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Fit SVG transformed element into the rect bounds with JavaScript

I am struggling with an issue to fit pragmatically transformed SVG element into the given rect bounds.
Destination rect is given and not transformed.
Input rect has any type of transformations.
Input rect can be a child of any transformed groups.
Transformations should be applied only to the input rect.
This question is only about the JavaScript element transformations.
It's an easy task when the element has only transformations by itself:
In this case proportion between the destination and input getBoundingClientRect (bounding rect in screen coordinates) is equals to a proper scaling factor.
But it's not working when parent elements are also transformed:
var inputElement = document.getElementById("input");
var destinationElement = document.getElementById("destination");
var inputBB = inputElement.getBoundingClientRect();
var outputBB = destinationElement.getBoundingClientRect();
var scaleX = outputBB.width / inputBB.width;
var scaleY = outputBB.height / inputBB.height;
// get offsets between figure center and destination rect center:
var offsetX = outputBB.x + outputBB.width / 2 - (inputBB.x + inputBB.width / 2);
var offsetY =
outputBB.y + outputBB.height / 2 - (inputBB.y + inputBB.height / 2);
// get current figure transformation
let currentMatrix = (
inputElement.transform.baseVal.consolidate() ||
inputElement.ownerSVGElement.createSVGTransform()
).matrix;
// Get center of figure in element coordinates:
const inputBBox = inputElement.getBBox();
const centerTransform = inputElement.ownerSVGElement.createSVGPoint();
centerTransform.x = inputBBox.x + inputBBox.width / 2;
centerTransform.y = inputBBox.y + inputBBox.height / 2;
// create scale matrix:
const svgTransform = inputElement.ownerSVGElement.createSVGTransform();
svgTransform.setScale(scaleX, scaleY);
let scalingMatrix = inputElement.ownerSVGElement
.createSVGMatrix()
// move the figure to the center of the destination rect.
.translate(offsetX, offsetY)
// Apply current matrix, so old transformations are not lost
.multiply(currentMatrix)
.translate(centerTransform.x, centerTransform.y)
// multiply is used instead of the scale method while for some reasons matrix scale is giving proportional scaling...
// From a transforms proper matrix is generated.
.multiply(svgTransform.matrix)
.translate(-centerTransform.x, -centerTransform.y);
// Apply new created matrix to element back:
const newTransform = inputElement.ownerSVGElement.createSVGTransform();
newTransform.setMatrix(scalingMatrix);
inputElement.transform.baseVal.initialize(newTransform);
var bboundsTest= document.getElementById("bboundsTest");
const resultBBounds = inputElement.getBoundingClientRect();
bboundsTest.setAttribute('x', resultBBounds .x);
bboundsTest.setAttribute('y', resultBBounds .y);
bboundsTest.setAttribute('width', resultBBounds .width);
bboundsTest.setAttribute('height', resultBBounds .height);
document.getElementById('test2').innerHTML = 'expected: 100x100 . Results: ' + resultBBounds.width + 'x' + resultBBounds.height
<svg
version="1.2"
viewBox="0 0 480 150"
width="480"
height="150"
xmlns="http://www.w3.org/2000/svg"
>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect
id="input"
transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)"
width="30"
height="30"
fill="red"
/>
</g>
</g>
</g>
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
<rect
id="bboundsTest"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="black"
/>
</svg>
<div id="test2"></div>
Any ideas on how to take parent transformations into the count to find proper scaling factors?
Thanks in advance for the ideas!
The given answer from Dipen Shah is focused on applying transformations to the parent element and this is also an option, but my goal is transforming the element to the destination rect bounds.

