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I have a web app that renders svg elements from cartesian points (lines, paths, etc) that come from a database.
I have a requirement that an end user can upload an svg file (icons) and drag the icon to fit within specific bounds of the points already defined and rendered in the app.
For example (see snippet), a user can upload the 'x' icon and drag it near the green line defined by two points, which should result in the icon being snapped and resized to the line - the upper left corner snapped to the line start point, and the width of the icon extending to the line end point. Same is true for the file icon being snapped to the red line. This is done dynamically during drag with js. I have omitted the js from the snippet to keep things simple, as I am confident that the answer lies with svg attributes and or style that I can set with js, but the svg properties/values are what I cannot pin down.
What I have tried - everything, I think. Given that I am nesting svg elements, I took the BBox values as an offset to used the x and y attributes on the icon svg element, and that moved it, but not to the start point. I also tried translate without success. I am able to move and resize, but not to the coordinates I need. I do not want to change the icon svg at all if possible, so i'd prefer to leave its viewBox as-is.
<svg height="700" width="700" fill="#e6e6e6" xmlns="http://www.w3.org/2000/svg">
<svg viewBox="0 0 512 512">
<path d="M443.6,387.1L312.4,255.4l131.5-130c5.4-5.4,5.4-14.2,0-19.6l-37.4-37.6c-2.6-2.6-6.1-4-9.8-4c-3.7,0-7.2,1.5-9.8,4 L256,197.8L124.9,68.3c-2.6-2.6-6.1-4-9.8-4c-3.7,0-7.2,1.5-9.8,4L68,105.9c-5.4,5.4-5.4,14.2,0,19.6l131.5,130L68.4,387.1 c-2.6,2.6-4.1,6.1-4.1,9.8c0,3.7,1.4,7.2,4.1,9.8l37.4,37.6c2.7,2.7,6.2,4.1,9.8,4.1c3.5,0,7.1-1.3,9.8-4.1L256,313.1l130.7,131.1 c2.7,2.7,6.2,4.1,9.8,4.1c3.5,0,7.1-1.3,9.8-4.1l37.4-37.6c2.6-2.6,4.1-6.1,4.1-9.8C447.7,393.2,446.2,389.7,443.6,387.1z"/>
</svg>
<svg viewBox="0 0 380 511.7">
<path fill-rule="nonzero" d="M26.18 0h221.14c3.1 0 5.85 1.51 7.56 3.84l122.88 145.08a9.27 9.27 0 0 1 2.21 6.05l.03 330.55c0 7.13-2.98 13.68-7.72 18.42l-.03.04c-4.75 4.74-11.29 7.72-18.43 7.72H26.18c-7.13 0-13.69-2.96-18.45-7.71l-.03-.04C2.97 499.22 0 492.69 0 485.52V26.18C0 19 2.95 12.46 7.68 7.72l.04-.04C12.46 2.95 19 0 26.18 0zm335.06 164.7c-134.78-5.58-134.35-17.38-129.82-134.02l.45-11.92H26.18c-2.05 0-3.91.83-5.26 2.16a7.482 7.482 0 0 0-2.16 5.26v459.34c0 2.02.84 3.88 2.18 5.23 1.36 1.35 3.22 2.19 5.24 2.19h327.64c2.01 0 3.86-.85 5.22-2.2 1.35-1.36 2.2-3.21 2.2-5.22V164.7zM250.25 27.32l-.15 4.01c-3.73 96.04-4.22 109.01 100.23 114.16L250.25 27.32z"/>
</svg>
<line x1="100" y1="20" x2="200" y2="20" stroke="green" />
<line x1="300" y1="20" x2="350" y2="20" stroke="red" />
</svg>
strong text
Although there may be several ways to accomplish this, I figured out one way that I am going to move forward with. The confusion with this was primarily due to my lack of understanding of the svg viewBox and how the coordinate system works.
The key to this is defining a new viewBox value for each nested svg based on its BBox coordinates. The purpose of doing this is to frame the drawing without 'whitespace' to enable its placement at the desired coordinates. Once you have the BBox data, you can set the viewBox and do some simple math to properly set the desired height and width (both of which must be defined for the nested svg). After updating the viewBox, width, and height, you can then move the svg to the new location.
