How to mapping "letter-spacing" value from text node of SVG to "charSpacing" property of fabric.TextBox in FabricJS? - html5-canvas

Question

I have problem with how to re-presentation of node in SVG with "letter-spacing" in SVG document to fabric.TextBox.
In file SVG text node is:
<text transform="matrix(1 0 0 1 51.5211 22.2889)" style="fill:#3C2415; font-size:11px; letter-spacing:3;">MINH TUẤN</text>
And my fabric.TextBox is:
var textbox_0_1 = new fabric.Textbox("MINH TUẤN", {
width: 200,
fontSize: 11,
fill: "#3C2415",
editable: true,
textAlign: "center",
charSpacing: 3,
});
Here is display on SVG & FabricJS:
How to find correct charSpacing which is respectively with letter-spacing attribute in SVG's Text node ?
Notes:
In fabric.TextBox document write:
charSpacing :Number
additional space between characters expressed in thousands of em unit
And in document for SVG write:
(if no unit identifier is provided) values in user space — for example, "15"
And Here is my code:
var canvasObject = document.getElementById("editorCanvas");
// set canvas equal size with div
$(canvasObject).width($("#canvasContainer").width());
$(canvasObject).height($("#canvasContainer").height());
var canvas = new fabric.Canvas('editorCanvas', {
backgroundColor: 'white',
selectionLineWidth: 2,
width: $("#canvasContainer").width(),
height: $("#canvasContainer").height()
});
var textbox_0_1 = new fabric.Textbox("MINH TUẤN", {
top: 20,
left: 20,
width: 200,
fontSize: 11,
fill: "#000000",
editable: true,
textAlign: "center",
charSpacing: 3,
});
canvas.add(textbox_0_1);
setObjectCoords();
canvas.renderAll();
function setObjectCoords() {
canvas.forEachObject(function(object) {
object.setCoords();
});
}
#canvasContainer {
width: 100%;
height: 100vh;
background-color: gray;
}
<script src="https://code.jquery.com/jquery-3.3.1.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.4.3/fabric.js"></script>
<div id="canvasContainer">
<canvas id="editorCanvas"></canvas>
</div>
Thank you,

Answer 1

You need to parse from pixel to em.
DEMO
var canvas = new fabric.Canvas('editorCanvas', {
backgroundColor: 'white',
width: 300,
height: 100
});
var letterSpacing = 5, fontSize = 30;
var textbox = new fabric.Text("MINH TUẤN", {
top: 20,
fontSize: fontSize,
fill: "#000000",
fontFamily : "Verdana"
});
canvas.add(textbox);
var parsedSpacing = fabric.util.parseUnit(letterSpacing, fontSize) / fontSize * 1000;
textbox.set({charSpacing : parsedSpacing});
canvas.requestRenderAll();
console.log(parsedSpacing)
canvas{
border:1px solid;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.4.3/fabric.js"></script>
<svg width="300" height="100" viewBox="0 0 300 100">
<text font-size="30" letter-spacing="5" font-family="Verdana" y="40">MINH TUẤN</text>
</svg>
<canvas id="editorCanvas"></canvas>