svgedit/editor/recalculate.js

/* globals jQuery */
/**
 * Recalculate.
 * @module recalculate
 * @license MIT
 */

import jqPluginSVG from './jQuery.attr.js'; // Needed for SVG attribute setting and array form with `attr`
import {NS} from './namespaces.js';
import {convertToNum} from './units.js';
import {isWebkit} from './browser.js';
import {getTransformList} from './svgtransformlist.js';
import {getRotationAngle, getHref, getBBox, getRefElem} from './utilities.js';
import {BatchCommand, ChangeElementCommand} from './history.js';
import {remapElement} from './coords.js';
import {
  isIdentity, matrixMultiply, transformPoint, transformListToTransform,
  hasMatrixTransform
} from './math.js';

const $ = jqPluginSVG(jQuery);

let context_;

/**
* @interface module:recalculate.EditorContext
*/
/**
 * @function module:recalculate.EditorContext#getSVGRoot
 * @returns {SVGSVGElement} The root DOM element
 */
/**
 * @function module:recalculate.EditorContext#getStartTransform
 * @returns {string}
*/
/**
 * @function module:recalculate.EditorContext#setStartTransform
 * @param {string} transform
 * @returns {undefined}
 */

/**
* @function module:recalculate.init
* @param {module:recalculate.EditorContext} editorContext
* @returns {undefined}
*/
export const init = function (editorContext) {
  context_ = editorContext;
};

/**
* Updates a `<clipPath>`s values based on the given translation of an element
* @function module:recalculate.updateClipPath
* @param {string} attr - The clip-path attribute value with the clipPath's ID
* @param {Float} tx - The translation's x value
* @param {Float} ty - The translation's y value
* @returns {undefined}
*/
export const updateClipPath = function (attr, tx, ty) {
  const path = getRefElem(attr).firstChild;
  const cpXform = getTransformList(path);
  const newxlate = context_.getSVGRoot().createSVGTransform();
  newxlate.setTranslate(tx, ty);

  cpXform.appendItem(newxlate);

  // Update clipPath's dimensions
  recalculateDimensions(path);
};

/**
* Decides the course of action based on the element's transform list
* @function module:recalculate.recalculateDimensions
* @param {Element} selected - The DOM element to recalculate
* @returns {Command} Undo command object with the resulting change
*/
export const recalculateDimensions = function (selected) {
  if (selected == null) { return null; }

  // Firefox Issue - 1081
  if (selected.nodeName === 'svg' && navigator.userAgent.includes('Firefox/20')) {
    return null;
  }

  const svgroot = context_.getSVGRoot();
  const tlist = getTransformList(selected);

  // remove any unnecessary transforms
  if (tlist && tlist.numberOfItems > 0) {
    let k = tlist.numberOfItems;
    const noi = k;
    while (k--) {
      const xform = tlist.getItem(k);
      if (xform.type === 0) {
        tlist.removeItem(k);
      // remove identity matrices
      } else if (xform.type === 1) {
        if (isIdentity(xform.matrix)) {
          if (noi === 1) {
            // Overcome Chrome bug (though only when noi is 1) with
            //    `removeItem` preventing `removeAttribute` from
            //    subsequently working
            // See https://bugs.chromium.org/p/chromium/issues/detail?id=843901
            selected.removeAttribute('transform');
            return null;
          }
          tlist.removeItem(k);
        }
      // remove zero-degree rotations
      } else if (xform.type === 4) {
        if (xform.angle === 0) {
          tlist.removeItem(k);
        }
      }
    }
    // End here if all it has is a rotation
    if (tlist.numberOfItems === 1 &&
        getRotationAngle(selected)) { return null; }
  }

  // if this element had no transforms, we are done
  if (!tlist || tlist.numberOfItems === 0) {
    // Chrome apparently had a bug that requires clearing the attribute first.
    selected.setAttribute('transform', '');
    // However, this still next line currently doesn't work at all in Chrome
    selected.removeAttribute('transform');
    // selected.transform.baseVal.clear(); // Didn't help for Chrome bug
    return null;
  }