$( document ).ready(function() {
const svg = document.querySelectorAll('svg.a');
svg.forEach(x => {
setSvg(x);
});
});
function setSvg(svg){
const { xMin, xMax, yMin, yMax } = [...svg.children].reduce((acc, el) => {
const { x, y, width, height } = el.getBBox();
if (!acc.xMin || x < acc.xMin) acc.xMin = x;
if (!acc.xMax || x + width > acc.xMax) acc.xMax = x + width;
if (!acc.yMin || y < acc.yMin) acc.yMin = y;
if (!acc.yMax || y + height > acc.yMax) acc.yMax = y + height;
return acc;
}, {});
const viewbox = `${xMin} ${yMin} ${xMax - xMin} ${yMax - yMin}`;
let newWidth = $(svg).attr('data-new-width');
let newPosition = $(svg).attr('data-new-position');
let newHeight = newWidth*(yMax - yMin)/(xMax - xMin);
svg.setAttribute('width', newWidth);
svg.setAttribute('height', newHeight);
svg.setAttribute('x', newPosition.split(",")[0]);
svg.setAttribute('y', newPosition.split(",")[1]);
svg.setAttribute('viewBox', viewbox);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<svg height="700" width="700" fill="#e6e6e6" xmlns="http://www.w3.org/2000/svg">
<svg class="a" data-new-width="100" data-new-position="100,20" viewBox="0 0 512 512">
<path d="M443.6,387.1L312.4,255.4l131.5-130c5.4-5.4,5.4-14.2,0-19.6l-37.4-37.6c-2.6-2.6-6.1-4-9.8-4c-3.7,0-7.2,1.5-9.8,4 L256,197.8L124.9,68.3c-2.6-2.6-6.1-4-9.8-4c-3.7,0-7.2,1.5-9.8,4L68,105.9c-5.4,5.4-5.4,14.2,0,19.6l131.5,130L68.4,387.1 c-2.6,2.6-4.1,6.1-4.1,9.8c0,3.7,1.4,7.2,4.1,9.8l37.4,37.6c2.7,2.7,6.2,4.1,9.8,4.1c3.5,0,7.1-1.3,9.8-4.1L256,313.1l130.7,131.1 c2.7,2.7,6.2,4.1,9.8,4.1c3.5,0,7.1-1.3,9.8-4.1l37.4-37.6c2.6-2.6,4.1-6.1,4.1-9.8C447.7,393.2,446.2,389.7,443.6,387.1z"/>
</svg>
<svg class="a" data-new-width="50" data-new-position="300,20" viewBox="0 0 380 511.7">
<path fill-rule="nonzero" d="M26.18 0h221.14c3.1 0 5.85 1.51 7.56 3.84l122.88 145.08a9.27 9.27 0 0 1 2.21 6.05l.03 330.55c0 7.13-2.98 13.68-7.72 18.42l-.03.04c-4.75 4.74-11.29 7.72-18.43 7.72H26.18c-7.13 0-13.69-2.96-18.45-7.71l-.03-.04C2.97 499.22 0 492.69 0 485.52V26.18C0 19 2.95 12.46 7.68 7.72l.04-.04C12.46 2.95 19 0 26.18 0zm335.06 164.7c-134.78-5.58-134.35-17.38-129.82-134.02l.45-11.92H26.18c-2.05 0-3.91.83-5.26 2.16a7.482 7.482 0 0 0-2.16 5.26v459.34c0 2.02.84 3.88 2.18 5.23 1.36 1.35 3.22 2.19 5.24 2.19h327.64c2.01 0 3.86-.85 5.22-2.2 1.35-1.36 2.2-3.21 2.2-5.22V164.7zM250.25 27.32l-.15 4.01c-3.73 96.04-4.22 109.01 100.23 114.16L250.25 27.32z"/>
</svg>
<line x1="100" y1="20" x2="200" y2="20" stroke="green" />
<line x1="300" y1="20" x2="350" y2="20" stroke="red" />
</svg>
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
I want to connect two SVG points (e.g. the centers of two circles) using arcs. If there is only one connection, the line (<path>) will be straight. If there are two connections, both will be rounded and will be symmetrical, this way:
So, in fact, there are few rules:
Everything should be symmetrical to to the imaginary line that connects the two points.
