概述
本文档详细介绍前端画布系统的核心功能实现，基于 ECS（Entity-Component-System）架构，提供高性能的图形渲染和交互能力。
项目地址：github.com/baiyuze/duc…
核心功能模块
graph TB
A[前端核心功能] --> B[ECS渲染引擎]
A --> C[图形拾取系统]
A --> D[选择交互系统]
A --> E[输入处理系统]
A --> F[事件管理系统]
A --> G[DSL解析系统]
B --> B1[RenderSystem]
B --> B2[渲染器注册表]
B --> B3[多种图形渲染器]
C --> C1[PickingSystem]
C --> C2[颜色编码算法]
C --> C3[离屏Canvas]
D --> D1[SelectionSystem]
D --> D2[单选/多选]
D --> D3[拖拽功能]
E --> E1[InputSystem]
E --> E2[鼠标事件]
E --> E3[键盘事件]
F --> F1[EventSystem]
F --> F2[事件队列]
F --> F3[事件分发]
G --> G1[DSL类]
G --> G2[配置验证]
G --> G3[组件实例化]
ECS 渲染引擎
渲染流程架构
sequenceDiagram
participant M as 主循环
participant E as EventSystem
participant R as RenderSystem
participant RR as RenderRegistry
participant RE as Renderer
participant C as Canvas
M->>E: 1. 处理事件队列
E->>E: 处理用户交互事件
M->>R: 2. 触发渲染更新
R->>R: 节流检查(100ms)
R->>C: 3. 清空画布
loop 遍历所有实体
R->>R: 获取实体type
R->>RR: 查找对应渲染器
RR->>RE: 返回渲染器实例
RE->>RE: 读取组件数据
RE->>C: 绘制图形
end
M->>M: requestAnimationFrame
渲染系统实现
RenderSystem 架构
graph LR
A[RenderSystem] --> B[RenderMap]
B --> C[rect: RectRenderer]
B --> D[ellipse: EllipseRenderer]
B --> E[text: TextRenderer]
B --> F[img: ImageRenderer]
B --> G[polygon: PolygonRenderer]
H[StateStore] --> A
A --> I[throttledRender]
I --> J[render方法]
J --> K[drawShape]
K --> C
K --> D
K --> E
K --> F
K --> G
RenderSystem 核心逻辑
export class RenderSystem extends System {
core: Core;
ctx: CanvasRenderingContext2D;
renderMap = new Map<string, System>();
constructor(ctx: CanvasRenderingContext2D, core: Core) {
super();
this.core = core;
this.ctx = ctx;
this.initRenderMap();
}
// 初始化渲染器映射表
initRenderMap() {
Object.entries(renderRegistry).forEach(([key, SystemClass]) => {
this.renderMap.set(key, new SystemClass(this.ctx, this.core));
});
}
// 节流渲染（100ms）
throttledRender = throttle((stateStore: StateStore) => {
this.render(stateStore, this.ctx);
}, 100);
// 绘制单个图形
drawShape(stateStore: StateStore, entityId: string) {
const type = stateStore.type.get(entityId);
if (!type) return;
const renderer = this.renderMap.get(type);
renderer?.draw(entityId);
}
// 主渲染方法
render(stateStore: StateStore, ctx: CanvasRenderingContext2D) {
// 清空画布
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
// 遍历所有实体并渲染
stateStore.position.forEach((pos, entityId) => {
ctx.save();
this.drawShape(stateStore, entityId);
ctx.restore();
});
}
// 每帧更新
update(stateStore: StateStore) {
this.throttledRender(stateStore);
}
}
渲染器实现
渲染器架构设计
graph TB
subgraph "渲染器基类"
A[System基类]
end
subgraph "具体渲染器"
B[RectRenderer<br/>矩形渲染]
C[EllipseRenderer<br/>椭圆渲染]
D[TextRenderer<br/>文本渲染]
E[ImageRenderer<br/>图片渲染]
F[PolygonRenderer<br/>多边形渲染]
end
subgraph "渲染流程"
G[读取Position]
H[读取Size]
I[读取Color]
J[读取其他组件]
K[Canvas绘制API]
end
A --> B
A --> C
A --> D
A --> E
A --> F
B --> G
B --> H
B --> I
B --> K
C --> G
C --> H
C --> I
C --> K
D --> G
D --> J
D --> K
E --> G
E --> H
E --> J
E --> K
矩形渲染器
export class RectRenderer extends System {
ctx: CanvasRenderingContext2D;
core: Core;
constructor(ctx: CanvasRenderingContext2D, core: Core) {
super();
this.ctx = ctx;
this.core = core;
}
draw(entityId: string) {
const position = this.core.stateStore.position.get(entityId);
const size = this.core.stateStore.size.get(entityId);
const color = this.core.stateStore.color.get(entityId);
