67.canvas绘制常规图形

//一个简单的画板

67.canvas绘制常规图形

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>putImageData</title>
    <style>
        body,
        html {
            margin: 0;
            padding: 0;
        }

        #myCanvas {
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
        }

        .tools {
            position: fixed;
            top: 0;
            right: 0;
            left: 0;
            padding: 15px 10px;
            font-size: 0;
            background: #1a1a1a;
            z-index: 1;
        }

        .tool {
            display: inline-block;
            font-size: 12px;
            background: #eee;
            padding: 5px;
            cursor: pointer;
            vertical-align: middle;
            /* width: 40px; */
            text-align: center;
        }

        .tool+.tool {
            margin-left: 5px;
        }
    </style>
</head>

<body>
    <div class="tools">
        <div class="tool" onclick="selToolClick('line')">线</div>
        <div class="tool" onclick="selToolClick('rect')">矩形</div>
        <div class="tool" onclick="selToolClick('circle')">圆</div>
        <div class="tool" onclick="selToolClick('ellipse')">椭圆</div>
        <div class="tool" onclick="selToolClick('cloud')">云线</div>
        <div class="tool" onclick="selToolClick('polygon')">多边形</div>
        <div class="tool" onclick="exportImgData()">导出图片</div>
    </div>
    <canvas id="myCanvas">

    </canvas>
    <script>
        function coord(startPoint, endPoint) {
            return {
                a: endPoint.x - startPoint.x, //x的差
                b: endPoint.y - startPoint.y, //y的差
                c: Math.sqrt(Math.pow(endPoint.x - startPoint.x, 2) + Math.pow(endPoint.y - startPoint.y, 2)), //两点间的距离
                k: Math.atan2(endPoint.y - startPoint.y, endPoint.x - startPoint.x) //斜率
            };
        }
        function polar(p, k) {
            // p 长度
            // k 角度, 斜率
            return {
                x: p * Math.cos(k),
                y: p * Math.sin(k)
            };
        }
        class baseTool {
            constructor(ctx) {
                this.canvasContext = ctx;
                this.startPoint = {};
                this.endPoint = {}
                this.points = []
            }
            setCanvasStyle() {
                this.canvasContext.lineWidth = 2;
                this.canvasContext.strokeStyle = "blue";
                this.canvasContext.fillStyle = "blue";
            }
            drawGraph() {

            }
        }
        class lineTool extends baseTool {
            constructor(ctx) {
                super(ctx);
            }
            drawGraph() {
                this.setCanvasStyle();
                this.canvasContext.beginPath();
                this.canvasContext.moveTo(this.startPoint.x, this.startPoint.y);
                this.canvasContext.lineTo(this.endPoint.x, this.endPoint.y);
                this.canvasContext.stroke();
            }

        }
        class rectTool extends baseTool {
            constructor(ctx) {
                super(ctx);
            }
            drawGraph() {
                this.setCanvasStyle();
                this.canvasContext.beginPath();
                this.canvasContext.rect(this.startPoint.x, this.startPoint.y, this.endPoint.x - this.startPoint.x, this.endPoint.y - this.startPoint.y);
                this.canvasContext.stroke();
            }
        }
        class circleTool extends baseTool {
            constructor(ctx) {
                super(ctx);
            }
            drawGraph() {
                this.setCanvasStyle();

                let _x = this.startPoint.x - this.endPoint.x;
                let _y = this.startPoint.y - this.endPoint.y;
                let r = Math.sqrt(_x * _x + _y * _y);

                this.canvasContext.beginPath();
                this.canvasContext.arc(this.startPoint.x, this.startPoint.y, 1, 0, 2 * Math.PI);
                this.canvasContext.stroke();
                this.canvasContext.beginPath();
                this.canvasContext.arc(this.startPoint.x, this.startPoint.y, r, 0, 2 * Math.PI);
                this.canvasContext.stroke();
            }
        }
        class ellipseTool extends baseTool {
            constructor(ctx) {
                super(ctx);
            }
            drawGraph() {
                this.setCanvasStyle();
                this.canvasContext.beginPath();
                //椭圆圆心坐标
                //圆心点
                let _x = (this.endPoint.x + this.startPoint.x) / 2;
                let _y = (this.endPoint.y + this.startPoint.y) / 2
                //
                let radiusX = Math.abs((this.startPoint.x - this.endPoint.x) / 2);
                let radiusY = Math.abs((this.startPoint.y - this.endPoint.y) / 2);
                this.canvasContext.ellipse(_x, _y, radiusX, radiusY, 0, 0, 2 * Math.PI);
                this.canvasContext.stroke();
                // this.canvasContext.fill();
            }
        }
        class polygonTool extends baseTool {
            constructor(ctx) {
                super(ctx);
                this.isCloseGraph = false;
                this.cloudRadiusMin = 20;
                this.cloudRadiusMax = 30;
            }
            get allPoints() {
                let points = [];
                points.push(this.startPoint);
                points = points.concat(this.points);
                points.push(this.endPoint);
                return points
            }
            set allPoints(val) {

