ImageGallery UI component

Purpose

ui.ImageGallery is the preferred linked image gallery API for actual visual content that users inspect. Render the returned node with ui.RenderHTML at the page boundary.

When every item passes validation, the component returns ImageGalleryResult with rendered HTML, the accepted Items, no diagnostics, and a nil error. When one or more items fail item validation, it returns partial safe gallery HTML for the accepted items, includes diagnostic entries for the omitted items, and returns ErrImageGalleryItemRejected. Invalid allowlist origins or unsafe root attributes fail before rendering and return an empty result with the corresponding error.

Inputs

Field Required Type Behavior
Items yes []ImageGalleryItem Src and Alt required; Caption optional text; Href optional safe URL for opening the source; item Attrs must be inert attributes.
ImageOrigins no []string Exact external https: origins accepted for Src and Href, such as https://media.example.com. Entries must be origins only, with no path, query, or fragment.
Attrs no map[string]string Inert root attributes. Event handlers, data-ai-*, and active browser attributes are rejected.
Log no ControlLogSink Receives public render and validation diagnostics.

Boundary

Every image has useful alt text. The component validates URL shape, origin allowlists, and inert attributes before rendering, but provider authorization and path resolution remain host-owned boundaries.

Example

package mediaui

import "github.com/busdk/bus-ui/pkg/ui"

var invoicePages = []ui.ImageItem{
	{Src: "/preview/a.png", Alt: "Invoice page 1", Caption: "Page 1"},
	{
		Src:     "https://media.example.com/invoices/2026-05/a.png",
		Href:    "https://media.example.com/invoices/2026-05/a.png",
		Alt:     "Invoice page 2",
		Caption: "Page 2",
	},
}

func renderInvoiceGallery() (string, error) {
	return ui.RenderHTML(ui.ImageGallery(ui.ImageGalleryProps{
		Items:        invoicePages,
		ImageOrigins: []string{"https://media.example.com"},
	}))
}

ImageItem is an alias for ImageGalleryItem from the public ui facade.

Legacy compatibility

ImageGalleryChecked remains available for callers that still need the historical checked helper and diagnostics.

Runtime Terms

Src and Href values must be root-relative same-origin paths such as /preview/a.png, with no .. segments, or external https: URLs whose exact origin appears in ImageGalleryProps.ImageOrigins. External image links are rejected by default. Rejected links fail validation and produce ImageGalleryDiagnostic values.

Code is image_alt_required for missing alt text and image_url_rejected for unsafe Src or Href. Rejected item attributes use the machine-readable code unsafe image gallery attribute, set Field to attrs, and set PathClass to attribute. Unsafe root Attrs are different: they fail the whole render before item diagnostics are built and return ErrImageGalleryUnsafeAttrs. Index is the zero-based item index, Field is alt, src, href, or attrs, Origin is populated only for rejected external URLs, and PathClass names the rejected URL class such as missing, relative, traversal, external-scheme, credentials, or unlisted-origin.

The compatibility helper does not name or call a resolver. The host or controller resolves provider paths first, then passes only resolved safe URLs in ImageGalleryItem.Src and ImageGalleryItem.Href.

Accepted examples: /preview/a.png and https://media.example.com/invoices/a.png when that exact origin is allowlisted. Rejected examples: https://cdn.example.net/a.png without an allowlist entry, javascript:alert(1), and ../private/a.png.

UI framework index

Sources