获取 Swift 中键盘代码的键名

Question

我知道其他人也问过类似的问题，但我没有看到明确的答案，我仍然卡住了。我正在尝试编写一个 Swift 函数，该函数采用硬件生成的键盘扫描代码（例如来自 NSEvent）和 returns 字母大写锁定的键名称，用于特定键当前在 OS 中有效的排列（Dvorak、Qwerty 等）（这可能与生成代码时有效的排列不同）。

据我了解，唯一的方法是调用一些非常古老的 Carbon 函数，绕过很多 Swift 的极端类型安全，我觉得这样做不太舒服。这是到目前为止的节目：

import  Cocoa
import  Carbon

func keyName (scanCode: UInt16) -> String?
  { let maxNameLength = 4,      modifierKeys: UInt32 = 0x00000004   //  Caps Lock (Carbon Era)

    let deadKeys      = UnsafeMutablePointer<UInt32>(bitPattern: 0x00000000),
        nameBuffer    = UnsafeMutablePointer<UniChar>.alloc(maxNameLength),
        nameLength    = UnsafeMutablePointer<Int>.alloc(1),
        keyboardType  = UInt32(LMGetKbdType())

    let source        = TISGetInputSourceProperty ( TISCopyCurrentKeyboardLayoutInputSource()
                                                        .takeRetainedValue(),
                                                    kTISPropertyUnicodeKeyLayoutData )

    let dataRef       = unsafeBitCast(source, CFDataRef.self)
    let dataBuffer    = CFDataGetBytePtr(dataRef)

    let keyboardLayout  = unsafeBitCast(dataBuffer, UnsafePointer <UCKeyboardLayout>.self)

    let osStatus  = UCKeyTranslate  (keyboardLayout, scanCode, UInt16(kUCKeyActionDown),
                        modifierKeys, keyboardType, UInt32(kUCKeyTranslateNoDeadKeysMask),
                        deadKeys, maxNameLength, nameLength, nameBuffer)
    switch  osStatus
      { case  0:    return  NSString (characters: nameBuffer, length: nameLength[0]) as String
        default:    NSLog (“Code: 0x%04X  Status: %+i", scanCode, osStatus);    return  nil   }
  }

它没有崩溃，在这一点上我几乎认为这本身就是一个游戏成就，但它也没有用。 UCKeyTranslate总是returns状态为-50，我理解是参数错误。我怀疑是“keyboardLayout”，因为它的设置最复杂。谁能看到参数问题？或者是否有针对此类事情的更新框架？

Answer 1

好的，我相信我已经找到问题所在了。虽然回答我自己的问题感觉很奇怪，但我知道在这种情况下这是正确的做法。

违规参数似乎是 deadKeys。在我遵循的模型代码中，这被定义为位模式。虽然据说是指向可变内容的指针，但我不确定它是否真的是那个，因为当我决定重新定义它以匹配 UCKeyTranslate 的其他两个按引用调用参数时，一切都开始完美运行。解决方案是执行显式 .alloc，然后将引用值显式归零。这是我更新的函数：

func    keyName       ( scanCode: UInt16  )     ->  String?
  { let maxNameLength = 4,      modifierKeys: UInt32  = 0x00000004,     //  Caps Lock (Carbon Era Mask)
        nameBuffer    = UnsafeMutablePointer <UniChar>  .alloc (maxNameLength),
        nameLength    = UnsafeMutablePointer <Int>      .alloc (1),
        deadKeys      = UnsafeMutablePointer <UInt32>   .alloc (1);     deadKeys[0] = 0x00000000

    let source        = TISGetInputSourceProperty ( TISCopyCurrentKeyboardLayoutInputSource()
                                                        .takeRetainedValue(),
                                                    kTISPropertyUnicodeKeyLayoutData  ),

    keyboardLayout    = unsafeBitCast ( CFDataGetBytePtr (unsafeBitCast (source, CFDataRef.self)),
                                        UnsafePointer <UCKeyboardLayout>.self),
    keyboardType      = UInt32 (LMGetKbdType())

    let osStatus      = UCKeyTranslate (keyboardLayout, scanCode, UInt16 (kUCKeyActionDown),
                            modifierKeys, keyboardType, UInt32 (kUCKeyTranslateNoDeadKeysMask),
                            deadKeys, maxNameLength, nameLength, nameBuffer)
    switch  osStatus
      { case  0:    return  String.init (utf16CodeUnits: nameBuffer, count: nameLength[0])
        default:    NSLog ("Code: 0x%04X  Status: %+i", scanCode, osStatus);    return  nil   }
  }

还有一些其他更改，非常漂亮：我删除了导致定义 keyboardLayout 的几个中间常量。（“BitCasts”只是为了满足 Swiftian 类型安全：它们实际上并没有做我能看到的任何其他事情。）但真正的问题是 deadKeys 的原始定义。我希望这对某些人有用，至少在出现非碳替代品之前是这样。（那会发生吗？）

Answer 2

正如您已经发现的，您必须传递 UInt32 的地址作为 deadKeyState 参数的变量。分配内存是一个解决该问题的方法，但您一定不要忘记释放内存最终，否则程序会泄漏内存。

另一种可能的解决方案是将变量的地址传递为带有 &:

的输入参数

var deadKeys : UInt32 = 0
// ...
let osStatus = UCKeyTranslate(..., &deadKeys, ...)

