Start on TTS support by logging the data that will become TTS lines

Includes some misc cleanup of haptic double-triggering (or
non-triggering), since those cases all end up being TTS event
double-reporting, which to me crosses the threshold from "annoying" to
"usability issue"

lib/luavgl/src/group.c

@@ -248,6 +248,14 @@ static int luavgl_group_get_focused(lua_State *L)
   return 1;
 }
 
+static int luavgl_group_clear_focus(lua_State *L)
+{
+  luavgl_group_t *g = luavgl_check_group(L, 1);
+  g->group->obj_focus = NULL;
+
+  return 0;
+}
+
 static int luavgl_group_remove_obj(lua_State *L)
 {
   lv_obj_t *obj = luavgl_to_obj(L, 1);
@@ -319,6 +327,7 @@ static const luaL_Reg group_methods[] = {
     {"get_wrap",      luavgl_group_get_wrap     },
     {"get_obj_count", luavgl_group_get_obj_count},
     {"get_focused",   luavgl_group_get_focused  },
+    {"clear_focus",   luavgl_group_clear_focus  },
 
     {NULL,            NULL                      },
 };

lua/playing.lua

@@ -126,6 +126,7 @@ return screen:new {
       range = { min = 0, max = 100 },
       value = 0,
     }
+    local scrubber_desc = widgets.Description(scrubber, "Scrubber")
 
     scrubber:onevent(lvgl.EVENT.RELEASED, function()
       local track = playback.track:get()
@@ -165,6 +166,7 @@ return screen:new {
     end)
     local repeat_img = repeat_btn:Image { src = img.repeat_src }
     theme.set_style(repeat_img, icon_enabled_class)
+    local repeat_desc = widgets.Description(repeat_btn)
 
 
     local prev_btn = controls:Button {}
@@ -177,6 +179,7 @@ return screen:new {
     end)
     local prev_img = prev_btn:Image { src = img.prev }
     theme.set_style(prev_img, icon_enabled_class)
+    local prev_desc = widgets.Description(prev_btn, "Previous track")
 
     local play_pause_btn = controls:Button {}
     play_pause_btn:onClicked(function()
@@ -185,11 +188,13 @@ return screen:new {
     play_pause_btn:focus()
     local play_pause_img = play_pause_btn:Image { src = img.pause }
     theme.set_style(play_pause_img, icon_enabled_class)
+    local play_pause_desc = widgets.Description(play_pause_btn, "Play")
 
     local next_btn = controls:Button {}
     next_btn:onClicked(queue.next)
     local next_img = next_btn:Image { src = img.next }
     theme.set_style(next_img, icon_disabled_class)
+    local next_desc = widgets.Description(next_btn, "Next track")
 
     local shuffle_btn = controls:Button {}
     shuffle_btn:onClicked(function()
@@ -197,6 +202,7 @@ return screen:new {
     end)
     local shuffle_img = shuffle_btn:Image { src = img.shuffle }
     theme.set_style(shuffle_img, icon_enabled_class)
+    local shuffle_desc = widgets.Description(shuffle_btn)
 
     controls:Object({ flex_grow = 1, h = 1 }) -- spacer
 
@@ -205,8 +211,10 @@ return screen:new {
       playback.playing:bind(function(playing)
         if playing then
           play_pause_img:set_src(img.pause)
+          play_pause_desc:set { text = "Pause" }
         else
           play_pause_img:set_src(img.play)
+          play_pause_desc:set { text = "Play" }
         end
       end),
       playback.position:bind(function(pos)
@@ -241,9 +249,19 @@ return screen:new {
       end),
       queue.random:bind(function(shuffling)
         theme.set_style(shuffle_img, shuffling and icon_enabled_class or icon_disabled_class)
+        if shuffling then
+          shuffle_desc:set { text = "Disable shuffle" }
+        else
+          shuffle_desc:set { text = "Enable shuffle" }
+        end
       end),
       queue.repeat_track:bind(function(en)
         theme.set_style(repeat_img, en and icon_enabled_class or icon_disabled_class)
+        if en then
+          repeat_desc:set { text = "Disable track repeat" }
+        else
+          repeat_desc:set { text = "Enable track repeat" }
+        end
       end),
       queue.size:bind(function(num)
         if not num then return end

lua/widgets.lua

@@ -10,21 +10,30 @@ local theme = require("theme")
 local screen = require("screen")
 
