In Svg, the coordinates of any figure always have an absolute value that is calculated from the upper left corner of the SVG canvas.
Therefore, when applying the scale (2) command, the coordinates of the center of the figure will also be doubled and the figure will shift to the right and down.
<svg id="SVGRoot" version="1.1" width="500" height="500" viewBox="0 0 500 500" xmlns="http://www.w3.org/2000/svg" style="border:1px solid grey;">
<rect id="rect9240" transform="scale(2)" x="100" y="100" width="100" height="100" style="fill-rule:evenodd;fill:#f00;> stroke:#000; paint-order:normal">
<animateTransform
xlink:href="#rect9240"
attributeName="transform"
type="scale"
values="1;2;2;1;1"
dur="8s"
fill="freeze"
repeatcount="indefinite"
/>
</rect>
<circle cx="150" cy="150" r="3" fill="black" />
<circle cx="300" cy="300" r="3" fill="dodgerblue" />
<text x="150" y="140" font-size="16px" text-anchor="middle" > Center (150,150) </text>
<text x="300" y="290" font-size="16px" text-anchor="middle" > Center (300,300) </text>
</svg>
To return the enlarged figure to its original position, you must use the command translate (X, Y)
There is a great post here by @Paul LeBeau where this is explained in detail.
CSS solution
In order not to calculate the position of the center of the figure, you can use the CSS rule transform-box: fill-box
When the value of the fill-box
attribute is selected
The object bounding box is used as the reference box.
Below is an example of increasing and decreasing the size of figures:
svg {
width:50%;
}
.ellipse1, .rect1, .path1 {
transform-box: fill-box;
animation: scale 3s linear infinite alternate;
animation-direction: alternate;
transform-origin:50% 50%;
}
@keyframes scale {
0% { transform: scale(0.5); }
100% { transform: scale(1); }
}
<svg id="SVGRoot" version="1.1" viewBox="0 0 700 500" xmlns="http://www.w3.org/2000/svg">
<ellipse class="ellipse1" id="path9238" cx="332.91" cy="143.85" rx="64.941" ry="67.676" style="fill-rule:evenodd;fill:#f00;stroke:#000"/>
<rect class="rect1" id="rect9240" x="400.59" y="270.31" width="173.63" height="177.73" style="fill-rule:evenodd;fill:#f00; stroke:#000; paint-order:normal"/>
<path class="path1" id="path9242" d="m233.79 453.52-153.64-138.25 196.55-63.937z" style="fill-rule:evenodd;fill:#f00;stroke:#000; paint-order:normal"/>
</svg>
svg {
width:50%;
}
.ellipse1, .rect1, .path1 {
transform-box: fill-box;
animation: spin 4s linear infinite alternate;
transform-origin:50% 50%;
}
@keyframes spin {
0% { transform: rotate(0deg); }
100% { transform: rotate(359deg); }
}
<path class="path1" id="path9242" d="m233.79 453.52-153.64-138.25 196.55-63.937z" style="fill-rule:evenodd;fill:#f00;stroke:#000; paint-order:normal"/>
</svg>
<svg id="SVGRoot" version="1.1" viewBox="0 0 700 500" xmlns="http://www.w3.org/2000/svg">
<ellipse class="ellipse1" id="path9238" cx="332.91" cy="143.85" rx="64.941" ry="67.676" style="fill-rule:evenodd;fill:#f00;stroke:#000"/>
<rect class="rect1" id="rect9240" x="400.59" y="270.31" width="173.63" height="177.73" style="fill-rule:evenodd;fill:#f00; stroke:#000; paint-order:normal"/>
<path class="path1" id="path9242" d="m233.79 453.52-153.64-138.25 196.55-63.937z" style="fill-rule:evenodd;fill:#f00;stroke:#000; paint-order:normal"/>
</svg>
svg {
width:50%;
}
.ellipse1, .rect1, .path1 {
transform-box: fill-box;
animation: scale1 4s linear, spin 4s linear 4s infinite alternate;
transform-origin:50% 50%;
}
@keyframes spin {
0% { transform: rotate(0deg); }
100% { transform: rotate(360deg); }
}
@keyframes scale1 {
0% { transform: scale(0.5);}
100% { transform: scale(1);}
}
<svg id="SVGRoot" version="1.1" viewBox="0 0 700 500" xmlns="http://www.w3.org/2000/svg">
<ellipse class="ellipse1" id="path9238" cx="332.91" cy="143.85" rx="64.941" ry="67.676" style="fill-rule:evenodd;fill:#f00;stroke:#000"/>
<rect class="rect1" id="rect9240" x="400.59" y="270.31" width="173.63" height="177.73" style="fill-rule:evenodd;fill:#f00; stroke:#000; paint-order:normal"/>
<path class="path1" id="path9242" d="m233.79 453.52-153.64-138.25 196.55-63.937z" style="fill-rule:evenodd;fill:#f00;stroke:#000; paint-order:normal"/>
</svg>