JSFiddle - React, Tailwind, and code Playground

by grapien

HTML

Enter Your Text: <br/>
<textarea id="inputtextuser" onkeyup="inputtextgo()" name="Text">Enter Your</textarea> <br/>
TextBaseline: 
<select id="inputtextbaseline" onchange="inputtextgo()";> 
    <option value="alphabetic">alphabetic</option>
    <option value="top">top</option>
    <option value="bottom">bottom</option>
    <option value="middle">middle</option>
    <option value="hanging">hanging</option>
</select> <br/>
<canvas id="canvas1"  width="300px" height="200px" >Your browser does not support the HTML5 canvas tag.</canvas> <br/>
<div id ="textheightentered"></div>

CSS

canvas {
    border: solid 1px black;
}

JavaScript

//Declaring the Canvas
var canvas1 = document.getElementById('canvas1');
context1 = canvas1.getContext('2d');

//running the funciton to update the canvase
 inputtextgo();

function inputtextgo() {
    //Retrieving the text entered by the user
    var inputtext = document.getElementById("inputtextuser").value;
    //Calling the function to calculate the height on the text entered by the user
    var textheight = fontheight(inputtext);
    //retrieving the baseline selected by the user
    var baseline = document.getElementById("inputtextbaseline").value;
    //calculating the new y needed to center the text based on the height of the text
    var y = 100 + textheight/2;
    
    //Updating the canvas for the new text entered by the user
    context1.clearRect(0, 0, 300, 200);
    context1.font = "36px arial";
    context1.textBaseline = baseline;
    context1.fillText (inputtext, 0, y);   
    
    //Drawing a line across the middle of the canvas for reference
    context1.strokeStyle="red";
    context1.moveTo(5,100);
    context1.lineTo(290,100);
    context1.stroke();
    $("#textheightentered").text("Text Height: " + textheight);
}

function fontheight(text){

    var canvas=document.createElement("canvas");
    canvas.width = 1000;
    canvas.height = 200;
    var ctx=canvas.getContext("2d");

    function measureTextHeight(left, top, width, height,text) {

        // Draw the text in the specified area
        ctx.save();
        ctx.clearRect(0,0, canvas.width, canvas.height);
		ctx.baseline = "top";
		ctx.fillText(text, 0, 35); // This seems like tall text...  Doesn't it?
		ctx.restore();

        // Get the pixel data from the canvas
        var data = ctx.getImageData(left, top, width, height).data,
            first = false, 
            last = false,
            r = height,
            c = 0;

        // Find the last line with a non-white pixel
        while(!last && r) {
            r--;
            for(c = 0; c < width; c++) {
               ...