linear-gradient(135deg, #0EA5E9 0%, #6366F1 48%, #EC4899 100%)"></mv-gradient-editor>
  </form>
</div>
<script type="module">
  const editor = document.getElementById("ge-demo-editor");
  const paint = () => {
    document.getElementById("ge-demo-ticket").style.background = editor.value;
    document.getElementById("ge-demo-css").textContent = `background: ${editor.value};`;
  };
  editor.addEventListener("mv-input", paint);
  editor.addEventListener("mv-change", paint);
  customElements.whenDefined("mv-gradient-editor").then(() => requestAnimationFrame(paint));
</script>

API

Attributes

Name	タイプ	Default	Description
`value`	string		Initial CSS gradient (linear, radial or conic; “to right”, deg/turn/rad angles; missing positions follow the CSS rules). Restored on form reset.
`label`	string	`Gradient`	Accessible name of the group (overrides strings.label).
`name / disabled / readonly`			Standard form behavior; readonly keeps stops focusable but frozen.
`data-type`	linear \| radial \| conic		Set by the component (for styling).
`data-dragging`	boolean		Set while a stop is dragged.

Properties

Name	タイプ	Description
`value`	string	Serialized gradient, e.g. “linear-gradient(90deg, #7C3AED 0%, #F472B6 100%)”. Also the submitted form value.
`type`	linear \| radial \| conic	Current type (read-only).
`angle`	number	Angle (linear) or start angle (conic) in degrees, 0 to 359 (read-only).
`stops`	{ pos, color }[]	Stops sorted by position, 0 to 100 (read-only).
`strings`	object	Default texts, for translation: label, type, linear, radial, conic, angle, start, reverse, stops, add, stop, stopRole, stopValue, color, position, remove, added, removed ({n}, {pos}, {color}, {count} placeholders). Assignable before the element is defined.

Methods

Name	Description
`parseGradient(str) / formatGradient(model)`	Module exports: parse a CSS gradient into { type, angle, stops } and serialize it back.

Events

Name	Description
`mv-input`	Live change (drag, typing, color preview). detail: { value, type, angle, stops }.
`mv-change`	Committed change: end of a drag, key press, field change, color picker closed, stop added or removed.

CSS classes

Name	Description
`mv-gradient-editor-bar / -stop / -angle / -list / -row`	Generated parts: the stop track, the stop sliders, the angle row, the stops list and one row per stop.
`mv-gradient-editor-preview / -dial / -field / -remove / -add / -reverse`	Generated parts: live swatch, angle dial, numeric fields and icon buttons.

CSS variables

Name	Default	Description
`--mv-gradient-editor-width`	`100%`	Width.

Accessibility

Named role="group"; the type is a radio group. Each stop on the bar is a role="slider" (0 to 100, roledescription “color stop”) named “Stop n” with an aria-valuetext of “40%, #7C3AED”, in visual order. Arrow keys move it (Shift ×10), Page Up/Down ×10, Home/End to the ends; + or Insert adds a stop halfway to its neighbor, Delete/Backspace removes it and moves focus to the neighbor, Enter/Space opens its color picker. Additions and removals are announced in a polite live region. Escape cancels a drag. The angle is a labelled spinbutton (Up/Down, Shift ×15, Page Up/Down ×45); the dial next to it is a pointer shortcut hidden from assistive tech. The list repeats each stop with its color well, a position spinbutton and a “Remove stop n” button (disabled at two stops). Hover effects only apply to fine pointers, motion follows reduced motion through the duration tokens, and forced colors keep the gradient visible with system-color outlines. The value is submitted with the form and restored on reset.