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refactor: order-independent scene setters, fragment-safe style extraction

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This commit is contained in:
navi 2026-09-27 23:00:24 +02:00
parent a7e463cb94
commit 14916e6416
3 changed files with 71 additions and 42 deletions
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18
src/main.ts
View file

@ -141,20 +141,22 @@ async function rebuildPreview(): Promise<void> {
compileError.hidden = true
compileError.textContent = ''
if (runtime) {
runtime.setTemplate(result.template)
runtime.setSlides(result.slides)
// Follow the slide being edited; the deck may just have grown.
if (currentSlide >= 0) {
runtime.goTo(currentSlide)
}
} else {
if (!runtime) {
runtime = createRuntime(stage, result.slides, {
template: result.template,
onCurrentChange: (index) => setSlide(index)
})
// A reload restores the slide you were on (history state): open
// the editor and the selection there too.
setSlide(runtime.current)
}
runtime.setTemplate(result.template)
runtime.setSlides(result.slides)
runtime.setCss(result.css)
// Follow the slide being edited; the deck may just have grown.
if (currentSlide >= 0) {
runtime.goTo(currentSlide)
}
} catch (error) {
// Half-typed Less should not blank the preview: keep the last good
// output on screen and report what broke.

12
src/slides/compile.ts
View file

@ -57,21 +57,25 @@ export interface CompiledPresentation {
* removed from the markup because their raw Less must never reach the DOM —
* the compiled CSS is injected separately, at `<?= css ?>`. A style tag that
* *is* that injection point is left alone.
*
* Parsed as a fragment rather than a full document: as a document a leading
* `<style>` would land in `<head>` and be lost from the body output, taking
* the injection point with it.
*/
export function extractStyles(markup: string): { html: string; style: string } {
if (!markup.includes('<style')) {
return { html: markup, style: '' }
}
const hidden = markup
const fragment = document.createElement('div')
fragment.innerHTML = markup
.split(HTML_PLACEHOLDER)
.join(HTML_SENTINEL)
.split(CSS_PLACEHOLDER)
.join(CSS_SENTINEL)
const parsed = new DOMParser().parseFromString(hidden, 'text/html')
const blocks: string[] = []
for (const element of Array.from(parsed.querySelectorAll('style'))) {
for (const element of Array.from(fragment.querySelectorAll('style'))) {
const source = element.textContent ?? ''
if (source.includes(CSS_SENTINEL)) {
// This tag is where the compiled CSS gets injected, not authoring.
@ -81,7 +85,7 @@ export function extractStyles(markup: string): { html: string; style: string } {
element.remove()
}
const html = parsed.body.innerHTML
const html = fragment.innerHTML
.split(HTML_SENTINEL)
.join('<?= html ?>')
.split(CSS_SENTINEL)

83
src/slides/runtime.ts
View file

@ -36,9 +36,16 @@ export interface Runtime {
previous(): void
/** Swap the deck in place (after recompiling) without resetting the view. */
setSlides(slides: readonly CompiledSlide[]): void
/** Set the global slide; a template re-renders the scene around the slides. */
/**
* Set the global slide; a template re-renders the scene around the slides.
* Order-independent: a scene re-render re-applies the stored stylesheet.
*/
setTemplate(template: string): void
/** Inject the compiled stylesheet at the scene's `<?= css ?>`, or in the head. */
/**
* Set the compiled stylesheet: injected at the scene's `<?= css ?>`, or in
* the head when the scene has no injection point. Stored, so re-renders of
* the scene re-apply it — safe to call in any order with the other setters.
*/
setCss(css: string): void
readonly current: number
readonly slides: readonly RuntimeSlide[]
@ -194,6 +201,7 @@ export function createRuntime(
let generation = 0
let destroyed = false
let template = options.template ?? ''
let css = ''
let mountPoint: HTMLElement = container
container.setAttribute('data-psslides-runtime', '')
@ -359,33 +367,30 @@ export function createRuntime(
window.addEventListener('popstate', onPopState)
/**
* Set the global slide. A template (`<?= html ?>` inside) is rendered once
* as the scene — slides are mounted where the placeholder was, `<?= css ?>`
* is filled by setCss. Anything else leaves the slide tree alone; its
* markup was already merged into the slides by the compiler.
* Render the global slide as the scene (or reset to plain slides when it
* is not a template) and re-apply the stored stylesheet to whatever the
* new scene offers: its `<?= css ?>`, or the head as a fallback.
*/
function setTemplate(value: string): void {
if (destroyed || value === template) {
return
function renderShell(): void {
// Start from a clean container so a previous scene never lingers
// after the template goes away. The slide elements survive as
// objects; the caller re-homes them into the fresh mount point.
container.replaceChildren()
mountPoint = container
if (HTML_PLACEHOLDER.test(template)) {
container.innerHTML = template.split(HTML_PLACEHOLDER).join(MOUNT_POINT)
mountPoint = container.querySelector<HTMLElement>(MOUNT_SELECTOR) ?? container
}
template = value
renderShell()
// The shell was rebuilt, but the slide elements themselves survive as
// objects: re-home them instead of recreating anything.
mountPoint.append(...records.map((record) => record.element))
applyCss()
}
/**
* Inject the compiled stylesheet. A `<style>` holding `<?= css ?>` inside
* the container takes it in place — tagged `data-ps-css` so recompiles
* keep aiming at it once the placeholder text is gone. With no such target
* the runtime keeps one stylesheet in the document head.
* Put the stored stylesheet in exactly one place: a `<style>` holding
* `<?= css ?>` inside the scene takes it in place — tagged `data-ps-css`
* so recompiles keep aiming at it once the placeholder text is gone. With
* no such target the runtime keeps one stylesheet in the document head.
*/
function setCss(css: string): void {
if (destroyed) {
return
}
function applyCss(): void {
let injected = false
for (const style of Array.from(container.querySelectorAll('style'))) {
const isTarget =
@ -403,19 +408,35 @@ export function createRuntime(
if (fallbackSheet) {
fallbackSheet.textContent = ''
}
} else {
} else if (css || fallbackSheet) {
headSheet().textContent = css
}
}
/** Render the global slide as the scene; plain markup leaves the DOM alone. */
function renderShell(): void {
mountPoint = container
if (!template || !HTML_PLACEHOLDER.test(template)) {
function setCss(value: string): void {
if (destroyed) {
return
}
container.innerHTML = template.split(HTML_PLACEHOLDER).join(MOUNT_POINT)
mountPoint = container.querySelector<HTMLElement>(MOUNT_SELECTOR) ?? container
css = value
applyCss()
}
/**
* Set the global slide. A template (`<?= html ?>` inside) is rendered once
* as the scene — slides are mounted where the placeholder was, and the
* stored stylesheet is re-applied where `<?= css ?>` is. Anything else
* leaves the slide tree alone; its markup was already merged into the
* slides by the compiler.
*/
function setTemplate(value: string): void {
if (destroyed || value === template) {
return
}
template = value
renderShell()
// The shell was rebuilt, but the slide elements themselves survive as
// objects: re-home them instead of recreating anything.
mountPoint.append(...records.map((record) => record.element))
}
return {
@ -443,6 +464,8 @@ export function createRuntime(
window.removeEventListener('popstate', onPopState)
container.replaceChildren()
container.removeAttribute('data-psslides-runtime')
fallbackSheet?.remove()
fallbackSheet = null
}
}
}