 local img = {
-    db = lvgl.ImgData("//lua/img/db.png"),
-    chg = lvgl.ImgData("//lua/img/bat/chg.png"),
-    bat_100 = lvgl.ImgData("//lua/img/bat/100.png"),
-    bat_80 = lvgl.ImgData("//lua/img/bat/80.png"),
-    bat_60 = lvgl.ImgData("//lua/img/bat/60.png"),
-    bat_40 = lvgl.ImgData("//lua/img/bat/40.png"),
-    bat_20 = lvgl.ImgData("//lua/img/bat/20.png"),
-    bat_0 = lvgl.ImgData("//lua/img/bat/0.png"),
-    bat_0chg = lvgl.ImgData("//lua/img/bat/0chg.png"),
-    bt_conn = lvgl.ImgData("//lua/assets/bt_conn.png"),
-    bt = lvgl.ImgData("//lua/assets/bt.png")
+  db = lvgl.ImgData("//lua/img/db.png"),
+  chg = lvgl.ImgData("//lua/img/bat/chg.png"),
+  bat_100 = lvgl.ImgData("//lua/img/bat/100.png"),
+  bat_80 = lvgl.ImgData("//lua/img/bat/80.png"),
+  bat_60 = lvgl.ImgData("//lua/img/bat/60.png"),
+  bat_40 = lvgl.ImgData("//lua/img/bat/40.png"),
+  bat_20 = lvgl.ImgData("//lua/img/bat/20.png"),
+  bat_0 = lvgl.ImgData("//lua/img/bat/0.png"),
+  bat_0chg = lvgl.ImgData("//lua/img/bat/0chg.png"),
+  bt_conn = lvgl.ImgData("//lua/assets/bt_conn.png"),
+  bt = lvgl.ImgData("//lua/assets/bt.png")
 }
 
 local widgets = {}
 
+function widgets.Description(obj, text)
+  local label = obj:Label {}
+  if text then
+    label:set { text = text }
+  end
+  label:add_flag(lvgl.FLAG.HIDDEN)
+  return label
+end
+
 widgets.MenuScreen = screen:new {
   show_back = false,
   title = "",
@@ -50,24 +59,24 @@ widgets.MenuScreen = screen:new {
 }
 
 function widgets.Row(parent, left, right)
-    local container = parent:Object{
-        flex = {
-            flex_direction = "row",
-            justify_content = "flex-start",
-            align_items = "flex-start",
-            align_content = "flex-start"
-        },
-        w = lvgl.PCT(100),
-        h = lvgl.SIZE_CONTENT
-    }
-    container:add_style(styles.list_item)
-    container:Label{
-        text = left,
-        flex_grow = 1
-    }
-    container:Label{
-        text = right
-    }
+  local container = parent:Object {
+    flex = {
+      flex_direction = "row",
+      justify_content = "flex-start",
+      align_items = "flex-start",
+      align_content = "flex-start"
+    },
+    w = lvgl.PCT(100),
+    h = lvgl.SIZE_CONTENT
+  }
+  container:add_style(styles.list_item)
+  container:Label {
+    text = left,
+    flex_grow = 1
+  }
+  container:Label {
+    text = right
+  }
 end
 
 local bindings_meta = {
@@ -102,7 +111,8 @@ function widgets.StatusBar(parent, opts)
       w = lvgl.SIZE_CONTENT,
       h = 12,
     }
-    back:Label({ text = "<", align = lvgl.ALIGN.CENTER })
+    local label = back:Label({ text = "<", align = lvgl.ALIGN.CENTER })
+    widgets.Description(label, "Back")
     back:onClicked(opts.back_cb)
   end
 
@@ -125,8 +135,8 @@ function widgets.StatusBar(parent, opts)
   local charge_icon = battery_icon:Image { src = img.chg }
   charge_icon:center()
 
