项目初始化
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leilei
285
src/core/index.js
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285
src/core/index.js
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import EventEmitter from "@/utils/emitter";
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/**
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* Canvas绘图类，支持多种图形绘制和多人同步
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* 使用百分比坐标系统确保跨设备一致性
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*/
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class Canvas extends EventEmitter {
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constructor(canvasId) {
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super();
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this.canvas = document.getElementById(canvasId);
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if (!this.canvas) {
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throw new Error(`Canvas element with id ${canvasId} not found`);
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}
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this.ctx = this.canvas.getContext('2d');
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this.shapes = []; // 所有已绘制形状
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this.currentShape = null; // 当前正在绘制的形状
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this.isDrawing = false;
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this.drawingTool = 'pencil';
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this.pathOptimizationEnabled = true;
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this.optimizationThreshold = 0.005;
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this.currentColor = '#ffcc00';
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this.currentThickness = 2;
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this.resize();
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// 绑定事件
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this.handleMouseDown = this.handleMouseDown.bind(this);
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this.handleMouseMove = this.handleMouseMove.bind(this);
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this.handleMouseUp = this.handleMouseUp.bind(this);
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this.handleMouseLeave = this.handleMouseLeave.bind(this);
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this.canvas.addEventListener('mousedown', this.handleMouseDown);
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this.canvas.addEventListener('mousemove', this.handleMouseMove);
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this.canvas.addEventListener('mouseup', this.handleMouseUp);
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this.canvas.addEventListener('mouseleave', this.handleMouseLeave);
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window.addEventListener('resize', () => this.resize());
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}
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resize() {
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const parent = this.canvas.parentElement;
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if (!parent) return;
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const containerWidth = parent.offsetWidth;
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const containerHeight = parent.offsetHeight;
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let width = containerWidth;
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let height = Math.floor((width * 9) / 16);
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if (height > containerHeight) {
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height = containerHeight;
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width = Math.floor((height * 16) / 9);
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}
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if (this.canvas.width === width && this.canvas.height === height) return;
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this.canvas.width = width;
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this.canvas.height = height;
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this.canvas.style.width = width + "px";
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this.canvas.style.height = height + "px";
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this.render();
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}
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setDrawingTool(tool) { this.drawingTool = tool; }
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setColor(color) { this.currentColor = color; }
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setThickness(size) { this.currentThickness = size; }
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setPathOptimization(enabled) { this.pathOptimizationEnabled = enabled; }
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setOptimizationThreshold(threshold) { this.optimizationThreshold = threshold; }
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getShapes() { return this.shapes; }
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setShapes(shapes) { this.shapes = shapes; this.render(); }
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getMouseCoordinates(e) {
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const rect = this.canvas.getBoundingClientRect();
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return {
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x: (e.clientX - rect.left) / this.canvas.width,
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y: (e.clientY - rect.top) / this.canvas.height
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};
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}
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handleMouseDown(e) {
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this.isDrawing = true;
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const coords = this.getMouseCoordinates(e);
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if (this.drawingTool === 'pencil') {
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this.currentShape = { type: 'pencil', data: { color: this.currentColor, path: [coords], thickness: this.currentThickness } };
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} else if (this.drawingTool === 'line') {
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this.currentShape = { type: 'line', data: { color: this.currentColor, start: coords, end: coords, thickness: this.currentThickness } };
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} else if (this.drawingTool === 'rectangle') {
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this.currentShape = { type: 'rectangle', data: { color: this.currentColor, start: coords, end: coords, thickness: this.currentThickness, fill: false } };
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} else if (this.drawingTool === 'circle') {
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this.currentShape = { type: 'circle', data: { color: this.currentColor, start: coords, end: coords, thickness: this.currentThickness, fill: false } };
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} else if (this.drawingTool === 'eraser') {
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this.currentShape = { type: 'eraser', data: { color: '#ffffff', start: coords, end: coords, thickness: 3 } };
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}
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this.emit('drawingStart', this.currentShape);
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}
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handleMouseMove(e) {
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if (!this.isDrawing || !this.currentShape) return;
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const coords = this.getMouseCoordinates(e);
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if (this.drawingTool === 'pencil') {
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this.currentShape.data.path.push(coords);
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} else {
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this.currentShape.data.end = coords;
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}
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this.render();
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this.emit('drawingUpdate', this.currentShape);
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}
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handleMouseUp(e) {
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if (!this.isDrawing || !this.currentShape) return;
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this.isDrawing = false;
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const coords = this.getMouseCoordinates(e);
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if (this.drawingTool === 'pencil' && this.pathOptimizationEnabled && this.currentShape.data.path.length > 10) {
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this.currentShape.data.path = this.optimizePath(this.currentShape.data.path);
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} else {
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this.currentShape.data.end = coords;
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}
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this.shapes.push({ ...this.currentShape });
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this.emit('drawingEnd', this.currentShape);
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this.currentShape = null;
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this.render();
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}
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handleMouseLeave(e) {
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if (this.isDrawing) this.handleMouseUp(e);
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}
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optimizePath(path) {
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if (path.length < 3) return path;
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const optimizedPath = [path[0]];
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for (let i = 1; i < path.length - 1;) {
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let a = 1;
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while (i + a < path.length && this.calculateDistance(path[i], path[i + a]) < this.optimizationThreshold) a++;
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optimizedPath.push(path[i]);
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i += a;
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}