const rotation = this.core.stateStore.rotation.get(entityId);
if (!position || !size || !color) return;
this.ctx.save();
// 应用旋转
if (rotation) {
const centerX = position.x + size.width / 2;
const centerY = position.y + size.height / 2;
this.ctx.translate(centerX, centerY);
this.ctx.rotate((rotation.value * Math.PI) / 180);
this.ctx.translate(-centerX, -centerY);
}
// 填充
if (color.fillColor) {
this.ctx.fillStyle = color.fillColor;
this.ctx.fillRect(position.x, position.y, size.width, size.height);
}
// 描边
if (color.strokeColor) {
const lineWidth = this.core.stateStore.lineWidth.get(entityId);
this.ctx.strokeStyle = color.strokeColor;
this.ctx.lineWidth = lineWidth?.value || 1;
this.ctx.strokeRect(position.x, position.y, size.width, size.height);
}
this.ctx.restore();
}
}
椭圆渲染器
export class EllipseRenderer extends System {
draw(entityId: string) {
const position = this.core.stateStore.position.get(entityId);
const size = this.core.stateStore.size.get(entityId);
const color = this.core.stateStore.color.get(entityId);
if (!position || !size || !color) return;
const centerX = position.x + size.width / 2;
const centerY = position.y + size.height / 2;
const radiusX = size.width / 2;
const radiusY = size.height / 2;
this.ctx.beginPath();
this.ctx.ellipse(centerX, centerY, radiusX, radiusY, 0, 0, 2 * Math.PI);
if (color.fillColor) {
this.ctx.fillStyle = color.fillColor;
this.ctx.fill();
}
if (color.strokeColor) {
this.ctx.strokeStyle = color.strokeColor;
this.ctx.stroke();
}
}
}
文本渲染器
export class TextRenderer extends System {
draw(entityId: string) {
const position = this.core.stateStore.position.get(entityId);
const font = this.core.stateStore.font.get(entityId);
if (!position || !font) return;
this.ctx.save();
// 设置字体样式
this.ctx.font = `${font.weight} ${font.size}px ${font.family}`;
this.ctx.fillStyle = font.fillColor;
this.ctx.textBaseline = 'top';
// 绘制文本
this.ctx.fillText(font.text, position.x, position.y);
this.ctx.restore();
}
}
图片渲染器
export class ImageRenderer extends System {
private imageCache = new Map<string, HTMLImageElement>();
draw(entityId: string) {
const position = this.core.stateStore.position.get(entityId);
const size = this.core.stateStore.size.get(entityId);
const img = this.core.stateStore.img.get(entityId);
if (!position || !size || !img) return;
let image = this.imageCache.get(img.src);
if (!image) {
image = new Image();
image.src = img.src;
this.imageCache.set(img.src, image);
image.onload = () => {
this.ctx.drawImage(image!, position.x, position.y, size.width, size.height);
};
} else if (image.complete) {
this.ctx.drawImage(image, position.x, position.y, size.width, size.height);
}
}
}
图形拾取系统
拾取系统架构
graph TB
subgraph "拾取系统设计"
A[PickingSystem]
B[离屏Canvas]
C[颜色映射表]
end
subgraph "拾取流程"
D[1. 为实体分配唯一颜色]
E[2. 在离屏Canvas绘制]
F[3. 读取点击位置像素]
G[4. 颜色反查实体ID]
end
subgraph "颜色编码算法"
H[实体索引 index]
I[转RGB颜色]
J[绘制到离屏]
K[点击获取RGB]
L[RGB转索引]
M[返回实体ID]
end
A --> B
A --> C
A --> D
D --> E
E --> F
F --> G
H --> I
I --> J
K --> L
L --> M
拾取原理图
sequenceDiagram
participant U as 用户点击
participant P as PickingSystem
participant O as 离屏Canvas
participant M as ColorMap
Note over P,O: 准备阶段
P->>P: 为每个实体分配唯一颜色ID
P->>M: 建立颜色→实体映射表
Note over U,M: 点击阶段
U->>P: 鼠标点击(x, y)