As you have discovered, this is a tricky problem. It's even trickier than you think (see later).
You have rectangles in two different corrdinate spaces. One of them is transformed. So you are trying to map one transformed rectangle to another, possibly transformed, rectangle. Since they are transformed, one or both of those rectangles is (probably) no longer a rectangle.
Since your requirement is to transform the "input" to the "destination", the way to get your head around the problem is to switch your coordinate space to the point of view of the "input" rect. What does the "destination" look like from the point of view of "input"? To see, we need to transform "destination" with the inverse of the transform that "input" has.
What the destination looks like to the <rect id="input" transform=""/>
<svg
version="1.2"
viewBox="-50 -50 160 260"
height="500"
xmlns="http://www.w3.org/2000/svg"
>
<rect
id="input"
transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)"
width="30"
height="30"
fill="red"
/>
<g transform="rotate(-10) translate(3,-4) skewX(-10)">
<g transform="rotate(-30) translate(3,-3) skewX(-30)">
<g transform="rotate(-30) translate(-95,-1) skewX(-10)">
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
</g>
</g>
</g>
What the destination looks like to the <rect id="input"/>
<svg
version="1.2"
viewBox="-80 -70 120 230"
height="500"
xmlns="http://www.w3.org/2000/svg"
>
<rect
id="input"
width="30"
height="30"
fill="red"
/>
<g transform="rotate(-45) translate(0,0) translate(50,50) scale(0.67) translate(-50,-50) skewX(-25) translate(-95,-76.5)">
<g transform="rotate(-10) translate(3,-4) skewX(-10)">
<g transform="rotate(-30) translate(3,-3) skewX(-30)">
<g transform="rotate(-30) translate(-95,-1) skewX(-10)">
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
</g>
</g>
</g>
</g>
So, you can see why it's so tricky now. We either have to find the transform that maps a parallelogram to another parallelogram, or a rectangle to a parallelogram. Obviously we'll want to choose the latter. You'd expect it to be the simpler of the two options.
We are also helped because we can assume that the transformations are affine. Straight lines stay straight, and parallel lines stay parallel.
So our task is to scale up our rectangle, so that it neatly fits inside our destination parallelogram. Also, because the parallelogram has 180° rotational symmetry, we know that the centre of our fitted rectangle will coincide with the centre of the parallelogram.
So, let's imagine the "input" rectangle is sitting at the centre of the "destination" parallelogram, then shoot imaginary rays out of the rectangle until they hit the sides of the parallelogram. Whichever ray hits the destination parallelogram first, gives us the scale we should apply to the rectangle to make it fit.
.ray {
stroke: lightgrey;
stroke-dasharray: 2 2;
}
<svg
version="1.2"
viewBox="0 0 120 230"
height="500"
xmlns="http://www.w3.org/2000/svg"
>
<g transform="translate(47.1,101.2)"><!-- positioning conveniently for our figure -->
<!-- scaling rays -->
<line class="ray" x1="-100" y1="0" x2="100" y2="0"/>
<line class="ray" x1="-100" y1="30" x2="100" y2="30"/>
<line class="ray" x1="0" y1="-100" x2="0" y2="100"/>
<line class="ray" x1="30" y1="-100" x2="30" y2="100"/>
<rect
id="input"
width="30"
height="30"
fill="red"
/>
</g>
<g transform="translate(80,70)"><!-- positioning conveniently for our figure -->
<g transform="rotate(-45) translate(0,0) translate(50,50) scale(0.67) translate(-50,-50) skewX(-25) translate(-95,-76.5)">
<g transform="rotate(-10) translate(3,-4) skewX(-10)">
<g transform="rotate(-30) translate(3,-3) skewX(-30)">
<g transform="rotate(-30) translate(-95,-1) skewX(-10)">
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
</g>
</g>
</g>
</g>
</g>
var inputElement = document.getElementById("input");
var destinationElement = document.getElementById("destination");
var svg = inputElement.ownerSVGElement;
// Get the four corner points of rect "input"
var inX = inputElement.x.baseVal.value;
var inY = inputElement.y.baseVal.value;
var inW = inputElement.width.baseVal.value;
var inH = inputElement.height.baseVal.value;
// Get the four corner points of rect "destination"
var destX = destinationElement.x.baseVal.value;
var destY = destinationElement.y.baseVal.value;
var destW = destinationElement.width.baseVal.value;
var destH = destinationElement.height.baseVal.value;
var destPoints = [
createPoint(svg, destX, destY),
createPoint(svg, destX + destW, destY),
createPoint(svg, destX + destW, destY + destH),
createPoint(svg, destX, destY + destH)
];
// Get total transform applied to input rect
var el = inputElement;
var totalMatrix = el.transform.baseVal.consolidate().matrix;
// Step up ancestor tree till we get to the element before the root SVG element
while (el.parentElement.ownerSVGElement != null) {
el = el.parentElement;
if (el.transform) {
totalMatrix = el.transform.baseVal.consolidate().matrix.multiply( totalMatrix );
}
}
//console.log("totalMatrix = ",totalMatrix);
// Transform the four "destination" rect corner points by the inverse of the totalMatrix
// We will then have the corner points in the same coordinate space as the "input" rect
for (var i=0; i<4; i++) {
destPoints[i] = destPoints[i].matrixTransform(totalMatrix.inverse());
}
//console.log("transformed destPoints=",destPoints);
// Find the equation for the rays that start at the centre of the "input" rect & "destination" parallelogram
// and pass through the corner points of the "input" rect.
var destMinX = Math.min(destPoints[0].x, destPoints[1].x, destPoints[2].x, destPoints[3].x);
var destMaxX = Math.max(destPoints[0].x, destPoints[1].x, destPoints[2].x, destPoints[3].x);
var destMinY = Math.min(destPoints[0].y, destPoints[1].y, destPoints[2].y, destPoints[3].y);
var destMaxY = Math.max(destPoints[0].y, destPoints[1].y, destPoints[2].y, destPoints[3].y);
var destCentreX = (destMinX + destMaxX) / 2;
var destCentreY = (destMinY + destMaxY) / 2;
// Find the scale in the X direction by shooting rays horizontally from the top and bottom of the "input" rect
var scale1 = findDistanceToDestination(destCentreX, destCentreY - inH/2, inW/2, 0, // line equation of ray line 1
destPoints);
var scale2 = findDistanceToDestination(destCentreX, destCentreY + inH/2, inW/2, 0, // line equation of ray line 2
destPoints);
var scaleX = Math.min(scale1, scale2);
// Find the scale in the Y direction by shooting rays vertically from the left and right of the "input" rect
scale1 = findDistanceToDestination(destCentreX - inW/2, destCentreY, 0, inH/2, // line equation of ray line 1
destPoints);
scale2 = findDistanceToDestination(destCentreX + inW/2, destCentreY, 0, inH/2, // line equation of ray line 2
destPoints);
var scaleY = Math.min(scale1, scale2);
// Now we can position and scale the "input" element to fit the "destination" rect
inputElement.transform.baseVal.appendItem( makeTranslate(svg, destCentreX, destCentreY));
inputElement.transform.baseVal.appendItem( makeScale(svg, scaleX, scaleY));
inputElement.transform.baseVal.appendItem( makeTranslate(svg, -(inX + inW)/2, -(inY + inH)/2));
function createPoint(svg, x, y)
{
var pt = svg.createSVGPoint();
pt.x = x;
pt.y = y;
return pt;
}
function makeTranslate(svg, x, y)
{
var t = svg.createSVGTransform();
t.setTranslate(x, y);
return t;
}
function makeScale(svg, sx, sy)
{
var t = svg.createSVGTransform();
t.setScale(sx, sy);
return t;
}
function findDistanceToDestination(centreX, centreY, rayX, rayY, // line equation of ray
destPoints) // parallelogram points
{
// Test ray against each side of the dest parallelogram
for (var i=0; i<4; i++) {
var from = destPoints[i];
var to = destPoints[(i + 1) % 4];
var dx = to.x - from.x;
var dy = to.y - from.y;
var k = intersection(centreX, centreY, rayX, rayY, // line equation of ray
from.x, from.y, dx, dy); // line equation of parallogram side
if (k >= 0 && k <= 1) {
// Ray intersected with this side
var interceptX = from.x + k * dx;
var interceptY = from.y + k * dy;
var distanceX = interceptX - centreX;
var distanceY = interceptY - centreY;
if (rayX != 0)
return Math.abs(distanceX / rayX);
else if (rayY != 0)
return Math.abs(distanceY / rayY);
else
return 0; // How to handle case where "input" rect has zero width or height?
}
}
throw 'Should have intersected one of the sides!'; // Shouldn't happen
}