-    local is_charging = nil
-    local percent = nil
+  local is_charging = nil
+  local percent = nil
 
   local function update_battery_icon()
     if is_charging == nil or percent == nil then return end
@@ -191,135 +201,138 @@ function widgets.StatusBar(parent, opts)
 end
 
 function widgets.IconBtn(parent, icon, text)
-    local btn = parent:Button{
-        flex = {
-            flex_direction = "row",
-            justify_content = "flex-start",
-            align_items = "center",
-            align_content = "center"
-        },
-        w = lvgl.SIZE_CONTENT,
-        h = lvgl.SIZE_CONTENT,
-        pad_top = 1,
-        pad_bottom = 1,
-        pad_left = 1,
-        pad_column = 1
-    }
-    btn:Image{
-        src = icon
-    }
-    btn:Label{
-        text = text,
-        text_font = font.fusion_10
-    }
-    return btn
+  local btn = parent:Button {
+    flex = {
+      flex_direction = "row",
+      justify_content = "flex-start",
+      align_items = "center",
+      align_content = "center"
+    },
+    w = lvgl.SIZE_CONTENT,
+    h = lvgl.SIZE_CONTENT,
+    pad_top = 1,
+    pad_bottom = 1,
+    pad_left = 1,
+    pad_column = 1
+  }
+  btn:Image {
+    src = icon
+  }
+  btn:Label {
+    text = text,
+    text_font = font.fusion_10
+  }
+  return btn
 end
 
 function widgets.InfiniteList(parent, iterator, opts)
-    local infinite_list = {}
+  local infinite_list = {}
 
-    infinite_list.root = lvgl.List(parent, {
-        w = lvgl.PCT(100),
-        h = lvgl.PCT(100),
-        flex_grow = 1,
-        scrollbar_mode = lvgl.SCROLLBAR_MODE.OFF
-    })
+  infinite_list.root = lvgl.List(parent, {
+    w = lvgl.PCT(100),
+    h = lvgl.PCT(100),
+    flex_grow = 1,
+    scrollbar_mode = lvgl.SCROLLBAR_MODE.OFF
+  })
 
-    local refreshing = false -- Used so that we can ignore focus events during this phase
-    local function refresh_group() 
-        refreshing = true
-        local group = lvgl.group.get_default()
-        local focused_obj = group:get_focused()
-        local num_children = infinite_list.root:get_child_cnt()
-        -- remove all children from the group and re-add them
-        for i = 0, num_children-1 do
-            lvgl.group.remove_obj(infinite_list.root:get_child(i))
-        end
-        for i = 0, num_children-1 do
-            group:add_obj(infinite_list.root:get_child(i))
-        end
-        if (focused_obj) then
-            lvgl.group.focus_obj(focused_obj)
-        end
-        refreshing = false
+  local refreshing = false -- Used so that we can ignore focus events during this phase
+  local function refresh_group()
+    refreshing = true
+    local group = lvgl.group.get_default()
+    local focused_obj = group:get_focused()
+    local num_children = infinite_list.root:get_child_cnt()
+    if (focused_obj) then
+      group:clear_focus()
+    end
+    -- remove all children from the group and re-add them
+    for i = 0, num_children - 1 do
+      lvgl.group.remove_obj(infinite_list.root:get_child(i))
+    end
+    for i = 0, num_children - 1 do
+      group:add_obj(infinite_list.root:get_child(i))
+    end
+    if (focused_obj) then
+      lvgl.group.focus_obj(focused_obj)
     end
+    refreshing = false
+  end
 
-    local fwd_iterator = iterator:clone()
-    local bck_iterator = iterator:clone()
+  local fwd_iterator = iterator:clone()
+  local bck_iterator = iterator:clone()
 
-    local last_selected = 0
-    local last_index = 0
-    local first_index = 0
+  local last_selected = 0
+  local last_index = 0
+  local first_index = 0
 
-    local function remove_top() 
-        local obj = infinite_list.root:get_child(0)
-        obj:delete()
-        first_index = first_index + 1
-        bck_iterator:next()
-    end
+  local function remove_top()
+    local obj = infinite_list.root:get_child(0)
+    obj:delete()
+    first_index = first_index + 1
+    bck_iterator:next()
+  end
 
-    local function remove_last() 
-        local obj = infinite_list.root:get_child(-1)
-        obj:delete()
-        last_index = last_index - 1
-        fwd_iterator:prev()
-    end
+  local function remove_last()
+    local obj = infinite_list.root:get_child(-1)
+    obj:delete()
+    last_index = last_index - 1
+    fwd_iterator:prev()
+  end
 