From 1, it's obvious that if the number of connections is:
odd: we do not display the straight line
even: we display the straight line
There should be a value k which defines the distance between two connections between same points.
The tangent that goes through the middle of the elliptical arc should be parallel with the straight line that connects the two points. And obviously, the middle of the line will be perpendicular to the tangent.
I'm struggling to get a formula to calculate the A parameters in the <path> element.
What I did until now is:
<path d="M100 100, A50,20 0 1,0 300,100" stroke="black" fill="transparent"/>
M100 100 is clear: that's the starting point (move to 100,100)
Last two numbers are also clear. The path ends in 300,100
I also saw that if I put 0 instead of 20, I obtain a straight line.
If I replace 1,0 with 1,1, the path is flipped.
What I don't know is how to calculate the A parameters. I read the docs, but the imagine is still unclear to me. How to calculate these values?
svg {
width: 100%;
height: 100%;
position: absolute;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS Bin</title>
</head>
<body>
<?xml version="1.0" standalone="no" ?>
<svg version="1.1" xmlns="http://www.w3.org/2000/svg">
<!-- Connect A(100,100) with B(300, 100) -->
<path d="M100 100, A50,0 0 1,0 300,100" stroke="black" fill="transparent" />
<path d="M100 100, A50,20 0 1,0 300,100" stroke="black" fill="transparent" />
<path d="M100 100, A50,20 0 1,1 300,100" stroke="black" fill="transparent" />
<path d="M100 100, A50,30 0 1,0 300,100" stroke="black" fill="transparent" />
<path d="M100 100, A50,30 0 1,1 300,100" stroke="black" fill="transparent" />
<!-- A(100, 100) B(300, 400) -->
<path d="M100 100, A50,0 57 1,0 300,400" stroke="black" fill="transparent" />
<path d="M100 100, A50,20 57 1,0 300,400" stroke="black" fill="transparent" />
<path d="M100 100, A50,20 57 1,1 300,400" stroke="black" fill="transparent" />
</svg>
</body>
</html>
I'm using SVG.js to create the paths.
You're making life very difficult for yourself by requiring circular arcs.
If you use quadratic curves instead, then the geometry becomes very simple — just offset the central X coordinate by half the difference in Y coordinates, and vice versa.
function arc_links(dwg,x1,y1,x2,y2,n,k) {
var cx = (x1+x2)/2;
var cy = (y1+y2)/2;
var dx = (x2-x1)/2;
var dy = (y2-y1)/2;
var i;
for (i=0; i<n; i++) {
if (i==(n-1)/2) {
dwg.line(x1,y1,x2,y2).stroke({width:1}).fill('none');
}
else {
dd = Math.sqrt(dx*dx+dy*dy);
ex = cx + dy/dd * k * (i-(n-1)/2);
ey = cy - dx/dd * k * (i-(n-1)/2);
dwg.path("M"+x1+" "+y1+"Q"+ex+" "+ey+" "+x2+" "+y2).stroke({width:1}).fill('none');
}
}
}
function create_svg() {
var draw = SVG('drawing').size(300, 300);
arc_links(draw,50,50,250,50,2,40);
arc_links(draw,250,50,250,250,3,40);
arc_links(draw,250,250,50,250,4,40);
arc_links(draw,50,250,50,50,5,40);
draw.circle(50).move(25,25).fill('#fff').stroke({width:1});
draw.circle(50).move(225,25).fill('#fff').stroke({width:1});
draw.circle(50).move(225,225).fill('#fff').stroke({width:1});
draw.circle(50).move(25,225).fill('#fff').stroke({width:1});
}
create_svg();
<script src="https://cdnjs.cloudflare.com/ajax/libs/svg.js/2.3.2/svg.min.js"></script>
<div id="drawing"></div>
For drawing SVG path's arc you need 2 points and radius, there are 2 points and you just need to calculate radius for given distances.
