input_method: Use for erasing

data/keyboards/de.yaml

@@ -45,7 +45,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "special"

data/keyboards/de_wide.yaml

@@ -45,7 +45,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "special"

data/keyboards/el.yaml

@@ -46,7 +46,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "altline"

data/keyboards/es.yaml

@@ -44,7 +44,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "default"

data/keyboards/fi.yaml

@@ -39,7 +39,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "altline"

data/keyboards/it.yaml

@@ -46,7 +46,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "default"

data/keyboards/jp+kana.yaml

@@ -195,7 +195,7 @@ buttons:
     BackSpace:
         outline: "wide"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     Return:
         outline: "wide"
         icon: "key-enter"

data/keyboards/jp+kana_wide.yaml

@@ -195,7 +195,7 @@ buttons:
     BackSpace:
         outline: "wide"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     Return:
         outline: "wide"
         icon: "key-enter"

data/keyboards/no.yaml

@@ -39,7 +39,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     preferences:
         action: "show_prefs"
         outline: "altline"

data/keyboards/number.yaml

@@ -16,7 +16,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     space:
         outline: spaceline
         text: " "

data/keyboards/se.yaml

@@ -39,7 +39,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     preferences:
         action: "show_prefs"
         outline: "altline"

data/keyboards/terminal.yaml

@@ -45,7 +45,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     preferences:
         action: "show_prefs"
         outline: "special"

data/keyboards/us.yaml

@@ -39,9 +39,9 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: erase
     preferences:
-        action: "show_prefs"
+        action: show_prefs
         outline: "special"
         icon: "keyboard-mode-symbolic"
     show_numbers:

data/keyboards/us_wide.yaml

@@ -39,7 +39,7 @@ buttons:
     BackSpace:
         outline: "altline"
         icon: "edit-clear-symbolic"
-        keysym: "BackSpace"
+        action: "erase"
     preferences:
         action: "show_prefs"
         outline: "special"

src/action.rs

@@ -37,5 +37,7 @@ pub enum Action {
         /// The key events this symbol submits when submitting text is not possible
         keys: Vec<KeySym>,
     },
+    /// Erase a position behind the cursor
+    Erase,
     ShowPreferences,
 }

src/data.rs

@@ -15,6 +15,7 @@ use std::vec::Vec;
 
 use xkbcommon::xkb;
 
+use ::action;
 use ::keyboard::{
     KeyState, PressType,
     generate_keymap, generate_keycodes, FormattingError
@@ -259,6 +260,9 @@ enum Action {
     SetView(String),
     #[serde(rename="show_prefs")]
     ShowPrefs,
+    /// Remove last character
+    #[serde(rename="erase")]
+    Erase,
 }
 
 #[derive(Debug, Clone, Deserialize, PartialEq)]
@@ -381,6 +385,10 @@ impl Layout {
                             )
                     }).collect()
                 },
+                action::Action::Erase => vec![
+                    *keymap.get("BackSpace")
+                        .expect(&format!("BackSpace missing from keymap")),
+                ],
                 _ => Vec::new(),
             };
             (
@@ -547,6 +555,7 @@ fn create_action<H: WarningHandler>(
         SubmitData::Action(
             Action::ShowPrefs
         ) => ::action::Action::ShowPreferences,
+        SubmitData::Action(Action::Erase) => action::Action::Erase,
         SubmitData::Keysym(keysym) => ::action::Action::Submit {
             text: None,
             keys: vec!(::action::KeySym(
@@ -581,7 +590,7 @@ fn create_action<H: WarningHandler>(
                     false => format!("U{:04X}", codepoint as u32),
                 })
             }).collect(),
-        }
+        },
     }
 }
 

src/imservice.c

@@ -55,6 +55,11 @@ eek_input_method_commit_string(struct zwp_input_method_v2 *zwp_input_method_v2,
     zwp_input_method_v2_commit_string(zwp_input_method_v2, text);
 }
 
+void
+eek_input_method_delete_surrounding_text(struct zwp_input_method_v2 *zwp_input_method_v2, uint32_t before_length, uint32_t after_length) {
+    zwp_input_method_v2_delete_surrounding_text(zwp_input_method_v2, before_length, after_length);
+};
+
 void
 eek_input_method_commit(struct zwp_input_method_v2 *zwp_input_method_v2, uint32_t serial)
 {

src/imservice.rs

@@ -35,6 +35,7 @@ pub mod c {
         #[allow(improper_ctypes)] // IMService will never be dereferenced in C
         pub fn imservice_connect_listeners(im: *mut InputMethod, imservice: *const IMService);
         pub fn eek_input_method_commit_string(im: *mut InputMethod, text: *const c_char);
+        pub fn eek_input_method_delete_surrounding_text(im: *mut InputMethod, before: u32, after: u32);
         pub fn eek_input_method_commit(im: *mut InputMethod, serial: u32);
         fn eekboard_context_service_set_hint_purpose(state: *const StateManager, hint: u32, purpose: u32);
         fn server_context_service_show_keyboard(imservice: *const UIManager);
@@ -375,6 +376,24 @@ impl IMService {
         }
     }
 
