24 lines
1.8 KiB
TypeScript
24 lines
1.8 KiB
TypeScript
/**
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* 交互会话通知的显示帧合并。每个订阅拥有一条 frame queue，读快照不等帧。
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* 这里只发现视图和手势的显示失效；选择、工具及预览事实继续保存在原 session。
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*/
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import type {SessionSnapshot} from '../canvas-core/gestures.ts';
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import type {ExternalSource} from './selectors.ts';
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import {createFrameQueue,type FrameClock} from './frame-queue.ts';
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/** One subscription owns one disposable frame queue. Reads always see current sessions. */
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/** 对比前后会话引用生成 view/element 脏 key；退订时同步撤销帧队列。 */
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export function createSessionFrameSource(source:ExternalSource<SessionSnapshot>,clock:FrameClock):ExternalSource<SessionSnapshot>{
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return Object.freeze({getSnapshot:source.getSnapshot,subscribe(notify:()=>void){
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let previous=source.getSnapshot();const queue=createFrameQueue<string>(clock,()=>notify());
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// 两次遍历覆盖视图新增/删除；手势结束要同时刷新旧目标，才能去掉它们的预览。
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const stop=source.subscribe(()=>{const next=source.getSnapshot(),dirty=new Set<string>();
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for(const [id,view]of previous.views)if(next.views.get(id)!==view)dirty.add(`view:${id}`);
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for(const [id,view]of next.views)if(previous.views.get(id)!==view)dirty.add(`view:${id}`);
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if(previous.gesture!==next.gesture)for(const state of [previous.gesture,next.gesture])for(const target of state?.targets??[])dirty.add(`element:${target.id}`);
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// 连线手势与普通几何手势分别跟踪，改变或取消时都让旧/新目标失效。
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if(previous.connectionGesture!==next.connectionGesture)for(const state of [previous.connectionGesture,next.connectionGesture])if(state)dirty.add(`element:${state.target.id}`);
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previous=next;queue.invalidate(dirty);
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});return()=>{stop();queue.dispose();};
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}});
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}
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