[英]Can I draw two shapes on top of each other and have a combined stroke/outline?
到目前为止我有这个: http : //jsfiddle.net/gautamadude/MQuxC/1/
但显然中风不正确,应该是不规则形状而不是交叉。
是否有可能通过一些globalCompositionOperator体操或其他方式来实现这一点,或者我必须“一步一步”地绘制它而不是在彼此之上绘制一个圆圈和一个矩形?
$(document).ready(function() {
var d_canvas = document.getElementById('canvas');
var context = d_canvas.getContext('2d');
context.beginPath();
var circle_x = 150;
var circle_y = 150;
var radius = 50;
var corners = 10;
var width = (radius*2)/1.1
var height = 50;
var x = circle_x - width/2;
var y = circle_y - 70;
context.moveTo(x + corners, y);
context.lineTo(x + width - corners, y);
context.quadraticCurveTo(x + width, y, x + width, y + corners);
context.lineTo(x + width, y + height - corners);
context.quadraticCurveTo(x + width, y + height, x + width - corners, y + height);
context.lineTo(x + corners, y + height);
context.quadraticCurveTo(x, y + height, x, y + height - corners);
context.lineTo(x, y + corners);
context.quadraticCurveTo(x, y, x + corners, y);
context.arc(circle_x, circle_y, radius, 0, 2*Math.PI);
context.fillStyle = "#000000";
context.fill();
context.strokeStyle = "red";
context.stroke();
context.endPath();
});
您可以通过剪切获得所需的效果:
- 填充和描边圆角矩形
- 填补下圈
- 然后,抚摸圆圈的右边部分:
- 首先剪辑整个画布
- 然后剪掉上方的直肠
- 现在抚摸圆圈。
使用lineWidth为0执行此操作,因为您要精确定义rect。
现在你可以绘制,它将绘制到任何地方,但在矩形。
我将上部矩形近似为常规矩形,在这种情况下可以:
http://jsfiddle.net/gamealchemist/MQuxC/3/
$(document).ready(function () {
var d_canvas = document.getElementById('canvas');
var context = d_canvas.getContext('2d');
context.lineWidth = 2;
context.strokeStyle = "red";
context.beginPath();
var circle_x = 150;
var circle_y = 150;
var radius = 50;
var corners = 10;
var width = (radius * 2) / 1.1
var height = 50;
var x = circle_x - width / 2;
var y = circle_y - 70;
context.moveTo(x + corners, y);
context.lineTo(x + width - corners, y);
context.quadraticCurveTo(x + width, y, x + width, y + corners);
context.lineTo(x + width, y + height - corners);
context.quadraticCurveTo(x + width, y + height, x + width - corners, y + height);
context.lineTo(x + corners, y + height);
context.quadraticCurveTo(x, y + height, x, y + height - corners);
context.lineTo(x, y + corners);
context.quadraticCurveTo(x, y, x + corners, y);
context.fillStyle = "#000000";
context.fill();
context.stroke();
context.beginPath();
context.arc(circle_x, circle_y, radius, 0, 2 * Math.PI);
context.fillStyle = "#000000";
context.fill();
context.save();
// clip the whole canvas...
clipCanvas();
// then draw a hole with the upper rect
context.moveTo(x, y);
context.lineTo(x, y + height);
context.lineTo(x + width, y + height);
context.lineTo(x + width, y);
context.lineTo(x, y);
context.clip();
// stroke the circle = everywhere except in the rect
context.beginPath();
context.lineWidth = 2;
context.arc(circle_x, circle_y, radius, 0, 2 * Math.PI);
context.stroke();
context.restore();
function clipCanvas() {
context.beginPath();
context.lineWidth = 0;
context.moveTo(0, 0);
context.lineTo(context.canvas.width, 0); // width/h should be cached if performance matters.
context.lineTo(context.canvas.width, context.canvas.height);
context.lineTo(0, context.canvas.height);
context.lineTo(0, 0);
context.clip();
}
});
您可以使用合成来勾勒出组合形状
演示: http : //jsfiddle.net/m1erickson/EucUZ/
如果你想同时描边和填充你的rect + arc,只需在stroke()之后执行fill()。
drawYourPath();
ctx.stroke();
ctx.fill();
如果只想要大纲描边,可以使用合成:
drawYourPath();
ctx.stroke();
ctx.globalCompositeOperation="destination-out";
ctx.fill();
此代码可以稍微增强
修订后的代码:
ctx.save();
drawYourPath();
ctx.lineWidth*=2;
ctx.stroke();
ctx.globalCompositeOperation="destination-out";
ctx.fill();
ctx.restore();
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