+    pub fn delete_surrounding_text(
+        &self,
+        before: u32, after: u32,
+    ) -> Result<(), SubmitError> {
+        match self.current.active {
+            true => {
+                unsafe {
+                    c::eek_input_method_delete_surrounding_text(
+                        self.im,
+                        before, after,
+                    )
+                }
+                Ok(())
+            },
+            false => Err(SubmitError::NotActive),
+        }
+    }
+
     pub fn commit(&mut self) -> Result<(), SubmitError> {
         match self.current.active {
             true => {

src/keyboard.rs

@@ -79,9 +79,10 @@ fn sorted<'a, I: Iterator<Item=&'a str>>(
 pub fn generate_keycodes<'a, C: IntoIterator<Item=&'a str>>(
     key_names: C
 ) -> HashMap<String, u32> {
+    let special_keysyms = ["BackSpace", "Return"].iter().map(|&s| s);
     HashMap::from_iter(
         // sort to remove a source of indeterminism in keycode assignment
-        sorted(key_names.into_iter())
+        sorted(key_names.into_iter().chain(special_keysyms))
             .map(|name| String::from(name))
             .zip(9..)
     )
@@ -108,7 +109,10 @@ impl From<io::Error> for FormattingError {
     }
 }
 
-/// Generates a de-facto single level keymap. TODO: actually drop second level
+/// Generates a de-facto single level keymap.
+// TODO: don't rely on keys and their order,
+// but rather on what keysyms and keycodes are in use.
+// Iterating actions makes it hard to deduplicate keysyms.
 pub fn generate_keymap(
     keystates: &HashMap::<String, KeyState>
 ) -> Result<String, FormattingError> {
@@ -123,17 +127,32 @@ pub fn generate_keymap(
     )?;
     
     for (name, state) in keystates.iter() {
-        if let Action::Submit { text: _, keys } = &state.action {
+        match &state.action {
-            if let 0 = keys.len() { eprintln!("Key {} has no keysyms", name); };
+            Action::Submit { text: _, keys } => {
-            for (named_keysym, keycode) in keys.iter().zip(&state.keycodes) {
+                if let 0 = keys.len() { eprintln!("Key {} has no keysyms", name); };
+                for (named_keysym, keycode) in keys.iter().zip(&state.keycodes) {
+                    write!(
+                        buf,
+                        "
+        <{}> = {};",
+                        named_keysym.0,
+                        keycode,
+                    )?;
+                }
+            },
+            Action::Erase => {
+                let mut keycodes = state.keycodes.iter();
                 write!(
                     buf,
                     "
-        <{}> = {};",
+        <BackSpace> = {};",
-                    named_keysym.0,
+                    keycodes.next().expect("Erase key has no keycode"),
-                    keycode,
                 )?;
-            }
+                if let Some(_) = keycodes.next() {
+                    eprintln!("BUG: Erase key has multiple keycodes");
+                }
+            },
+            _ => {},
         }
     }
     
@@ -145,7 +164,9 @@ pub fn generate_keymap(
     xkb_symbols \"squeekboard\" {{
 
         name[Group1] = \"Letters\";
-        name[Group2] = \"Numbers/Symbols\";"
+        name[Group2] = \"Numbers/Symbols\";
+        
+        key <BackSpace> {{ [ BackSpace ] }};"
     )?;
     
     for (name, state) in keystates.iter() {

src/layout.rs

@@ -887,7 +887,9 @@ mod seat {
 
         // process changes
         match action {
-            Action::Submit { text: _, keys: _ } => {
+            Action::Submit { text: _, keys: _ }
+                | Action::Erase
+            => {
                 unstick_locks(layout).apply();
                 submission.handle_release(KeyState::get_id(rckey), time);
             },

src/submission.rs

@@ -116,16 +116,18 @@ impl Submission {
         key: &KeyState, key_id: KeyStateId,
         time: Timestamp,
     ) {
-        let key_string = match &key.action {
+        match &key.action {
-            Action::Submit { text, keys: _ } => text,
+            Action::Submit { text: _, keys: _ }
+                | Action::Erase
+            => (),
             _ => {
-                eprintln!("BUG: Submitted key with action other than Submit");
+                eprintln!("BUG: Submitted key with action other than Submit or Erase");
                 return;
             },
         };
 
-        let text_was_committed = match (&mut self.imservice, key_string) {
+        let was_committed_as_text = match (&mut self.imservice, &key.action) {
-            (Some(imservice), Some(text)) => {
+            (Some(imservice), Action::Submit { text: Some(text), keys: _ }) => {
                 let submit_result = imservice.commit_string(text)
                     .and_then(|_| imservice.commit());
                 match submit_result {
@@ -133,10 +135,18 @@ impl Submission {
                     Err(imservice::SubmitError::NotActive) => false,
                 }
             },
+            (Some(imservice), Action::Erase) => {
+                let submit_result = imservice.delete_surrounding_text(1, 0)
+                    .and_then(|_| imservice.commit());
+                match submit_result {
+                    Ok(()) => true,
+                    Err(imservice::SubmitError::NotActive) => false,
+                }
+            }
             (_, _) => false,
         };
         
-        let submit_action = match text_was_committed {
+        let submit_action = match was_committed_as_text {
             true => SubmittedAction::IMService,
             false => {
                 self.virtual_keyboard.switch(