// Returns the position along the 'side' line, that the ray hits.
// If it intersects the line, thre return value will be between 0 and 1.
function intersection(rayX, rayY, rayDX, rayDY,
sideX, sideY, sideDX, sideDY)
{
// We want to find where:
// rayXY + t * rayDXDY = sideXY + k * sideDXDY
// Returning k.
// See: https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection
var den = -rayDX * -sideDY - -rayDY * -sideDX;
return (den != 0) ? - (-rayDX * (rayY-sideY) - -rayDY * (rayX-sideX)) / den
: -9999; // Lines don't intersect. Return a value outside range 0..1.
}
<svg
version="1.2"
viewBox="0 0 480 150"
width="480"
height="150"
xmlns="http://www.w3.org/2000/svg"
>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect
id="input"
transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)"
width="30"
height="30"
fill="red"
/>
</g>
</g>
</g>
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
</svg>
<div id="test2"></div>
We got close, but we're a little oversized. What happened?
If we go back to looking at it in "input" rect space, like before, we can see the problem better.
<svg width="500" height="500" viewBox="-40 -40 50 180">
<polygon points="-38.5008, 79.5321,
-32.7704, -35.2044,
3.5896, 12.3685,
-2.1406, 127.1050"
fill="none"
stroke="blue"
stroke-width="0.5"/>
<!-- input -->
<rect x="-32.4555" y="30.9503" width="30" height="30"
fill="red"/>
<!-- centre of dest -->
<circle cx="-17.4555" cy="45.9503" r="1"/>
<!-- intercepts X -->
<circle cx="-36.0744" cy="30.9503" r="1" fill="green"/>
<circle cx="-37.5727" cy="60.9503" r="1" fill="green"/>
<!-- intercepts Y -->
<circle cx="-32.4555" cy="-34.7923" r="1" fill="green"/>
<circle cx="-2.4555" cy="4.4590" r="1" fill="green"/>
<!-- scaled input -->
<rect x="-32.4555" y="30.9503" width="30" height="30"
fill="red" fill-opacity="0.2"
transform="translate(-17.4556 45.9503) scale(1.24126 2.76608) translate(17.4556 -45.9503)"/>
</svg>
The green dots represent the intersection points we got from shooting the rays horizontally and vertically from our "input" rectangle. The faded red rectangle represents the "input" rectangle scaled up to touch our intercept points. It overflows our "destination" shape. Which is why our shape from the previous snippet overflows, also.
This is what I meant, at the very top, when I said it is trickier than you think. To make the "input" match the "destination", you have to tweak two inter-dependent X and Y scales. If you adjust the X scale to fit, it'll no long fit in the Y direction. And vice versa.
This is as far as I want to go. I've spent a couple of hours on this answer already.
Perhaps their's a mathematical solution for finding a rectangle that fits inside a
parallelogram and touches all four sides. But I don't really want to spend the time to
work it out. Sorry. :)
Perhaps you or someone else can take this further. You could also try an iterative
solution that nudges the X and Y scales iteratively until it gets close enough.
Finally, if you are prepared to accept the condition that you don't stretch the input both horizontally and vertically, and if you are okay with just scaling up (or down) the input to fit (ie keeping the aspect ratio the same), then that's a simpler thing to solve.
var inputElement = document.getElementById("input");
var destinationElement = document.getElementById("destination");
var svg = inputElement.ownerSVGElement;
// Get the four corner points of rect "input"
var inX = inputElement.x.baseVal.value;
var inY = inputElement.y.baseVal.value;
var inW = inputElement.width.baseVal.value;
var inH = inputElement.height.baseVal.value;
// Get the four corner points of rect "destination"
var destX = destinationElement.x.baseVal.value;
var destY = destinationElement.y.baseVal.value;
var destW = destinationElement.width.baseVal.value;
var destH = destinationElement.height.baseVal.value;
var destPoints = [
createPoint(svg, destX, destY),
createPoint(svg, destX + destW, destY),
createPoint(svg, destX + destW, destY + destH),
createPoint(svg, destX, destY + destH)
];
// Get total transform applied to input rect
var el = inputElement;
var totalMatrix = el.transform.baseVal.consolidate().matrix;
// Step up ancestor tree till we get to the element before the root SVG element
while (el.parentElement.ownerSVGElement != null) {
el = el.parentElement;
if (el.transform) {
totalMatrix = el.transform.baseVal.consolidate().matrix.multiply( totalMatrix );
}
}
//console.log("totalMatrix = ",totalMatrix);
// Transform the four "destination" rect corner points by the inverse of the totalMatrix
// We will then have the corner points in the same coordinate space as the "input" rect
for (var i=0; i<4; i++) {
destPoints[i] = destPoints[i].matrixTransform(totalMatrix.inverse());
}
//console.log("transformed destPoints=",destPoints);
// Find the equation for the rays that start at the centre of the "input" rect & "destination" parallelogram
// and pass through the corner points of the "input" rect.
var destMinX = Math.min(destPoints[0].x, destPoints[1].x, destPoints[2].x, destPoints[3].x);
var destMaxX = Math.max(destPoints[0].x, destPoints[1].x, destPoints[2].x, destPoints[3].x);
var destMinY = Math.min(destPoints[0].y, destPoints[1].y, destPoints[2].y, destPoints[3].y);
var destMaxY = Math.max(destPoints[0].y, destPoints[1].y, destPoints[2].y, destPoints[3].y);
var destCentreX = (destMinX + destMaxX) / 2;
var destCentreY = (destMinY + destMaxY) / 2;
// Shoot diagonal rays from the centre through two adjacent corners of the "input" rect.
// Whichever one hits the destination shape first, provides the scaling factor we need.
var scale1 = findDistanceToDestination(destCentreX, destCentreY, inW/2, inH/2, // line equation of ray line 1
destPoints);
var scale2 = findDistanceToDestination(destCentreX, destCentreY, -inW/2, inW/2, // line equation of ray line 2
destPoints);
var scale = Math.min(scale1, scale2);
// Now we can position and scale the "input" element to fit the "destination" rect
inputElement.transform.baseVal.appendItem( makeTranslate(svg, destCentreX, destCentreY));
inputElement.transform.baseVal.appendItem( makeScale(svg, scale, scale));
inputElement.transform.baseVal.appendItem( makeTranslate(svg, -(inX + inW)/2, -(inY + inH)/2));
function createPoint(svg, x, y)
{
var pt = svg.createSVGPoint();
pt.x = x;
pt.y = y;
return pt;
}
function makeTranslate(svg, x, y)
{
var t = svg.createSVGTransform();
t.setTranslate(x, y);
return t;
}
function makeScale(svg, sx, sy)
{
var t = svg.createSVGTransform();
t.setScale(sx, sy);
return t;
}
function findDistanceToDestination(centreX, centreY, rayX, rayY, // line equation of ray
destPoints) // parallelogram points
{
// Test ray against each side of the dest parallelogram
for (var i=0; i<4; i++) {
var from = destPoints[i];
var to = destPoints[(i + 1) % 4];
var dx = to.x - from.x;
var dy = to.y - from.y;
var k = intersection(centreX, centreY, rayX, rayY, // line equation of ray
from.x, from.y, dx, dy); // line equation of parallogram side
if (k >= 0 && k <= 1) {
// Ray intersected with this side
var interceptX = from.x + k * dx;
var interceptY = from.y + k * dy;
var distanceX = interceptX - centreX;
var distanceY = interceptY - centreY;
if (rayX != 0)
return Math.abs(distanceX / rayX);
else if (rayY != 0)
return Math.abs(distanceY / rayY);
else
return 0; // How to handle case where "input" rect has zero width or height?
}
}
throw 'Should have intersected one of the sides!'; // Shouldn't happen
}
// Returns the position along the 'side' line, that the ray hits.
// If it intersects the line, thre return value will be between 0 and 1.
function intersection(rayX, rayY, rayDX, rayDY,
sideX, sideY, sideDX, sideDY)
{
// We want to find where:
// rayXY + t * rayDXDY = sideXY + k * sideDXDY
// Returning k.
// See: https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection
var den = -rayDX * -sideDY - -rayDY * -sideDX;
return (den != 0) ? - (-rayDX * (rayY-sideY) - -rayDY * (rayX-sideX)) / den
: -9999; // Lines don't intersect. Return a value outside range 0..1.
}
<svg
version="1.2"
viewBox="0 0 480 150"
width="480"
height="150"
xmlns="http://www.w3.org/2000/svg"
>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect
id="input"
transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)"
width="30"
height="30"
fill="red"
/>
</g>
</g>
</g>
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
</svg>
<div id="test2"></div>

