From a410720347dbca8a5e52509eedae1d5f7cca15ce Mon Sep 17 00:00:00 2001 From: Unmesh100 Date: Mon, 30 Mar 2026 14:00:10 +0530 Subject: [PATCH 1/2] added server-side canvas support --- src/layout.ts | 5 +++++ src/measurement.ts | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/src/layout.ts b/src/layout.ts index 465a0673..000aed1f 100644 --- a/src/layout.ts +++ b/src/layout.ts @@ -56,6 +56,7 @@ import { getSegmentGraphemeWidths, getSegmentMetrics, textMayContainEmoji, + setCustomContext, } from './measurement.js' import { countPreparedLines, @@ -715,3 +716,7 @@ export function setLocale(locale?: string): void { setAnalysisLocale(locale) clearCache() } + +export function setContext(ctx: CanvasRenderingContext2D): void { + setCustomContext(ctx) +} diff --git a/src/measurement.ts b/src/measurement.ts index b2fb6d57..9c573f80 100644 --- a/src/measurement.ts +++ b/src/measurement.ts @@ -16,6 +16,7 @@ export type EngineProfile = { } let measureContext: CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D | null = null +let customContext: CanvasRenderingContext2D | null = null const segmentMetricCaches = new Map>() let cachedEngineProfile: EngineProfile | null = null @@ -25,6 +26,7 @@ let sharedGraphemeSegmenter: Intl.Segmenter | null = null const emojiCorrectionCache = new Map() export function getMeasureContext(): CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D { + if (customContext !== null) return customContext if (measureContext !== null) return measureContext if (typeof OffscreenCanvas !== 'undefined') { @@ -40,6 +42,10 @@ export function getMeasureContext(): CanvasRenderingContext2D | OffscreenCanvasR throw new Error('Text measurement requires OffscreenCanvas or a DOM canvas context.') } +export function setCustomContext(ctx: CanvasRenderingContext2D): void { + customContext = ctx +} + export function getSegmentMetricCache(font: string): Map { let cache = segmentMetricCaches.get(font) if (!cache) { From 4eb98b95076dcbefb1eeec10496f0b27b3f2b2e1 Mon Sep 17 00:00:00 2001 From: Unmesh100 Date: Mon, 30 Mar 2026 14:33:44 +0530 Subject: [PATCH 2/2] Built a working masonry demo that positions cards in columns using Pretext's layout() for height prediction without any DOM reads. --- pages/demos/index.html | 2 +- pages/demos/masonry.html | 199 +++++++++++++++++++++++ pages/demos/masonry.ts | 333 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 533 insertions(+), 1 deletion(-) create mode 100644 pages/demos/masonry.html create mode 100644 pages/demos/masonry.ts diff --git a/pages/demos/index.html b/pages/demos/index.html index a15f4efd..f8f07f30 100644 --- a/pages/demos/index.html +++ b/pages/demos/index.html @@ -134,7 +134,7 @@

Rich Text

Masonry

-

A text-card occlusion demo where height prediction comes from Pretext instead of DOM reads.

+

A text-card layout where height prediction comes from Pretext instead of DOM reads.

 diff --git a/pages/demos/masonry.html b/pages/demos/masonry.html new file mode 100644 index 00000000..cdd44504 --- /dev/null +++ b/pages/demos/masonry.html @@ -0,0 +1,199 @@ + + + + + +Masonry — Pretext + + + +
+

Pretext Demo

+

Masonry

+

+ A Pinterest-style layout with cards positioned in columns based on + predicted heights — computed without any DOM reads in the layout path. + Adjust the column count to see how Pretext handles the reflow. +

