Nimage/src/viewer/render.ts at main · NeaByteLab/Nimage · GitHub

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import type * as Types from '@app/types.ts'

import * as Viewer from '@app/viewer/index.ts'

import Shared from '@app/shared.ts'

/**

* Viewer render layer.

* @description Draws the overlay and handles navigation.

export class Render extends Viewer.State {

/** Close the viewer overlay */

close(): void {

this.isOpen = false

this.stopSlideshow()

this.resetTransform()

this.overlay.classList.remove('nimg-open')

document.body.style.overflow = ''

if (document.fullscreenElement !== null) {

document.exitFullscreen().catch(() => {})

}

if (this.triggerElement !== null) {

this.triggerElement.focus()

this.triggerElement = null

}

/** Destroy the viewer and free listeners */

destroy(): void {

this.close()

this.abortController.abort()

this.overlay.remove()

this.popover.remove()

}

/**

* Go to a specific item.

* @description Loads the item when the index is valid.

* @param targetIndex - Index of the item to show

goTo(targetIndex: number): void {

if (targetIndex < 0 || targetIndex >= this.items.length) {

return

}

this.currentIndex = targetIndex

this.loadImage(targetIndex)

this.syncStrip()

}

/** Advance to the next item */

next(): void {

if (this.currentIndex < this.items.length - 1) {

this.currentIndex += 1

this.loadImage(this.currentIndex)

} else if (this.options.loopEnabled) {

this.currentIndex = 0

this.loadImage(this.currentIndex)

} else {

return

}

this.syncStrip()

}

/**

* Open a group in the viewer.

* @description Activates the overlay at the start index.

* @param startIndex - Index to open at

* @param groupName - Group name to open

open(startIndex = 0, groupName = 'default'): void {

const groupItems = this.groups.get(groupName)

if (groupItems === undefined || groupItems.length === 0) {

return

}

const activeElement = document.activeElement

this.triggerElement = activeElement instanceof HTMLElement ? activeElement : null

this.items = groupItems

this.currentIndex = Shared.clamp(startIndex, 0, groupItems.length - 1)

this.isOpen = true

this.hidePopover()

this.buildStrip()

this.overlay.classList.add('nimg-open')

document.body.style.overflow = 'hidden'

this.loadImage(this.currentIndex)

this.updateNav()

this.overlay.focus()

}

/** Go back to the previous item */

prev(): void {

if (this.currentIndex > 0) {

this.currentIndex -= 1

this.loadImage(this.currentIndex)

} else if (this.options.loopEnabled) {

this.currentIndex = this.items.length - 1

this.loadImage(this.currentIndex)

} else {

return

}

this.syncStrip()

}

/**

* Replace a group with new items.

* @description Stores the items under the group name.

* @param groupName - Group name to set

* @param items - Gallery items for the group

setGroup(groupName: string, items: Types.GalleryItem[]): void {

this.groups.set(groupName, items)

}

/** Apply the current transform to the image */

protected applyTransform(): void {

this.imageElement.style.transform =

`translate(${this.translateX}px, ${this.translateY}px) scale(${this.currentScale})`

this.imageElement.classList.toggle('nimg-zoomed', this.currentScale > 1)

}

/** Build the thumbnail strip */

protected buildStrip(): void {

this.strip.innerHTML = ''

this.thumbElements = this.items.map((galleryItem, itemIndex) => {

const thumbNode = Shared.create('img', 'nimg-thumb')

thumbNode.src = galleryItem.thumbSrc

thumbNode.alt = galleryItem.altText

thumbNode.loading = 'lazy'

thumbNode.decoding = 'async'

thumbNode.addEventListener('click', () => {

this.goTo(itemIndex)

}, { signal: this.abortController.signal })

this.strip.appendChild(thumbNode)

return thumbNode

})

this.syncStrip()

}

/** Download the current image */

protected downloadImage(): void {

const galleryItem = this.items[this.currentIndex]

if (galleryItem === undefined) {

return

}

const downloadLink = document.createElement('a')

downloadLink.href = galleryItem.imageSrc

downloadLink.download = (galleryItem.altText || 'image').replace(/[^\w.-]+/g, '_') || 'image'

downloadLink.rel = 'noopener'

document.body.appendChild(downloadLink)

downloadLink.click()

downloadLink.remove()

}

/** Hide the hover preview popover */

protected hidePopover(): void {

this.popover.classList.remove('nimg-visible')

}

/**

* Load an image into the viewer.

* @description Shows a spinner then swaps in the image.

* @param targetIndex - Index of the item to load

protected loadImage(targetIndex: number): void {

const galleryItem = this.items[targetIndex]

if (galleryItem === undefined) {

return

}

this.resetTransform()

this.showSpinner(true)

const loaderImage = new Image()

loaderImage.decoding = 'async'

loaderImage.onload = () => {

this.imageElement.src = galleryItem.imageSrc

this.imageElement.alt = galleryItem.altText

this.showSpinner(false)

}

loaderImage.onerror = () => {

this.showSpinner(false)

this.imageElement.alt = 'Failed to load'

}

loaderImage.src = galleryItem.imageSrc

this.titleElement.textContent = galleryItem.altText

this.counterElement.textContent = `${targetIndex + 1} / ${this.items.length}`

this.preloadNeighbour(targetIndex + 1)

this.preloadNeighbour(targetIndex - 1)

}

/**

* Move the hover preview popover.

* @description Positions the popover near the pointer.

