Show a confirmed shutdown screen before cutting power

Tactility/Include/Tactility/hal/display/DisplayDevice.h

@@ -29,6 +29,14 @@ class DisplayDevice : public Device {
     /** For e-paper screens */
     virtual void requestFullRefresh() {}
 
+    /** Blocks until any frame already handed to this display has physically
+     * finished drawing. Displays that draw synchronously within their flush
+     * callback can rely on the default no-op; displays with an asynchronous
+     * refresh pipeline (e.g. e-paper, where a full refresh can take seconds)
+     * should override this so callers can safely do something irreversible
+     * (like cutting power) right after a screen update. */
+    virtual void waitForFlushComplete() {}
+
     /** Could return nullptr if not started */
     virtual std::shared_ptr<touch::TouchDevice> getTouchDevice() = 0;
 

Tactility/Source/Tactility.cpp

@@ -103,6 +103,7 @@ namespace app {
     namespace localesettings { extern const AppManifest manifest; }
     namespace notes { extern const AppManifest manifest; }
     namespace power { extern const AppManifest manifest; }
+    namespace poweroff { extern const AppManifest manifest; }
     namespace selectiondialog { extern const AppManifest manifest; }
     namespace settings { extern const AppManifest manifest; }
     namespace setup { extern const AppManifest manifest; }
@@ -157,6 +158,7 @@ static void registerInternalApps() {
     addAppManifest(app::launcher::manifest);
     addAppManifest(app::localesettings::manifest);
     addAppManifest(app::notes::manifest);
+    addAppManifest(app::poweroff::manifest);
     addAppManifest(app::settings::manifest);
     addAppManifest(app::selectiondialog::manifest);
     addAppManifest(app::setup::manifest);

Tactility/Source/app/launcher/Launcher.cpp

@@ -66,6 +66,11 @@ class LauncherApp final : public App {
         return apps_button;
     }
 
+    static void onAppPressed(lv_event_t* e) {
+        auto* appId = static_cast<const char*>(lv_event_get_user_data(e));
+        start(appId);
+    }
+
     static bool shouldShowPowerButton() {
         bool show_power_button = false;
         hal::findDevices<hal::power::PowerDevice>(hal::Device::Type::Power, [&show_power_button](const auto& device) {
@@ -79,18 +84,6 @@ class LauncherApp final : public App {
         return show_power_button;
     }
 
-    static void onAppPressed(lv_event_t* e) {
-        auto* appId = static_cast<const char*>(lv_event_get_user_data(e));
-        start(appId);
-    }
-
-    static void onPowerOffPressed(lv_event_t* e) {
-        auto power = hal::findFirstDevice<hal::power::PowerDevice>(hal::Device::Type::Power);
-        if (power != nullptr && power->supportsPowerOff()) {
-            power->powerOff();
-        }
-    }
-
     // The screen object outlives the launcher's views (it's recreated by GuiService::redraw()
     // via lv_obj_clean() on every app switch), so the LV_EVENT_SIZE_CHANGED callback registered
     // on it must be removed once buttons_wrapper is destroyed, to avoid a dangling user-data
@@ -202,11 +195,13 @@ class LauncherApp final : public App {
         lv_obj_add_event_cb(lv_obj_get_screen(parent), onButtonsWrapperResized, LV_EVENT_SIZE_CHANGED, buttons_wrapper);
         lv_obj_add_event_cb(buttons_wrapper, onButtonsWrapperDeleted, LV_EVENT_DELETE, nullptr);
 
+        // Some devices (e.g. T-Lora Pager) have no other way to power off, so the
+        // button stays in the launcher; the confirmation flow lives in the PowerOff app.
         if (shouldShowPowerButton()) {
             auto* power_button = lv_button_create(parent);
             lv_obj_set_style_pad_all(power_button, 8, 0);
             lv_obj_align(power_button, LV_ALIGN_BOTTOM_MID, 0, -10);
-            lv_obj_add_event_cb(power_button, onPowerOffPressed, LV_EVENT_SHORT_CLICKED, nullptr);
+            lv_obj_add_event_cb(power_button, onAppPressed, LV_EVENT_SHORT_CLICKED, (void*)"PowerOff");
             lv_obj_set_style_shadow_width(power_button, 0, LV_STATE_DEFAULT);
             lv_obj_set_style_bg_opa(power_button, 0, LV_PART_MAIN);
 

