svgedit/src/editor/extensions/ext-grid/ext-grid.js

/**
 * @file ext-grid.js
 *
 * @license Apache-2.0
 *
 * @copyright 2010 Redou Mine, 2010 Alexis Deveria
 *
 */

const name = 'grid'

const loadExtensionTranslation = async function (svgEditor) {
  let translationModule
  const lang = svgEditor.configObj.pref('lang')
  try {
    translationModule = await import(`./locale/${lang}.js`)
  } catch (_error) {
    console.warn(`Missing translation (${lang}) for ${name} - using 'en'`)
    translationModule = await import('./locale/en.js')
  }
  svgEditor.i18next.addResourceBundle(lang, name, translationModule.default)
}

export default {
  name,
  async init () {
    const svgEditor = this
    await loadExtensionTranslation(svgEditor)
    const { svgCanvas } = svgEditor
    const { $id, NS } = svgCanvas
    const svgdoc = $id('svgcanvas').ownerDocument
    const { assignAttributes } = svgCanvas
    const hcanvas = document.createElement('canvas')
    const canvBG = $id('canvasBackground')
    const units = svgCanvas.getTypeMap() // Assumes prior `init()` call on `units.js` module
    const intervals = [0.01, 0.1, 1, 10, 100, 1000]
    let showGrid = svgEditor.configObj.curConfig.showGrid || false

    hcanvas.style.display = 'none'
    svgEditor.$svgEditor.appendChild(hcanvas)

    const canvasGrid = svgdoc.createElementNS(NS.SVG, 'svg')
    assignAttributes(canvasGrid, {
      id: 'canvasGrid',
      width: '100%',
      height: '100%',
      x: 0,
      y: 0,
      overflow: 'visible',
      display: 'none'
    })
    canvBG.appendChild(canvasGrid)
    const gridDefs = svgdoc.createElementNS(NS.SVG, 'defs')
    // grid-pattern
    const gridPattern = svgdoc.createElementNS(NS.SVG, 'pattern')
    assignAttributes(gridPattern, {
      id: 'gridpattern',
      patternUnits: 'userSpaceOnUse',
      x: 0, // -(value.strokeWidth / 2), // position for strokewidth
      y: 0, // -(value.strokeWidth / 2), // position for strokewidth
      width: 100,
      height: 100
    })

    const gridimg = svgdoc.createElementNS(NS.SVG, 'image')
    assignAttributes(gridimg, {
      x: 0,
      y: 0,
      width: 100,
      height: 100
    })
    gridPattern.append(gridimg)
    gridDefs.append(gridPattern)
    $id('canvasGrid').appendChild(gridDefs)

    // grid-box
    const gridBox = svgdoc.createElementNS(NS.SVG, 'rect')
    assignAttributes(gridBox, {
      width: '100%',
      height: '100%',
      x: 0,
      y: 0,
      'stroke-width': 0,
      stroke: 'none',
      fill: 'url(#gridpattern)',
      style: 'pointer-events: none; display:visible;'
    })
    $id('canvasGrid').appendChild(gridBox)

    /**
     *
     * @param {Float} zoom
     * @returns {void}
     */
    const updateGrid = (zoom) => {
      // TODO: Try this with <line> elements, then compare performance difference
      const unit = units[svgEditor.configObj.curConfig.baseUnit] // 1 = 1px
      const uMulti = unit * zoom
      // Calculate the main number interval
      const rawM = 100 / uMulti
      let multi = 1
      intervals.some((num) => {
        multi = num
        return rawM <= num
      })
      const bigInt = multi * uMulti

      // Set the canvas size to the width of the container
      hcanvas.width = bigInt
      hcanvas.height = bigInt
      const ctx = hcanvas.getContext('2d')
      const curD = 0.5
      const part = bigInt / 10

      ctx.globalAlpha = 0.2
      ctx.strokeStyle = svgEditor.configObj.curConfig.gridColor
      for (let i = 1; i < 10; i++) {
        const subD = Math.round(part * i) + 0.5
        // const lineNum = (i % 2)?12:10;
        const lineNum = 0
        ctx.moveTo(subD, bigInt)
        ctx.lineTo(subD, lineNum)
        ctx.moveTo(bigInt, subD)
        ctx.lineTo(lineNum, subD)
      }
      ctx.stroke()
      ctx.beginPath()
      ctx.globalAlpha = 0.5
      ctx.moveTo(curD, bigInt)
      ctx.lineTo(curD, 0)

      ctx.moveTo(bigInt, curD)
      ctx.lineTo(0, curD)
      ctx.stroke()

      const datauri = hcanvas.toDataURL('image/png')
      gridimg.setAttribute('width', bigInt)
      gridimg.setAttribute('height', bigInt)
      gridimg.parentNode.setAttribute('width', bigInt)
      gridimg.parentNode.setAttribute('height', bigInt)
      svgCanvas.setHref(gridimg, datauri)
    }

    /**
     *
     * @returns {void}
     */
    const gridUpdate = () => {
      if (showGrid) {
        updateGrid(svgCanvas.getZoom())
      }
      $id('canvasGrid').style.display = (showGrid) ? 'block' : 'none'
      $id('view_grid').pressed = showGrid
    }
    return {
      name: svgEditor.i18next.t(`${name}:name`),
      zoomChanged (zoom) {
        if (showGrid) { updateGrid(zoom) }
      },
      callback () {
        // Add the button and its handler(s)
        const buttonTemplate = document.createElement('template')
        const title = `${name}:buttons.0.title`
        buttonTemplate.innerHTML = `
          <se-button id="view_grid" title="${title}" src="grid.svg"></se-button>
        `
        $id('editor_panel').append(buttonTemplate.content.cloneNode(true))
        $id('view_grid').addEventListener('click', () => {
          svgEditor.configObj.curConfig.showGrid = showGrid = !showGrid
          gridUpdate()
        })
        if (showGrid) {
          gridUpdate()
        }
      }
    }
  }
}