Open the search when typing on a physical keyboard

Typing on a physical keyboard while the home screen is shown now opens the
search page and inserts the typed character, so the launcher can be used
without touching the screen. It works for any printable key, appends the
characters in order even when the user types faster than the launcher can
recompose, and the search bar can still be tapped to edit the query with
the on-screen keyboard as usual.

While the search is driven by the keyboard, the search bar's text field is
left unfocused on purpose: a focused text field would make the system show
the on-screen keyboard, which is not wanted when there is a physical
keyboard. The handler therefore inserts and deletes characters itself,
including backspace and enter (to launch the best match).

The behaviour is controlled by a new "Search on typing" preference in
Settings -> Search, which is enabled by default.

Implementation notes:
- The key events are intercepted in SharedLauncherActivity.dispatchKeyEvent,
  which is the only place that sees hardware key events while no view has
  focus. The scaffold installs the handler while it is shown.
- Key events are not forwarded to the search bar's text field, so the
  characters are inserted into the search view model directly.
- SearchBar keeps a TextFieldValue instead of a String so that the cursor
  moves to the end of the text when the value is changed from the outside.
  Without this the next typed character ended up in front of the text.

core/i18n/src/main/res/values-da/strings.xml

@@ -425,6 +425,8 @@
     <string name="no_account_nextcloud">Du har ikke tilknyttet en Nextcloud-konto endnu</string>
     <string name="preference_screen_buildinfo_summary">Flere oplysninger om denne udgave af denne app</string>
     <string name="preference_search_bar_launch_on_enter_summary">Start fremhævet match eller hurtig handling, når du trykker gå</string>
+    <string name="preference_search_bar_search_on_typing">Søg ved indtastning</string>
+    <string name="preference_search_bar_search_on_typing_summary">Åbn søgningen og begynd at skrive, når du trykker på et fysisk tastatur</string>
     <string name="search_action_message">Send besked</string>
     <string name="apps_profile_work">Arbejde</string>
     <plurals name="calendar_widget_running_events">

core/i18n/src/main/res/values/strings.xml

@@ -675,6 +675,8 @@
     <string name="preference_search_bar_auto_focus_summary">Automatically show the keyboard when opening the app drawer</string>
     <string name="preference_search_bar_launch_on_enter">Launch on enter</string>
     <string name="preference_search_bar_launch_on_enter_summary">Launch highlighted match or quick action upon tapping go</string>
+    <string name="preference_search_bar_search_on_typing">Search on typing</string>
+    <string name="preference_search_bar_search_on_typing_summary">Open the search and start typing when you press a key on a physical keyboard</string>
     <string name="preference_hidden_items">Excluded search results</string>
     <string name="preference_hidden_items_summary">Manage excluded apps and search results</string>
     <string name="preference_hidden_items_reveal_button">Show reveal button</string>

core/preferences/src/main/java/de/mm20/launcher2/preferences/LauncherSettingsData.kt

@@ -116,6 +116,11 @@ data class LauncherSettingsData internal constructor(
     val searchBarColors: SearchBarColors = SearchBarColors.Auto,
     val searchBarKeyboard: Boolean = true,
     val searchLaunchOnEnter: Boolean = true,
+    /**
+     * Open the search and start typing when a printable key is pressed on a physical keyboard
+     * while the home screen is shown.
+     */
+    val searchOnTyping: Boolean = true,
     val searchBarBottom: Boolean = false,
     val searchBarFixed: Boolean = false,
 

core/preferences/src/main/java/de/mm20/launcher2/preferences/ui/SearchUiSettings.kt

@@ -52,6 +52,18 @@ class SearchUiSettings internal constructor(
         }
     }
 
+    /**
+     * Whether typing on a physical keyboard while the home screen is shown opens the search.
+     */
+    val searchOnTyping
+        get() = launcherDataStore.data.map { it.searchOnTyping }.distinctUntilChanged()
+
+    fun setSearchOnTyping(searchOnTyping: Boolean) {
+        launcherDataStore.update {
+            it.copy(searchOnTyping = searchOnTyping)
+        }
+    }
+
     val reversedResults
         get() = launcherDataStore.data.map { it.searchResultsReversed }.distinctUntilChanged()