Update:
I was able to fit source element to match target element. The way I was able to achieve that is by translating top most container of the source element relative to target element and scaling container based on size ratio between source and target elements.
function applyTransformations(source, sourceContainer, target, includeMagicScaleMargin) {
var sourceBB = source.getBoundingClientRect();
var inputBB = sourceContainer.getBoundingClientRect();
var outputBB = target.getBoundingClientRect();
var scaleX = (outputBB.width - (includeMagicScaleMargin ? 10 : 0)) / sourceBB.width;
var scaleY = (outputBB.height - (includeMagicScaleMargin ? 10 : 0)) / sourceBB.height;
// get offsets between figure center and destination rect center:
var offsetX = outputBB.x + outputBB.width / 2 - (inputBB.x + inputBB.width / 2);
var offsetY =
outputBB.y + outputBB.height / 2 - (inputBB.y + inputBB.height / 2);
// get current figure transformation
let currentMatrix = (
sourceContainer.transform.baseVal.consolidate() ||
sourceContainer.ownerSVGElement.createSVGTransform()
).matrix;
// Get center of figure in element coordinates:
const inputBBox = sourceContainer.getBBox();
const centerTransform = sourceContainer.ownerSVGElement.createSVGPoint();
centerTransform.x = inputBBox.x + inputBBox.width / 2;
centerTransform.y = inputBBox.y + inputBBox.height / 2;
// create scale matrix:
const svgTransform = sourceContainer.ownerSVGElement.createSVGTransform();
svgTransform.setScale(scaleX, scaleY);
let scalingMatrix = sourceContainer.ownerSVGElement
.createSVGMatrix()
// move the figure to the center of the destination rect.
.translate(offsetX, offsetY)
// Apply current matrix, so old transformations are not lost
.multiply(currentMatrix)
.translate(centerTransform.x, centerTransform.y)
// multiply is used instead of the scale method while for some reasons matrix scale is giving proportional scaling...
// From a transforms proper matrix is generated.
.multiply(svgTransform.matrix)
.translate(-centerTransform.x, -centerTransform.y);
// Apply new created matrix to element back:
const newTransform = sourceContainer.ownerSVGElement.createSVGTransform();
newTransform.setMatrix(scalingMatrix);
sourceContainer.transform.baseVal.initialize(newTransform);
}
function isDescendant(parent, child) {
var node = child.parentNode;
while (node != null) {
if (node == parent) {
return true;
}
node = node.parentNode;
}
return false;
}
function transformSVG1() {
var destinationElem = document.getElementById("destination");
var inputElem = document.getElementById("input");
var inputContainerElem = inputElem;
while (inputContainerElem.parentNode != null) {
let candidateParent = inputContainerElem.parentNode;
if (isDescendant(candidateParent, destinationElem)) {
break;
}
inputContainerElem = candidateParent;
}
applyTransformations(inputElem, inputContainerElem, destinationElem);
}
function transformSVG2() {
var destinationElem = document.getElementById("destination2");
var inputElem = document.getElementById("input2");
var inputContainerElem = inputElem;
while (inputContainerElem.parentNode != null) {
let candidateParent = inputContainerElem.parentNode;
if (isDescendant(candidateParent, destinationElem)) {
break;
}
inputContainerElem = candidateParent;
}
applyTransformations(inputElem, inputContainerElem, destinationElem, true);
}
transformSVG1();
transformSVG2();
<svg version="1.2" viewBox="0 0 480 200" width="480" height="200" xmlns="http://www.w3.org/2000/svg">
<g>
<text x="0" y="20" font-size="20">No magic margins</text>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect id="input" transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)" width="30" height="30" fill="red" />
</g>
</g>
</g>
<rect id="destination" x="40" y="40" width="100" height="100" fill="transparent" stroke="blue" />
</g>
</svg>
<svg version="1.2" viewBox="0 0 480 200" width="480" height="200" xmlns="http://www.w3.org/2000/svg">
<g>
<text x="0" y="20" font-size="20">Magic margins!</text>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect id="input2" transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)" width="30" height="30" fill="red" />
</g>
</g>
</g>
<rect id="destination2" x="40" y="40" width="100" height="100" fill="transparent" stroke="blue" />
</g>
</svg>
Original answer:
I don't think this is an exact answer to what you are looking for but easier thing to do would be either:
Approach 1:
keep on applying same transformation as input element and its parent until common parent node is found.
function applyTransformations(source, target) {
var inputBB = source.getBoundingClientRect();
var outputBB = target.getBoundingClientRect();
var scaleX = outputBB.width / inputBB.width;
var scaleY = outputBB.height / inputBB.height;
// get offsets between figure center and destination rect center:
var offsetX = outputBB.x + outputBB.width / 2 - (inputBB.x + inputBB.width / 2);
var offsetY =
outputBB.y + outputBB.height / 2 - (inputBB.y + inputBB.height / 2);
// get current figure transformation
let currentMatrix = (
source.transform.baseVal.consolidate() ||
source.ownerSVGElement.createSVGTransform()
).matrix;
// Get center of figure in element coordinates:
const inputBBox = source.getBBox();
const centerTransform = source.ownerSVGElement.createSVGPoint();
centerTransform.x = inputBBox.x + inputBBox.width / 2;
centerTransform.y = inputBBox.y + inputBBox.height / 2;
// create scale matrix:
const svgTransform = source.ownerSVGElement.createSVGTransform();
svgTransform.setScale(scaleX, scaleY);
let scalingMatrix = source.ownerSVGElement
.createSVGMatrix()
// move the figure to the center of the destination rect.
.translate(offsetX, offsetY)
// Apply current matrix, so old transformations are not lost
.multiply(currentMatrix)
.translate(centerTransform.x, centerTransform.y)
// multiply is used instead of the scale method while for some reasons matrix scale is giving proportional scaling...
// From a transforms proper matrix is generated.
.multiply(svgTransform.matrix)
.translate(-centerTransform.x, -centerTransform.y);
// Apply new created matrix to element back:
const newTransform = source.ownerSVGElement.createSVGTransform();
newTransform.setMatrix(scalingMatrix);
source.transform.baseVal.initialize(newTransform);
}
function isDescendant(parent, child) {
var node = child.parentNode;
while (node != null) {
if (node == parent) {
return true;
}
node = node.parentNode;
}
return false;
}
var destinationElement = document.getElementById("destination");
var inputElement = document.getElementById("input");
while (inputElement.parentNode != null) {
applyTransformations(inputElement, destinationElement);
let candidateParent = inputElement.parentNode;
if (isDescendant(candidateParent, destinationElement)) {
break;
}
inputElement = candidateParent;
}
// Test:
var bboundsTest= document.getElementById("bboundsTest");
const resultBBounds = document.getElementById("input").getBoundingClientRect();
bboundsTest.setAttribute('x', resultBBounds.x);
bboundsTest.setAttribute('y', resultBBounds.y);
bboundsTest.setAttribute('width', resultBBounds.width);
bboundsTest.setAttribute('height', resultBBounds.height);
<svg version="1.2" viewBox="0 0 480 240" width="480" height="240" xmlns="http://www.w3.org/2000/svg">
<g>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect
id="input"
transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)"
width="30"
height="30"
fill="red"
/>
</g>
</g>
</g>
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
<rect
id="bboundsTest"
fill="transparent"
stroke="black"
/>
</g>
</svg>
Approach 2:
Or find parent of input that is not parent of destination first and than apply same transformations as parent node.
function applyTransformations(source, target) {
var inputBB = source.getBoundingClientRect();
var outputBB = target.getBoundingClientRect();
var scaleX = outputBB.width / inputBB.width;
var scaleY = outputBB.height / inputBB.height;
// get offsets between figure center and destination rect center:
var offsetX = outputBB.x + outputBB.width / 2 - (inputBB.x + inputBB.width / 2);
var offsetY =
outputBB.y + outputBB.height / 2 - (inputBB.y + inputBB.height / 2);
// get current figure transformation
let currentMatrix = (
source.transform.baseVal.consolidate() ||
source.ownerSVGElement.createSVGTransform()
).matrix;
// Get center of figure in element coordinates:
const inputBBox = source.getBBox();
const centerTransform = source.ownerSVGElement.createSVGPoint();
centerTransform.x = inputBBox.x + inputBBox.width / 2;
centerTransform.y = inputBBox.y + inputBBox.height / 2;
// create scale matrix:
const svgTransform = source.ownerSVGElement.createSVGTransform();
svgTransform.setScale(scaleX, scaleY);
let scalingMatrix = source.ownerSVGElement
.createSVGMatrix()
// move the figure to the center of the destination rect.
.translate(offsetX, offsetY)
// Apply current matrix, so old transformations are not lost
.multiply(currentMatrix)
.translate(centerTransform.x, centerTransform.y)
// multiply is used instead of the scale method while for some reasons matrix scale is giving proportional scaling...
// From a transforms proper matrix is generated.
.multiply(svgTransform.matrix)
.translate(-centerTransform.x, -centerTransform.y);
// Apply new created matrix to element back:
const newTransform = source.ownerSVGElement.createSVGTransform();
newTransform.setMatrix(scalingMatrix);
source.transform.baseVal.initialize(newTransform);
}
function isDescendant(parent, child) {
var node = child.parentNode;
while (node != null) {
if (node == parent) {
return true;
}
node = node.parentNode;
}
return false;
}
var destinationElement = document.getElementById("destination");
var inputElement = document.getElementById("input");
while (inputElement.parentNode != null) {
let candidateParent = inputElement.parentNode;
if (isDescendant(candidateParent, destinationElement)) {
break;
}
inputElement = candidateParent;
}
applyTransformations(inputElement, destinationElement);
// Test:
var bboundsTest= document.getElementById("bboundsTest");
const resultBBounds = document.getElementById("input").getBoundingClientRect();
bboundsTest.setAttribute('x', resultBBounds.x);
bboundsTest.setAttribute('y', resultBBounds.y);
bboundsTest.setAttribute('width', resultBBounds.width);
bboundsTest.setAttribute('height', resultBBounds.height);
<svg version="1.2" viewBox="0 0 480 240" width="480" height="240" xmlns="http://www.w3.org/2000/svg">
<g>
<g transform="skewX(10) translate(95,1) rotate(30)">
<g transform="skewX(30) translate(-3,3) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<rect
id="input"
transform="translate(95,76.5) skewX(25) translate(50,50) scale(1.5) translate(-50,-50) translate(0,0) rotate(45)"
width="30"
height="30"
fill="red"
/>
</g>
</g>
</g>
<rect
id="destination"
x="20"
y="20"
width="100"
height="100"
fill="transparent"
stroke="blue"
/>
<rect
id="bboundsTest"
fill="transparent"
stroke="black"
/>
</g>
</svg>
Note: Both approach will yield different results based on transformations involved on parent elements as second approach doesn't apply all transformations to destination but rather same transformations as parent node of input that is not also parent for destination.