  // TODO: Make this work for more than 2
  if (tlist) {
    let mxs = [];
    let k = tlist.numberOfItems;
    while (k--) {
      const xform = tlist.getItem(k);
      if (xform.type === 1) {
        mxs.push([xform.matrix, k]);
      } else if (mxs.length) {
        mxs = [];
      }
    }
    if (mxs.length === 2) {
      const mNew = svgroot.createSVGTransformFromMatrix(matrixMultiply(mxs[1][0], mxs[0][0]));
      tlist.removeItem(mxs[0][1]);
      tlist.removeItem(mxs[1][1]);
      tlist.insertItemBefore(mNew, mxs[1][1]);
    }

    // combine matrix + translate
    k = tlist.numberOfItems;
    if (k >= 2 && tlist.getItem(k - 2).type === 1 && tlist.getItem(k - 1).type === 2) {
      const mt = svgroot.createSVGTransform();

      const m = matrixMultiply(
        tlist.getItem(k - 2).matrix,
        tlist.getItem(k - 1).matrix);
      mt.setMatrix(m);
      tlist.removeItem(k - 2);
      tlist.removeItem(k - 2);
      tlist.appendItem(mt);
    }
  }

  // If it still has a single [M] or [R][M], return null too (prevents BatchCommand from being returned).
  switch (selected.tagName) {
  // Ignore these elements, as they can absorb the [M]
  case 'line':
  case 'polyline':
  case 'polygon':
  case 'path':
    break;
  default:
    if ((tlist.numberOfItems === 1 && tlist.getItem(0).type === 1) ||
        (tlist.numberOfItems === 2 && tlist.getItem(0).type === 1 && tlist.getItem(0).type === 4)) {
      return null;
    }
  }

  // Grouped SVG element
  const gsvg = $(selected).data('gsvg');

  // we know we have some transforms, so set up return variable
  const batchCmd = new BatchCommand('Transform');

  // store initial values that will be affected by reducing the transform list
  let changes = {};
  let initial = null;
  let attrs = [];
  switch (selected.tagName) {
  case 'line':
    attrs = ['x1', 'y1', 'x2', 'y2'];
    break;
  case 'circle':
    attrs = ['cx', 'cy', 'r'];
    break;
  case 'ellipse':
    attrs = ['cx', 'cy', 'rx', 'ry'];
    break;
  case 'foreignObject':
  case 'rect':
  case 'image':
    attrs = ['width', 'height', 'x', 'y'];
    break;
  case 'use':
  case 'text':
  case 'tspan':
    attrs = ['x', 'y'];
    break;
  case 'polygon':
  case 'polyline': {
    initial = {};
    initial.points = selected.getAttribute('points');
    const list = selected.points;
    const len = list.numberOfItems;
    changes.points = new Array(len);
    for (let i = 0; i < len; ++i) {
      const pt = list.getItem(i);
      changes.points[i] = {x: pt.x, y: pt.y};
    }
    break;
  } case 'path':
    initial = {};
    initial.d = selected.getAttribute('d');
    changes.d = selected.getAttribute('d');
    break;
  } // switch on element type to get initial values

  if (attrs.length) {
    changes = $(selected).attr(attrs);
    $.each(changes, function (attr, val) {
      changes[attr] = convertToNum(attr, val);
    });
  } else if (gsvg) {
    // GSVG exception
    changes = {
      x: $(gsvg).attr('x') || 0,
      y: $(gsvg).attr('y') || 0
    };
  }

  // if we haven't created an initial array in polygon/polyline/path, then
  // make a copy of initial values and include the transform
  if (initial == null) {
    initial = $.extend(true, {}, changes);
    $.each(initial, function (attr, val) {
      initial[attr] = convertToNum(attr, val);
    });
  }
  // save the start transform value too
  initial.transform = context_.getStartTransform() || '';

  let oldcenter, newcenter;

  // if it's a regular group, we have special processing to flatten transforms
  if ((selected.tagName === 'g' && !gsvg) || selected.tagName === 'a') {
    const box = getBBox(selected);

    oldcenter = {x: box.x + box.width / 2, y: box.y + box.height / 2};
    newcenter = transformPoint(
      box.x + box.width / 2,
      box.y + box.height / 2,
      transformListToTransform(tlist).matrix
    );
    let m = svgroot.createSVGMatrix();

