AnyGraph示例：采用“取色法”实现拾取功能
本示例演示：使用取色法实现几何对象的拾取功能。
实现要点：
1、初始化图形对象时增加 hitGetColor=true 选项
2、在图形对象中增加mouseMove事件;
3、从快照画布中获取鼠标位置的颜色值，并从缓存的viewGeomList清单中获取几何对象;
4、下图的右侧画布为功能演示用，在应用环境中可不显示该画布;
xxxxxxxxxx<div id="graphWrapper" data-type="graph" style="display:inline-block; width:500px; height:500px; border:solid 1px #CCC;"></div><div id="graphColor" data-type="graph" style="position:absolute; display:inline-block; width:500px; height:500px; border:solid 1px #CCC; background-image: url('../images/transparent.png');"></div>xxxxxxxxxx import { Graph, Layer, VectorSource, BgUtil, Color, MathUtil, Collide, circle2LineRing, getStarLineRing, GGeometryType, Rect, Point, Circle, Ellipse, Text, Polyline, Polygon, EventType } from "../../src/index.js"; // graph对象 let graph = new Graph({ "target": "graphWrapper", "hitGetColor": true }); // 网格水印层 let bgLayer = BgUtil.generateGrid(Object.assign({ "interval": 10, "graph": graph }, graph.getSize())); bgLayer.getSource().add(new Text({ "text": "按点拾取（取色法）Demo", "x": graph.getSize().width / 2, "y": graph.getSize().height / 2, "vectorSize": false, "style": { "fillColor": "#D0D0D0", "fontSize": 30, "fontName": "黑体", "textAlign": "center", "textBaseline": "middle" } })); // 新建绘图图层 let layer = graph.addLayer(); // 浮动层 let overLayer = graph.addOverLayer(); let lastPosition = [0, 0]; // pageload $(document).ready(function () { let colorCanvas = graph.getRenderer().getHitImage(); $("#graphColor").append(colorCanvas); // 鼠标移动事件 graph.getRenderObject().on('mousemove', function (e) { let point = [e.offsetX, e.offsetY]; let coord = graph.getCoordinateFromPixel(point, true); // 清空浮动层数据 overLayer.getSource().clearData(); // 碰撞检测 _collideCheck(point); // 鼠标位置点 overLayer.getSource().add(new Point({ "x": coord[0], "y": coord[1], "size": -5, "style": { "fillColor": "blue", "fillStyle": 1, "color": "none" } })); lastPosition = [point[0], point[1]]; }); // 取色法进行碰撞检测 function _collideCheck(coord) { // 显示颜色值 let hitColor = graph.getRenderer().getColor(coord); if (hitColor) { if (graph.viewGeomList.has(hitColor)) { let geom = graph.viewGeomList.get(hitColor).clone(); geom.setStyle({ "fillColor": "#FF2020", "color": "#FF2020", "lineWidth": 4 }); overLayer.getSource().add(geom); return true; } } return false; } // 在颜色Canvas上绘制圆点, 非演示环境不需要该段代码 let tmpCanvas = document.createElement("canvas"); $("#graphColor").append(tmpCanvas) tmpCanvas.width = colorCanvas.width; tmpCanvas.height = colorCanvas.height; tmpCanvas.style.position = "absolute"; tmpCanvas.style.top = 0; tmpCanvas.style.left = 0; let ctxColor = tmpCanvas.getContext('2d'); graph.on(EventType.RenderAfter, function (args) { ctxColor.clearRect(0, 0, ctxColor.canvas.width, ctxColor.canvas.height); // 绘制圆点 ctxColor.beginPath(); ctxColor.arc(lastPosition[0], lastPosition[1], 3, 0, 2 * Math.PI); ctxColor.fillStyle = "blue"; ctxColor.fill(); }); // 复选框状态事件：清空或随机生成对象 $("#chkPoint").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(6, 10); i++) { layer.getSource().add(new Point({ "x": MathUtil.getRandomNum(50, 450), "y": MathUtil.getRandomNum(50, 450), "size": MathUtil.getRandomNum(10, 20), "style": { "fillColor": "#FFDFDF", "fillStyle": 1, "lineWidth": 1, "color": "#FFA5E8" } })); } } else { layer.getSource().clearTypeData(GGeometryType.POINT); } graph.render(); }); // 复选框状态事件：清空或随机生成对象 $("#chkRect").