垂直對齊，使用CSS很容易實現，如果想在HTML5 Canvas中實現垂直對齊，如何設置呢，這就是今天要分享的筆記。

HTML畫布垂直對齊的文本，我們可以使用的textBaseline在畫布范圍內的屬性值。textBaseline可以設置以下值之一 ：top, hanging, middle, alphabetic, ideographic, and bottom。除非另有規定，textBaseline屬性默認為字母。

context.textBaseline=[value];

html5_canvas_text_baseline

body {margin: 0px;padding: 0px;}

#myCanvas {border: 1px solid #9C9898; margin:0 auto;margin-top:200px; margin-left:100px;}

window.onload = function(){

var canvas = document.getElementById("myCanvas");

var context = canvas.getContext("2d");

var x = canvas.width / 2;

var y = canvas.height / 2;

context.font = "30pt Calibri";

// textAlign aligns text horizontally relative to placement

context.textAlign = "center";

// textBaseline aligns text vertically relative to font style

context.textBaseline = "middle";

context.fillStyle = "blue";

context.fillText("Hello World!", x, y);

};