    // temporarily strip off the rotate and save the old center
    const gangle = getRotationAngle(selected);
    if (gangle) {
      const a = gangle * Math.PI / 180;
      let s;
      if (Math.abs(a) > (1.0e-10)) {
        s = Math.sin(a) / (1 - Math.cos(a));
      } else {
        // FIXME: This blows up if the angle is exactly 0!
        s = 2 / a;
      }
      for (let i = 0; i < tlist.numberOfItems; ++i) {
        const xform = tlist.getItem(i);
        if (xform.type === 4) {
          // extract old center through mystical arts
          const rm = xform.matrix;
          oldcenter.y = (s * rm.e + rm.f) / 2;
          oldcenter.x = (rm.e - s * rm.f) / 2;
          tlist.removeItem(i);
          break;
        }
      }
    }
    const N = tlist.numberOfItems;
    let tx = 0, ty = 0, operation = 0;

    let firstM;
    if (N) {
      firstM = tlist.getItem(0).matrix;
    }

    let oldStartTransform;
    // first, if it was a scale then the second-last transform will be it
    if (N >= 3 && tlist.getItem(N - 2).type === 3 &&
      tlist.getItem(N - 3).type === 2 && tlist.getItem(N - 1).type === 2) {
      operation = 3; // scale

      // if the children are unrotated, pass the scale down directly
      // otherwise pass the equivalent matrix() down directly
      const tm = tlist.getItem(N - 3).matrix,
        sm = tlist.getItem(N - 2).matrix,
        tmn = tlist.getItem(N - 1).matrix;

      const children = selected.childNodes;
      let c = children.length;
      while (c--) {
        const child = children.item(c);
        tx = 0;
        ty = 0;
        if (child.nodeType === 1) {
          const childTlist = getTransformList(child);

          // some children might not have a transform (<metadata>, <defs>, etc)
          if (!childTlist) { continue; }

          const m = transformListToTransform(childTlist).matrix;

          // Convert a matrix to a scale if applicable
          // if (hasMatrixTransform(childTlist) && childTlist.numberOfItems == 1) {
          //   if (m.b==0 && m.c==0 && m.e==0 && m.f==0) {
          //     childTlist.removeItem(0);
          //     const translateOrigin = svgroot.createSVGTransform(),
          //       scale = svgroot.createSVGTransform(),
          //       translateBack = svgroot.createSVGTransform();
          //     translateOrigin.setTranslate(0, 0);
          //     scale.setScale(m.a, m.d);
          //     translateBack.setTranslate(0, 0);
          //     childTlist.appendItem(translateBack);
          //     childTlist.appendItem(scale);
          //     childTlist.appendItem(translateOrigin);
          //   }
          // }

          const angle = getRotationAngle(child);
          oldStartTransform = context_.getStartTransform();
          const childxforms = [];
          context_.setStartTransform(child.getAttribute('transform'));
          if (angle || hasMatrixTransform(childTlist)) {
            const e2t = svgroot.createSVGTransform();
            e2t.setMatrix(matrixMultiply(tm, sm, tmn, m));
            childTlist.clear();
            childTlist.appendItem(e2t);
            childxforms.push(e2t);
          // if not rotated or skewed, push the [T][S][-T] down to the child
          } else {
            // update the transform list with translate,scale,translate

            // slide the [T][S][-T] from the front to the back
            // [T][S][-T][M] = [M][T2][S2][-T2]

            // (only bringing [-T] to the right of [M])
            // [T][S][-T][M] = [T][S][M][-T2]
            // [-T2] = [M_inv][-T][M]
            const t2n = matrixMultiply(m.inverse(), tmn, m);
            // [T2] is always negative translation of [-T2]
            const t2 = svgroot.createSVGMatrix();
            t2.e = -t2n.e;
            t2.f = -t2n.f;

