Export text on path to SVG

[qaywsx22]

Hello, an export a text on path to SVG is not working.
Test case:
https://jsfiddle.net/meugen22/ojatr2cL/5/

[asturur]

The only implementation of svg textpath that works across firefox and chrome is the hardest one to replicate.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[hoomanaskari]

Okay, I have made some progress on this one, while it works, there are some things I am having trouble getting right.
pathSide right now only works in FF, so I don't know what to do with it. Also the size of the SVG, I have no idea how to accurately calculate it. Either way, here is my code:

My guess was that for fabric.Text we would not need tspan element in the SVG export. After getting rid of those, it was a simple solution. I am still not sure about the side effects of the following approach.

fabric.Text.prototype.toSVG = function (reviver) {
  if (this.type === 'text') {
    var noShadow = true,
      textDecoration = this.getSvgTextDecoration(this);

    var pathString = '';

    this.path?.path.forEach(p => {
      pathString += p.join(' ');
      pathString += ', ';
    });

    return this._createBaseSVGMarkup(
      this.path?.path ?
        [
          '<defs>',
          '<path id="textOnPathId" fill="none" stroke="none" d="',
          pathString,
          '" />',
          '</defs>',
          '\t\t<text xml:space="preserve" ',
          (this.fontFamily ? 'font-family="' + this.fontFamily.replace(/"/g, '\'') + '" ' : ''),
          (this.fontSize ? 'font-size="' + this.fontSize + '" ' : ''),
          (this.fontStyle ? 'font-style="' + this.fontStyle + '" ' : ''),
          (this.fontWeight ? 'font-weight="' + this.fontWeight + '" ' : ''),
          (textDecoration ? 'text-decoration="' + textDecoration + '" ' : ''),
          'style="', this.getSvgStyles(noShadow), '"', this.addPaintOrder(), ' >',
          '<textPath side="',
          this.pathSide,
          '" href="#textOnPathId">',
          this.text,
          '</textPath>',
          '</text>\n'
        ]
      :
        [
          '\t\t<text xml:space="preserve" ',
          (this.fontFamily ? 'font-family="' + this.fontFamily.replace(/"/g, '\'') + '" ' : ''),
          (this.fontSize ? 'font-size="' + this.fontSize + '" ' : ''),
          (this.fontStyle ? 'font-style="' + this.fontStyle + '" ' : ''),
          (this.fontWeight ? 'font-weight="' + this.fontWeight + '" ' : ''),
          (textDecoration ? 'text-decoration="' + textDecoration + '" ' : ''),
          'style="', this.getSvgStyles(noShadow), '"', this.addPaintOrder(), ' >',
          this.text,
          '</text>\n'
        ],
      { reviver: reviver, noStyle: true, withShadow: true }
    );
  } else {
    return this._createBaseSVGMarkup(
      this._toSVG(),
      { reviver: reviver, noStyle: true, withShadow: true }
    );
  }
};

[asturur]

great! textOnPathId needs to be mixed with this.__uid in order to don't clash with multiple text on path on the same svg.

Also there is a common part of text code that we can reuse, right?

If you manage to get a single color, single path example working, open a PR. I m sure for styles and tSpan will be more complicated

[khajaamin]

facing same issue here
https://web-platform-n8kzvg.stackblitz.io

you can check using developer tool console with below command - Please add text and then run in console

canvas.loadFromJSON(canvas.toJSON(['p1', 'p0', 'p2', 'line','canvas']))

This command should add same components again

[ramonortigosa]

Hello!
Is there any improvement on this?

[nagendra-y]

https://jsfiddle.net/3btoymjd/

Does this help? Used hoomanaskari's approach and some transformations. Need to think of a bounding rect or something to make it generalise

[mudassirali007]

Added more parameters.
side="right" will work on Firefox.

fabric.Text.prototype.toSVG = function (reviver) {
    if (this.path) {
        var noShadow = true,
            textDecoration = this.getSvgTextDecoration(this);

        var pathString = this.path?.path
            .map(function (segment) {
                return segment.join(" ");
            })
            .join(" ");
        const id = Math.random().toString(36).substr(2, 9);

