JSFiddle - React, Tailwind, and code Playground

by v1r00z

HTML

<canvas id="canvas" width="800" height="600"></canvas>
<script type="text/javascript">
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var scale = 1;
var originx = 0;
var originy = 0;

function draw(){
    context.fillStyle = "white";
    context.fillRect(originx,originy,800/scale,600/scale);
    context.fillStyle = "black";
    context.fillRect(50,50,100,100);
}
setInterval(draw,100);

canvas.onmousedown = function (event){
    var mousex = event.clientX - canvas.offsetLeft;
    var mousey = event.clientY - canvas.offsetTop;
    var wheel = event.wheelDelta/120;//n or -n

    var zoom = 1 + wheel/2;

    context.translate(
        originx,
        originy
    );
    context.scale(zoom,zoom);
    context.translate(
        -( mousex / scale + originx - mousex / ( scale * zoom ) ),
        -( mousey / scale + originy - mousey / ( scale * zoom ) )
    );

    originx = ( mousex / scale + originx - mousex / ( scale * zoom ) );
    originy = ( mousey / scale + originy - mousey / ( scale * zoom ) );
    scale *= zoom;
}

</script>