P->>O: 渲染所有实体到离屏Canvas
Note over O: 使用唯一颜色填充
P->>O: getImageData(x, y, 1, 1)
O->>P: 返回像素RGB值
P->>M: 查询RGB对应的实体
M->>P: 返回实体ID
P->>U: 返回被点击的实体
PickingSystem 实现
export class PickingSystem extends System {
core: Core;
ctx: CanvasRenderingContext2D;
offscreenCanvas: HTMLCanvasElement;
offscreenCtx: CanvasRenderingContext2D;
colorToEntityMap = new Map<string, string>();
constructor(ctx: CanvasRenderingContext2D, core: Core) {
super();
this.core = core;
this.ctx = ctx;
// 创建离屏 Canvas
this.offscreenCanvas = document.createElement('canvas');
this.offscreenCanvas.width = ctx.canvas.width;
this.offscreenCanvas.height = ctx.canvas.height;
this.offscreenCtx = this.offscreenCanvas.getContext('2d')!;
this.generateColorMap();
}
// 为每个实体生成唯一颜色
generateColorMap() {
let colorIndex = 1;
this.core.stateStore.position.forEach((_, entityId) => {
const color = this.indexToColor(colorIndex);
this.colorToEntityMap.set(color, entityId);
colorIndex++;
});
}
// 索引转颜色
indexToColor(index: number): string {
const r = (index & 0xFF0000) >> 16;
const g = (index & 0x00FF00) >> 8;
const b = (index & 0x0000FF);
return `rgb(${r},${g},${b})`;
}
// 颜色转索引
colorToIndex(r: number, g: number, b: number): number {
return (r << 16) | (g << 8) | b;
}
// 渲染到离屏 Canvas
renderOffscreen() {
this.offscreenCtx.clearRect(0, 0, this.offscreenCanvas.width, this.offscreenCanvas.height);
let colorIndex = 1;
this.core.stateStore.position.forEach((position, entityId) => {
const size = this.core.stateStore.size.get(entityId);
if (!size) return;
const color = this.indexToColor(colorIndex);
this.offscreenCtx.fillStyle = color;
this.offscreenCtx.fillRect(position.x, position.y, size.width, size.height);
colorIndex++;
});
}
// 拾取实体
pick(x: number, y: number): string | null {
this.renderOffscreen();
const pixel = this.offscreenCtx.getImageData(x, y, 1, 1).data;
const color = `rgb(${pixel[0]},${pixel[1]},${pixel[2]})`;
return this.colorToEntityMap.get(color) || null;
}
}
选择系统
选择系统架构
graph TB
subgraph "选择模式"
A[SelectionSystem]
B[单选模式]
C[多选模式Ctrl/Cmd]
D[框选模式拖拽]
end
subgraph "选择状态"
E[未选中 value:false]
F[选中 value:true]
G[悬停 hovered:true]
end
subgraph "视觉反馈"
H[选择框绘制]
I[控制点绘制]
J[高亮显示]
end
A --> B
A --> C
A --> D
B --> E
B --> F
C --> F
F --> H
F --> I
G --> J
选择状态流转
stateDiagram-v2
[*] --> 未选中
未选中 --> 悬停: 鼠标移入
悬停 --> 未选中: 鼠标移出
悬停 --> 选中: 点击
未选中 --> 选中: 直接点击
选中 --> 拖拽中: 按住并移动
拖拽中 --> 选中: 释放鼠标
选中 --> 未选中: 点击空白区域
选中 --> 多选: Ctrl+点击其他实体
多选 --> 选中: Ctrl+点击已选实体
多选 --> 未选中: 点击空白区域
SelectionSystem 实现
export class SelectionSystem extends System {
core: Core;
ctx: CanvasRenderingContext2D;
constructor(ctx: CanvasRenderingContext2D, core: Core) {
super();
this.core = core;
this.ctx = ctx;
}
// 选中实体
selectEntity(entityId: string) {
const selected = this.core.stateStore.selected.get(entityId);
if (selected) {
selected.value = true;
}
}
// 取消选中
deselectEntity(entityId: string) {
const selected = this.core.stateStore.selected.get(entityId);
if (selected) {
selected.value = false;
}
}
// 取消所有选中
deselectAll() {
this.core.stateStore.selected.forEach((selected) => {
selected.value = false;
});
}
// 绘制选择框
drawSelectionBox(entityId: string) {
const position = this.core.stateStore.position.get(entityId);
const size = this.core.stateStore.size.get(entityId);