It took me some time to realize an answer, but finally, I got it and it's quite simple!
Get the bounding boxes of both rectangles in the 'screen' coordinates.
For example: getBoundingClientRect.
By comparing the rectangle boxes you can get the desired scaling factors.
While scaling should be done in screen coordinates, we should convert the current element transformation including all the parent transformations to the screen coordinates, transform all those with given scale and convert back to the element coordinates.
Exact line is:
var toScreenMatrix = inputElement.getScreenCTM();
// Scale element by a matrix in screen coordinates and convert it back to the element coordinates:
currentMatrix = currentMatrix.multiply(toScreenMatrix.inverse().multiply(scaleAndTransform).multiply(toScreenMatrix));
This code is generic for all the svg elements, so any shape can be fit into the given rect:
function fitElement(from, to, changePosition) {
var inputElement = document.getElementById(from);
var destinationElement = document.getElementById(to);
// Get center of figure in element coordinates:
var inputScreenBBox = inputElement.getBoundingClientRect();
var destinationScreenBBox = destinationElement.getBoundingClientRect();
var scaleX = destinationScreenBBox.width / inputScreenBBox.width;
var scaleY = destinationScreenBBox.height / inputScreenBBox.height;
var inputCenter = getCenter(inputScreenBBox);
var offsetX = 0;
var offsetY = 0;
if (changePosition) {
var destCenter = getCenter(destinationScreenBBox);
offsetX = destCenter.x - inputCenter.x;
offsetY = destCenter.y - inputCenter.y;
}
// create scale matrix:
var scaleMatrix = getScaleMatrix(scaleX, scaleY, inputElement);
// get element self transformation matrix:
var currentMatrix = getElementMatrix(inputElement);
scaleAndTransform = inputElement.ownerSVGElement.createSVGMatrix()
.translate(offsetX, offsetY)
// Scale in screen coordinates around the element center:
.translate(inputCenter.x, inputCenter.y)
.multiply(scaleMatrix)
.translate(-inputCenter.x, -inputCenter.y)
var toScreenMatrix = inputElement.getScreenCTM();
// Scale element by a matrix in screen coordinates and convert it back to the element coordinates:
currentMatrix = currentMatrix.multiply(toScreenMatrix.inverse().multiply(scaleAndTransform).multiply(toScreenMatrix));
// Apply new created transform back to the element:
var newTransform = inputElement.ownerSVGElement.createSVGTransform();
newTransform.setMatrix(currentMatrix);
inputElement.transform.baseVal.initialize(newTransform);
}
function getElementMatrix(element) {
// Get consolidated element matrix:
var currentMatrix =
(element.transform.baseVal.consolidate() ||
element.ownerSVGElement.createSVGTransform()).matrix;
return currentMatrix;
}
function getScaleMatrix(scaleX, scaleY, el) {
// Return DOM matrix
var svgTransform = el.ownerSVGElement.createSVGTransform();
// Transform type is used because of the bug in chrome applying scale to the DOM matrix:
svgTransform.setScale(scaleX, scaleY);
var scaleMatrix = svgTransform.matrix;
return scaleMatrix
}
function getCenter(rect) {
return new DOMPoint((rect.x + rect.width / 2), (rect.y + rect.height / 2));
}
fitElement('source', 'destination', true);
<svg width="1380" height="1340" xmlns="http://www.w3.org/2000/svg">
<g transform="skewX(10) translate(-3,4) rotate(30)">
<g transform="skewX(30) translate(-3,4) rotate(30)">
<g transform="skewX(10) translate(-3,4) rotate(10)">
<g transform="translate(350,30) skewX(10) rotate(30)">
<rect id="source" transform="scale(2) rotate(30) skewX(10)" x="20" y="50" width="30" height="30"
fill="red" />
</g>
</g>
</g>
</g>
<rect id="destination" x="30" y="30" width="120" height="100" fill="transparent" stroke="blue" />
</svg>
GitHub gist link

