javascript - 随着窗口大小的改变,缩放全屏画布以适应内容
问题描述
基本上,我有一个绘制网格的画布。当窗口改变大小时,它会刷新网格和场景以用网格填充整个屏幕。
当我将浏览器窗口调整为更小的尺寸时,我希望网格和画布内的所有内容都随之缩小,同时保持网格框为方形。像Agar.io这样的网站在他们的画布上使用了这个。
var canvas = document.getElementById("mainCanvas");
var ctx = canvas.getContext("2d");
function resize() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
}
function createMap() {
var gridOptions = {
majorLines: {
separation: 30,
color: '#e8e8e8'
}
};
drawGridLines(canvas, gridOptions.majorLines);
return;
}
function drawGridLines(canvas, lineOptions) {
var iWidth = canvas.width;
var iHeight = canvas.height;
ctx.strokeStyle = lineOptions.color;
ctx.strokeWidth = 1;
ctx.beginPath();
var iCount = null;
var i = null;
var x = null;
var y = null;
iCount = Math.floor(iWidth / lineOptions.separation);
for (i = 1; i <= iCount; i++) {
x = (i * lineOptions.separation);
ctx.moveTo(x, 0);
ctx.lineTo(x, iHeight);
ctx.stroke();
}
iCount = Math.floor(iHeight / lineOptions.separation);
for (i = 1; i <= iCount; i++) {
y = (i * lineOptions.separation);
ctx.moveTo(0, y);
ctx.lineTo(iWidth, y);
ctx.stroke();
}
ctx.closePath();
return;
}
function refresh() {
resize();
createMap();
}
window.onresize = function() {
refresh();
}
refresh();
body,
html {
align-content: center;
overflow: hidden;
border: 0;
margin: 0;
padding: 0;
}
#mainCanvas {
top: 0;
left: 0;
position: absolute;
overflow: hidden;
border: 0;
margin: 0;
padding: 0;
}
<canvas id="mainCanvas"></canvas>
换句话说,画布的视图就像鸟瞰图,如果从屏幕中心到左侧有 10 个网格框。当窗口完全放大时,屏幕将保持从中心到左侧的相同数字或网格框,就像将浏览器窗口调整为较小状态时一样。(当然,根据屏幕比例,大概有10个格子框左右,但大致就在这个范围内)
我尝试使用 CSS 将画布大小设置为100%
宽度和高度,但这会导致网格正方形变成模糊的矩形。
我可以添加什么来使画布中的元素随着窗口大小而缩小和增长?
解决方案
这是一个示例,其中画布中的元素随着窗口大小而缩小和增长:
<style>body{margin:0}</style>
<canvas id="mainCanvas"></canvas>
<script>
var canvas = document.getElementById("mainCanvas");
var ctx = canvas.getContext("2d");
function resize() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
var gridOptions = {
majorLines: {
separation: 20,
color: '#e8e8e8'
}
};
drawGridLines(canvas, gridOptions.majorLines);
}
function drawGridLines(canvas, lineOptions) {
ctx.strokeStyle = lineOptions.color;
ctx.strokeWidth = 1;
ctx.beginPath();
var size = Math.floor(canvas.width / lineOptions.separation);
for (var i = 1; i <= lineOptions.separation; i++) {
var x = (i * size);
ctx.moveTo(x, 0);
ctx.lineTo(x, canvas.height);
ctx.stroke();
}
for (var i = 1; i <= Math.floor(canvas.height / size); i++) {
var y = (i * size);
ctx.moveTo(0, y);
ctx.lineTo(canvas.width, y);
ctx.stroke();
}
ctx.closePath();
}
window.onresize = function() { resize(); }
resize();
</script>
这是一个现场样本:
https://raw.githack.com/heldersepu/hs-scripts/master/HTML/canvasResize2.html
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