canvas基础2 -- 形状-编程知识

canvas基础2 -- 形状

七巧板

七巧板本质上就是分别由几个直线拼成一个个图形，再将这些图形结合起来

var tangram = [{ p: [{ x: 0, y: 0 }, { x: 800, y: 0 }, { x: 400, y: 400 }], color: "#caff67" },{ p: [{ x: 0, y: 0 }, { x: 400, y: 400 }, { x: 0, y: 800 }], color: "#67beef" },{ p: [{ x: 800, y: 0 }, { x: 800, y: 400 }, { x: 600, y: 600 }, { x: 600, y: 200 }], color: "#ef3d61" },{ p: [{ x: 600, y: 200 }, { x: 600, y: 600 }, { x: 400, y: 400 }], color: "#f9f5la" },{ p: [{ x: 400, y: 400 }, { x: 600, y: 600 }, { x: 400, y: 800 }, { x: 200, y: 600 }], color: "#a594c0" },{ p: [{ x: 200, y: 600 }, { x: 400, y: 800 }, { x: 0, y: 800 }], color: "#fa8ecc" },{ p: [{ x: 800, y: 400 }, { x: 800, y: 800 }, { x: 400, y: 800 }], color: "#f6ca29" }]const canvas = document.getElementById('canvas')canvas.width = 800canvas.height = 800const context = canvas.getContext('2d')for (let i = 0; i < tangram.length; i++) {draw(tangram[i], context)}function draw(piece, cxt) {cxt.beginPath()cxt.moveTo(piece.p[0].x, piece.p[0].y)for (var i = 1; i < piece.p.length; i++) {cxt.lineTo(piece.p[i].x, piece.p[i].y)}cxt.closePath()cxt.fillStyle = piece.colorcxt.fill()cxt.strokeStyle = "black"cxt.lineWidth = 3cxt.stroke()}

图示：

箭头

    context.beginPath()context.moveTo(100, 350) context.lineTo(500, 350) context.lineTo(500, 200) context.lineTo(700, 400)context.lineTo(500, 600)context.lineTo(500, 450)context.lineTo(100, 450)context.closePath()context.lineWidth = 5  context.strokeStyle = '#058'context.stroke()

图示：