调整HTML5画布大小以适应窗口

如何自动缩放HTML5 <canvas>元素以适应页面?

例如，我可以得到一个<div>通过设置高度和宽度属性为100%缩放，但一个<canvas>不会缩放，会吗?

当前回答

一个最小的设置

HTML

<canvas></canvas>

CSS

html,
body {
  height: 100%;
  margin: 0;
}

canvas {
  width: 100%;
  height: 100%;
  display: block;
}

JavaScript

const canvas = document.querySelector('canvas');

const resizeObserver = new ResizeObserver(() => {
  canvas.width = Math.round(canvas.clientWidth * devicePixelRatio);
  canvas.height = Math.round(canvas.clientHeight * devicePixelRatio);
});

resizeObserver.observe(canvas);

对于 WebGL

const canvas = document.querySelector('canvas');
const gl = canvas.getContext('webgl');

const resizeObserver = new ResizeObserver(() => {
  canvas.width = Math.round(canvas.clientWidth * devicePixelRatio);
  canvas.height = Math.round(canvas.clientHeight * devicePixelRatio);
  gl.viewport(0, 0, canvas.width, canvas.height);
});

resizeObserver.observe(canvas);

注意，我们应该考虑到设备像素比，特别是对于HD-DPI显示。

2022-10-26 06:31:55

其他回答

除非你想让画布自动提升你的图像数据(这就是James Black的答案，但它看起来不漂亮)，你必须自己调整它的大小并重新绘制图像。画布居中

2009-11-04 13:52:23

一个最小的设置

HTML

<canvas></canvas>

CSS

html,
body {
  height: 100%;
  margin: 0;
}

canvas {
  width: 100%;
  height: 100%;
  display: block;
}

JavaScript

const canvas = document.querySelector('canvas');

const resizeObserver = new ResizeObserver(() => {
  canvas.width = Math.round(canvas.clientWidth * devicePixelRatio);
  canvas.height = Math.round(canvas.clientHeight * devicePixelRatio);
});

resizeObserver.observe(canvas);

对于 WebGL

const canvas = document.querySelector('canvas');
const gl = canvas.getContext('webgl');

const resizeObserver = new ResizeObserver(() => {
  canvas.width = Math.round(canvas.clientWidth * devicePixelRatio);
  canvas.height = Math.round(canvas.clientHeight * devicePixelRatio);
  gl.viewport(0, 0, canvas.width, canvas.height);
});

resizeObserver.observe(canvas);

注意，我们应该考虑到设备像素比，特别是对于HD-DPI显示。

2022-10-26 06:31:55

基本上你要做的是将onresize事件绑定到你的body，一旦你捕捉到事件，你只需要使用window调整画布的大小。innerWidth和window.innerHeight。

<!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>
    <title>Canvas Resize</title>

    <script type="text/javascript">
        function resize_canvas(){
            canvas = document.getElementById("canvas");
            if (canvas.width  < window.innerWidth)
            {
                canvas.width  = window.innerWidth;
            }

            if (canvas.height < window.innerHeight)
            {
                canvas.height = window.innerHeight;
            }
        }
    </script>
</head>

<body onresize="resize_canvas()">
        <canvas id="canvas">Your browser doesn't support canvas</canvas>
</body>
</html>

2011-09-08 22:18:59

这对我很管用。伪代码:

// screen width and height
scr = {w:document.documentElement.clientWidth,h:document.documentElement.clientHeight}
canvas.width = scr.w
canvas.height = scr.h

另外，就像devyn说的，您可以替换“document.documentElement”。宽度和高度均为“inner”的客户端:

**document.documentElement.client**Width
**inner**Width
**document.documentElement.client**Height
**inner**Height

它仍然有效。

2020-10-24 17:08:50

function resize() {

    var canvas = document.getElementById('game');
    var canvasRatio = canvas.height / canvas.width;
    var windowRatio = window.innerHeight / window.innerWidth;
    var width;
    var height;

    if (windowRatio < canvasRatio) {
        height = window.innerHeight;
        width = height / canvasRatio;
    } else {
        width = window.innerWidth;
        height = width * canvasRatio;
    }

    canvas.style.width = width + 'px';
    canvas.style.height = height + 'px';
};

window.addEventListener('resize', resize, false);

2013-10-16 09:59:10

调整HTML5画布大小以适应窗口

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