Animated cursor lags behind on fast songs

[Danielku15]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

On fast songs the cursor can lag behind the place where it should be.
https://github.com/user-attachments/assets/67c3c82e-d18d-48e5-8c44-9c7d81253c88

Expected Behavior

The cursor should be always at the correct location.

Steps To Reproduce

1. Start playground with canon.gp5
2. Play the fast part after the intro.

Link to jsFiddle, CodePen, Project

No response

Version and Environment

[AlphaTab][VersionInfo] alphaTab 1.6.0
Logger.ts:7 [AlphaTab][VersionInfo] commit: b08102e1e209cfc7880c524366eae49d3b23e5db
Logger.ts:7 [AlphaTab][VersionInfo] build date: 2025-06-14T22:50:35.117Z
Logger.ts:7 [AlphaTab][VersionInfo] High DPI: 1
Logger.ts:7 [AlphaTab][VersionInfo] Browser: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36
Logger.ts:7 [AlphaTab][VersionInfo] Platform: BrowserModule
Logger.ts:7 [AlphaTab][VersionInfo] WebPack: false
Logger.ts:7 [AlphaTab][VersionInfo] Vite: false
Logger.ts:7 [AlphaTab][VersionInfo] Window Size: 1495x1039
Logger.ts:7 [AlphaTab][VersionInfo] Screen Size: 1680x1050

Platform

Web

Anything else?

The problem was likely introduced when with the optimization of cursor updates to avoid jumping/flickering:

alphaTab/src/AlphaTabApiBase.ts

Line 2197 in b08102e

const jumpCursor =

I'd expect the cursor to catch up as the animation tells to reach the target position in a certain time. So if it lags behind it should get "faster".

Maybe the calculated animation times are wrong after the different changes. Removing the jumpCursor check again, also shows a weird jumping of the cursor as if the duration is not correct.

alphaTab/src/AlphaTabApiBase.ts

Line 2204 in b08102e

if (jumpCursor) {