const selected = this.core.stateStore.selected.get(entityId);
if (!position || !size || !selected?.value) return;
this.ctx.save();
// 绘制选择框
this.ctx.strokeStyle = '#0078D4';
this.ctx.lineWidth = 2;
this.ctx.setLineDash([5, 5]);
this.ctx.strokeRect(
position.x - 2,
position.y - 2,
size.width + 4,
size.height + 4
);
// 绘制控制点
this.drawHandles(position, size);
this.ctx.restore();
}
// 绘制控制点
drawHandles(position: Position, size: Size) {
const handleSize = 8;
const handles = [
{ x: position.x, y: position.y }, // 左上
{ x: position.x + size.width, y: position.y }, // 右上
{ x: position.x, y: position.y + size.height }, // 左下
{ x: position.x + size.width, y: position.y + size.height }, // 右下
];
handles.forEach(handle => {
this.ctx.fillStyle = '#FFFFFF';
this.ctx.strokeStyle = '#0078D4';
this.ctx.lineWidth = 2;
this.ctx.fillRect(
handle.x - handleSize / 2,
handle.y - handleSize / 2,
handleSize,
handleSize
);
this.ctx.strokeRect(
handle.x - handleSize / 2,
handle.y - handleSize / 2,
handleSize,
handleSize
);
});
}
update(stateStore: StateStore) {
stateStore.selected.forEach((selected, entityId) => {
if (selected.value) {
this.drawSelectionBox(entityId);
}
});
}
}
输入系统
输入系统架构
graph TB
subgraph "输入源"
A[鼠标事件]
B[键盘事件]
C[触摸事件]
end
subgraph "InputSystem"
D[事件监听器]
E[事件处理器]
F[状态管理]
end
subgraph "鼠标事件处理"
G[mousedown]
H[mousemove]
I[mouseup]
J[click]
end
subgraph "交互功能"
K[选择实体]
L[拖拽移动]
M[缩放控制]
N[旋转操作]
end
A --> D
B --> D
C --> D
D --> E
E --> F
E --> G
E --> H
E --> I
E --> J
G --> L
H --> L
I --> L
J --> K
拖拽交互流程
sequenceDiagram
participant U as 用户
participant I as InputSystem
participant P as PickingSystem
participant S as StateStore
participant R as RenderSystem
U->>I: mousedown(x, y)
I->>P: pick(x, y)
P->>I: 返回entityId
I->>I: 记录拖拽开始位置
I->>I: isDragging = true
loop 鼠标移动
U->>I: mousemove(x, y)
I->>I: 计算偏移量(dx, dy)
I->>S: 更新Position组件
S->>R: 触发重绘
end
U->>I: mouseup
I->>I: isDragging = false
I->>I: 清空拖拽状态
InputSystem 实现
export class InputSystem extends System {
canvas: HTMLCanvasElement;
core: Core;
pickingSystem: PickingSystem;
isDragging = false;
dragStartPos: { x: number; y: number } | null = null;
selectedEntity: string | null = null;
constructor(canvas: HTMLCanvasElement, core: Core, pickingSystem: PickingSystem) {
super();
this.canvas = canvas;
this.core = core;
this.pickingSystem = pickingSystem;
this.bindEvents();
}
bindEvents() {
this.canvas.addEventListener('mousedown', this.handleMouseDown);
this.canvas.addEventListener('mousemove', this.handleMouseMove);
this.canvas.addEventListener('mouseup', this.handleMouseUp);
this.canvas.addEventListener('click', this.handleClick);
}
handleClick = (e: MouseEvent) => {
const rect = this.canvas.getBoundingClientRect();
const x = e.clientX - rect.left;
const y = e.clientY - rect.top;
// 拾取实体
const entityId = this.pickingSystem.pick(x, y);
if (entityId) {
// 如果按下 Ctrl/Cmd，则多选
if (e.ctrlKey || e.metaKey) {
const selected = this.core.stateStore.selected.get(entityId);
if (selected) {
selected.value = !selected.value;
}
} else {
// 单选
this.core.stateStore.selected.forEach((s) => (s.value = false));
const selected = this.core.stateStore.selected.get(entityId);
if (selected) {
selected.value = true;
}
}
} else {
// 点击空白，取消所有选中