+ +
+
+ +
+ + + 2 +
+ + + + \ No newline at end of file diff --git a/pages/demos/masonry.ts b/pages/demos/masonry.ts new file mode 100644 index 00000000..f6222ce9 --- /dev/null +++ b/pages/demos/masonry.ts @@ -0,0 +1,333 @@ +import { + layout, + prepareWithSegments, + type PreparedTextWithSegments, +} from '../../src/layout.ts' + +type CardItem = { + id: string + label: string + text: string + imageIndex: number +} + +type PreparedCard = { + id: string + prepared: PreparedTextWithSegments +} + +type RenderedCard = { + id: string + column: number + top: number + text: string + imageIndex: number +} + +type State = { + events: { + columnCount: number | null + } + columnCount: number +} + +const CARD_WIDTH = 280 +const LINE_HEIGHT = 22 +const CARD_PADDING_X = 20 +const CARD_PADDING_Y = 16 +const COLUMN_GAP = 20 +const TOP_MARGIN = 24 + +const FONT = '15px "Helvetica Neue", Helvetica, Arial, sans-serif' + +const rawCards: CardItem[] = [ + { + id: 'c1', + label: 'Architecture', + text: 'The building emerged from morning fog, its glass facade catching the first light. Steel beams and concrete formed a quiet dialogue with the mountains beyond.', + imageIndex: 0, + }, + { + id: 'c2', + label: ' ceramics', + text: 'Glazed vessels lined the shelf — pale blue, oxidized copper, ash white. Each one held the memory of hands and fire.', + imageIndex: 1, + }, + { + id: 'c3', + label: 'Letters', + text: 'She found the box in the attic, its contents undisturbed for decades. The handwriting was unfamiliar, the stamps exotic.', + imageIndex: 2, + }, + { + id: 'c4', + label: 'Morning', + text: 'The café opened at six. Steam rose from cups as commuters hurried past, each carrying their own quiet urgency.', + imageIndex: 3, + }, + { + id: 'c5', + label: 'Field Notes', + text: 'Observations from the research station: migration patterns, weather cycles, the patient work of cataloguing what endures.', + imageIndex: 4, + }, + { + id: 'c6', + label: 'Restoration', + text: 'The painting spent three years in the lab. Conservators uncovered layers beneath the varnish — an earlier version, almost forgotten.', + imageIndex: 5, + }, + { + id: 'c7', + label: 'Transit', + text: 'The train followed the river north. Farms gave way to forest, and the sky deepened into evening as the landscape changed.', + imageIndex: 6, + }, + { + id: 'c8', + label: 'Gathering', + text: 'The market filled the square. Merchants called their wares, families browsed, and the afternoon unfolded at its own pace.', + imageIndex: 7, + }, + { + id: 'c9', + label: 'Compost', + text: 'Turning the pile revealed earth, worms, and the slow alchemy of decay. What was waste became the soil for next season.', + imageIndex: 0, + }, + { + id: 'c10', + label: 'Survey', + text: 'The team mapped the coastline mile by mile. Cliffs, coves, tide pools — a landscape that resists easy description.', + imageIndex: 1, + }, + { + id: 'c11', + label: 'Candle', + text: 'The flame steadied as the room darkened. Shadows moved on the walls, and conversation found its natural rhythm.', + imageIndex: 2, + }, + { + id: 'c12', + label: 'Archive', + text: 'Files filled the basement shelves. Each folder held a negotiation, a decision, a moment when someone chose a particular path.', + imageIndex: 3, + }, + { + id: 'c13', + label: 'Evening', + text: 'The bridge crossed at dusk. Walkers shared the path, dogs pulled at leashes, and the city lights began to appear on the far shore.', + imageIndex: 4, + }, + { + id: 'c14', + label: 'Recipe', + text: 'Flour, butter, a generational knowledge of texture. The dough came together by feel, not measurement.', + imageIndex: 5, + }, + { + id: 'c15', + label: 'Mapping', + text: 'Streets appeared in layers — the citys present and past overlapping, one neighborhood named for a family, another for a trade.', + imageIndex: 6, + }, + { + id: 'c16', + label: 'Repair', + text: 'The mechanism had worn smooth. Oil, adjustment, patience — eventually it ran again, neither new nor broken.', + imageIndex: 7, + }, + { + id: 'c17', + label: 'Tide', + text: 'Low tide exposed the reef. Pools held small worlds — anemones, hermit crabs, the slow negotiation of salt and life.', + imageIndex: 0, + }, + { + id: 'c18', + label: 'Studio', + text: 'The space collected light from the north. Sketches covered the wall, and the day found its purpose in the materials at hand.', + imageIndex: 1, + }, +] + +const preparedCards: PreparedCard[] = rawCards.map(card => ({ + id: card.id, + prepared: prepareWithSegments(card.text, FONT), +})) + +const domCache = { + root: document.documentElement, + grid: getRequiredDiv('grid'), + columnSlider: getRequiredInput('column-slider'), + columnValue: getRequiredSpan('column-value'), +} + +const st: State = { + events: { + columnCount: null, + }, + columnCount: 2, +} + +let scheduledRaf: number | null = null + +if (document.readyState === 'loading') { + document.addEventListener('DOMContentLoaded', boot, { once: true }) +} else { + boot() +} + +function getRequiredDiv(id: string): HTMLDivElement { + const element = document.getElementById(id) + if (!