Tactility/Source/app/poweroff/PowerOff.cpp

@@ -0,0 +1,104 @@
+#include <Tactility/app/AppContext.h>
+#include <Tactility/app/AppRegistration.h>
+#include <Tactility/hal/display/DisplayDevice.h>
+#include <Tactility/hal/power/PowerDevice.h>
+#include <Tactility/service/loader/Loader.h>
+
+#include <lvgl.h>
+#include <tactility/hal/Device.h>
+#include <tactility/lvgl_fonts.h>
+#include <tactility/lvgl_icon_shared.h>
+
+namespace tt::app::poweroff {
+
+extern const AppManifest manifest;
+
+class PowerOffApp final : public App {
+
+    /** Replaces the screen with a plain "powered off" message, forces it to draw
+     * synchronously, and waits for the display to confirm the draw physically
+     * finished. On e-paper this is what's left showing once power cuts, so it
+     * doubles as visual confirmation that the device shut down cleanly rather
+     * than crashed or hung. Called from an LVGL button click callback, so it's
+     * already running on the LVGL thread. */
+    static void showPoweredOffScreenAndWait(hal::display::DisplayDevice* display) {
+        auto* screen = lv_obj_create(nullptr);
+        lv_obj_set_style_bg_color(screen, lv_color_white(), 0);
+        lv_obj_set_flex_flow(screen, LV_FLEX_FLOW_COLUMN);
+        lv_obj_set_flex_align(screen, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+
+        auto* title = lv_label_create(screen);
+        lv_label_set_text(title, "Tactility OS");
+        lv_obj_set_style_text_font(title, lvgl_get_text_font(FONT_SIZE_LARGE), 0);
+        lv_obj_set_style_text_color(title, lv_color_black(), 0);
+
+        auto* subtitle = lv_label_create(screen);
+        lv_label_set_text(subtitle, "Powered off");
+        lv_obj_set_style_text_color(subtitle, lv_color_black(), 0);
+
+        lv_screen_load(screen);
+
+        if (display != nullptr) {
+            auto* lvgl_display = display->getLvglDisplay();
+            if (lvgl_display != nullptr) {
+                lv_refr_now(lvgl_display);
+            }
+            display->waitForFlushComplete();
+        }
+    }
+
+    static void onYesPressed(lv_event_t* /*event*/) {
+        auto power = hal::findFirstDevice<hal::power::PowerDevice>(hal::Device::Type::Power);
+        if (power == nullptr || !power->supportsPowerOff()) {
+            return;
+        }
+
+        auto display = hal::findFirstDevice<hal::display::DisplayDevice>(hal::Device::Type::Display);
+        showPoweredOffScreenAndWait(display.get());
+
+        power->powerOff();
+    }
+
+    static void onNoPressed(lv_event_t* /*event*/) {
+        stop(manifest.appId);
+    }
+
+public:
+
+    void onShow(AppContext& /*app*/, lv_obj_t* parent) override {
+        lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
+        lv_obj_set_flex_align(parent, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+
+        auto* label = lv_label_create(parent);
+        lv_label_set_text(label, "Power off?");
+        lv_obj_set_style_text_font(label, lvgl_get_text_font(FONT_SIZE_LARGE), 0);
+
+        auto* button_wrapper = lv_obj_create(parent);
+        lv_obj_set_flex_flow(button_wrapper, LV_FLEX_FLOW_ROW);
+        lv_obj_set_size(button_wrapper, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
+        lv_obj_set_style_pad_all(button_wrapper, 0, 0);
+        lv_obj_set_style_border_width(button_wrapper, 0, 0);
+        lv_obj_set_flex_align(button_wrapper, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+
+        auto* yes_button = lv_button_create(button_wrapper);
+        auto* yes_label = lv_label_create(yes_button);
+        lv_label_set_text(yes_label, "Yes");
+        lv_obj_add_event_cb(yes_button, onYesPressed, LV_EVENT_SHORT_CLICKED, nullptr);
+
+        auto* no_button = lv_button_create(button_wrapper);
+        auto* no_label = lv_label_create(no_button);
+        lv_label_set_text(no_label, "No");
+        lv_obj_add_event_cb(no_button, onNoPressed, LV_EVENT_SHORT_CLICKED, nullptr);
+    }
+};
+
+extern const AppManifest manifest = {
+    .appId = "PowerOff",
+    .appName = "Power Off",
+    .appIcon = LVGL_ICON_SHARED_POWER_SETTINGS_NEW,
+    .appCategory = Category::Settings,
+    .appFlags = AppManifest::Flags::HideStatusBar,
+    .createApp = create<PowerOffApp>
+};
+
+} // namespace