/**
* Provides tools for the layer concept.
* @module layer
* @license MIT
*
* @copyright 2011 Jeff Schiller, 2016 Flint O'Brien
*/
import { NS } from './namespaces.js'
import { toXml, walkTree } from './utilities.js'
/**
* This class encapsulates the concept of a layer in the drawing. It can be constructed with
* an existing group element or, with three parameters, will create a new layer group element.
*
* @example
* const l1 = new Layer('name', group); // Use the existing group for this layer.
* const l2 = new Layer('name', group, svgElem); // Create a new group and add it to the DOM after group.
* const l3 = new Layer('name', null, svgElem); // Create a new group and add it to the DOM as the last layer.
* @memberof module:layer
*/
class Layer {
/**
* @param {string} name - Layer name
* @param {SVGGElement|null} group - An existing SVG group element or null.
* If group and no svgElem, use group for this layer.
* If group and svgElem, create a new group element and insert it in the DOM after group.
* If no group and svgElem, create a new group element and insert it in the DOM as the last layer.
* @param {SVGGElement} [svgElem] - The SVG DOM element. If defined, use this to add
* a new layer to the document.
*/
constructor (name, group, svgElem) {
this.name_ = name
this.group_ = svgElem ? null : group
if (svgElem) {
// Create a group element with title and add it to the DOM.
const svgdoc = svgElem.ownerDocument
this.group_ = svgdoc.createElementNS(NS.SVG, 'g')
const layerTitle = svgdoc.createElementNS(NS.SVG, 'title')
layerTitle.textContent = name
this.group_.append(layerTitle)
if (group) {
group.insertAdjacentElement('afterend', this.group_)
} else {
svgElem.append(this.group_)
}
}
addLayerClass(this.group_)
walkTree(this.group_, function (e) {
e.setAttribute('style', 'pointer-events:inherit')
})
this.group_.setAttribute('style', svgElem ? 'pointer-events:all' : 'pointer-events:none')
}
/**
* Get the layer's name.
* @returns {string} The layer name
*/
getName () {
return this.name_
}
/**
* Get the group element for this layer.
* @returns {SVGGElement} The layer SVG group
*/
getGroup () {
return this.group_
}
/**
* Active this layer so it takes pointer events.
* @returns {void}
*/
activate () {
this.group_.setAttribute('style', 'pointer-events:all')
}
/**
* Deactive this layer so it does NOT take pointer events.
* @returns {void}
*/
deactivate () {
this.group_.setAttribute('style', 'pointer-events:none')
}
/**
* Set this layer visible or hidden based on 'visible' parameter.
* @param {boolean} visible - If true, make visible; otherwise, hide it.
* @returns {void}
*/
setVisible (visible) {
const expected = visible === undefined || visible ? 'inline' : 'none'
const oldDisplay = this.group_.getAttribute('display')
if (oldDisplay !== expected) {
this.group_.setAttribute('display', expected)
}
}
/**
* Is this layer visible?
* @returns {boolean} True if visible.
*/
isVisible () {
return this.group_.getAttribute('display') !== 'none'
}
/**
* Get layer opacity.
* @returns {Float} Opacity value.
*/
getOpacity () {
const opacity = this.group_.getAttribute('opacity')
if (!opacity) {
return 1
}
return Number.parseFloat(opacity)
}
/**
* Sets the opacity of this layer. If opacity is not a value between 0.0 and 1.0,
* nothing happens.
* @param {Float} opacity - A float value in the range 0.0-1.0
* @returns {void}
*/
setOpacity (opacity) {
if (typeof opacity === 'number' && opacity >= 0.0 && opacity <= 1.0) {
this.group_.setAttribute('opacity', opacity)
}
}
/**
* Append children to this layer.
* @param {SVGGElement} children - The children to append to this layer.
* @returns {void}
*/
appendChildren (children) {
for (const child of children) {
this.group_.append(child)
}
}
/**
* @returns {SVGTitleElement|null}
*/
getTitleElement () {
const len = this.group_.childNodes.length
for (let i = 0; i < len; ++i) {
const child = this.group_.childNodes.item(i)
if (child?.tagName === 'title') {
return child
}
}
return null
}
/**
* Set the name of this layer.
* @param {string} name - The new name.
* @param {module:history.HistoryRecordingService} hrService - History recording service
* @returns {string|null} The new name if changed; otherwise, null.
*/
setName (name, hrService) {
const previousName = this.name_
name = toXml(name)
// now change the underlying title element contents
const title = this.getTitleElement()
if (title) {
while (title.firstChild) { title.removeChild(title.firstChild) }
title.textContent = name
this.name_ = name
if (hrService) {
hrService.changeElement(title, { '#text': previousName })
}
return this.name_
}
return null
}
/**
* Remove this layer's group from the DOM. No more functions on group can be called after this.
* @returns {SVGGElement} The layer SVG group that was just removed.
*/
removeGroup () {
const group = this.group_
this.group_.remove()
this.group_ = undefined
return group
}
/**
* Test whether an element is a layer or not.
* @param {SVGGElement} elem - The SVGGElement to test.
* @returns {boolean} True if the element is a layer
*/
static isLayer (elem) {
return elem && elem.tagName === 'g' && Layer.CLASS_REGEX.test(elem.getAttribute('class'))
}
}
/**
* @property {string} CLASS_NAME - class attribute assigned to all layer groups.
*/
Layer.CLASS_NAME = 'layer'
/**
* @property {RegExp} CLASS_REGEX - Used to test presence of class Layer.CLASS_NAME
*/
Layer.CLASS_REGEX = new RegExp('(\\s|^)' + Layer.CLASS_NAME + '(\\s|$)')
/**
* Add class `Layer.CLASS_NAME` to the element (usually `class='layer'`).
*
* @param {SVGGElement} elem - The SVG element to update
* @returns {void}
*/
function addLayerClass (elem) {
const classes = elem.getAttribute('class')
if (!classes || !classes.length) {
elem.setAttribute('class', Layer.CLASS_NAME)
} else if (!Layer.CLASS_REGEX.test(classes)) {
elem.setAttribute('class', classes + ' ' + Layer.CLASS_NAME)
}
}
export default Layer