LMMS/lmms

LCD Widgets reduce value by 2 when finishing trackpad "wheel scroll" action

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#3,370 建立於 2017年2月19日

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 (5 留言) (0 反應) (0 負責人)C++ (7,132 star) (961 fork)batch import
buggood first issueguimacos

描述

Here is a demonstration using the tempo control: lmms-extra-change-scroll-wheel-bug

The following events happen in the gif:

  1. When two fingers are placed first on the trackpad (the beginning of the wheel scroll motion) the tempo drops from 140 to 138;
  2. After a pause, the normal scrolling action changes the tempo to 128;
  3. The fingers are then lifted off the trackpad and the tempo mistakenly changes to 126.

More details on cause and suggested solution to follow.

貢獻者指南

技術棧
cpp
領域
desktop
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
1-2 days
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
mostly clear
前置要求
C++Qt event handling
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
40
研究方向
Investigate the LCD widget implementation in LMMS, likely in src/gui/widgets/LcdSpinBox.cpp or similar. The bug occurs during trackpad wheel scroll events where the value decrements by 2 when starting and stopping scrolling. Look for how wheel events are handled and if there is a duplicate event or incorrect delta calculation. Check for any Qt mouse wheel event handling differences between regular mouse and trackpad. Review comments in issue #3370 for any maintainer hints.