Formula for radius:
let r = (d, x) => 0.125*d*d/x + x/2;
where:
d - distance between points
x - distance between arcs
it derived from Pythagorean theorem:
a here is a half of distance between points
let r = (d, x) => !x?1e10:0.125*d*d/x + x/2;
upd();
function upd() {
let n = +count.value;
let s = +step.value/10;
let x1 = c1.getAttribute('cx'), y1 = c1.getAttribute('cy');
let x2 = c2.getAttribute('cx'), y2 = c2.getAttribute('cy');
let dx = Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
paths.innerHTML = [...Array(n)].map((_, i) => [
n%2&&i===n-1?0:1+parseInt(i/2),
i%2
]).map(i => `<path d="${[
'M', x1, y1,
'A', r(dx, s*i[0]), r(dx, s*i[0]), 0, 0, i[1], x2, y2
].join(' ')}"></path>`).join('');
}
<input id="count" type="range" min=1 max=9 value=5 oninput=upd() >
<input id="step" type="range" min=1 max=200 value=100 oninput=upd() >
<svg viewbox=0,0,300,100 stroke=red fill=none >
<circle id=c1 r=10 cx=50 cy=60></circle>
<circle id=c2 r=10 cx=250 cy=40></circle>
<g id=paths></g>
</svg>
Here is a solution that uses arcs, as asked for, rather than quadratic curves.
// Internal function
function connectInternal(x1,y1,x2,y2,con){
var dx=x2-x1
var dy=y2-y1
var dist=Math.sqrt(dx*dx+dy*dy)
if(dist==0 || con==0){
return "M"+x1+","+y1+"L"+x2+","+y2
}
var xRadius=dist*0.75
var yRadius=dist*0.3*(con*0.75)
var normdx=dx/dist
if(normdx<-1)normdx=-1
if(normdx>1)normdx=1
var angle=Math.acos(normdx)*180/Math.PI
if(x1>x2){
angle=-angle
}
return "M"+x1+","+y1+"A"+xRadius+","+yRadius+","+
angle+",00"+x2+","+y2+
"M"+x1+","+y1+"A"+xRadius+","+yRadius+","+
angle+",01"+x2+","+y2
}
// Returns an SVG path that represents
// "n" connections between two points.
function connect(x1,y1,x2,y2,n){
var ret=""
var con=n
if(con%2==1){
ret+=connectInternal(x1,y1,x2,y2,con)
con-=1
}
for(var i=2;i<=con;i+=2){
ret+=connectInternal(x1,y1,x2,y2,i)
}
return ret
}
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.
I've dynamacally added the circle elements to the svg displayed in a iFrame. Chrome isnt showing the new elements, not tried FF yet. Is there somekind of redraw/refresh I need to call? The first circle is actually in the svg document, the rest come from script.
<iframe id="svgFrame" src="xmlfile1.svg" width="300" height="300">
<svg xmlns="http://www.w3.org/2000/svg" id="SVG1" width="200" height="200">
<circle cx="20" cy="20" r="5"/>
<circle cx="165" cy="80" r="32"/>
<circle cx="15" cy="38" r="32"/>
<circle cx="140" cy="39" r="30"/>
<circle cx="178" cy="32" r="22"/>
...etc
<circle cx="166" cy="130" r="16"/>
</svg>
</iframe>
The javascript which creates the elements:
function RandomNumber(min, max) {
var r;
r = Math.floor(Math.random() * (max - min + 1)) + min;
return r;
}
var svg = document.getElementById("svgFrame").contentDocument;
for (var i = 0; i < 99; i++) {
var n = svg.createElement("circle");
n.setAttribute("cx" , RandomNumber( 0 , 200) );
n.setAttribute("cy" , RandomNumber(0, 200) );
n.setAttribute("r" , RandomNumber(5, 35) );
svg.documentElement.appendChild(n);
}
I haven't tried what you are doing where you essentially have two sources but I do know Chrome doesn't need a refresh/redraw when dynamically adding content.
Here is my code maybe this will help you.
xmlns = "http://www.w3.org/2000/svg";
var C = document.createElementNS(xmlns,"circle");
C.setAttributeNS(null, "cx", cx);
C.setAttributeNS(null, "cy", cy);
C.setAttributeNS(null, "r", rad);
document.getElementById("background").appendChild(C);
Where background is just the id of a group (g tag)
I'm guessing, but have you tried createElementNS("http://www.w3.org/2000/svg","circle") instead of createElement("circle")?