From 000f479b2f5103c2f32e25c69c1a2d05155f2d5c Mon Sep 17 00:00:00 2001
From: flop <flop@cttue.de>
Date: Fri, 22 May 2026 17:48:48 +0200
Subject: [PATCH] fix: timestamps for timespan sections

---
 ts/src/browser.ts | 32 +++++++++++++++++++++++++-------
 ts/src/file.ts    | 23 ++++++++++++-----------
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/ts/src/browser.ts b/ts/src/browser.ts
index 1b22ce2..f4c650d 100644
--- a/ts/src/browser.ts
+++ b/ts/src/browser.ts
@@ -227,6 +227,14 @@ function setSectionType(si: number, sectionType: string) {
     (sec as any).elements = [];
     (sec as any).flags = {};
     delete (sec as any).fontData;
+    if ((sec as any).sectionType === MonoDisplay.SectionType.ElementsTimespan) {
+      const now = BigInt(Math.floor(Date.now() / 1000));
+      (sec as any).startTimestamp = now;
+      (sec as any).endTimestamp = now + 3600n;
+    } else {
+      delete (sec as any).startTimestamp;
+      delete (sec as any).endTimestamp;
+    }
   }
   markDirty(); triggerPreview();
 }
@@ -364,7 +372,8 @@ function loadBin(input: HTMLInputElement) {
   const reader = new FileReader();
   reader.onload = e => {
     try {
-      file = new window.MonoDisplay.MonoDisplayParser().parse(e.target!.result as ArrayBuffer);
+      const parsed = new window.MonoDisplay.MonoDisplayParser().parse(e.target!.result as ArrayBuffer);
+      file = new MonoDisplayFile(parsed.sections);
       activeSecIndex = null;
       activeElIndex = null;
       triggerPreview();
@@ -512,15 +521,24 @@ const SectionCard: m.Component<{ si: number }> = {
       section.sectionType === MonoDisplay.SectionType.ElementsTimespan
         ? m(".el-list",
             ([ ["Start Time", "startTimestamp"], ["Stop Time", "endTimestamp"] ] as [string, string][])
-              .map(([label, key]) =>
-                m(".field",
+              .map(([label, key]) => {
+                let posix: bigint = (section as any)[key];
+                if (!posix) {
+                  posix = BigInt(Math.floor(Date.now() / 1000));
+                  setSectionField(si, key, posix);
+                }
+                const dtLocal = new Date(Number(posix) * 1000).toISOString().slice(0, 16);
+                return m(".field",
                   m("label", label),
                   m("input[type=datetime-local]", {
-                    value: (section as any)[key],
-                    onchange: (e: Event) => setSectionField(si, key, (e.target as HTMLInputElement).value),
+                    value: dtLocal,
+                    onchange: (e: Event) => {
+                      const ms = new Date((e.target as HTMLInputElement).value).getTime();
+                      setSectionField(si, key, BigInt(Math.floor(ms / 1000)));
+                    },
                   }),
-                )
-              )
+                );
+              })
           )
         : null,
       m(".el-list",
diff --git a/ts/src/file.ts b/ts/src/file.ts
index 940997b..fddf599 100644
--- a/ts/src/file.ts
+++ b/ts/src/file.ts
@@ -108,25 +108,26 @@ export class MonoDisplayFile implements MonoFormatFile {
       (section.flags.clearBuffer ?? false ? 0x04 : 0);
 
     const encodedEls = section.elements.map(el => this.#encodeElement(el));
-    const sectionDataSize = 4 + encodedEls.reduce((s, e) => s + e.byteLength, 0);
+    // sub-header: flags(2) + numElements(2) + startTimestamp(8) + endTimestamp(8) = 20 bytes
+    const sectionDataSize = 20 + encodedEls.reduce((s, e) => s + e.byteLength, 0);
     // sectionSize (in header) = 4 (header) + sectionDataSize
     const sectionSize = 4 + sectionDataSize;
 
-    const hdr = new Uint8Array(4 + 5*4); // section header (4) + section sub-header (4)
+    const hdr = new Uint8Array(4 + 20); // section header (4) + sub-header (20)
     const v   = new DataView(hdr.buffer);
     v.setUint8(0, section.sectionType);
     v.setUint8(1,  sectionSize        & 0xFF);
     v.setUint8(2, (sectionSize >> 8)  & 0xFF);
     v.setUint8(3, (sectionSize >> 16) & 0xFF);
-    v.setUint16(4, flagBits,        true); // flags
-    v.setUint16(6, section.elements.length, true); // numElements
-
-    // section.startTimestamp.valueOf()
-    const startTimestampLow = 0, startTimestampHigh = 0, endTimestampLow = 0, endTimestampHigh = 0;
-    v.setUint32(8, startTimestampLow, true); // flags
-    v.setUint32(12, startTimestampHigh, true); // numElements
-    v.setUint32(16, endTimestampLow, true); // numElements
-    v.setUint32(20, endTimestampHigh, true); // numElements
+    v.setUint16(4, flagBits,                   true); // flags
+    v.setUint16(6, section.elements.length,    true); // numElements
+
+    const start = section.startTimestamp ?? 0n;
+    const end   = section.endTimestamp   ?? 0n;
+    v.setUint32( 8, Number(start & 0xFFFFFFFFn),        true);
+    v.setUint32(12, Number((start >> 32n) & 0xFFFFFFFFn), true);
+    v.setUint32(16, Number(end   & 0xFFFFFFFFn),        true);
+    v.setUint32(20, Number((end   >> 32n) & 0xFFFFFFFFn), true);
 
     return this.#concat(hdr, ...encodedEls);
   }