            }
            drawGraph() {
                this.setCanvasStyle();
                this.canvasContext.beginPath();
                this.canvasContext.moveTo(this.startPoint.x, this.startPoint.y);
                for (let i = 0; i < this.points.length; i++) {
                    var point = { ...this.points[i] }
                    this.canvasContext.lineTo(point.x, point.y);
                }
                this.canvasContext.lineTo(this.endPoint.x, this.endPoint.y);
                this.canvasContext.stroke();
            }
        }
        class cloudTool extends polygonTool {
            constructor(ctx) {
                super(ctx);
            }
            drawGraph() {
                this.setCanvasStyle();
                for (let i = 0; i < this.allPoints.length - 1; i++) {
                    const CPoint = this.allPoints[i];
                    const NPoint = this.allPoints[i + 1];
                    const c = coord(CPoint, NPoint).c;//俩点之间的距离
                    const k = coord(CPoint, NPoint).k;//俩点之间的斜率
                    let tmpPoints = [];//俩点之间的分割点集
                    let tmpPoints2 = []; let index = 0;
                    index = index + 1;
                    tmpPoints.push({ ...CPoint })
                    for (let j = 0; j < Math.round((c + this.cloudRadiusMin / 2) / this.cloudRadiusMin); j++) {
                        let newPoint = {
                            x: this.cloudRadiusMin * Math.cos(k) + tmpPoints[index - 1].x,
                            y: this.cloudRadiusMin * Math.sin(k) + tmpPoints[index - 1].y
                        }
                        tmpPoints.push({ ...newPoint });
                        index = index + 1;
                    }
                    for (let n = 0; n < tmpPoints.length; n++) {
                        var point = {
                            x: tmpPoints[n].x - polar(this.cloudRadiusMin / 2, k).x,
                            y: tmpPoints[n].y - polar(this.cloudRadiusMin / 2, k).y
                        };
                        tmpPoints2.push(point)
                    }
                    for (let m = 0; m < tmpPoints2.length - 1; m++) {
                        const tp = tmpPoints2[m];
                        var c1 = coord(tmpPoints2[m], tmpPoints2[m + 1]).c;//俩点之间的距离
                        var x1 = polar(c1 / 2, k).x + tmpPoints2[m].x;
                        var y1 = polar(c1 / 2, k).y + tmpPoints2[m].y;
                        let r1 = c1 / 2 / Math.cos(30 / 180 * Math.PI);
                        var distance = coord({ x: x1, y: y1 }, NPoint).c;
                        var distanceHalf = distance / 2;
                        if (m == tmpPoints2.length - 1) {
                            this.canvasContext.beginPath();
                            this.canvasContext.arc(x1, y1, r1, k, k + Math.PI * 7 / 6, true);
                            this.canvasContext.stroke();

                        } else {
                            this.canvasContext.beginPath();
                            this.canvasContext.arc(x1, y1, r1, k, k + Math.PI * 7 / 6, true);
                            this.canvasContext.stroke();
                        }
                    }
                }
            }
            isNearStartPoint() {

            }
        }

        class Print {
            constructor(id) {
                this.id = id;
                this.canvas = null;
                this.ctx = null;
                this.canvasGraph = null;
                this.canvasGraphContext = null;
                this.canvasMedia = null;
                this.canvasMediaContext = null;
                this.tool = null;
                this.tools = [];//所有的数据
                this.toolName = null;
                this.viewStyle = {};
                this.mouse = {
                    down: {
                        x: null, y: null
                    },
                    move: {
                        x: null, y: null
                    },
                    up: {
                        x: null, y: null
                    },
                    isMove: false
                }
                this.init();
                this.bindEvent();
            }
            init() {
                var height = document.documentElement.clientHeight;
                var width = document.documentElement.clientWidth;
                this.viewStyle.height = height;
                this.viewStyle.width = width;
                this.canvas = document.getElementById(this.id);
                this.canvas.width = width;
                this.canvas.height = height;
                this.ctx = this.canvas.getContext('2d');
            }
            saveData() {
                this.tools.push(this.tool);
            }
            newGraph() {
                this.setTool();
                this.tool.startPoint = { ...this.mouse.down };
                this.saveData();
            }
            update() {
                this.clear();
                this.draw();
            }
            draw() {
                this.tools.forEach(d => {
                    d.drawGraph()
                })
            }

