Add camera presets snapshots and continuous recording playback

web/recording-ranges.js

@@ -0,0 +1,21 @@
+'use strict';
+// Pure range logic shared by the UI and regression tests. All ranges are [start,end).
+const RecordingRanges=(()=>{
+  function normalize(items,start,end){
+    const lo=+start,hi=+end;if(!Number.isFinite(lo)||!Number.isFinite(hi)||hi<=lo)return [];
+    const ranges=(Array.isArray(items)?items:[]).filter(s=>s&&Number.isFinite(+new Date(s.start))&&Number.isFinite(Number(s.duration))&&Number(s.duration)>0).map(s=>({start:Math.max(lo,+new Date(s.start)),end:Math.min(hi,+new Date(s.start)+Number(s.duration)*1000)}))
+      .filter(s=>Number.isFinite(s.start)&&Number.isFinite(s.end)&&s.end>s.start).sort((a,b)=>a.start-b.start);
+    const result=[];for(const r of ranges){const last=result.at(-1);if(last&&r.start<=last.end)last.end=Math.max(last.end,r.end);else result.push({...r});}return result;
+  }
+  function at(ranges,time){const t=+time,s=ranges.find(s=>t>=s.start&&t<s.end);return s?{start:t,end:Math.min(s.end,t+3600000)}:null;}
+  function next(ranges,end){const s=ranges.find(s=>s.end>+end);return s?at(ranges,Math.max(s.start,+end)):null;}
+  function clip(ranges,start,end){
+    const a=+start,b=+end;
+    if(!Number.isFinite(a)||!Number.isFinite(b)||b<=a)throw Error('结束时间必须晚于开始时间');
+    if(b-a>3600000)throw Error('一次下载最多一小时，请缩短片段');
+    if(!ranges.some(s=>a>=s.start&&b<=s.end))throw Error('所选片段跨越无录像时段或超出查询日期，请选择同一连续录像时段');
+    return {start:a,end:b};
+  }
+  return {normalize,at,next,clip};
+})();
+if(typeof module!=='undefined')module.exports=RecordingRanges;