        return this._createBaseSVGMarkup(
            this.path?.path
                ? [
                    "<defs>",
                    '<path id="textOnPath' + id + '" fill="none" stroke="none" d="',
                    pathString,
                    '" />',
                    "</defs>\n",
                    '<text xml:space="preserve" ',
                    this.fontFamily
                        ? 'font-family="' + this.fontFamily.replace(/"/g, "'") + '" '
                        : "",
                    this.fontSize ? 'font-size="' + this.fontSize + '" ' : "",
                    this.fontStyle ? 'font-style="' + this.fontStyle + '" ' : "",
                    this.fontWeight ? 'font-weight="' + this.fontWeight + '" ' : "",
                    textDecoration ? 'text-decoration="' + textDecoration + '" ' : "",
                    'style="',
                    this.getSvgStyles(noShadow),
                    '"',
                    this.addPaintOrder(),
                    " >\n",
                    '<textPath side="' + this.pathSide + '" ',
                    'startOffset="' + this.pathStartOffset + '" ',
                    'href="#textOnPath' + id + '" ',
                    'xlink:href="#textOnPath' + id + '"> ',
                    this.text,
                    "</textPath>\n",
                    "</text>\n",
                ]
                : [
                    '\t\t<text xml:space="preserve" ',
                    this.fontFamily
                        ? 'font-family="' + this.fontFamily.replace(/"/g, "'") + '" '
                        : "",
                    this.fontSize ? 'font-size="' + this.fontSize + '" ' : "",
                    this.fontStyle ? 'font-style="' + this.fontStyle + '" ' : "",
                    this.fontWeight ? 'font-weight="' + this.fontWeight + '" ' : "",
                    textDecoration ? 'text-decoration="' + textDecoration + '" ' : "",
                    'style="',
                    this.getSvgStyles(noShadow),
                    '"',
                    this.addPaintOrder(),
                    " >",
                    this.text,
                    "</text>\n",
                ],
            { reviver: reviver, noStyle: true, withShadow: true }
        );
    } else {
        return this._createBaseSVGMarkup(this._toSVG(), {
            reviver: reviver,
            noStyle: true,
            withShadow: true,
        });
    }
};

[herrstrietzel]

Based on hoomanaskari's and mudassirali007's approaches - You might also add a function to reverse path direction.

This way we get a workaround for the unsupported "side" attribute (at least in chromium).
Besides, I added some conditions to translate fabric.js baseline alignment options to svg's dominant-basline values.

fabric.Text.prototype.toSVG = function (reviver) {
  let fontFamily = this.fontFamily.replace(/"/g, "'");
  let fontSize = this.fontSize;
  let fontStyle = this.fontStyle;
  let fontWeight = this.fontWeight;
  let fill = this.fill;

  if (this.path) {
    let path = this.path;
    let fillPath = path.fill ? path.fill : "none";
    let strokePath = path.stroke ? path.stroke : "none";
    let strokeWidth = path.strokeWidth ? path.strokeWidth : 0;

    // get path length
    let pathData = this.path.path;
    let pathInfo = fabric.util.getPathSegmentsInfo(pathData);
    let pathLength = pathInfo[pathInfo.length - 1].length;

    // reverse pathdata to emulate side="right"
    if (this.pathSide === "right") {
      // clone pathdata for reversing
      pathData = JSON.parse(JSON.stringify(pathData));
      pathData = reversePathData(pathData);
    }
    // get pathdata d string
    let d = pathData.flat().join(" ");

    let id = Math.random().toString(36).substr(2, 9);
    let dominantbaseline = "auto";
    let pathStartOffset = this.pathStartOffset;
    let dy = 0;

    // translate fabric.js baseline offsets to svg dominant baseline values
    if (this.pathAlign === "center") {
      dominantbaseline = "middle";
    } else if (this.pathAlign === "baseline") {
      dominantbaseline = "auto";
    } else if (this.pathAlign === "ascender") {
      dominantbaseline = "hanging";
    } else if (this.pathAlign === "descender") {
      dominantbaseline = "auto";
      dy = (fontSize / 100) * -22;
    }

    let textAnchor = "start";
    if (this.textAlign == "center") {
      textAnchor = "middle";
      pathStartOffset += pathLength / 2;
    }

    if (this.textAlign == "right") {
      textAnchor = "end";
      pathStartOffset += pathLength;
    }