-    local function add_item(item, index)
-        if not item then
-            return
-        end
-        local this_item = index
-        local add_to_top = false
-        if this_item < first_index then 
-            first_index = this_item 
-            add_to_top = true
-        end
-        if this_item > last_index then last_index = index end
-        local btn = infinite_list.root:add_btn(nil, tostring(item))
-        if add_to_top then
-            btn:move_to_index(0)
-        end
-        -- opts.callback should take an item and return a function matching the arg of onClicked
-        if opts.callback then
-          btn:onClicked(opts.callback(item))
+  local function add_item(item, index)
+    if not item then
+      return
+    end
+    local this_item = index
+    local add_to_top = false
+    if this_item < first_index then
+      first_index = this_item
+      add_to_top = true
+    end
+    if this_item > last_index then last_index = index end
+    local btn = infinite_list.root:add_btn(nil, tostring(item))
+    if add_to_top then
+      btn:move_to_index(0)
+    end
+    -- opts.callback should take an item and return a function matching the arg of onClicked
+    if opts.callback then
+      btn:onClicked(opts.callback(item))
+    end
+    btn:onevent(lvgl.EVENT.FOCUSED, function()
+      if refreshing then return end
+      if this_item > last_selected and this_item - first_index > 3 then
+        -- moving forward
+        local to_add = fwd_iterator:next()
+        if to_add then
+          remove_top()
+          add_item(to_add, last_index + 1)
         end
-        btn:onevent(lvgl.EVENT.FOCUSED, function()
-          if refreshing then return end
-          if this_item > last_selected and this_item - first_index > 3 then
-            -- moving forward
-            local to_add = fwd_iterator:next()
-            if to_add then
-                remove_top()
-                add_item(to_add, last_index+1)
-            end
-          end
-          if this_item < last_selected then
-            -- moving backward
-            if (first_index > 0 and last_index - this_item > 3) then
-                local to_add = bck_iterator:prev();
-                if to_add then
-                  remove_last()
-                  add_item(to_add, first_index-1)
-                  refresh_group()
-                end
-            end
+      end
+      if this_item < last_selected then
+        -- moving backward
+        if (first_index > 0 and last_index - this_item > 3) then
+          local to_add = bck_iterator:prev();
+          if to_add then
+            remove_last()
+            add_item(to_add, first_index - 1)
+            refresh_group()
           end
-          last_selected = this_item
-        end)
-        btn:add_style(styles.list_item)
-        return btn
-    end
-
-    for idx = 0, 8 do
-        local val = fwd_iterator()
-        if not val then
-            break
         end
-        add_item(val, idx)
+      end
+      last_selected = this_item
+    end)
+    btn:add_style(styles.list_item)
+    return btn
+  end
+
+  for idx = 0, 8 do
+    local val = fwd_iterator()
+    if not val then
+      break
     end
+    add_item(val, idx)
+  end
 
-    return infinite_list
+  return infinite_list
 end
 
 return widgets

src/tangara/CMakeLists.txt

@@ -4,7 +4,7 @@
 
 idf_component_register(
   SRC_DIRS "app_console" "audio" "battery" "database" "dev_console" "events"
-  "input" "lua" "system_fsm" "ui"
+  "input" "lua" "system_fsm" "ui" "tts"
   INCLUDE_DIRS "."
   REQUIRES "codecs" "drivers" "locale" "memory" "tasks" "util" "graphics"
   "tinyfsm" "lvgl" "esp_timer" "luavgl" "esp_app_format" "libcppbor" "libtags"

src/tangara/input/device_factory.cpp

@@ -9,6 +9,7 @@
 #include <memory>
 
 #include "input/feedback_haptics.hpp"
+#include "input/feedback_tts.hpp"
 #include "input/input_device.hpp"
 #include "input/input_nav_buttons.hpp"
 #include "input/input_touch_dpad.hpp"
@@ -52,7 +53,10 @@ auto DeviceFactory::createInputs(drivers::NvsStorage::InputModes mode)
 
 auto DeviceFactory::createFeedbacks()
     -> std::vector<std::shared_ptr<IFeedbackDevice>> {
-  return {std::make_shared<Haptics>(services_->haptics())};
+  return {
+      std::make_shared<Haptics>(services_->haptics()),
+      std::make_shared<TextToSpeech>(services_->tts()),
+  };
 }
 
 }  // namespace input

src/tangara/input/feedback_device.hpp

@@ -7,6 +7,7 @@
 #pragma once
 
 #include <cstdint>
+#include "core/lv_group.h"
 
 namespace input {
 
@@ -23,7 +24,7 @@ class IFeedbackDevice {
  public:
   virtual ~IFeedbackDevice() {}
 