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(3, 5); i++) { layer.getSource().add(new Rect({ "x": MathUtil.getRandomNum(50, 450), "y": MathUtil.getRandomNum(50, 450), "width": MathUtil.getRandomNum(40, 70), "height": MathUtil.getRandomNum(20, 40), "style": { "fillColor": "#FFDFDF", "fillStyle": 1, "lineWidth": 1, "color": "#FFA5E8" } })); } } else { layer.getSource().clearTypeData(GGeometryType.RECT); } graph.render(); }); $("#chkCircle").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(3, 5); i++) { layer.getSource().add(new Circle({ "x": MathUtil.getRandomNum(50, 450), "y": MathUtil.getRandomNum(50, 450), "radius": MathUtil.getRandomNum(20, 40), "style": { "fillColor": "#DFFFBF", "fillStyle": 1, "lineWidth": 1, "color": "#FFA5E8" } })); } } else { layer.getSource().clearTypeData(GGeometryType.CIRCLE); } graph.render(); }); $("#chkText").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(3, 5); i++) { layer.getSource().add(new Text({ "x": MathUtil.getRandomNum(50, 450), "y": MathUtil.getRandomNum(50, 450), "rotation": MathUtil.getRandomNum(0, 90), "text": "碰撞检测文本", "style": { "fontSize": 24, "fontName": "黑体", "fillColor": "#0000FF", } })); } } else { layer.getSource().clearTypeData(GGeometryType.TEXT); } graph.render(); }); $("#chkEllipse").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(2, 4); i++) { layer.getSource().add(new Ellipse({ "x": MathUtil.getRandomNum(50, 450), "y": MathUtil.getRandomNum(50, 450), "radiusX": MathUtil.getRandomNum(20, 40), "radiusY": MathUtil.getRandomNum(20, 20), "style": { "fillColor": "#9FFFFF", "fillStyle": 1, "lineWidth": 1, "color": "#FFA5E8" } })); } } else { layer.getSource().clearTypeData(GGeometryType.ELLIPSE); } graph.render(); }); $("#chkPolyline").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(3, 5); i++) { let [x, y] = [MathUtil.getRandomNum(50, 400), MathUtil.getRandomNum(50, 400)]; layer.getSource().add(new Polyline({ "coords": [[x, y], [x + MathUtil.getRandomNum(10, 300), y + MathUtil.getRandomNum(-100, 100)]], "style": { "lineWidth": 4, "color": "#00957D" } })); } } else { layer.getSource().clearTypeData(GGeometryType.POLYLINE); } graph.render(); }); $("#chkPolygon").on("change", function () { if ($(this).prop("checked")) { for (let i = 0; i < MathUtil.getRandomNum(3, 5); i++) { let center = [MathUtil.getRandomNum(150, 400), MathUtil.getRandomNum(50, 400)]; let sideNum = MathUtil.getRandomNum(3, 8); let radius = MathUtil.getRandomNum(20, 40); layer.getSource().add(new Polygon({ "coords": circle2LineRing(center, radius, sideNum), "style": { "fillColor": "#E5FFF5", "fillStyle": 1, "lineWidth": 1, "color": "#FF9F9F" } })); center = [MathUtil.getRandomNum(150, 620), MathUtil.getRandomNum(50, 400)]; layer.getSource().add(new Polygon({ "coords": getStarLineRing(center, radius, null, sideNum >= 6 ? sideNum - 3 : sideNum), "style": { "fillColor": "#E5FFF5", "fillStyle": 1, "lineWidth": 1, "color": "#FF9F9F" } })); } } else { layer.getSource().clearTypeData(GGeometryType.POLYGON); } graph.render(); }); $("#chkRect").click(); $("#chkPolygon").click(); })