为什么更改画布大小会重置其参数? [英] Why changing canvas size resets its parameters?

问题描述

当我更改画布大小时，我注意到参数'mozImageSmoothingEnabled'正在重置.

When I change the canvas size, I notice the parameter 'mozImageSmoothingEnabled' is being reset.

HTML

<canvas id='canv'>Your browser don't support canvas.</canvas>

JavaScript

Javascript

var cnv = document.getElementById('canv');
var ctx = cnv.getContext('2d');
console.log(ctx.mozImageSmoothingEnabled); // default 'true'
ctx.mozImageSmoothingEnabled = false;
console.log(ctx.mozImageSmoothingEnabled); // shows 'false'
cnv.width = 100;
console.log(ctx.mozImageSmoothingEnabled); // shows 'true'

JSFiddle: https://jsfiddle.net/epvtuz37/

JSFiddle: https://jsfiddle.net/epvtuz37/

这是错误，还是预期的行为?

Is this a bug, or expected behavior?

推荐答案

由于更改画布width或height参数时，附加上下文的每个属性均重置为其默认值

Because when you change the canvas width or height parameters, every properties of the attached context are reset to their default.

摘自规范

在创建canvas元素时，随后每当设置width和height属性(无论是新值还是之前的值)时，都必须将位图和任何关联的上下文清除回其初始状态，并使用新指定的坐标空间尺寸.

When the canvas element is created, and subsequently whenever the width and height attributes are set (whether to a new value or to the previous value), the bitmap and any associated contexts must be cleared back to their initial state and reinitialized with the newly specified coordinate space dimensions.

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