Moving SVG object on guideline using javascript

I'm trying to move SVG object on <path> guideline I created, my code is based on this one, but I can't figure out why mine doesn't work and the codepen I shared does.
function positionTheElement() {
var html = document.documentElement;
var body = document.body;
var scrollPercentage = (html.scrollTop + body.scrollTop) / (html.scrollHeight - html.clientHeight);
var path = document.getElementById("trace");
var pathLen = path.getTotalLength();
var pt = path.getPointAtLength(scrollPercentage * pathLen );
var element = document.getElementById("etoile");
element.setAttribute("transform", "translate("+ pt.x + "," + pt.y + ")");
};
window.addEventListener("scroll", positionTheElement);
positionTheElement();
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
viewBox="0 0 1920 4000" style="enable-background:new 0 0 1920 4000;" xml:space="preserve">
<g>
<path class="st12" id="trace" d="M1491.8,3999l-7.8-365c0,0-1156-14-1240.5-1.3S155,3552,155,3552s3-594-0.3-688.1
c-3.3-94.1,94.3-81.9,94.3-81.9l689,5c0,0,645,5,751.9,6s90.1-93,90.1-93s20-468,14-576s-96.2-89.6-96.2-89.6S288,2039,208,2034.4
S120,1931,120,1931s13-1156,6-1184s4-60,10-89c0-33,141-28,141-28s764-1,867,0s154-11,169-19c36.8-10.9,26.8-27.7,28-53l2.5-525.5"
stroke="tomato" fill="none" stroke-width="4"/>
<polygon class="st11" id="etoile" stroke="tomato" fill="none" stroke-width="4" points="1367.7,59.8 1345.4,49.8 1324.5,62.3 1327.3,38.3 1308.8,22.4 1332.8,17.6 1342.3,-4.7 1354.3,16.3
1378.7,18.4 1362.2,36.2 "/>
</g>
</svg>
How can I animate the SVG polygon on the path guideline correctly?