-  virtual auto feedback(uint8_t event_type) -> void = 0;
+  virtual auto feedback(lv_group_t* group, uint8_t event_type) -> void = 0;
 
   // TODO: Add configuration; likely the same shape of interface that
   // IInputDevice uses.

src/tangara/input/feedback_haptics.cpp

@@ -8,6 +8,7 @@
 
 #include <cstdint>
 
+#include "core/lv_group.h"
 #include "lvgl/lvgl.h"
 
 #include "core/lv_event.h"
@@ -21,7 +22,13 @@ using Effect = drivers::Haptics::Effect;
 
 Haptics::Haptics(drivers::Haptics& haptics_) : haptics_(haptics_) {}
 
-auto Haptics::feedback(uint8_t event_type) -> void {
+auto Haptics::feedback(lv_group_t* group, uint8_t event_type) -> void {
+  lv_obj_t* obj = lv_group_get_focused(group);
+  if (obj == last_selection_) {
+    return;
+  }
+  last_selection_ = obj;
+
   switch (event_type) {
     case LV_EVENT_FOCUSED:
       haptics_.PlayWaveformEffect(Effect::kMediumClick1_100Pct);

src/tangara/input/feedback_haptics.hpp

@@ -8,6 +8,8 @@
 
 #include <cstdint>
 
+#include "core/lv_obj.h"
+
 #include "drivers/haptics.hpp"
 #include "input/feedback_device.hpp"
 
@@ -17,10 +19,11 @@ class Haptics : public IFeedbackDevice {
  public:
   Haptics(drivers::Haptics& haptics_);
 
-  auto feedback(uint8_t event_type) -> void override;
+  auto feedback(lv_group_t*, uint8_t event_type) -> void override;
 
  private:
   drivers::Haptics& haptics_;
+  lv_obj_t* last_selection_;
 };
 
 }  // namespace input

src/tangara/input/feedback_tts.cpp

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "input/feedback_tts.hpp"
+
+#include <cstdint>
+#include <variant>
+
+#include "lvgl/lvgl.h"
+
+#include "core/lv_event.h"
+#include "core/lv_group.h"
+#include "core/lv_obj.h"
+#include "core/lv_obj_class.h"
+#include "core/lv_obj_tree.h"
+#include "extra/widgets/list/lv_list.h"
+#include "tts/events.hpp"
+#include "widgets/lv_label.h"
+
+#include "tts/events.hpp"
+#include "tts/provider.hpp"
+
+namespace input {
+
+TextToSpeech::TextToSpeech(tts::Provider& tts)
+    : tts_(tts), last_obj_(nullptr) {}
+
+auto TextToSpeech::feedback(lv_group_t* group, uint8_t event_type) -> void {
+  if (group != last_group_) {
+    last_group_ = group;
+    last_obj_ = nullptr;
+    if (group) {
+      tts_.feed(tts::SimpleEvent::kContextChanged);
+    }
+  }
+
+  if (group) {
+    lv_obj_t* focused = lv_group_get_focused(group);
+    if (focused == last_obj_) {
+      return;
+    }
+
+    last_obj_ = focused;
+    if (focused != nullptr) {
+      describe(*focused);
+    }
+  }
+}
+
+auto TextToSpeech::describe(lv_obj_t& obj) -> void {
+  if (lv_obj_check_type(&obj, &lv_btn_class) ||
+      lv_obj_check_type(&obj, &lv_list_btn_class)) {
+    auto desc = findDescription(obj);
+    tts_.feed(tts::SelectionChanged{
+        .new_selection =
+            tts::SelectionChanged::Selection{
+                .description = desc,
+                .is_interactive = true,
+            },
+    });
+  } else {
+    auto desc = findDescription(obj);
+    tts_.feed(tts::SelectionChanged{
+        .new_selection =
+            tts::SelectionChanged::Selection{
+                .description = desc,
+                .is_interactive = false,
+            },
+    });
+  }
+}
+
+auto TextToSpeech::findDescription(lv_obj_t& obj)
+    -> std::optional<std::string> {
+  if (lv_obj_get_child_cnt(&obj) > 0) {
+    for (size_t i = 0; i < lv_obj_get_child_cnt(&obj); i++) {
+      auto res = findDescription(*lv_obj_get_child(&obj, i));
+      if (res) {
+        return res;
+      }
+    }
+  }
+
+  if (lv_obj_check_type(&obj, &lv_label_class)) {
+    std::string text = lv_label_get_text(&obj);
+    if (!text.empty()) {
+      return text;
+    }
+  }
+
+  return {};
+}
+
+}  // namespace input

