feat(settings): 新设置程序在 macOS 上也显示中英切换键

#579 的开关写在旧偏好设置里，那时新设置程序还没转正；支持表里 mac 改成支持，只列单击 Shift（单击 Ctrl 与 Ctrl + Alt + Space mac 没做，另记一项）。文档改指新设置程序，补上英文版。

apps/settings/src/support/mod.rs

@@ -18,6 +18,8 @@ pub enum Feature {
     Schemes,
     /// 中英文切换键。
     SwitchKeys,
+    /// 切换键里的单击 Ctrl 与 Ctrl + Alt + Space：macOS 只认单击 Shift。
+    SwitchKeyCombos,
     /// 切换键里的「Ctrl + Space（系统）」：改的是 Windows 的系统热键。
     SystemCtrlSpace,
     DefaultEnglish,
@@ -50,10 +52,11 @@ pub enum Feature {
 
 impl Feature {
     #[cfg(test)]
-    pub const ALL: [Self; 21] = [
+    pub const ALL: [Self; 22] = [
         Self::AuxCode,
         Self::Schemes,
         Self::SwitchKeys,
+        Self::SwitchKeyCombos,
         Self::SystemCtrlSpace,
         Self::DefaultEnglish,
         Self::RememberModePerApp,
@@ -94,8 +97,9 @@ impl Feature {
         match self {
             Self::AuxCode => [Yes, Yes, Todo],
             Self::Schemes => [Yes, Yes, Todo],
-            // macOS 用 Caps Lock，由系统决定
-            Self::SwitchKeys => [No, Yes, Yes],
+            Self::SwitchKeys => [Yes, Yes, Yes],
+            // macOS 只做了单击 Shift，Caps Lock 仍是系统那一套
+            Self::SwitchKeyCombos => [No, Yes, Yes],
             Self::SystemCtrlSpace => [No, Yes, No],
             Self::DefaultEnglish => [Todo, Yes, Yes],
             Self::RememberModePerApp => [Todo, Yes, Todo],
@@ -130,6 +134,7 @@ impl Feature {
             Self::AuxCode => "辅码",
             Self::Schemes => "形码与自定义方案",
             Self::SwitchKeys => "中英文切换键",
+            Self::SwitchKeyCombos => "单击 Ctrl 与 Ctrl + Alt + Space 切换",
             Self::SystemCtrlSpace => "系统的 Ctrl + Space",
             Self::DefaultEnglish => "默认英文模式",
             Self::RememberModePerApp => "按应用记住中英模式",
@@ -179,7 +184,8 @@ impl Feature {
             Self::KeyHint => &[(PageId::Input, "键位提示")],
             Self::ShowTones => &[(PageId::Candidates, "拼音行显示声调")],
             Self::NumpadDigit => &[(PageId::Candidates, "小键盘数字")],
-            Self::SystemCtrlSpace
+            Self::SwitchKeyCombos
+            | Self::SystemCtrlSpace
             | Self::EnglishPunctuation
             | Self::StatusBar
             | Self::HorizontalGrid

apps/settings/src/view/pages/language.rs

@@ -185,10 +185,15 @@ fn width_label(full: bool) -> &'static str {
 }
 
 /// 中英切换键可以多选，一个都不勾就只剩按钮能切；最后一个是 Windows 自己的 Ctrl + Space，改的是系统设置。
+/// macOS 只有单击 Shift 一项，勾上后 Caps Lock 只管大小写。
 fn switch_keys(ui: &mut Ui<Message>, page: &Page) -> Result<NodeId, RenderError> {
     let keys = page.settings.config.shortcut.switch_mode;
+    let combos = Feature::SwitchKeyCombos.here();
     let mut boxes = Vec::new();
     for key in SwitchKey::ALL {
+        if !combos && key != SwitchKey::Shift {
+            continue;
+        }
         let on = keys.contains(key);
         let values = keys
             .with(key, !on)
@@ -225,7 +230,13 @@ fn switch_keys(ui: &mut Ui<Message>, page: &Page) -> Result<NodeId, RenderError>
     with_notice(
         ui,
         page,
-        SettingRow::new("切换键").info("可以多选").control(column),
+        SettingRow::new("切换键")
+            .info(if combos {
+                "可以多选"
+            } else {
+                "勾上后 Caps Lock 只管大小写"
+            })
+            .control(column),
         "switch-keys",
     )
 }