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optimizedPath.push(path[path.length - 1]);
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return optimizedPath;
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}
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calculateDistance(p1, p2) {
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return Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2));
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}
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addShape(shapeData) {
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if (Array.isArray(shapeData)) this.shapes.push(...shapeData);
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else this.shapes.push(shapeData);
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this.render();
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}
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clearCanvas() {
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this.shapes = [];
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this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
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this.emit('clear');
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}
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exportToDataURL(type = 'image/png', quality = 1) {
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return this.canvas.toDataURL(type, quality);
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}
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render() {
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this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
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// 绘制历史形状
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this.shapes.forEach(shape => this.drawShape(shape));
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// 绘制当前正在绘制的形状
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if (this.currentShape) this.drawShape(this.currentShape);
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// 画画布边框
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this.ctx.save();
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this.ctx.strokeStyle = "#000";
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this.ctx.lineWidth = 2;
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this.ctx.strokeRect(0, 0, this.canvas.width, this.canvas.height);
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this.ctx.restore();
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}
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drawShape(shape) {
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switch (shape.type) {
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case 'pencil': this.drawPencil(shape.data); break;
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case 'line': this.drawLine(shape.data); break;
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case 'rectangle': this.drawRectangle(shape.data); break;
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case 'circle': this.drawCircle(shape.data); break;
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case 'eraser': this.drawEraser(shape.data, shape); break;
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}
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}
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drawPencil(p) {
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if (p.path.length < 2) return;
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const path = p.path.map(pt => ({ x: pt.x * this.canvas.width, y: pt.y * this.canvas.height }));
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this.ctx.beginPath();
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this.ctx.strokeStyle = p.color;
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this.ctx.lineWidth = p.thickness;
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this.ctx.lineCap = 'round';
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this.ctx.lineJoin = 'round';
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this.drawSmoothCurve(this.ctx, path);
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this.ctx.stroke();
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}
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drawSmoothCurve(ctx, path) {
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if (path.length < 3) { ctx.moveTo(path[0].x, path[0].y); for (let i = 1; i < path.length; i++) ctx.lineTo(path[i].x, path[i].y); return; }
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ctx.moveTo(path[0].x, path[0].y);
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const threshold = 5;
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for (let i = 1; i < path.length - 2;) {
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let a = 1;
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while (i + a < path.length - 2 &&
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Math.sqrt(Math.pow(path[i].x - path[i + a].x, 2) + Math.pow(path[i].y - path[i + a].y, 2)) < threshold) a++;
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const xc = (path[i].x + path[i + a].x) / 2;
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const yc = (path[i].y + path[i + a].y) / 2;
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ctx.quadraticCurveTo(path[i].x, path[i].y, xc, yc);
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i += a;
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}
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ctx.lineTo(path[path.length - 1].x, path[path.length - 1].y);
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}
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drawLine(l) {
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const sx = l.start.x * this.canvas.width, sy = l.start.y * this.canvas.height;
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const ex = l.end.x * this.canvas.width, ey = l.end.y * this.canvas.height;
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this.ctx.beginPath();
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this.ctx.moveTo(sx, sy);
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this.ctx.lineTo(ex, ey);
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this.ctx.strokeStyle = l.color;
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this.ctx.lineWidth = l.thickness;
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this.ctx.stroke();
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}
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drawRectangle(r) {
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const sx = r.start.x * this.canvas.width, sy = r.start.y * this.canvas.height;
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const ex = r.end.x * this.canvas.width, ey = r.end.y * this.canvas.height;
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const w = ex - sx, h = ey - sy;
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this.ctx.beginPath();
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this.ctx.rect(sx, sy, w, h);
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if (r.fill) { this.ctx.fillStyle = r.color; this.ctx.fill(); }
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else { this.ctx.strokeStyle = r.color; this.ctx.lineWidth = r.thickness; this.ctx.stroke(); }
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}
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drawCircle(c) {
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const sx = c.start.x * this.canvas.width, sy = c.start.y * this.canvas.height;
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const ex = c.end.x * this.canvas.width, ey = c.end.y * this.canvas.height;
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const cx = (sx + ex) / 2, cy = (sy + ey) / 2;
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const rx = Math.abs(ex - sx) / 2, ry = Math.abs(ey - sy) / 2;
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this.ctx.beginPath();
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this.ctx.ellipse(cx, cy, rx, ry, 0, 0, 2 * Math.PI);
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if (c.fill) { this.ctx.fillStyle = c.color; this.ctx.fill(); }
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else { this.ctx.strokeStyle = c.color; this.ctx.lineWidth = c.thickness; this.ctx.stroke(); }
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}
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drawEraser(e, shapeObj) {
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const sx = e.start.x * this.canvas.width, sy = e.start.y * this.canvas.height;
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const ex = e.end.x * this.canvas.width, ey = e.end.y * this.canvas.height;
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const w = Math.abs(ex - sx), h = Math.abs(ey - sy);
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const x = Math.min(sx, ex), y = Math.min(sy, ey);
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this.ctx.beginPath();
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this.ctx.rect(x, y, w, h);
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this.ctx.fillStyle = 'rgba(255,255,255)';
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this.ctx.fill();
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// 仅当前正在绘制的橡皮擦显示边框
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if (this.currentShape && shapeObj === this.currentShape) {
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this.ctx.save();
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this.ctx.strokeStyle = '#000';
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this.ctx.lineWidth = 1;
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this.ctx.strokeRect(x, y, w, h);
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this.ctx.restore();
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}
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}
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destroy() {
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this.canvas.removeEventListener('mousedown', this.handleMouseDown);
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this.canvas.removeEventListener('mousemove', this.handleMouseMove);
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this.canvas.removeEventListener('mouseup', this.handleMouseUp);
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this.canvas.removeEventListener('mouseleave', this.handleMouseLeave);
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window.removeEventListener('resize', this.resize);
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}
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}
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export default Canvas;
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