我正在尝试调整大小以正确地将其放置在中间和更大的 div 中。我希望它是 500x500。我想做的是制作 Windows Paint 的经典版本。
问题是将“ Canvas ”调整到中间会阻止画笔“绘制”。
这是我到目前为止的代码。
<!DOCTYPE HTML>
<html>
<head>
<style>
body {
width: 500px;
height: 500px;
margin: auto;
top: 50%;
left: 50%;
width: 90%;
border: 3px solid #73AD21;
padding: 10px;
}
</style>
</head>
<body>
<div id="paint" >
<canvas id="myCanvas"></canvas>
</div>
<script>
var canvas = document.getElementById('myCanvas');
var ctx = canvas.getContext('2d');
var painting = document.getElementById('paint');
var paint_style = getComputedStyle(painting);
canvas.width = parseInt(paint_style.getPropertyValue('width'));
canvas.height = parseInt(paint_style.getPropertyValue('height'));
var mouse = {x: 0, y: 0};
canvas.addEventListener('mousemove', function(e) {
mouse.x = e.pageX - this.offsetLeft;
mouse.y = e.pageY - this.offsetTop;
}, false);
ctx.lineWidth = 10;
ctx.lineJoin = 'round';
ctx.lineCap = 'round';
ctx.strokeStyle = '#00CC99';
canvas.addEventListener('mousedown', function(e) {
ctx.beginPath();
ctx.moveTo(mouse.x, mouse.y);
canvas.addEventListener('mousemove', onPaint, false);
}, false);
canvas.addEventListener('mouseup', function() {
canvas.removeEventListener('mousemove', onPaint, false);
}, false);
var onPaint = function() {
ctx.lineTo(mouse.x, mouse.y);
ctx.stroke();
};
</script>
</body>
</html>
最佳答案
去掉body上的样式并将其替换为:
#paint {
height: 500px;
margin: auto;
width: 90%; /* you also had width: 500px, which one did you want? */
border: 3px solid #73AD21;
padding: 10px;
}
Fiddle - 看起来这个改变工作正常。
关于javascript - HTML Canvas 和正确显示的小问题？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36242833/