docs/user/getting-started/keys.md

@@ -11,7 +11,7 @@ description: 青简在 macOS、Windows 与 Linux 上的缺省按键：切换、
 
 | 操作 | macOS | Windows | Linux |
 |---|---|---|---|
-| 中 / 英切换 | `Caps Lock`；在「偏好设置 → 快捷键」勾上「单击 Shift 切换中英文」后也可单击 `Shift`（此时 `Caps Lock` 只管大小写）。切换时屏幕右上角闪一个「中」/「英」提示 | 单击 `Shift`；系统的 `Ctrl + Space`；点任务栏或悬浮状态条上的「中 / 英」 | 单击 `Shift` |
+| 中 / 英切换 | `Caps Lock`；在「设置 → 中英文」的「切换键」里勾上「单击 Shift」后也可单击 `Shift`（此时 `Caps Lock` 只管大小写）。切换时屏幕右上角闪一个「中」/「英」提示 | 单击 `Shift`；系统的 `Ctrl + Space`；点任务栏或悬浮状态条上的「中 / 英」 | 单击 `Shift` |
 | 直接输入大写英文 | 英文模式下按住 `⇧`；勾了单击 Shift 后 `Caps Lock` 亮着也是大写 | `Caps Lock` 亮起（中英模式均可） | `Caps Lock` 亮起 |
 | 输入拼音时临时打一个大写字母 | `⇧ + 字母` | `Shift + 字母` | `Shift + 字母` |
 | 切换全角 / 半角标点 | 可启用 `⌃ + .`（缺省关） | 点悬浮状态条上的「，。」格；可启用 `Ctrl + .`（缺省关） | — |

docs/user/i18n/en/getting-started/keys.md

@@ -11,7 +11,7 @@ For keys you can change, see [Changing keys](../personalize/keys-settings.md); A
 
 | Action | macOS | Windows | Linux |
 |---|---|---|---|
-| Switch Chinese / English | `Caps Lock` | Tap `Shift`; the system's `Ctrl + Space`; click 中 / 英 on the taskbar or the floating status bar | Tap `Shift` |
+| Switch Chinese / English | `Caps Lock`; after ticking 单击 Shift (Tap Shift) under 切换键 (Switch key) in 设置 → 中英文 (Settings → Chinese/English), also a tap of `Shift` (`Caps Lock` then only controls capitals). A 中 / 英 hint flashes in the top-right corner of the screen when you switch | Tap `Shift`; the system's `Ctrl + Space`; click 中 / 英 on the taskbar or the floating status bar | Tap `Shift` |
 | Type uppercase English directly | Hold `⇧` in English mode | `Caps Lock` on (in either mode) | `Caps Lock` on |
 | Type one capital letter while typing pinyin | `⇧ + letter` | `Shift + letter` | `Shift + letter` |
 | Switch full-width / half-width punctuation | `⌃ + .` can be enabled (off by default) | Click the ，。 cell on the floating status bar; `Ctrl + .` can be enabled (off by default) | — |

docs/user/i18n/en/input/english-mode.md

@@ -9,6 +9,10 @@ description: "Entering English mode, changing or turning off the Chinese/English
 - **macOS**: English mode is on while the `Caps Lock` light is on; turn it off to return to Chinese.
   If you want `Caps Lock` to switch between Qingjian and "ABC" the way the system pinyin input does, turn on the option to switch to ABC with Caps Lock in System Settings → Keyboard → Text Input → Edit:
   a quick press of `Caps Lock` then switches input methods and holding it still locks capitals; Qingjian's own English mode is no longer needed.
+  You can also tick 单击 Shift (Tap Shift) under 切换键 (Switch key) in 设置 → 中英文 (Settings → Chinese/English): a tap of `Shift` (press and release on its own) then switches between Chinese and English.
+  Leave it off if you often hit Shift by accident while typing. Once it's on, `Caps Lock` only controls capitals, so with it lit you type capital letters directly.
+  A 中 / 英 hint flashes in the top-right corner of the screen when you switch (with Tap Shift on, toggling `Caps Lock` flashes 大写 / 小写, capitals / lowercase).
+  **Tapping Shift while typing pinyin**: the letters you've typed are committed as they are (`nihao` → `nihao`) and English mode starts, so you don't need to press Enter first.
 - **Windows**: tap `Shift` (press and release on its own, without another key) to switch between Chinese and English. The taskbar shows 中 or 英 to match, and A while Caps Lock is on.
   Clicking the 中 / 英 icon on the taskbar also switches.
   On Windows, `Caps Lock` only controls case: while it's on, capital letters are typed directly in either mode (as with Microsoft Pinyin).

docs/user/input/english-mode.md

@@ -9,7 +9,7 @@ description: 进入英文模式、改掉或关掉中英切换、默认模式与
 - **macOS**：`Caps Lock` 亮起为英文模式，熄灭回到中文。
   想让 `Caps Lock` 像系统拼音那样在青简与「ABC」之间切换输入法，在「系统设置 → 键盘 → 文本输入 → 编辑」里打开用 Caps Lock 切换「ABC」的选项：
   轻按 `Caps Lock` 切换输入法，按住仍是大写锁定；这时青简自己的英文模式就用不到了。
-  也可以在「偏好设置 → 快捷键」勾上「单击 Shift 切换中英文」：此后点一下 `Shift`（按下即松开、不与其他键组合）在中 / 英之间切换，
+  也可以在「设置 → 中英文」的「切换键」里勾上「单击 Shift」：此后点一下 `Shift`（按下即松开、不与其他键组合）在中 / 英之间切换，
   打字时误触 Shift 的话不用勾；勾上后 `Caps Lock` 退化成只管大小写，亮着直接输出大写英文。
   切换的那一刻屏幕右上角会闪一个「中」/「英」提示（勾了单击 Shift 后，`Caps Lock` 切大小写也会闪「大写」/「小写」）。
   **正在输入拼音时点 Shift**：已经敲的拼音按原样当英文上屏（`nihao` → `nihao`），再进入英文模式 —— 不用先回车再切。