src/tangara/input/feedback_tts.hpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#pragma once
+
+#include <cstdint>
+
+#include "core/lv_obj.h"
+#include "drivers/haptics.hpp"
+
+#include "input/feedback_device.hpp"
+#include "tts/events.hpp"
+#include "tts/provider.hpp"
+
+namespace input {
+
+class TextToSpeech : public IFeedbackDevice {
+ public:
+  TextToSpeech(tts::Provider&);
+
+  auto feedback(lv_group_t*, uint8_t event_type) -> void override;
+
+ private:
+  tts::Provider& tts_;
+
+  auto describe(lv_obj_t&) -> void;
+  auto findDescription(lv_obj_t&) -> std::optional<std::string>;
+
+  lv_group_t* last_group_;
+  lv_obj_t* last_obj_;
+};
+
+}  // namespace input

src/tangara/input/lvgl_input_driver.cpp

@@ -10,6 +10,8 @@
 #include <memory>
 #include <variant>
 
+#include "core/lv_event.h"
+#include "core/lv_indev.h"
 #include "lua.hpp"
 #include "lvgl.h"
 
@@ -91,6 +93,16 @@ LvglInputDriver::LvglInputDriver(drivers::NvsStorage& nvs,
   registration_ = lv_indev_drv_register(&driver_);
 }
 
+auto LvglInputDriver::setGroup(lv_group_t* g) -> void {
+  if (!g) {
+    return;
+  }
+  lv_indev_set_group(registration_, g);
+  // Emit a synthetic 'focus' event for the current selection, since otherwise
+  // our feedback devices won't know that the selection changed.
+  feedback(LV_EVENT_FOCUSED);
+}
+
 auto LvglInputDriver::read(lv_indev_data_t* data) -> void {
   // TODO: we should pass lock state on to the individual devices, since they
   // may wish to either ignore the lock state, or power down until unlock.
@@ -107,7 +119,7 @@ auto LvglInputDriver::feedback(uint8_t event) -> void {
     return;
   }
   for (auto&& device : feedbacks_) {
-    device->feedback(event);
+    device->feedback(registration_->group, event);
   }
 }
 

src/tangara/input/lvgl_input_driver.hpp

@@ -17,12 +17,12 @@
 #include "input/device_factory.hpp"
 #include "input/feedback_device.hpp"
 
+#include "drivers/nvs.hpp"
+#include "drivers/touchwheel.hpp"
 #include "input/input_device.hpp"
 #include "input/input_hook.hpp"
 #include "lua/lua_thread.hpp"
 #include "lua/property.hpp"
-#include "drivers/nvs.hpp"
-#include "drivers/touchwheel.hpp"
 
 namespace input {
 
@@ -37,10 +37,10 @@ class LvglInputDriver {
 
   auto mode() -> lua::Property& { return mode_; }
 
+  auto setGroup(lv_group_t*) -> void;
   auto read(lv_indev_data_t* data) -> void;
   auto feedback(uint8_t) -> void;
 
-  auto registration() -> lv_indev_t* { return registration_; }
   auto lock(bool l) -> void { is_locked_ = l; }
 
   auto pushHooks(lua_State* L) -> int;

src/tangara/system_fsm/booting.cpp

@@ -38,6 +38,7 @@
 #include "system_fsm/service_locator.hpp"
 #include "system_fsm/system_events.hpp"
 #include "tasks.hpp"
+#include "tts/provider.hpp"
 #include "ui/ui_fsm.hpp"
 
 namespace system_fsm {
@@ -99,6 +100,7 @@ auto Booting::entry() -> void {
       std::make_unique<audio::TrackQueue>(sServices->bg_worker()));
   sServices->tag_parser(std::make_unique<database::TagParserImpl>());
   sServices->collator(locale::CreateCollator());
+  sServices->tts(std::make_unique<tts::Provider>());
 