    // append texpath to defs or as rendered element
    let textPathEl;
    if (
      (fillPath && fillPath !== "none") ||
      (!strokePath && strokePath !== "none")
    ) {
      textPathEl = `<path id="textOnPath${id}" fill="${fillPath}" stroke="${strokePath}" stroke-width="${strokeWidth}" d="${d}" />`;
    } else {
      textPathEl = `<defs>
        <path id="textOnPath${id}" d="${d}" />
      </defs>`;
    }

    return this._createBaseSVGMarkup(
      this.path?.path
        ? [
            textPathEl,
            `<text 
              font-family="${fontFamily.replace(/"/g, "'")}" 
              fill="${fill}"
              font-size="${fontSize}" 
              font-style="${fontStyle}" 
              font-weight="${fontWeight}"
              >
                <textPath text-anchor="${textAnchor}" 
                dominant-baseline="${dominantbaseline}" 
                startOffset="${pathStartOffset}" 
                href="#textOnPath${id}" 
                xlink:href="#textOnPath${id}"> 
                <tspan dy="${dy}">${this.text}</tspan>
                </textPath>
              </text>`
          ]
        : [
            `<text 
            xml:space="preserve" 
            font-family="${fontFamily}" 
            font-size="${fontSize}" 
            font-style="${fontStyle}" 
            font-weight="${fontWeight}" 
            > 
            ${this.addPaintOrder()}
            ${this.text}
            </text>`
          ],
      { reviver: reviver, noStyle: true, withShadow: true }
    );
  } else {
    return this._createBaseSVGMarkup(this._toSVG(), {
      reviver: reviver,
      noStyle: true,
      withShadow: true
    });
  }
};

/**
 * Reverse pathdata
 */
function reversePathData(pathData) {
  // start compiling new path data
  let pathDataNew = [];

  // helper to rearrange control points for all command types
  const reverseControlPoints = (values) => {
    let controlPoints = [];
    let endPoint = [];
    for (let p = 0; p < values.length; p += 2) {
      controlPoints.push([values[p], values[p + 1]]);
    }
    endPoint = controlPoints.pop();
    controlPoints.reverse();
    return [controlPoints, endPoint];
  };

  let closed =
    pathData[pathData.length - 1][0].toLowerCase() === "z" ? true : false;
  if (closed) {
    // add lineto closing space between Z and M
    pathData = addClosePathLineto(pathData);
    // remove Z closepath
    pathData.pop();
  }

  // define last point as new M if path isn't closed
  let valuesLast = pathData[pathData.length - 1];
  let valuesLastL = valuesLast.length;
  let M = closed
    ? pathData[0]
    : ["M", valuesLast[valuesLastL - 2], valuesLast[valuesLastL - 1]];
  // starting M stays the same – unless the path is not closed
  pathDataNew.push(M);

  // reverse path data command order for processing
  pathData.reverse();
  for (let i = 1; i < pathData.length; i++) {
    let com = pathData[i];
    let values = com.slice(1);
    let comPrev = pathData[i - 1];
    let typePrev = comPrev[0];
    let valuesPrev = comPrev.slice(1);
    // get reversed control points and new end coordinates
    let [controlPointsPrev, endPointsPrev] = reverseControlPoints(valuesPrev);
    let [controlPoints, endPoints] = reverseControlPoints(values);

    // create new path data
    let newValues = [];
    newValues = controlPointsPrev.flat().concat(endPoints);
    pathDataNew.push([typePrev, ...newValues]);
  }

  // add previously removed Z close path
  if (closed) {
    pathDataNew.push(["z"]);
  }
  return pathDataNew;
}

/**
 * Add closing lineto:
 * needed for path reversing or adding points
 */
function addClosePathLineto(pathData) {
  let pathDataL = pathData.length;
  let closed = pathData[pathDataL - 1][0] === "Z";
  let M = pathData[0];
  let [x0, y0] = [M[1], M[2]];
  let lastCom = closed ? pathData[pathDataL - 2] : pathData[pathDataL - 1];
  let lastComL = lastCom.length;
  let [xE, yE] = [lastCom[lastComL - 2], lastCom[lastComL - 1]];
  if (closed && (x0 !== xE || y0 !== yE)) {
    pathData.pop();
    pathData.push(["L", x0, y0], ["Z"]);
  }
  return path;
}

See codepen example

[Clemweb]

@herrstrietzel pretty good! but I don't know why if I change the path the svg is weird (not at the good place). For example with this : M 75 0 A 10 10 0 0 1 75 -150 A 1 1 0 0 1 75 0 Z
Have you a idea ?

[celioFagundes]

@Clemweb have you found a solution to this? facing the same problem, any different path get's posicioned wrong on the export

[herrstrietzel]

@herrstrietzel, @Clemweb: sorry for the late response.
See new codepen example
Not sure, but I added a cropping/repositioning function so off-viewBox paths get aligned to x/y=0 origin point