            clear() {
                this.ctx.clearRect(0, 0, this.viewStyle.width, this.viewStyle.height);
            }
            bindEvent() {
                this.onEvent();
            }
            createImgData() {
                // this.canvas.toDataURL('image/jpeg', 0.99);
                this.canvas.toBlob(function (blob) {
                    var link = document.getElementById('downMyCavans');
                    if (!link) {
                        link = document.createElement('a');
                        document.body.appendChild(link);
                    }
                    var url = URL.createObjectURL(blob);

                    link.href = url;
                    link.download = Math.floor(Math.random() * 10000000) + "Download.jpg";

                    link.click();

                    URL.revokeObjectURL(url);

                }, 'image/jpeg', 0.99);
            }
            selTool(toolName) {
                this.toolName = toolName;
            }
            setTool() {
                switch (this.toolName) {
                    case 'line':
                        this.tool = new lineTool(this.ctx);
                        break;
                    case 'rect':
                        this.tool = new rectTool(this.ctx);
                        break;
                    case 'circle':
                        this.tool = new circleTool(this.ctx);
                        break;
                    case 'ellipse':
                        this.tool = new ellipseTool(this.ctx);
                        break;
                    case 'cloud':
                        this.tool = new cloudTool(this.ctx);
                        break;
                    case 'polygon':
                        this.tool = new polygonTool(this.ctx);
                        break;
                    default:
                        break;
                }

            }
            onEvent() {

                this.canvas.onmousedown = (e) => {
                    this.mouseDown(e);
                }
                this.canvas.onmouseup = (e) => {
                    this.mouseUp(e);
                }
                this.canvas.onmousemove = (e) => {
                    this.mouseMove(e);

                }
                this.canvas.ondblclick = (e) => {
                    this.dblClick(e);
                }
            }
            offEvent() {
                this.canvas.onmousedown = null;
                this.canvas.onmouseup = null;
                this.canvas.onmousemove = null;
            }
            mouseDown(e) {

                this.mouse.isMove = true;
                let x = e.x, y = e.y;
                let point = { x: x, y: y };
                this.mouse.down = { x: x, y: y };
                if (['cloud', 'polygon'].indexOf(this.toolName) >= 0) {
                    if (this.tool && !this.tool.isCloseGraph) {
                        this.tool.points.push({ ...this.mouse.down });
                        return true;
                    }
                }
                this.newGraph();

            }
            mouseMove(e) {
                if (this.mouse.isMove) {
                    let x = e.x, y = e.y;
                    let point = { x: x, y: y };
                    this.mouse.move = { x: x, y: y };
                    this.tool.endPoint = { ...this.mouse.move }
                    this.update();
                }
            }
            mouseUp(e) {
                if (['cloud', 'polygon'].indexOf(this.toolName) >= 0) {
                    let x = e.x, y = e.y;
                    let point = { x: x, y: y };
                    this.mouse.up = { x: x, y: y };

                } else {
                    this.mouse.isMove = false;
                }

            }
            clearMouse() {
                this.mouse = {
                    down: {
                        x: null, y: null
                    },
                    move: {
                        x: null, y: null
                    },
                    up: {
                        x: null, y: null
                    },
                    isMove: false
                }
            }
            dblClick(e) {
                if (['cloud', 'polygon'].indexOf(this.toolName) >= 0) {
                    //结束
                    let point = { ...this.tool.startPoint }
                    const { x, y } = point;
                    if (this.tool) {
                        this.tool.isCloseGraph = true;
                        this.tool.endPoint = { x, y };
                    }
                    this.clearMouse();
                    this.update();
                }
            }
        }
        let canvas = new Print('myCanvas');
        function selToolClick(toolName) {
            canvas.selTool(toolName);
        }
        function exportImgData() {
            canvas.createImgData()
        }
    </script>
</body>

</html>

  

 

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