this.core.stateStore.selected.forEach((s) => (s.value = false));
}
};
handleMouseDown = (e: MouseEvent) => {
const rect = this.canvas.getBoundingClientRect();
const x = e.clientX - rect.left;
const y = e.clientY - rect.top;
const entityId = this.pickingSystem.pick(x, y);
if (entityId) {
this.isDragging = true;
this.selectedEntity = entityId;
this.dragStartPos = { x, y };
}
};
handleMouseMove = (e: MouseEvent) => {
if (!this.isDragging || !this.selectedEntity || !this.dragStartPos) return;
const rect = this.canvas.getBoundingClientRect();
const x = e.clientX - rect.left;
const y = e.clientY - rect.top;
const dx = x - this.dragStartPos.x;
const dy = y - this.dragStartPos.y;
// 更新位置
const position = this.core.stateStore.position.get(this.selectedEntity);
if (position) {
position.x += dx;
position.y += dy;
}
this.dragStartPos = { x, y };
};
handleMouseUp = () => {
this.isDragging = false;
this.selectedEntity = null;
this.dragStartPos = null;
};
update(stateStore: StateStore) {
// 输入系统主要是事件驱动，不需要每帧更新
}
}
事件系统
事件系统架构
graph TB
subgraph "事件源"
A[InputSystem]
B[SelectionSystem]
C[业务逻辑]
end
subgraph "EventSystem"
D[EventQueue事件队列]
E[事件处理器]
F[事件分发器]
end
subgraph "事件类型"
G[entity:select 选中]
H[entity:deselect 取消选中]
I[entity:move 移动]
J[entity:delete 删除]
K[entity:resize 缩放]
L[entity:rotate 旋转]
end
subgraph "系统响应"
M[更新StateStore]
N[触发重绘]
O[执行业务逻辑]
end
A --> D
B --> D
C --> D
D --> E
E --> F
F --> G
F --> H
F --> I
F --> J
F --> K
F --> L
G --> M
H --> M
I --> M
J --> M
M --> N
事件处理流程
sequenceDiagram
participant I as InputSystem
participant Q as EventQueue
participant E as EventSystem
participant H as EventHandler
participant S as StateStore
I->>Q: 添加事件
Note over Q: {type: 'entity:move', data: {...}}
loop 每帧更新
E->>Q: 读取事件队列
Q->>E: 返回事件列表
loop 处理每个事件
E->>E: switch(event.type)
E->>H: 调用对应处理器
H->>S: 更新组件数据
end
E->>Q: 清空已处理事件
end
EventSystem 实现
import type { Core } from "../Core";
import { Entity } from "../Entity/Entity";
import type { StateStore } from "../types";
import type { ClickSystem } from "./ClickSystem";
import type { DragSystem } from "./DragSystem";
import type { HoverSystem } from "./HoverSystem";
import type { SelectionSystem } from "./SelectionSystem";
import { System } from "./System";
import { throttle } from "lodash";
export class EventSystem extends System {
core: Core;
ctx: CanvasRenderingContext2D;
offCtx: CanvasRenderingContext2D | null = null;
entityManager: Entity = new Entity();
stateStore: StateStore | null = null;
throttledMouseMove: ReturnType<typeof throttle>;
constructor(ctx: CanvasRenderingContext2D, core: Core) {
super();
this.ctx = ctx;
this.core = core;
this.dispose();
this.throttledMouseMove = throttle(this.onMouseMove.bind(this), 16);
ctx.canvas.addEventListener("click", this.onClick.bind(this));
ctx.canvas.addEventListener("mouseup", this.onMouseUp.bind(this));
ctx.canvas.addEventListener("mousedown", this.onMouseDown.bind(this));
document.addEventListener("mousemove", this.throttledMouseMove);
}
dispose() {
this.ctx.canvas.removeEventListener("click", this.onClick.bind(this));
document.removeEventListener("mousemove", this.throttledMouseMove);
this.ctx.canvas.removeEventListener("mouseup", this.onMouseUp.bind(this));
this.ctx.canvas.removeEventListener(
