制作模糊形状的 HTML 画布

2022-01-17 00:00:00 canvas javascript html html5-canvas

我想使用 HTML 制作简单的形状.但是形状需要很大.而且画布是全屏的

I want to make simple shapes using HTML. But the shapes need to be big. And the canvas is in full screen

示例:http://jsfiddle.net/xLgg43s9/1/embedded/result/

代码:

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style>
* { margin: 0; padding: 0;}

body, html { height:100%; }

#canvas {
    position:absolute;
    width:100%;
    height:100%;
}
</style>
</head>

<body>
<canvas id="canvas">
</canvas>
<script>
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
ctx.fillStyle = "#000";
var w=canvas.width;
var h=canvas.height;
ctx.fillRect(0,0,w,h);
ctx.fillStyle="#fff";
ctx.beginPath();
var a=w/2;
var b=0;
ctx.arc(a,b,20,0,Math.PI,false);
ctx.closePath();
ctx.fill();
ctx.stroke();
ctx.beginPath();
ctx.fillStyle="red";
ctx.fillRect(0,0,10,100);
ctx.stroke();
ctx.save();

ctx.translate(240, 120);

ctx.rotate(Math.PI / 4); // 45 degrees

ctx.fillStyle = "yellow";
ctx.fillRect(-40, -40, 20, 20);

ctx.restore();

</script>
</body>
</html>

请修复它.

推荐答案

不要通过 CSS 设置画布的大小，这会拉伸画布元素，而不是实际使画布变大.

Don't set the canvas's size through CSS, that stretches the canvas element, instead of actually making the canvas larger.

改用 HTML 属性:

Use HTML attributes, instead:

<canvas id="canvas" width="500" height="500"></canvas>

现在，由于您想将画布设置为 100% 的宽度/高度，这些预设属性对您不起作用，您将不得不使用一些 JS:

Now, since you want to set the canvas to 100% width / height, those pre-set attributes aren't going to do the trick for you, you're going to have to use some JS:

var canvas = document.getElementById("canvas");
canvas.width  = window.innerWidth;
canvas.height = window.innerHeight;
var ctx=canvas.getContext("2d");
// etc...

如果您想在调整窗口大小时调整画布大小，建议您查看 this answer.

If you want to have the canvas resize when the window gets resized, I'd suggest you look at this answer.

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