* @param pointerEvent - Mouse event driving the position

protected movePopover(pointerEvent: MouseEvent): void {

if (!this.popover.classList.contains('nimg-visible')) {

return

}

const edgePadding = 16

const popoverRect = this.popover.getBoundingClientRect()

let posX = pointerEvent.clientX + edgePadding

let posY = pointerEvent.clientY + edgePadding

if (posX + popoverRect.width > globalThis.innerWidth) {

posX = pointerEvent.clientX - popoverRect.width - edgePadding

}

if (posY + popoverRect.height > globalThis.innerHeight) {

posY = pointerEvent.clientY - popoverRect.height - edgePadding

}

this.popover.style.left = `${Math.max(edgePadding, posX)}px`

this.popover.style.top = `${Math.max(edgePadding, posY)}px`

}

/**

* Preload a neighbouring image.

* @description Warms the browser cache for the item.

* @param targetIndex - Index of the neighbour to preload

protected preloadNeighbour(targetIndex: number): void {

const galleryItem = this.items[targetIndex]

if (galleryItem === undefined) {

return

}

const preloadImage = new Image()

preloadImage.src = galleryItem.imageSrc

}

/** Reset zoom scale and translation */

protected resetTransform(): void {

this.currentScale = 1

this.translateX = 0

this.translateY = 0

this.imageElement.classList.remove('nimg-zoomed', 'nimg-dragging')

this.applyTransform()

}

/** Run the slideshow progress bar */

protected runProgress(): void {

if (this.progressFrame !== null) {

globalThis.cancelAnimationFrame(this.progressFrame)

}

Shared.runProgress(

this.progressBar,

this.options.slideshowInterval,

() => this.slideshowTimer !== null,

(frameId) => {

this.progressFrame = frameId

}

)

}

/**

* Show the hover preview popover.

* @description Displays the full image near the pointer.

* @param pointerEvent - Mouse event driving the position

* @param imageSrc - Image source to preview

protected showPopover(pointerEvent: MouseEvent, imageSrc: string): void {

if (this.isOpen) {

return

}

this.popoverImage.src = imageSrc

this.popover.classList.add('nimg-visible')

this.movePopover(pointerEvent)

}

/**

* Toggle the loading spinner.

* @description Shows or hides the spinner element.

* @param shouldShow - Whether the spinner is visible

protected showSpinner(shouldShow: boolean): void {

this.spinner.classList.toggle('nimg-visible', shouldShow)

}

/** Start the slideshow autoplay */

protected startSlideshow(): void {

if (this.items.length < 2) {

return

}

this.playButton.innerHTML = Shared.customIcons.pause

this.playButton.classList.add('nimg-active')

this.runProgress()

this.slideshowTimer = globalThis.setInterval(() => {

this.next()

this.runProgress()

}, this.options.slideshowInterval)

}

/** Stop the slideshow autoplay */

protected stopSlideshow(): void {

if (this.slideshowTimer !== null) {

globalThis.clearInterval(this.slideshowTimer)

}

this.slideshowTimer = null

if (this.progressFrame !== null) {

globalThis.cancelAnimationFrame(this.progressFrame)

}

this.progressBar.style.width = '0'

this.playButton.innerHTML = Shared.customIcons.play

this.playButton.classList.remove('nimg-active')

}

/** Sync thumbnail active state and labels */

protected syncStrip(): void {

if (this.thumbElements.length === 0) {

return

}

this.thumbElements.forEach((thumbNode, itemIndex) => {

const isActive = itemIndex === this.currentIndex

thumbNode.classList.toggle('nimg-active', isActive)

if (isActive) {

thumbNode.scrollIntoView({ inline: 'center', block: 'nearest', behavior: 'smooth' })

}

})

const activeItem = this.items[this.currentIndex]

this.counterElement.textContent = `${this.currentIndex + 1} / ${this.items.length}`

this.titleElement.textContent = activeItem !== undefined ? activeItem.altText : ''

}

/** Toggle fullscreen for the overlay */

protected toggleFullscreen(): void {

if (document.fullscreenElement !== null) {

document.exitFullscreen().catch(() => {})

} else {

this.overlay.requestFullscreen().catch(() => {})

}

/** Toggle the slideshow on or off */

protected toggleSlideshow(): void {

if (this.slideshowTimer !== null) {

this.stopSlideshow()

} else {

this.startSlideshow()

}

/** Update navigation and strip visibility */

protected updateNav(): void {

const hasMultiple = this.items.length > 1

this.prevButton.style.display = hasMultiple ? '' : 'none'

this.nextButton.style.display = hasMultiple ? '' : 'none'

this.playButton.style.display = hasMultiple ? '' : 'none'

const showStrip = hasMultiple && this.options.thumbnailsEnabled

this.strip.style.display = showStrip ? '' : 'none'

}

/**

* Change the image zoom scale.

* @description Zooms toward a point and clamps the scale.

* @param deltaScale - Amount to change the scale by

* @param pointerX - Optional pointer x to zoom toward

* @param pointerY - Optional pointer y to zoom toward

protected zoom(deltaScale: number, pointerX?: number, pointerY?: number): void {

const previousScale = this.currentScale

this.currentScale = Shared.clamp(

this.currentScale + deltaScale,

this.options.minZoom,

this.options.maxZoom

)

if (this.currentScale === previousScale) {

return

}

if (pointerX !== undefined && pointerY !== undefined && previousScale > 0) {

const stageRect = this.stage.getBoundingClientRect()

const offsetX = pointerX - stageRect.left - stageRect.width / 2

const offsetY = pointerY - stageRect.top - stageRect.height / 2

const scaleRatio = this.currentScale / previousScale

this.translateX = offsetX - (offsetX - this.translateX) * scaleRatio

this.translateY = offsetY - (offsetY - this.translateY) * scaleRatio

}

if (this.currentScale === 1) {

this.translateX = 0

this.translateY = 0

}

this.applyTransform()

}

Nimage/src/viewer/render.ts at main · NeaByteLab/Nimage · GitHub

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