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Use html5 canvas to draw a tangram

一个新手Original: 2017-10-13 09:34:591724browse

What does the tangram look like?

Use canvas to draw it. In fact, it is to find the coordinates of each point in the graphics of these 7 areas, and then use moveTo and lineTo to connect the lines with different settings. color.

<head>
    <meta charset=&#39;utf-8&#39; />
    <style>
        #canvas {
            border: 1px dashed #aaa;
        }
    </style>
    <script>
        window.onload = function () {
            var oCanvas = document.querySelector("#canvas"),
                oGc = oCanvas.getContext(&#39;2d&#39;),
                width = oCanvas.width, height = oCanvas.height,
                tangram = [
                { p: [{ x: 0, y: 0 }, { x: 800, y: 0 }, { x: 400, y: 400 }], color: "#caff67" }, //正上方绿色三角形区域
                { p: [{ x: 0, y: 0 }, { x: 400, y: 400 }, { x: 0, y: 800 }], color: "#67becf" }, //左方蓝色三角形区域
                { 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: "#f9f51a" },
                { p: [{ x: 400, y: 400 }, { x: 600, y: 600 }, { x: 400, y: 800 }, { x: 200, y: 600 }], color: "#a54c09" },
                { p: [{ x: 200, y: 600 }, { x: 400, y: 800 }, { x: 0, y: 800 }], color: "#fa8ccc" },
                { p: [{ x: 800, y: 400 }, { x: 800, y: 800 }, { x: 400, y: 800 }], color: "#f6ca29" }
            ];
            for (var i = 0; i < tangram.length; i++) {
                draw( oGc, tangram[i]);
            };
            function draw( cxt, piece ) {
                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.color;
                cxt.fill();
            }
        }
    </script>
</head>
<body>
    <canvas id="canvas" width="800" height="800"></canvas>
</body>

tangram stores the vertex coordinates and fill color of each shape. p is an array composed of the vertices of each area. Each point in the array is stored with a json object. ., one has 7 shapes, tangram is 7 items, and then uses a loop to connect the vertices of each area with other points with lines. Note that the points in each area must use paths. Why? You can refer to this article of mine: [JS Master’s Road] HTML5 Canvas Tutorial Series - Detailed explanation of begin path beginPath and close path closePath

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