其中鼠標光標移動加速度和滾輪加速度在MacOSX中實現

Question

MacOSX中鼠標光標移動加速度和滾輪加速度在哪裏？

在API級別上，Core Graphics/Quartz Event Services提供CGEvent類型。

在應用程序方面，也有在this Chrome change review很多相關的和有趣的評論，並從那裏this comment提取：

// Of Mice and Men 
// --------------- 
// 
// There are three types of scroll data available on a scroll wheel CGEvent. 
// Apple's documentation ([1]) is rather vague in their differences, and not 
// terribly helpful in deciding which to use. This is what's really going on. 
// 
// First, these events behave very differently depending on whether a standard 
// wheel mouse is used (one that scrolls in discrete units) or a 
// trackpad/Mighty Mouse is used (which both provide continuous scrolling). 
// You must check to see which was used for the event by testing the 
// kCGScrollWheelEventIsContinuous field. 
// 
// Second, these events refer to "axes". Axis 1 is the y-axis, and axis 2 is 
// the x-axis. 
// 
// Third, there is a concept of mouse acceleration. Scrolling the same amount 
// of physical distance will give you different results logically depending on 
// whether you scrolled a little at a time or in one continuous motion. Some 
// fields account for this while others do not. 
// 
// Fourth, for trackpads there is a concept of chunkiness. When scrolling 
// continuously, events can be delivered in chunks. That is to say, lots of 
// scroll events with delta 0 will be delivered, and every so often an event 
// with a non-zero delta will be delivered, containing the accumulated deltas 
// from all the intermediate moves. [2] 
// 
// For notchy wheel mice (kCGScrollWheelEventIsContinuous == 0) 
// ------------------------------------------------------------ 
// 
// kCGScrollWheelEventDeltaAxis* 
// This is the rawest of raw events. For each mouse notch you get a value of 
// +1/-1. This does not take acceleration into account and thus is less 
// useful for building UIs. 
// 
// kCGScrollWheelEventPointDeltaAxis* 
// This is smarter. In general, for each mouse notch you get a value of 
// +1/-1, but this _does_ take acceleration into account, so you will get 
// larger values on longer scrolls. This field would be ideal for building 
// UIs except for one nasty bug: when the shift key is pressed, this set of 
// fields fails to move the value into the axis2 field (the other two types 
// of data do). This wouldn't be so bad except for the fact that while the 
// number of axes is used in the creation of a CGScrollWheelEvent, there is 
// no way to get that information out of the event once created. 
// 
// kCGScrollWheelEventFixedPtDeltaAxis* 
// This is a fixed value, and for each mouse notch you get a value of 
// +0.1/-0.1 (but, like above, scaled appropriately for acceleration). This 
// value takes acceleration into account, and in fact is identical to the 
// results you get from -[NSEvent delta*]. (That is, if you linked on Tiger 
// or greater; see [2] for details.) 
// 
// A note about continuous devices 
// ------------------------------- 
// 
// There are two devices that provide continuous scrolling events (trackpads 
// and Mighty Mouses) and they behave rather differently. The Mighty Mouse 
// behaves a lot like a regular mouse. There is no chunking, and the 
// FixedPtDelta values are the PointDelta values multiplied by 0.1. With the 
// trackpad, though, there is chunking. While the FixedPtDelta values are 
// reasonable (they occur about every fifth event but have values five times 
// larger than usual) the Delta values are unreasonable. They don't appear to 
// accumulate properly. 
// 
// For continuous devices (kCGScrollWheelEventIsContinuous != 0) 
// ------------------------------------------------------------- 
// 
// kCGScrollWheelEventDeltaAxis* 
// This provides values with no acceleration. With a trackpad, these values 
// are chunked but each non-zero value does not appear to be cumulative. 
// This seems to be a bug. 
// 
// kCGScrollWheelEventPointDeltaAxis* 
// This provides values with acceleration. With a trackpad, these values are 
// not chunked and are highly accurate. 
// 
// kCGScrollWheelEventFixedPtDeltaAxis* 
// This provides values with acceleration. With a trackpad, these values are 
// chunked but unlike Delta events are properly cumulative. 
// 
// Summary 
// ------- 
// 
// In general the best approach to take is: determine if the event is 
// continuous. If it is not, then use the FixedPtDelta events (or just stick 
// with Cocoa events). They provide both acceleration and proper horizontal 
// scrolling. If the event is continuous, then doing pixel scrolling with the 
// PointDelta is the way to go. In general, avoid the Delta events. They're 
// the oldest (dating back to 10.4, before CGEvents were public) but they lack 
// acceleration and precision, making them useful only in specific edge cases. 
// 
// References 
// ---------- 
// 
// [1] <http://developer.apple.com/documentation/Carbon/Reference/QuartzEventServicesRef/Reference/reference.html> 
// [2] <http://developer.apple.com/releasenotes/Cocoa/AppKitOlderNotes.html> 
//  Scroll to the section headed "NSScrollWheel events". 
// 
// P.S. The "smooth scrolling" option in the system preferences is utterly 
// unrelated to any of this. 

在內核級別，I/O Kit是基本的驅動程序接口，和我猜的鼠標HID（人機界面設備）系列（IOHIDFamily）。 XNU kernel source can be seen here但我不確定這是否完整，因爲當我搜索IOHIDFamily時我沒有找到一個匹配項。代碼可能是here at IOHIDFamily。其實我在IOHIPointing.cpp發現註釋：

/* 
* 17 July 1998 sdouglas Initial creation 
* 01 April  2002 ryepez  added support for scroll acceleration 
*/ 

而且從代碼，它看起來像它的實現存在。有人可以確認嗎？ 另請參閱here。

IOHIPointing中的邏輯如何最終進入CGEvent？這是Core Graphics/Quartz的所有部分嗎？之間有什麼？這是一些馬赫事件嗎？關於通用體系結構有什麼好的概述？

請注意，我在想這個問題，因爲正在進行的討論在哪裏實施mouse scroll wheel acceleration in Linux/Xorg/libinput here。

Answer 1

好，問題 - 那是一個很大的問題。我應該注意到，我沒有完整的信息 - 正如你發現的那樣，很多信息都是封閉的。據我已經能夠告訴，這些都是重要的幾點：

• 鼠標設置（跟蹤速度，滾動速度等），你在系統偏好看到一個通用的，非蘋果鼠標都在WindowServer內部處理 - 其中CGEvent是源於此。有一些HID報告在IOHIDPointing等按摩，但從我看到這主要是爲了保持與古怪的設備兼容性。
• 更新：（參見注釋討論）看起來WindowServer可能通過在其IORegistry條目上設置屬性將加速參數傳遞給內核驅動程序。
• 我相信蘋果觸控設備（觸控板，魔術鼠標）的動量滾動可能實際上至少部分在其各自的閉源內核驅動程序中實現，如AppleMultitouchTrackpadHIDEventDriver。
• HID堆棧的較低級別用戶空間一側的源代碼可在IOKitUser源包中找到。這包括IOHIDManager等。
• 從裝置到CGEvent旅程大致是：設備 - >IOHIDDevice - >IOHIDInterface - >IOHIDEventDriver - > [IOHIDevice] - >IOHIDSystem - >IOHIDUserClient - >由於IOKit內核 - 用戶通信機制（使用馬赫端口內部） - > HID部分IOKitUser - > WindowServer（核心圖形）。
• 您可以通過IOHIDLibUserClient直接連接到IOHIDDevice從用戶空間進程繞過此路徑。

IOKitUser源可能會更詳細地回答您的一些問題。或者如果你想要做一些特定的事情，請爲此提出一個新問題。