"mousedown",
this.onMouseDown.bind(this)
);
this.throttledMouseMove?.cancel();
}
onMouseUp(event: MouseEvent) {
if (!this.stateStore) return;
this.stateStore.eventQueue.push({
type: "mouseup",
event,
});
this.render();
}
onMouseDown(event: MouseEvent) {
if (!this.stateStore) return;
this.stateStore.eventQueue.push({
type: "mousedown",
event,
});
this.render();
}
nextTick(cb: () => void) {
return Promise.resolve().then(cb);
}
update(stateStore: StateStore) {
this.stateStore = stateStore;
}
render() {
const core = this.core;
const selectionSystem =
core.getSystemByName<SelectionSystem>("SelectionSystem");
const hoverSystem = core.getSystemByName<HoverSystem>("HoverSystem");
const clickSystem = core.getSystemByName<ClickSystem>("ClickSystem");
const dragSystem = core.getSystemByName<DragSystem>("DragSystem");
if (!this.stateStore) return;
if (hoverSystem) {
hoverSystem.update(this.stateStore);
}
if (clickSystem) {
clickSystem.update(this.stateStore);
}
if (selectionSystem) {
selectionSystem.update(this.stateStore);
}
if (dragSystem) {
dragSystem.update(this.stateStore);
}
this.stateStore.eventQueue = [];
}
/**
* 点击
* @param event MouseEvent
* @returns
*/
onClick(event: MouseEvent) {
if (!this.stateStore) return;
this.stateStore.eventQueue = [
{
type: "click",
event,
},
];
this.render();
}
onMouseMove(event: MouseEvent) {
if (!this.stateStore) return;
if (this.stateStore.eventQueue.length) return;
this.stateStore.eventQueue = [{ type: "mousemove", event }];
this.render();
}
destroyed(): void {
this.dispose();
this.offCtx = null;
this.stateStore = null;
this.entityManager = null as any;
this.core = null as any;
this.ctx = null as any;
}
}
DSL 解析器
DSL 解析架构
graph TB
subgraph DSL配置
A[JSON配置对象]
B[必填字段]
C[可选字段]
end
subgraph DSL解析器
D[DSL构造器]
E[字段验证]
F[默认值填充]
G[组件实例化]
end
subgraph 组件注册
H[Position]
I[Size]
J[Color]
K[Rotation]
L[其他组件]
end
subgraph StateStore
M[position Map]
N[size Map]
O[color Map]
P[其他 Map]
end
A --> D
B --> E
C --> F
D --> E
E --> G
G --> H
G --> I
G --> J
G --> K
G --> L
H --> M
I --> N
J --> O
L --> P
DSL 解析流程
sequenceDiagram
participant C as JSON Config
participant D as DSL Parser
participant V as Validator
participant S as StateStore
participant E as Entity Manager
C->>D: 传入配置对象
D->>V: 验证必填字段
alt 验证失败
V->>D: 抛出错误
D->>C: Error: 缺少必填字段
else 验证成功
V->>D: 验证通过
D->>D: 填充默认值
D->>D: 创建DSL实例
loop 遍历组件属性
D->>S: 将组件存入对应Map
Note over S: position.set(id, {x, y})
Note over S: size.set(id, {w, h})
Note over S: color.set(id, {fill, stroke})
end
D->>E: 注册实体ID
E->>D: 注册成功
D->>C: 返回DSL实例
end
DSL 类实现
export class DSL {
id: string;
type: string;
position: Position;
size: Size;
color: Color;
selected?: { value: boolean; hovered: boolean };
rotation?: { value: number };
font?: Font;
lineWidth?: { value: number };
img?: Img;
scale?: Scale;
polygon?: Polygon;
ellipseRadius?: EllipseRadius;
constructor(config: any) {
this.id = config.id;
this.type = config.type;
this.position = config.position;
this.size = config.size;
this.color = config.color;
this.selected = config.selected || { value: false, hovered: false };
this.rotation = config.rotation || { value: 0 };
this.font = config.font;
this.lineWidth = config.lineWidth || { value: 1 };
this.img = config.img;
