javascript - How to make a HTML5 canvas fit dynamic parent/flex box container -


is there way can create canvas inside dynamic re-sizing flex-box container?

preferably css solution think javascript required redraw?

i think 1 solution listen re-sizing event , scale canvas meet size of flex box parent force redraw preferably use css possible or more clean/less code solution.

the current approach css based canvas re-sized according parent flex box element. graphics blurred, re positioned , overflowed canvas in below screenshot.

stretched image/graphics overflowing canvas

css:

html,body{             margin:0;             width:100%;             height:100%;         }         body{             display:flex;             flex-direction:column;         } header{             width:100%;             height:40px;             background-color:red;         }         main{             display:flex;             flex: 1 1 auto;             border: 1px solid blue;             width:80vw;         }         canvas{             flex: 1 1 auto;             background-color:black;         }

html:

<header> </header> <main>     <canvas id="stage"></canvas> </main>

javascript:

$( document ).ready(function() {     var ctx = $("#stage")[0].getcontext("2d");     ctx.strokestyle="#ffffff";     ctx.beginpath();     ctx.arc(100,100,50,0,2*math.pi);     ctx.stroke(); });

js fiddle showing issue: https://jsfiddle.net/h2v1w0a1/

think of canvas image. if scale different size original appear blurry @ point, , perhaps on depending on interpolation algorithm chosen browser. canvas browser tend chose bi-linear on bi-cubic there higher risk of blur actual image.

you want have things in canvas rendered sharp possible , way adapt size parent using javascript, , avoid css (the latter things printing, or when need "retina resolutions").

to parent container size in pixels can use getcomputedstyle() (see update below):

var parent = canvas.parentnode,     styles = getcomputedstyle(parent),     w = parseint(styles.getpropertyvalue("width"), 10),     h = parseint(styles.getpropertyvalue("height"), 10);  canvas.width = w; canvas.height = h;

fiddle

(note: chrome seem have issues computed flex @ moment)

update

here's simpler way:

var rect = canvas.parentnode.getboundingclientrect(); canvas.width = rect.width; canvas.height = rect.height;

fiddle


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