            // [T][S][-T][M] = [M][T2][S2][-T2]
            // [S2] = [T2_inv][M_inv][T][S][-T][M][-T2_inv]
            const s2 = matrixMultiply(t2.inverse(), m.inverse(), tm, sm, tmn, m, t2n.inverse());

            const translateOrigin = svgroot.createSVGTransform(),
              scale = svgroot.createSVGTransform(),
              translateBack = svgroot.createSVGTransform();
            translateOrigin.setTranslate(t2n.e, t2n.f);
            scale.setScale(s2.a, s2.d);
            translateBack.setTranslate(t2.e, t2.f);
            childTlist.appendItem(translateBack);
            childTlist.appendItem(scale);
            childTlist.appendItem(translateOrigin);
            childxforms.push(translateBack);
            childxforms.push(scale);
            childxforms.push(translateOrigin);
            // logMatrix(translateBack.matrix);
            // logMatrix(scale.matrix);
          } // not rotated
          batchCmd.addSubCommand(recalculateDimensions(child));
          // TODO: If any <use> have this group as a parent and are
          // referencing this child, then we need to impose a reverse
          // scale on it so that when it won't get double-translated
          // const uses = selected.getElementsByTagNameNS(NS.SVG, 'use');
          // const href = '#' + child.id;
          // let u = uses.length;
          // while (u--) {
          //   const useElem = uses.item(u);
          //   if (href == getHref(useElem)) {
          //     const usexlate = svgroot.createSVGTransform();
          //     usexlate.setTranslate(-tx,-ty);
          //     getTransformList(useElem).insertItemBefore(usexlate,0);
          //     batchCmd.addSubCommand( recalculateDimensions(useElem) );
          //   }
          // }
          context_.setStartTransform(oldStartTransform);
        } // element
      } // for each child
      // Remove these transforms from group
      tlist.removeItem(N - 1);
      tlist.removeItem(N - 2);
      tlist.removeItem(N - 3);
    } else if (N >= 3 && tlist.getItem(N - 1).type === 1) {
      operation = 3; // scale
      m = transformListToTransform(tlist).matrix;
      const e2t = svgroot.createSVGTransform();
      e2t.setMatrix(m);
      tlist.clear();
      tlist.appendItem(e2t);
    // next, check if the first transform was a translate
    // if we had [ T1 ] [ M ] we want to transform this into [ M ] [ T2 ]
    // therefore [ T2 ] = [ M_inv ] [ T1 ] [ M ]
    } else if ((N === 1 || (N > 1 && tlist.getItem(1).type !== 3)) &&
      tlist.getItem(0).type === 2) {
      operation = 2; // translate
      const T_M = transformListToTransform(tlist).matrix;
      tlist.removeItem(0);
      const mInv = transformListToTransform(tlist).matrix.inverse();
      const M2 = matrixMultiply(mInv, T_M);

      tx = M2.e;
      ty = M2.f;

      if (tx !== 0 || ty !== 0) {
        // we pass the translates down to the individual children
        const children = selected.childNodes;
        let c = children.length;

        let clipPathsDone = [];

        while (c--) {
          const child = children.item(c);
          if (child.nodeType === 1) {
            // Check if child has clip-path
            if (child.getAttribute('clip-path')) {
              // tx, ty
              const attr = child.getAttribute('clip-path');
              if (!clipPathsDone.includes(attr)) {
                updateClipPath(attr, tx, ty);
                clipPathsDone.push(attr);
              }
            }

            oldStartTransform = context_.getStartTransform();
            context_.setStartTransform(child.getAttribute('transform'));

            const childTlist = getTransformList(child);
            // some children might not have a transform (<metadata>, <defs>, etc)
            if (childTlist) {
              const newxlate = svgroot.createSVGTransform();
              newxlate.setTranslate(tx, ty);
              if (childTlist.numberOfItems) {
                childTlist.insertItemBefore(newxlate, 0);
              } else {
                childTlist.appendItem(newxlate);
              }
              batchCmd.addSubCommand(recalculateDimensions(child));
              // If any <use> have this group as a parent and are
              // referencing this child, then impose a reverse translate on it
              // so that when it won't get double-translated
              const uses = selected.getElementsByTagNameNS(NS.SVG, 'use');
              const href = '#' + child.id;
              let u = uses.length;
              while (u--) {
                const useElem = uses.item(u);
                if (href === getHref(useElem)) {
                  const usexlate = svgroot.createSVGTransform();
                  usexlate.setTranslate(-tx, -ty);
                  getTransformList(useElem).insertItemBefore(usexlate, 0);
                  batchCmd.addSubCommand(recalculateDimensions(useElem));
                }
              }
              context_.setStartTransform(oldStartTransform);
            }
          }
        }

