html5 - Drawing shape on canvas with relative size -


i have code draws circle. how change code red circle 100% of browser window? want red circle resize browser window.

  <canvas width="100%" height="100%"></canvas>     var ctx;      function draw() {      ctx = $('canvas').get(0).getcontext('2d');        ctx.canvas.width  = window.innerwidth;       ctx.canvas.height = window.innerheight;     }       function circle(x, y, r, c) {         ctx.beginpath();         var rad = ctx.createradialgradient(x, y, 1, x, y, r);         rad.addcolorstop(0, 'rgba('+c+',1)');         rad.addcolorstop(1, 'rgba('+c+',0)');         ctx.fillstyle = rad;         ctx.arc(x, y, r, 0, math.pi*2, false);         ctx.fill();     }       draw();       circle(128, 128, 200, '255,0,0');

consider jsfiddle

on load/resize:

create circle draw() setvars() circle(...)

draw() (which sets width/height of canvas) clear canvas (see: how clear canvas redrawing)

var ctx, canvas, x, y, w, h, r;  function draw() {     ctx = $('canvas').get(0).getcontext('2d');     canvas = ctx.canvas;     canvas.width = window.innerwidth;     canvas.height = window.innerheight; }  function setvars() {     w = canvas.width;     h = canvas.height;     x = w/2;     y = h/2;     r = x < y ? x : y; }  function circle(x, y, r, c) {     ctx.beginpath();     var rad = ctx.createradialgradient(x, y, 1, x, y, r);     rad.addcolorstop(0, 'rgba(' + c + ',1)');     rad.addcolorstop(1, 'rgba(' + c + ',0)');     ctx.fillstyle = rad;     ctx.arc(x, y, r, 0, math.pi * 2, false);     ctx.fill(); }  function makecircle() {     draw();     setvars();     circle(x, y, r, '255,0,0'); }  $(window).resize(function () {     // redraw (onresize)     makecircle(); });  // draw (onload) makecircle();

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