这次简单分享一个canvas坐标效果和矩形动画效果。
<!DOCTYPE html>
<head>
<meta charset="UTF-8">
<title>canvas</title>
</head>
<body>
<script>
// 矩形动画效果
var juxing = new JuXing(ctx,100,100,10,10,2,'black');
juxing.draw();
setInternal(function(){
ctx.clearRect(0,0,cvs.width,cvs.height);
juxing.startX += 2;
juxing.draw();
},50);
</script>
<script>
ctx.setLineDash([4,2,1]);
// 绘制虚线，内部加入数组，表示4px实现，2px空白，1px实线。（实线与空白间隔就是虚线）
var i = 0 ;
for(var len = 255;i <= len;i++){
ctx.beginPath();
ctx.moveTo(10,10+i);
ctx.lineTo(210,10+i);
ctx.strokeStyle = "rgb("+0+","+ i +','+255+")";
ctx.stroke();
}
// 绘制一个渐变的矩形
var cvs = document.getElementById('cvs');
var ctx = cvs.getContext('2d');
ctx.lineDashOffset = 3;
// 设置虚线绘制时偏移量
ctx.setLineDash([4,3,2]);
ctx.moveTo(10,10);
ctx.lineTo(100,10);
ctx.stroke();
console.log(ctx.getLineDash());
</script>
<script>
// 绘制坐标轴
var cvs = document.getElementById('cvs');
var ctx = cvs.getContext('2d');
var padding = {
top:20,
right:20,
bottom:20,
left:20
}
// 箭头尺寸
var arrow = {
width:20,
height:20
}
// Y轴顶点坐标
var vertexTop = {
x:padding.left,
y:padding.top
}
// 原点坐标
var origin = {
x:padding.left,
y:cvs.height - padding.bottom
}
// X轴顶点坐标
var vertexRight = {
x:cvs.width - padding.right,
y:cvs.height - padding.bottom
}
// 两个坐标轴
ctx.moveTo(vertexTop.x, vertexTop.y);
ctx.lineTo(origin.x,origin.y);
ctx.lineTo(vertexRight.x,vertexRight.y);
ctx.stroke();
// 绘制坐标轴箭头
ctx.beginPath();
ctx.moveTo(vertexTop.x,vertexTop.y);
ctx.lineTo(vertexTop.x - arrow.width/2,vertexTop.y + arrow.height);
ctx.moveTo(vertexTop.x,vertexTop.y);
ctx.lineTo(vertexTop.x + arrow.width/2,vertexTop.y + arrow.height);
ctx.closePath();
cts.fill();
ctx.stroke();
ctx.beginPath();
ctx.moveTo(vertexRight.x,vertexRight.y);
ctx.lineTo(vertexRight.x - arrow.height,vertexRight.y - arrow.width/2);
ctx.moveTo(vertexRight.x,vertexRight.y);
ctx.lineTo(vertexRight.x - arrow.height, vertexRight.y + arrow.width/2);
ctx.closePath();
ctx.fill();
ctx.stroke();
// 在坐标轴内指定位置画一个点（小矩形）
var point = {
x:100,
y:200
}
ctx.fillRect(origin.x + point.x, origin.x - point.y, 2, 2);
</script>
</body>
</html>