        clipPathsDone = [];
        context_.setStartTransform(oldStartTransform);
      }
    // else, a matrix imposition from a parent group
    // keep pushing it down to the children
    } else if (N === 1 && tlist.getItem(0).type === 1 && !gangle) {
      operation = 1;
      const m = tlist.getItem(0).matrix,
        children = selected.childNodes;
      let c = children.length;
      while (c--) {
        const child = children.item(c);
        if (child.nodeType === 1) {
          oldStartTransform = context_.getStartTransform();
          context_.setStartTransform(child.getAttribute('transform'));
          const childTlist = getTransformList(child);

          if (!childTlist) { continue; }

          const em = matrixMultiply(m, transformListToTransform(childTlist).matrix);
          const e2m = svgroot.createSVGTransform();
          e2m.setMatrix(em);
          childTlist.clear();
          childTlist.appendItem(e2m, 0);

          batchCmd.addSubCommand(recalculateDimensions(child));
          context_.setStartTransform(oldStartTransform);

          // Convert stroke
          // TODO: Find out if this should actually happen somewhere else
          const sw = child.getAttribute('stroke-width');
          if (child.getAttribute('stroke') !== 'none' && !isNaN(sw)) {
            const avg = (Math.abs(em.a) + Math.abs(em.d)) / 2;
            child.setAttribute('stroke-width', sw * avg);
          }
        }
      }
      tlist.clear();
    // else it was just a rotate
    } else {
      if (gangle) {
        const newRot = svgroot.createSVGTransform();
        newRot.setRotate(gangle, newcenter.x, newcenter.y);
        if (tlist.numberOfItems) {
          tlist.insertItemBefore(newRot, 0);
        } else {
          tlist.appendItem(newRot);
        }
      }
      if (tlist.numberOfItems === 0) {
        selected.removeAttribute('transform');
      }
      return null;
    }

    // if it was a translate, put back the rotate at the new center
    if (operation === 2) {
      if (gangle) {
        newcenter = {
          x: oldcenter.x + firstM.e,
          y: oldcenter.y + firstM.f
        };

        const newRot = svgroot.createSVGTransform();
        newRot.setRotate(gangle, newcenter.x, newcenter.y);
        if (tlist.numberOfItems) {
          tlist.insertItemBefore(newRot, 0);
        } else {
          tlist.appendItem(newRot);
        }
      }
    // if it was a resize
    } else if (operation === 3) {
      const m = transformListToTransform(tlist).matrix;
      const roldt = svgroot.createSVGTransform();
      roldt.setRotate(gangle, oldcenter.x, oldcenter.y);
      const rold = roldt.matrix;
      const rnew = svgroot.createSVGTransform();
      rnew.setRotate(gangle, newcenter.x, newcenter.y);
      const rnewInv = rnew.matrix.inverse(),
        mInv = m.inverse(),
        extrat = matrixMultiply(mInv, rnewInv, rold, m);

      tx = extrat.e;
      ty = extrat.f;

      if (tx !== 0 || ty !== 0) {
        // now push this transform down to the children
        // we pass the translates down to the individual children
        const children = selected.childNodes;
        let c = children.length;
        while (c--) {
          const child = children.item(c);
          if (child.nodeType === 1) {
            oldStartTransform = context_.getStartTransform();
            context_.setStartTransform(child.getAttribute('transform'));
            const childTlist = getTransformList(child);
            const newxlate = svgroot.createSVGTransform();
            newxlate.setTranslate(tx, ty);
            if (childTlist.numberOfItems) {
              childTlist.insertItemBefore(newxlate, 0);
            } else {
              childTlist.appendItem(newxlate);
            }

            batchCmd.addSubCommand(recalculateDimensions(child));
            context_.setStartTransform(oldStartTransform);
          }
        }
      }

      if (gangle) {
        if (tlist.numberOfItems) {
          tlist.insertItemBefore(rnew, 0);
        } else {
          tlist.appendItem(rnew);
        }
      }
    }
  // else, it's a non-group
  } else {
    // FIXME: box might be null for some elements (<metadata> etc), need to handle this
    const box = getBBox(selected);

