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?
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
我相信我已经找到了一个优雅的解决方案:
JavaScript
/* important! for alignment, you should make things
* relative to the canvas' current width/height.
*/
function draw() {
var ctx = (a canvas context);
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
//...drawing code...
}
CSS
html, body {
width: 100%;
height: 100%;
margin: 0;
}
到目前为止,还没有对我的表现产生任何大的负面影响。
其他回答
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。
设置初始大小。
const canvas = document.getElementById('canvas');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
更新窗口大小调整。
function windowResize() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
};
window.addEventListener('resize', windowResize);
我认为这正是我们应该做的:http://www.html5rocks.com/en/tutorials/casestudies/gopherwoord-studios-resizing-html5-games/
function resizeGame() {
var gameArea = document.getElementById('gameArea');
var widthToHeight = 4 / 3;
var newWidth = window.innerWidth;
var newHeight = window.innerHeight;
var newWidthToHeight = newWidth / newHeight;
if (newWidthToHeight > widthToHeight) {
newWidth = newHeight * widthToHeight;
gameArea.style.height = newHeight + 'px';
gameArea.style.width = newWidth + 'px';
} else {
newHeight = newWidth / widthToHeight;
gameArea.style.width = newWidth + 'px';
gameArea.style.height = newHeight + 'px';
}
gameArea.style.marginTop = (-newHeight / 2) + 'px';
gameArea.style.marginLeft = (-newWidth / 2) + 'px';
var gameCanvas = document.getElementById('gameCanvas');
gameCanvas.width = newWidth;
gameCanvas.height = newHeight;
}
window.addEventListener('resize', resizeGame, false);
window.addEventListener('orientationchange', resizeGame, false);
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);
一个纯CSS的方法添加到解决方案@jerseyboy上面。 适用于Firefox (v29测试),Chrome (v34测试)和Internet Explorer (v11测试)。
<!DOCTYPE html>
<html>
<head>
<style>
html,
body {
width: 100%;
height: 100%;
margin: 0;
}
canvas {
background-color: #ccc;
display: block;
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
width: 100%;
height: 100%;
}
</style>
</head>
<body>
<canvas id="canvas" width="500" height="500"></canvas>
<script>
var canvas = document.getElementById('canvas');
if (canvas.getContext) {
var ctx = canvas.getContext('2d');
ctx.fillRect(25,25,100,100);
ctx.clearRect(45,45,60,60);
ctx.strokeRect(50,50,50,50);
}
</script>
</body>
</html>
链接到示例:http://temporaer.net/open/so/140502_canvas-fit-to-window.html
但要小心,正如@jerseyboy在他的评论中所说:
用CSS重新缩放画布是很麻烦的。至少在Chrome和 Safari中,鼠标/触摸事件的位置不会1:1对应 Canvas像素位置,你需要变换坐标 系统。