this.scale = config.scale;
this.polygon = config.polygon;
this.ellipseRadius = config.ellipseRadius;
this.validate();
}
validate() {
if (!this.id) throw new Error('DSL 缺少 id 字段');
if (!this.type) throw new Error('DSL 缺少 type 字段');
if (!this.position) throw new Error('DSL 缺少 position 字段');
if (!this.size) throw new Error('DSL 缺少 size 字段');
if (!this.color) throw new Error('DSL 缺少 color 字段');
}
}
DSL 使用示例
const dsls = [
{
id: "rect-1",
type: "rect",
position: { x: 100, y: 100 },
size: { width: 200, height: 100 },
color: {
fillColor: "#FF5000",
strokeColor: "#000000"
},
rotation: { value: 0 },
selected: { value: false },
},
{
id: "text-1",
type: "text",
position: { x: 120, y: 130 },
size: { width: 160, height: 40 },
color: { fillColor: "", strokeColor: "" },
font: {
family: "Arial",
size: 24,
weight: "bold",
text: "Hello World",
fillColor: "#FFFFFF",
},
},
{
id: "ellipse-1",
type: "ellipse",
position: { x: 350, y: 100 },
size: { width: 120, height: 80 },
color: {
fillColor: "#00BFFF",
strokeColor: "#000000"
},
},
];
// 初始化 Core
const core = new Core(dsls);
Canvas 组件集成
Canvas 组件架构
graph TB
subgraph "React组件"
A[Canvas组件]
B[canvasRef]
C[useEffect钩子]
end
subgraph "Core初始化"
D[创建Core实例]
E[加载DSL配置]
F[初始化Canvas]
end
subgraph "系统初始化"
G[RenderSystem]
H[PickingSystem]
I[SelectionSystem]
J[EventSystem]
K[InputSystem]
end
subgraph "主循环"
L[requestAnimationFrame]
M[事件处理]
N[渲染更新]
O[选择框绘制]
end
A --> B
A --> C
C --> D
C --> E
C --> F
F --> G
F --> H
F --> I
F --> J
F --> K
G --> L
J --> M
G --> N
I --> O
L --> L
系统初始化流程
sequenceDiagram
participant R as React
participant C as Canvas组件
participant Core as Core引擎
participant S as Systems
participant L as 主循环
R->>C: 组件挂载
C->>C: useEffect触发
C->>Core: 创建Core实例(dsls)
Core->>Core: 解析DSL
Core->>Core: 初始化StateStore
C->>Core: initCanvas(canvasRef)
Core->>Core: 设置DPR
Core->>C: 返回ctx
C->>S: new RenderSystem(ctx, core)
C->>S: new PickingSystem(ctx, core)
C->>S: new SelectionSystem(ctx, core)
C->>S: new EventSystem(core)
C->>S: new InputSystem(canvas, core, picking)
C->>L: 启动主循环loop()
loop 每帧
L->>S: eventSystem.update()
L->>S: renderSystem.update()
L->>S: selectionSystem.update()
L->>L: requestAnimationFrame
end
Canvas.tsx 实现
import { useEffect, useRef, useState } from "react";
import { Core } from "../Core/Core";
import { RenderSystem } from "../Core/System/RenderSystem/RenderSystem";
import { SelectionSystem } from "../Core/System/SelectionSystem";
import { PickingSystem } from "../Core/System/PickingSystem";
import { EventSystem } from "../Core/System/EventSystem";
import { InputSystem } from "../Core/System/InputSystem";
function Canvas() {
const canvasRef = useRef<HTMLCanvasElement>(null);
const [core, setCore] = useState<Core | null>(null);
useEffect(() => {
if (!canvasRef.current) return;
// 初始化 Core
const dsls = []; // 从服务器或状态加载 DSL
const coreInstance = new Core(dsls);
const ctx = coreInstance.initCanvas(canvasRef.current);
// 初始化系统
const renderSystem = new RenderSystem(ctx, coreInstance);
const pickingSystem = new PickingSystem(ctx, coreInstance);
const selectionSystem = new SelectionSystem(ctx, coreInstance);
const eventSystem = new EventSystem(coreInstance);
const inputSystem = new InputSystem(
canvasRef.current,
coreInstance,
pickingSystem
