Coordinate picker

As explained in Web Components in Action

A coordinate picker is a two-dimensional user-interface control for selecting values by dragging along horizontal and vertical axes.

A coordinate picker is a two-dimensional control for selecting values along horizontal and vertical axes. Dragging horizontally changes saturation; dragging vertically changes brightness. Unlike a slider, it tracks two percentage values, x and y, while its thumbnail moves in both directions. section 11.1 section 11.2

Minimal coordinate picker demo

Load the component as an ES module, size the custom element, and provide an initial background color: <wcia-coord-picker backgroundcolor="#ff0000"></wcia-coord-picker>. A 400-by-400 element gives the x and y percentages visible room for dragging.

Figure 11.5. Saturation and brightness picker as a candidate for a web component

Use the saturation-and-brightness picker figure to connect the two-axis interaction with the component’s color-selection role. section 11.1

How Web Components in Action covers it

How deep it goes

Explains attributes, event handling, coordinate normalization, clamping, rendering, and CSS overlays, while deferring library-based reflection utilities.

Examples

Demonstrates saturation and brightness selection, gradient overlays, draggable thumbnails, and a custom-element demo page.

What it assumes

Assumes familiarity with slider behavior and JavaScript classes while demonstrating the component’s DOM structure and interaction logic.

What you can do after

Build from scratch a draggable coordinate picker custom element with reflected x and y attributes and bounded thumbnail movement.

How it connects

Connects Web Components with custom elements, Shadow DOM, DOM events, CSS gradients, sliders, and color pickers.

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Related concepts

• componentkind of · A software component is a modular part of a larger system that provides related functionality and interacts with other parts through defined boundaries or interfaces.
• color pickerpart of · A color picker is an interactive user-interface control for selecting, inspecting, or specifying a color and optionally related properties such as transparency.
• slidercontrasts with · A slider is an interactive interface control for selecting or adjusting a value within a continuous or discrete range.
• Web Componentskind of · Web Components are browser standards and APIs, including custom elements and shadow DOM, for creating reusable web interface elements with encapsulated structure, presentation, and behavior.
• color scaleuses · A color scale is a mapping from data values or categories to colors, often arranged as a continuous gradient or discrete set for visual representation.
• saturationconfigured by · Saturation is the intensity or purity of a color relative to a neutral gray, commonly expressed as a percentage.

This explainer was generated by Manning's knowledge graph from the text of Web Components in Action. The section links point to the parts of the book it draws on.