    // Paths (and possbly other shapes) will have no BBox while still in <defs>,
    // but we still may need to recalculate them (see issue 595).
    // TODO: Figure out how to get BBox from these elements in case they
    // have a rotation transform

    if (!box && selected.tagName !== 'path') return null;

    let m = svgroot.createSVGMatrix();
    // temporarily strip off the rotate and save the old center
    const angle = getRotationAngle(selected);
    if (angle) {
      oldcenter = {x: box.x + box.width / 2, y: box.y + box.height / 2};
      newcenter = transformPoint(
        box.x + box.width / 2,
        box.y + box.height / 2,
        transformListToTransform(tlist).matrix
      );

      const a = angle * Math.PI / 180;
      const s = (Math.abs(a) > (1.0e-10))
        ? Math.sin(a) / (1 - Math.cos(a))
        // FIXME: This blows up if the angle is exactly 0!
        : 2 / a;

      for (let i = 0; i < tlist.numberOfItems; ++i) {
        const xform = tlist.getItem(i);
        if (xform.type === 4) {
          // extract old center through mystical arts
          const rm = xform.matrix;
          oldcenter.y = (s * rm.e + rm.f) / 2;
          oldcenter.x = (rm.e - s * rm.f) / 2;
          tlist.removeItem(i);
          break;
        }
      }
    }

    // 2 = translate, 3 = scale, 4 = rotate, 1 = matrix imposition
    let operation = 0;
    const N = tlist.numberOfItems;

    // Check if it has a gradient with userSpaceOnUse, in which case
    // adjust it by recalculating the matrix transform.
    // TODO: Make this work in Webkit using transformlist.SVGTransformList
    if (!isWebkit()) {
      const fill = selected.getAttribute('fill');
      if (fill && fill.startsWith('url(')) {
        const paint = getRefElem(fill);
        let type = 'pattern';
        if (paint.tagName !== type) type = 'gradient';
        const attrVal = paint.getAttribute(type + 'Units');
        if (attrVal === 'userSpaceOnUse') {
          // Update the userSpaceOnUse element
          m = transformListToTransform(tlist).matrix;
          const gtlist = getTransformList(paint);
          const gmatrix = transformListToTransform(gtlist).matrix;
          m = matrixMultiply(m, gmatrix);
          const mStr = 'matrix(' + [m.a, m.b, m.c, m.d, m.e, m.f].join(',') + ')';
          paint.setAttribute(type + 'Transform', mStr);
        }
      }
    }

    // first, if it was a scale of a non-skewed element, then the second-last
    // transform will be the [S]
    // if we had [M][T][S][T] we want to extract the matrix equivalent of
    // [T][S][T] and push it down to the element
    if (N >= 3 && tlist.getItem(N - 2).type === 3 &&
      tlist.getItem(N - 3).type === 2 && tlist.getItem(N - 1).type === 2) {
      // Removed this so a <use> with a given [T][S][T] would convert to a matrix.
      // Is that bad?
      //  && selected.nodeName != 'use'
      operation = 3; // scale
      m = transformListToTransform(tlist, N - 3, N - 1).matrix;
      tlist.removeItem(N - 1);
      tlist.removeItem(N - 2);
      tlist.removeItem(N - 3);
    // if we had [T][S][-T][M], then this was a skewed element being resized
    // Thus, we simply combine it all into one matrix
    } else if (N === 4 && tlist.getItem(N - 1).type === 1) {
      operation = 3; // scale
      m = transformListToTransform(tlist).matrix;
      const e2t = svgroot.createSVGTransform();
      e2t.setMatrix(m);
      tlist.clear();
      tlist.appendItem(e2t);
      // reset the matrix so that the element is not re-mapped
      m = svgroot.createSVGMatrix();
    // if we had [R][T][S][-T][M], then this was a rotated matrix-element
    // if we had [T1][M] we want to transform this into [M][T2]
    // therefore [ T2 ] = [ M_inv ] [ T1 ] [ M ] and we can push [T2]
    // down to the element
    } else if ((N === 1 || (N > 1 && tlist.getItem(1).type !== 3)) &&
      tlist.getItem(0).type === 2) {
      operation = 2; // translate
      const oldxlate = tlist.getItem(0).matrix,
        meq = transformListToTransform(tlist, 1).matrix,
        meqInv = meq.inverse();
      m = matrixMultiply(meqInv, oldxlate, meq);
      tlist.removeItem(0);
    // else if this child now has a matrix imposition (from a parent group)
    // we might be able to simplify
    } else if (N === 1 && tlist.getItem(0).type === 1 && !angle) {
      // Remap all point-based elements
      m = transformListToTransform(tlist).matrix;
      switch (selected.tagName) {
      case 'line':
        changes = $(selected).attr(['x1', 'y1', 'x2', 'y2']);
        // Fallthrough
      case 'polyline':
      case 'polygon':
        changes.points = selected.getAttribute('points');
        if (changes.points) {
          const list = selected.points;
          const len = list.numberOfItems;
          changes.points = new Array(len);
          for (let i = 0; i < len; ++i) {
            const pt = list.getItem(i);
            changes.points[i] = {x: pt.x, y: pt.y};
          }
        }
        // Fallthrough
      case 'path':
        changes.d = selected.getAttribute('d');
        operation = 1;
        tlist.clear();
        break;
      default:
        break;
      }
    // if it was a rotation, put the rotate back and return without a command
    // (this function has zero work to do for a rotate())
    } else {
      operation = 4; // rotation
      if (angle) {
        const newRot = svgroot.createSVGTransform();
        newRot.setRotate(angle, newcenter.x, newcenter.y);

