LMMS/lmms

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

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#3,370 创建于 2017年2月19日

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 (5 评论) (0 反应) (0 负责人)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.

贡献者指南

技术栈
cpp
领域
desktop
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-2 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
mostly clear
前置要求
C++Qt event handling
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
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.