   ESP_LOGI(kTag, "init bluetooth");
   sServices->bluetooth(std::make_unique<drivers::Bluetooth>(

src/tangara/system_fsm/service_locator.hpp

@@ -10,17 +10,18 @@
 
 #include "audio/track_queue.hpp"
 #include "battery/battery.hpp"
-#include "drivers/bluetooth.hpp"
 #include "collation.hpp"
 #include "database/database.hpp"
 #include "database/tag_parser.hpp"
+#include "drivers/bluetooth.hpp"
 #include "drivers/gpios.hpp"
 #include "drivers/haptics.hpp"
 #include "drivers/nvs.hpp"
 #include "drivers/samd.hpp"
 #include "drivers/storage.hpp"
-#include "tasks.hpp"
 #include "drivers/touchwheel.hpp"
+#include "tasks.hpp"
+#include "tts/provider.hpp"
 
 namespace system_fsm {
 
@@ -69,6 +70,13 @@ class ServiceLocator {
 
   auto battery(std::unique_ptr<battery::Battery> i) { battery_ = std::move(i); }
 
+  auto tts() -> tts::Provider& {
+    assert(tts_ != nullptr);
+    return *tts_;
+  }
+
+  auto tts(std::unique_ptr<tts::Provider> i) { tts_ = std::move(i); }
+
   auto touchwheel() -> std::optional<drivers::TouchWheel*> {
     if (!touchwheel_) {
       return {};
@@ -140,6 +148,7 @@ class ServiceLocator {
 
   std::unique_ptr<audio::TrackQueue> queue_;
   std::unique_ptr<battery::Battery> battery_;
+  std::unique_ptr<tts::Provider> tts_;
 
   std::shared_ptr<database::Database> database_;
   std::unique_ptr<database::ITagParser> tag_parser_;

src/tangara/tts/events.hpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#pragma once
+
+#include <optional>
+#include <string>
+#include <variant>
+
+namespace tts {
+
+/*
+ * 'Simple' TTS events are events that do not have any extra event-specific
+ * details.
+ */
+enum class SimpleEvent {
+  /*
+   * Indicates that the screen's content has substantially changed. e.g. a new
+   * screen has been pushed.
+   */
+  kContextChanged,
+};
+
+/*
+ * Event indicating that the currently selected LVGL object has changed.
+ */
+struct SelectionChanged {
+  struct Selection {
+    std::optional<std::string> description;
+    bool is_interactive;
+  };
+
+  std::optional<Selection> new_selection;
+};
+
+using Event = std::variant<SimpleEvent, SelectionChanged>;
+
+}  // namespace tts

src/tangara/tts/provider.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "tts/provider.hpp"
+
+#include <optional>
+#include <string>
+#include <variant>
+
+#include "esp_log.h"
+
+#include "tts/events.hpp"
+
+namespace tts {
+
+[[maybe_unused]] static constexpr char kTag[] = "tts";
+
+Provider::Provider() {}
+
+auto Provider::feed(const Event& e) -> void {
+  if (std::holds_alternative<SimpleEvent>(e)) {
+    // ESP_LOGI(kTag, "context changed");
+  } else if (std::holds_alternative<SelectionChanged>(e)) {
+    auto ev = std::get<SelectionChanged>(e);
+    if (!ev.new_selection) {
+      // ESP_LOGI(kTag, "no selection");
+    } else {
+      // ESP_LOGI(kTag, "new selection: '%s', interactive? %i",
+      // ev.new_selection->description.value_or("").c_str(),
+      // ev.new_selection->is_interactive);
+    }
+  }
+}
+
+}  // namespace tts

src/tangara/tts/provider.hpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#pragma once
+
+#include <optional>
+#include <string>
+#include <variant>
+
+#include "tts/events.hpp"
+
+namespace tts {
+
+class Provider {
+ public:
+  Provider();
+  auto feed(const Event&) -> void;
+};
+
+}  // namespace tts

src/tangara/ui/lvgl_task.cpp

@@ -68,14 +68,14 @@ auto UiTask::Main() -> void {
     if (screen != current_screen_ && screen != nullptr) {
       lv_scr_load(screen->root());
       if (input_) {
-        lv_indev_set_group(input_->registration(), screen->group());
+        input_->setGroup(screen->group());
       }
       current_screen_ = screen;
     }
 
     if (input_ && current_screen_->group() != current_group) {
       current_group = current_screen_->group();
-      lv_indev_set_group(input_->registration(), current_group);
+      input_->setGroup(current_group);
     }
 
     TickType_t delay = lv_timer_handler();