        if (tlist.numberOfItems) {
          tlist.insertItemBefore(newRot, 0);
        } else {
          tlist.appendItem(newRot);
        }
      }
      if (tlist.numberOfItems === 0) {
        selected.removeAttribute('transform');
      }
      return null;
    }

    // if it was a translate or resize, we need to remap the element and absorb the xform
    if (operation === 1 || operation === 2 || operation === 3) {
      remapElement(selected, changes, m);
    } // if we are remapping

    // if it was a translate, put back the rotate at the new center
    if (operation === 2) {
      if (angle) {
        if (!hasMatrixTransform(tlist)) {
          newcenter = {
            x: oldcenter.x + m.e,
            y: oldcenter.y + m.f
          };
        }
        const newRot = svgroot.createSVGTransform();
        newRot.setRotate(angle, newcenter.x, newcenter.y);
        if (tlist.numberOfItems) {
          tlist.insertItemBefore(newRot, 0);
        } else {
          tlist.appendItem(newRot);
        }
      }
      // We have special processing for tspans:  Tspans are not transformable
      // but they can have x,y coordinates (sigh).  Thus, if this was a translate,
      // on a text element, also translate any tspan children.
      if (selected.tagName === 'text') {
        const children = selected.childNodes;
        let c = children.length;
        while (c--) {
          const child = children.item(c);
          if (child.tagName === 'tspan') {
            const tspanChanges = {
              x: $(child).attr('x') || 0,
              y: $(child).attr('y') || 0
            };
            remapElement(child, tspanChanges, m);
          }
        }
      }
    // [Rold][M][T][S][-T] became [Rold][M]
    // we want it to be [Rnew][M][Tr] where Tr is the
    // translation required to re-center it
    // Therefore, [Tr] = [M_inv][Rnew_inv][Rold][M]
    } else if (operation === 3 && angle) {
      const m = transformListToTransform(tlist).matrix;
      const roldt = svgroot.createSVGTransform();
      roldt.setRotate(angle, oldcenter.x, oldcenter.y);
      const rold = roldt.matrix;
      const rnew = svgroot.createSVGTransform();
      rnew.setRotate(angle, newcenter.x, newcenter.y);
      const rnewInv = rnew.matrix.inverse();
      const mInv = m.inverse();
      const extrat = matrixMultiply(mInv, rnewInv, rold, m);

      remapElement(selected, changes, extrat);
      if (angle) {
        if (tlist.numberOfItems) {
          tlist.insertItemBefore(rnew, 0);
        } else {
          tlist.appendItem(rnew);
        }
      }
    }
  } // a non-group

  // if the transform list has been emptied, remove it
  if (tlist.numberOfItems === 0) {
    selected.removeAttribute('transform');
  }

  batchCmd.addSubCommand(new ChangeElementCommand(selected, initial));

  return batchCmd;
};