这个更短更简单，你不需要发布记忆。同样可以应用于 nameBuffer 和 nameLength.

unsafeBitCast()可以通过使用Unmanaged类型来避免，比较的类似问题和更详细的解释。

您还可以利用之间的免费电话桥接 CFData 和 NSData.

那么您的函数可能如下所示 (Swift 2):

import Carbon

func keyName(virtualKeyCode: UInt16) -> String?
{
    let maxNameLength = 4
    var nameBuffer = [UniChar](count : maxNameLength, repeatedValue: 0)
    var nameLength = 0

    let modifierKeys = UInt32(alphaLock >> 8) & 0xFF // Caps Lock
    var deadKeys : UInt32 = 0
    let keyboardType = UInt32(LMGetKbdType())
    
    let source = TISCopyCurrentKeyboardLayoutInputSource().takeRetainedValue()
    let ptr = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData)
    let layoutData = Unmanaged<CFData>.fromOpaque(COpaquePointer(ptr)).takeUnretainedValue() as NSData
    let keyboardLayout = UnsafePointer<UCKeyboardLayout>(layoutData.bytes)
    
    let osStatus = UCKeyTranslate(keyboardLayout, virtualKeyCode, UInt16(kUCKeyActionDown),
        modifierKeys, keyboardType, UInt32(kUCKeyTranslateNoDeadKeysMask),
        &deadKeys, maxNameLength, &nameLength, &nameBuffer)
    guard osStatus == noErr else {
        NSLog("Code: 0x%04X  Status: %+i", virtualKeyCode, osStatus);
        return nil
    }
    
    return  String(utf16CodeUnits: nameBuffer, count: nameLength)
}

Swift3 的更新：

import Carbon

func keyName(virtualKeyCode: UInt16) -> String? {
    let maxNameLength = 4
    var nameBuffer = [UniChar](repeating: 0, count : maxNameLength)
    var nameLength = 0
    
    let modifierKeys = UInt32(alphaLock >> 8) & 0xFF // Caps Lock
    var deadKeys: UInt32 = 0
    let keyboardType = UInt32(LMGetKbdType())
    
    let source = TISCopyCurrentKeyboardLayoutInputSource().takeRetainedValue()
    guard let ptr = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData) else {
        NSLog("Could not get keyboard layout data")
        return nil
    }
    let layoutData = Unmanaged<CFData>.fromOpaque(ptr).takeUnretainedValue() as Data
    let osStatus = layoutData.withUnsafeBytes {
        UCKeyTranslate([=12=], virtualKeyCode, UInt16(kUCKeyActionDown),
                       modifierKeys, keyboardType, UInt32(kUCKeyTranslateNoDeadKeysMask),
                       &deadKeys, maxNameLength, &nameLength, &nameBuffer)
    }
    guard osStatus == noErr else {
        NSLog("Code: 0x%04X  Status: %+i", virtualKeyCode, osStatus);
        return nil
    }
    
    return  String(utf16CodeUnits: nameBuffer, count: nameLength)
}

Swift4 的更新：

从 Swift 4 开始，Data.withUnsafeBytes 使用 UnsafeRawBufferPointer 调用闭包，它必须绑定指向 [=25 的指针=]:

import Carbon

func keyName(virtualKeyCode: UInt16) -> String? {
    let maxNameLength = 4
    var nameBuffer = [UniChar](repeating: 0, count : maxNameLength)
    var nameLength = 0

    let modifierKeys = UInt32(alphaLock >> 8) & 0xFF // Caps Lock
    var deadKeys: UInt32 = 0
    let keyboardType = UInt32(LMGetKbdType())

    let source = TISCopyCurrentKeyboardLayoutInputSource().takeRetainedValue()
    guard let ptr = TISGetInputSourceProperty(source, kTISPropertyUnicodeKeyLayoutData) else {
        NSLog("Could not get keyboard layout data")
        return nil
    }
    let layoutData = Unmanaged<CFData>.fromOpaque(ptr).takeUnretainedValue() as Data
    let osStatus = layoutData.withUnsafeBytes {
        UCKeyTranslate([=13=].bindMemory(to: UCKeyboardLayout.self).baseAddress, virtualKeyCode, UInt16(kUCKeyActionDown),
                       modifierKeys, keyboardType, UInt32(kUCKeyTranslateNoDeadKeysMask),
                       &deadKeys, maxNameLength, &nameLength, &nameBuffer)
    }
    guard osStatus == noErr else {
        NSLog("Code: 0x%04X  Status: %+i", virtualKeyCode, osStatus);
        return nil
    }

    return  String(utf16CodeUnits: nameBuffer, count: nameLength)
}

获取 Swift 中键盘代码的键名

Getting key names for keyboard codes in Swift

macos-carbon

keyboard-events

swift