(element instanceof HTMLDivElement)) throw new Error(`#${id} not found`) + return element +} + +function getRequiredInput(id: string): HTMLInputElement { + const element = document.getElementById(id) + if (!(element instanceof HTMLInputElement)) throw new Error(`#${id} not found`) + return element +} + +function getRequiredSpan(id: string): HTMLSpanElement { + const element = document.getElementById(id) + if (!(element instanceof HTMLSpanElement)) throw new Error(`#${id} not found`) + return element +} + +function computeCardHeight(prepared: PreparedTextWithSegments, maxWidth: number): number { + const metrics = layout(prepared, maxWidth, LINE_HEIGHT) + return Math.ceil(metrics.height) + CARD_PADDING_Y * 2 + 70 +} + +function layoutMasonry( + preparedCards: PreparedCard[], + columnCount: number, + viewportWidth: number, +): RenderedCard[] { + const columnWidth = Math.floor( + (viewportWidth - COLUMN_GAP * (columnCount - 1)) / columnCount, + ) + const contentWidth = columnWidth - CARD_PADDING_X * 2 + + const columnHeights = new Array(columnCount).fill(TOP_MARGIN) + const rendered: RenderedCard[] = [] + + for (let cardIndex = 0; cardIndex < preparedCards.length; cardIndex++) { + const card = preparedCards[cardIndex]! + const cardData = rawCards.find(c => c.id === card.id)! + + let minColumn = 0 + let minHeight = columnHeights[0]! + + for (let c = 1; c < columnCount; c++) { + if (columnHeights[c]! < minHeight) { + minColumn = c + minHeight = columnHeights[c]! + } + } + + const cardHeight = computeCardHeight(card.prepared, contentWidth) + columnHeights[minColumn] = minHeight + cardHeight + COLUMN_GAP + + rendered.push({ + id: card.id, + column: minColumn, + top: minHeight, + text: cardData.text, + imageIndex: cardData.imageIndex, + }) + } + + return rendered +} + +function renderGrid(cards: RenderedCard[], columnCount: number, viewportWidth: number): void { + const grid = domCache.grid + grid.textContent = '' + + const columnWidth = Math.floor( + (viewportWidth - COLUMN_GAP * (columnCount - 1)) / columnCount, + ) + + const fragment = document.createDocumentFragment() + + for (let cardIndex = 0; cardIndex < cards.length; cardIndex++) { + const card = cards[cardIndex]! + const cardElement = document.createElement('div') + cardElement.className = 'masonry-card' + cardElement.style.setProperty('--card-width', `${columnWidth}px`) + cardElement.style.setProperty('--card-left', `${card.column * (columnWidth + COLUMN_GAP)}px`) + cardElement.style.setProperty('--card-top', `${card.top}px`) + + const labelEl = document.createElement('span') + labelEl.className = 'card-label' + const cardData = rawCards.find(c => c.id === card.id)! + labelEl.textContent = cardData.label + + const imageBlock = document.createElement('div') + imageBlock.className = 'card-image' + imageBlock.style.setProperty('background-color', `var(--color-${(card.imageIndex % 8) + 1})`) + + const textEl = document.createElement('p') + textEl.className = 'card-text' + textEl.textContent = card.text + + cardElement.appendChild(imageBlock) + cardElement.appendChild(labelEl) + cardElement.appendChild(textEl) + fragment.appendChild(cardElement) + } + + grid.appendChild(fragment) +} + +function scheduleRender(): void { + if (scheduledRaf !== null) return + scheduledRaf = requestAnimationFrame(function renderFrame() { + scheduledRaf = null + render() + }) +} + +function boot(): void { + domCache.columnSlider.addEventListener('input', () => { + const value = Number.parseInt(domCache.columnSlider.value, 10) + st.events.columnCount = value + scheduleRender() + }) + + window.addEventListener('resize', () => { + scheduleRender() + }) + + document.fonts.ready.then(() => { + scheduleRender() + }) + + scheduleRender() +} + +function render(): void { + const viewportWidth = document.documentElement.clientWidth + + let columnCount = st.columnCount + if (st.events.columnCount !== null) { + columnCount = st.events.columnCount + st.columnCount = columnCount + st.events.columnCount = null + } + + const minColumns = Math.max(1, Math.floor(viewportWidth / (CARD_WIDTH + COLUMN_GAP))) + const maxColumns = Math.max(1, Math.floor(viewportWidth / (CARD_WIDTH * 0.5 + COLUMN_GAP))) + const clampedColumns = Math.max(minColumns, Math.min(maxColumns, columnCount)) + + domCache.columnSlider.min = String(minColumns) + domCache.columnSlider.max = String(maxColumns) + domCache.columnSlider.value = String(clampedColumns) + domCache.columnValue.textContent = `${clampedColumns}` + + const cards = layoutMasonry(preparedCards, clampedColumns, viewportWidth) + renderGrid(cards, clampedColumns, viewportWidth) +} \ No newline at end of file