You have 2 errors:
the star should have the center in the origin of the svg canvas (x=0; y=0).
the path trace has to be reversed. The way it's drawn (from the bottom up) would make the star begin it's movement from the bottom of the document to the top.
function positionTheElement() {
var html = document.documentElement;
var body = document.body;
var scrollPercentage = (html.scrollTop + body.scrollTop) / (html.scrollHeight - html.clientHeight);
var path = document.getElementById("trace");
var pathLen = path.getTotalLength();
var pt = path.getPointAtLength(scrollPercentage * pathLen );
var element = document.getElementById("etoile");
element.setAttribute("transform", "translate("+ pt.x + "," + pt.y + ")");
};
window.addEventListener("scroll", positionTheElement);
positionTheElement();
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<svg viewBox="0 0 1920 4000" >
<g>
<path class="st12" id="trace" d="M1343.5,32.5
L1341,558C1339.8,583.3 1349.8,600.1 1313,611C1298,619 1247,631 1144,630C1041,629 277,630 277,630C277,630 136,625 136,658C130,687 119,719 126,747C133,775 120,1931 120,1931C120,1931 128,2029.8000000000002 208,2034.4C288,2039 1697.8,2034.4 1697.8,2034.4C1697.8,2034.4 1788,2016 1794,2124C1800,2232 1780,2700 1780,2700C1780,2700 1796.8000000000002,2794 1689.9,2793C1583,2792 938,2787 938,2787L249,2782C249,2782 151.39999999999998,2769.8 154.7,2863.9C158,2958 155,3552 155,3552C155,3552 159,3645.3999999999996 243.5,3632.7C328,3620 1484,3634 1484,3634L1491.8,3999"
stroke="tomato" fill="none" stroke-width="4"/>
<path class="st11" id="etoile" stroke="tomato" fill="none" stroke-width="4" d="M25,33.5l-22.3,-10l-20.9,12.5l2.8,-24l-18.5,-15.9l24,-4.8l9.5,-22.3l12,21l24.4,2.1l-16.5,17.8z"/>
</g>
</svg>

D3 How to keep element same size while transform scale / translate

This example illustrates my problem: https://bl.ocks.org/feketegy/ce9ab2efa9439f3c59c381f567522dd3
I have a couple of paths in a group element and I want to pan/zoom these elements except the blue rectangle path, which is in another group element.
The zooming and panning is done by applying transform="translate(0,0) scale(1) to the outer most group element then capturing the zoom delta and applying it to the same-size group element to keep it the same size.
This is working, but the blue rectangle position, which should remain the same size, is messed up, I would like to keep it in the same relative position to the other paths.
The rendered html structure looks like this:
<svg width="100%" height="100%">
<g class="outer-group" transform="translate(0,0)scale(1)">
<path d="M100,100 L140,140 L200,250 L100,250 Z" fill="#cccccc" stroke="#8191A2" stroke-width="2px"></path>
<path d="M400,100 L450,100 L450,250 L400,250 Z" fill="#cccccc" stroke="#8191A2" stroke-width="2px"></path>
<g class="same-size-position" transform="translate(300,250)">
<g class="same-size" transform="scale(1)">
<path d="M0,0 L50,0 L50,50 L0,50 Z" fill="#0000ff"></path>
</g>
</g>
</g>
</svg>
I've tried to get the X/Y position of the same-size-position group and create a delta from the translate x/y of the outer-group, but that doesn't seem to work.

After dusting off my high school geometry books I found a solution.
You need to get the bounding box of the element you want to keep the same size of and calculate a matrix conversion on it like so:
const zoomDelta = 1 / d3.event.transform.k;
const sameSizeElem = d3.select('.same-size');
const bbox = sameSizeElem.node().getBBox();
const cx = bbox.x + (bbox.width / 2);
const cy = bbox.y + (bbox.height / 2);
const zx = cx - zoomDelta * cx;
const zy = cy - zoomDelta * cy;
sameSizeElem
.attr('transform', 'matrix(' + zoomDelta + ', 0, 0, ' + zoomDelta + ', ' + zx + ', ' + zy + ')');
The matrix transformation will keep the relative position of the element which size remains the same and the other elements will pan/zoom.

SVG find orientation(angle) of a point to the x axis on a path

I am making parallax by moving an object on a path and it is working fine with getPointAtlength() but I also need to rotate this object with the path.
I need something like getPointAtLength() but for angles that I get the angle of the point. Rapheal seems to have a method to it but it isn't friendly to svg elements that is created in html or I don't know how to deal with it. Any ideas?
var l = document.getElementById('path');
var element=$('#svg_26')
$(window).scroll(function(){
var pathOffset=parseInt($('#l1').css('stroke-dashoffset'));
var p = l.getPointAtLength(-1*pathOffset);
translation = 'translate('+p.x+'px,'+p.y+'px)'
$(element).css('transform',translation);
})

Using a library for this kind of task would be overkill. Its actually quite simple to write your own function to calculate the angle. All you have to do is use pointAtLength two time with a little offset:
var p1 = path.getPointAtLength(l)
var p2 = path.getPointAtLength(l + 3)
and then calculate the angle of the resulting line and the x-axis using Math.atan2
var deg = Math.atan2(p1.y - p2.y, p1.x - p2.x) * (180 / Math.PI);
here is a little example using the above formula
var path = document.getElementById("path")
var obj = document.getElementById("obj")
var l = 0
var tl = path.getTotalLength()
function getPointAtLengthWithRotation(path, length) {
var p1 = path.getPointAtLength(length)
var p2 = path.getPointAtLength(length + 3)
var deg = Math.atan2(p1.y - p2.y, p1.x - p2.x) * (180 / Math.PI);
return {
x: p1.x,
y: p1.y,
angle: deg
}
}
setInterval(function() {
l += 1
if (l > tl) l = 0;
var p = getPointAtLengthWithRotation(path, l)
obj.setAttribute("transform", "translate(" + p.x + "," + p.y + ") rotate(" + (p.angle + 180) + ")")
}, 30)
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="200" height="200">
<path id="path" d="M 81.713425,82.629068 C 77.692791,85.788547 73.298237,77.367896 68.194886,79.039107 63.091534,80.710434 58.027628,96.952068 53.04637,97.140958 48.065112,97.329732 50.503508,75.285207 45.397105,74.05952 40.290703,72.833834 38.487501,93.968537 33.85932,91.287114 29.23114,88.605807 32.245641,70.914733 29.647307,66.19971 27.048973,61.484686 19.604932,68.733636 17.542589,63.315055 15.480245,57.896474 32.172733,59.004979 32.053727,53.363216 31.93472,47.721442 8.0865997,39.989401 9.2246856,34.665848 10.362772,29.342295 28.830448,38.693055 31.065274,33.7132 33.300101,28.733334 22.734045,13.601966 26.210126,9.6067771 29.686208,5.6115765 41.809938,29.357138 46.524268,27.383715 c 4.71433,-1.973424 3.011846,-23.1001292 8.022646,-23.3332919 5.0108,-0.2331744 4.529056,18.3713929 9.45006,20.4259809 4.921003,2.054588 12.017373,-15.4803016 16.717604,-13.058602 4.700233,2.421699 -6.261038,14.180819 -2.913997,18.778859 3.347041,4.59804 12.339067,-3.78046 13.896719,1.543011 1.557652,5.323471 -9.713912,13.199372 -9.176986,18.679109 0.536926,5.479772 19.347976,2.957331 18.124596,8.213665 -1.223374,5.256392 -21.036293,1.236997 -24.253076,5.968111 -3.216785,4.731114 9.342224,14.869033 5.321591,18.028511 z"
fill="none" stroke="grey" />
<path id="obj" d="M-5 -5 L5 0L-5 5z" fill="green" />
</svg>