);
// 主循环
function loop() {
eventSystem.update(coreInstance.stateStore);
renderSystem.update(coreInstance.stateStore);
selectionSystem.update(coreInstance.stateStore);
requestAnimationFrame(loop);
}
loop();
setCore(coreInstance);
return () => {
// 清理事件监听
};
}, []);
return (
<div className="canvas-container">
<canvas
ref={canvasRef}
width={800}
height={600}
style={{ border: '1px solid #ccc' }}
/>
</div>
);
}
export default Canvas;
性能优化技巧
性能优化架构
graph TB
subgraph "渲染优化"
A[节流渲染<br/>Throttle 100ms]
B[离屏Canvas<br/>拾取优化]
C[增量更新<br/>只更新变化]
D[可视区域裁剪<br/>只渲染可见]
end
subgraph "内存优化"
E[Map数据结构<br/>O1查询]
F[图片缓存<br/>避免重复加载]
G[对象池模式<br/>复用对象]
end
subgraph "事件优化"
H[事件委托<br/>Canvas统一监听]
I[防抖处理<br/>resize事件]
J[事件队列<br/>批量处理]
end
subgraph "Canvas优化"
K[DPR适配<br/>高清显示]
L[willReadFrequently<br/>频繁读取优化]
M[save/restore<br/>状态管理]
end
离屏 Canvas
// 用于图形拾取，不显示
const offscreenCanvas = document.createElement('canvas');
const offscreenCtx = offscreenCanvas.getContext('2d');
图片缓存
private imageCache = new Map<string, HTMLImageElement>();
loadImage(src: string): HTMLImageElement {
if (this.imageCache.has(src)) {
return this.imageCache.get(src)!;
}
const img = new Image();
img.src = src;
this.imageCache.set(src, img);
return img;
}
完整数据流架构
端到端数据流
graph TB
subgraph "用户交互层"
A[用户操作]
B[鼠标事件]
C[键盘事件]
end
subgraph "输入处理层"
D[InputSystem]
E[事件绑定]
F[事件转换]
end
subgraph "事件管理层"
G[EventQueue]
H[EventSystem]
I[事件分发]
end
subgraph "状态管理层"
J[StateStore]
K[Position Map]
L[Size Map]
M[Color Map]
N[Selected Map]
end
subgraph "拾取判断层"
O[PickingSystem]
P[离屏Canvas]
Q[颜色编码]
end
subgraph "选择管理层"
R[SelectionSystem]
S[选中状态更新]
T[选择框绘制]
end
subgraph "渲染输出层"
U[RenderSystem]
V[渲染器注册表]
W[Canvas绘制]
end
A --> B
A --> C
B --> D
C --> D
D --> E
E --> F
F --> G
G --> H
H --> I
I --> J
D --> O
O --> P
O --> Q
J --> R
R --> S
S --> T
J --> U
U --> V
V --> W
T --> W
完整交互流程
sequenceDiagram
participant U as 用户
participant I as InputSystem
participant P as PickingSystem
participant E as EventSystem
participant S as StateStore
participant Sel as SelectionSystem
participant R as RenderSystem
participant C as Canvas
Note over U,C: 1. 点击选择阶段
U->>I: 点击画布(x, y)
I->>P: pick(x, y)
P->>P: 读取离屏Canvas像素
P->>I: 返回entityId
I->>E: 添加'entity:select'事件
Note over U,C: 2. 事件处理阶段
E->>E: 处理事件队列
E->>S: 更新selected组件
S->>S: selected.set(id, true)
Note over U,C: 3. 拖拽移动阶段
U->>I: mousedown + mousemove
I->>I: 计算偏移量(dx, dy)
I->>S: 更新position组件
S->>S: position.x += dx
Note over U,C: 4. 渲染更新阶段
R->>R: throttledRender触发
R->>S: 读取所有组件数据
R->>C: 清空画布
loop 遍历所有实体
R->>V: 查找渲染器
V->>C: 绘制图形
end
Sel->>S: 读取selected组件
Sel->>C: 绘制选择框
架构优势总结
设计优势
mindmap
root((ECS架构优势))
高性能
数据局部性
缓存友好
Map O1查询
节流渲染
可扩展性
添加新组件
添加新系统
添加新渲染器
插件化设计
可维护性
数据逻辑分离
单一职责
模块化设计
清晰的依赖关系
灵活性
组合优于继承
动态添加删除组件
运行时修改
DSL配置驱动
技术亮点
| 特性 |
实现方式 |
优势 |
| ECS 架构 |
Entity-Component-System 模式 |
数据与逻辑分离，高性能 |
| 颜色编码拾取 |
离屏 Canvas + RGB 映射 |
精确快速，支持复杂图形 |
| 节流渲染 |
Lodash throttle 100ms |
降低 CPU 使用，提升性能 |
| Map 数据结构 |
StateStore 使用 Map |
O(1) 查询，内存高效 |
| 图片缓存 |
ImageCache Map |
避免重复加载，提升速度 |
| 事件队列 |
EventQueue 批量处理 |
解耦系统，灵活扩展 |
| DSL 配置 |
JSON 声明式配置 |
易于序列化，可视化编辑 |
| DPR 适配 |
Canvas 高清适配 |
支持 Retina 屏幕 |
最后
项目在不断迭代中，后面可能存在代码和文章有差异的地方，具体可以看github.com/baiyuze/duc…
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