getPointAtLength in Raphael returns an object with attribute 'alpha'. Alpha is the angle that you need along the curve. In the example above it would be p.alpha
So you should be able to apply a rotation to the object rotated by p.alpha,
Eg..
myRaphElement.transform('t' + p.x + ',' + p.y + 'r' + p.alpha).
The last part will rotate the element around its center.
If you can't create the raph element itself as the svg is inline, I suspect you may be better off with a library like Snap.svg (which has mostly same commands as by same author), or you could possibly dynamically rotate by css transform using something like 'rotate('+l.alpha+','+l.x+','+l.y+')'
Edit: I misread as it had Raphael in the tags, when its not being used.
I personally would use Snap for this case, as Raphael doesn't add a lot here. You could possibly create a Raphael element off screen with the same path as the inline element just to use the angle, but feels like overkill to load a library for that.
In Snap you could access the element with..
myElement = Snap('#svg_26')
p = myElement.getPointAtLength(-1*pathOffset);
myElement.transform('t' + p.x + ',' + p.y + 'r' + p.alpha)

<animateMotion rotate="auto" ... performs the guidance of automatically
<svg viewBox="0 0 150 100" width="300" height="200">
<path id="path" d="M 81.713425,82.629068 C 77.692791,85.788547 73.298237,77.367896 68.194886,79.039107 63.091534,80.710434 58.027628,96.952068 53.04637,97.140958 48.065112,97.329732 50.503508,75.285207 45.397105,74.05952 40.290703,72.833834 38.487501,93.968537 33.85932,91.287114 29.23114,88.605807 32.245641,70.914733 29.647307,66.19971 27.048973,61.484686 19.604932,68.733636 17.542589,63.315055 15.480245,57.896474 32.172733,59.004979 32.053727,53.363216 31.93472,47.721442 8.0865997,39.989401 9.2246856,34.665848 10.362772,29.342295 28.830448,38.693055 31.065274,33.7132 33.300101,28.733334 22.734045,13.601966 26.210126,9.6067771 29.686208,5.6115765 41.809938,29.357138 46.524268,27.383715 c 4.71433,-1.973424 3.011846,-23.1001292 8.022646,-23.3332919 5.0108,-0.2331744 4.529056,18.3713929 9.45006,20.4259809 4.921003,2.054588 12.017373,-15.4803016 16.717604,-13.058602 4.700233,2.421699 -6.261038,14.180819 -2.913997,18.778859 3.347041,4.59804 12.339067,-3.78046 13.896719,1.543011 1.557652,5.323471 -9.713912,13.199372 -9.176986,18.679109 0.536926,5.479772 19.347976,2.957331 18.124596,8.213665 -1.223374,5.256392 -21.036293,1.236997 -24.253076,5.968111 -3.216785,4.731114 9.342224,14.869033 5.321591,18.028511 z"
fill="none" stroke="grey" />
<polygon points="0,0 -5,-5 -5,5" style="fill:green">
<animateMotion begin="0s" dur="10s" rotate="auto" repeatCount="indefinite">
<mpath xlink:href="#path"></mpath>
</animateMotion>
</polygon>
</svg>

Apply updated co-ordinates from parent rotation to children

In the code below, I am rotating a selection box (parent) with two children in SVG.
It works fine, however, when the parent (selection box) is removed, the children go back to their original (pre-rotation) co-ordinates.
How can I apply the updated co-ordinates on the children once the parent is removed. I specifically need to maintain the new position of the children in X,Y co-oridinates, i.e. the rotate should be converted to translate, r.g. transform = translate (X , Y) . I only need New x,y for children so that i can 'translate' them to new location.
here is the fiddle link http://jsfiddle.net/rehankhalid/QK8L8/6/
HTML CODE:-
<button data-action="rotate" onclick="rotateMainRect()">Rotate +5 Angle</button>
<button data-action="rotate" onclick="removeRectRotation()">Remove Selection</button>
<br/>
<svg id="mainSvg" xmlns="http://www.w3.org/2000/svg" version="1.1" width="600" height="500">
<g id="selectedRect">
<rect id="rectangle" x="135" y="135" width="110" height="35" stroke="red" stroke-width="2" fill="grey" opacity="0.4" />
<g id="button_1" transform="translate(0,0)">
<circle cx="150" cy="150" r="5" stroke="grey" stroke-width="1" fill="none" />
</g>
<g id="button_2" transform="translate(0,0)">
<circle cx="230" cy="150" r="5" stroke="grey" stroke-width="1" fill="none" />
</g>
</g>
</svg>
JAVASCRIPT CODE
var angle_incr = 5;
var angle = 0;
function rotateMainRect() {
var selectedRect = document.getElementById('selectedRect');
var rectangle = document.getElementById('rectangle');
var x = rectangle.getAttribute('x');
if (x != 0) {
var centxy = calculateCenterXY(selectedRect);
angle += angle_incr;
selectedRect.setAttributeNS(null, 'transform', 'rotate(' + angle + ',' + centxy.x + ',' + centxy.y + ')');
} else {
rectangle.setAttribute('x', '135');
rectangle.setAttribute('y', '135');
rectangle.setAttribute('width', '110');
rectangle.setAttribute('height', '35');
}
}
function calculateCenterXY(node) {
var x = node.getBBox().x + (node.getBBox().width / 2);
var y = node.getBBox().y + (node.getBBox().height / 2);
var xy_co = {
x: x,
y: y
};
return xy_co;
}
function removeRectRotation() {
var selectedRect = document.getElementById('selectedRect');
selectedRect.setAttributeNS(null, 'transform', '');
var rectangle = document.getElementById('rectangle');
rectangle.setAttribute('x', '0');
rectangle.setAttribute('y', '0');
rectangle.setAttribute('width', '0');
rectangle.setAttribute('height', '0');
angle = 0;
}
- What i Want:-
First Rotate the selection rectangle to some angle, and then press 'Remove selection'. After Removing the selection, Childrens must be placed at the New postion. (which now, move back to the original position)

If you are asking if you can read the absolute positions of the two transformed circles directly using JS, then the answer is no.
You will need to calculate their positions yourself using a bit of trigonometry.