mod: adapt mod activities to #774 render() pattern

Migrate 5 mod Activity subclasses from old polling-based
display task pattern to the upstream render() super-class
pattern with freeRTOS notification:

- EpubReaderBookmarkSelectionActivity
- DictionaryWordSelectActivity
- DictionarySuggestionsActivity
- DictionaryDefinitionActivity
- LookedUpWordsActivity

Changes: remove own TaskHandle/SemaphoreHandle/updateRequired,
use requestUpdate() + render(RenderLock&&) override, fix
potential deadlocks around enterNewActivity() calls.

Also fix stale conflict marker in EpubReaderMenuActivity.h.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/activities/reader/DictionaryDefinitionActivity.cpp

@@ -11,40 +11,14 @@
 #include "components/UITheme.h"
 #include "fontIds.h"
 
-void DictionaryDefinitionActivity::taskTrampoline(void* param) {
-  auto* self = static_cast<DictionaryDefinitionActivity*>(param);
-  self->displayTaskLoop();
-}
-
-void DictionaryDefinitionActivity::displayTaskLoop() {
-  while (true) {
-    if (updateRequired) {
-      updateRequired = false;
-      xSemaphoreTake(renderingMutex, portMAX_DELAY);
-      renderScreen();
-      xSemaphoreGive(renderingMutex);
-    }
-    vTaskDelay(10 / portTICK_PERIOD_MS);
-  }
-}
-
 void DictionaryDefinitionActivity::onEnter() {
   Activity::onEnter();
-  renderingMutex = xSemaphoreCreateMutex();
   wrapText();
-  updateRequired = true;
+  requestUpdate();
-  xTaskCreate(&DictionaryDefinitionActivity::taskTrampoline, "DictDefTask", 4096, this, 1, &displayTaskHandle);
 }
 
 void DictionaryDefinitionActivity::onExit() {
   Activity::onExit();
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  if (displayTaskHandle) {
-    vTaskDelete(displayTaskHandle);
-    displayTaskHandle = nullptr;
-  }
-  vSemaphoreDelete(renderingMutex);
-  renderingMutex = nullptr;
 }
 
 // ---------------------------------------------------------------------------
@@ -442,12 +416,12 @@ void DictionaryDefinitionActivity::loop() {
 
   if (prevPage && currentPage > 0) {
     currentPage--;
-    updateRequired = true;
+    requestUpdate();
   }
 
   if (nextPage && currentPage < totalPages - 1) {
     currentPage++;
-    updateRequired = true;
+    requestUpdate();
   }
 
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
@@ -465,7 +439,7 @@ void DictionaryDefinitionActivity::loop() {
   }
 }
 
-void DictionaryDefinitionActivity::renderScreen() {
+void DictionaryDefinitionActivity::render(Activity::RenderLock&&) {
   renderer.clearScreen();
 
   const bool landscape = orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW ||

src/activities/reader/DictionaryDefinitionActivity.h

@@ -1,8 +1,5 @@
 #pragma once
 #include <EpdFontFamily.h>
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
-#include <freertos/task.h>
 
 #include <functional>
 #include <string>
@@ -27,6 +24,7 @@ class DictionaryDefinitionActivity final : public Activity {
   void onEnter() override;
   void onExit() override;
   void loop() override;
+  void render(Activity::RenderLock&&) override;
 
  private:
   // A positioned text segment within a wrapped line (pre-calculated x offset and style).
@@ -61,17 +59,10 @@ class DictionaryDefinitionActivity final : public Activity {
   int currentPage = 0;
   int linesPerPage = 0;
   int totalPages = 0;
-  bool updateRequired = false;
   bool firstRender = true;
 
-  TaskHandle_t displayTaskHandle = nullptr;
-  SemaphoreHandle_t renderingMutex = nullptr;
-
   std::vector<TextAtom> parseHtml(const std::string& html);
   static std::string decodeEntity(const std::string& entity);
   static bool isRenderableCodepoint(uint32_t cp);
   void wrapText();
-  void renderScreen();
-  static void taskTrampoline(void* param);
-  [[noreturn]] void displayTaskLoop();
 };

src/activities/reader/DictionarySuggestionsActivity.cpp

@@ -8,39 +8,13 @@
 #include "fontIds.h"
 #include "util/Dictionary.h"
 
-void DictionarySuggestionsActivity::taskTrampoline(void* param) {
-  auto* self = static_cast<DictionarySuggestionsActivity*>(param);
-  self->displayTaskLoop();
-}
-
-void DictionarySuggestionsActivity::displayTaskLoop() {
-  while (true) {
-    if (updateRequired && !subActivity) {
-      updateRequired = false;
-      xSemaphoreTake(renderingMutex, portMAX_DELAY);
-      renderScreen();
-      xSemaphoreGive(renderingMutex);
-    }
-    vTaskDelay(10 / portTICK_PERIOD_MS);
-  }
-}
-
 void DictionarySuggestionsActivity::onEnter() {
   ActivityWithSubactivity::onEnter();
-  renderingMutex = xSemaphoreCreateMutex();
+  requestUpdate();
-  updateRequired = true;
-  xTaskCreate(&DictionarySuggestionsActivity::taskTrampoline, "DictSugTask", 4096, this, 1, &displayTaskHandle);
 }
 
 void DictionarySuggestionsActivity::onExit() {
   ActivityWithSubactivity::onExit();
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  if (displayTaskHandle) {
-    vTaskDelete(displayTaskHandle);
-    displayTaskHandle = nullptr;
-  }
-  vSemaphoreDelete(renderingMutex);
-  renderingMutex = nullptr;
 }
 
 void DictionarySuggestionsActivity::loop() {
@@ -49,7 +23,7 @@ void DictionarySuggestionsActivity::loop() {
     if (pendingBackFromDef) {
       pendingBackFromDef = false;
       exitActivity();
-      updateRequired = true;
+      requestUpdate();
     }
     if (pendingExitToReader) {
       pendingExitToReader = false;
@@ -68,12 +42,12 @@ void DictionarySuggestionsActivity::loop() {
 
   buttonNavigator.onNext([this] {
     selectedIndex = ButtonNavigator::nextIndex(selectedIndex, static_cast<int>(suggestions.size()));
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onPrevious([this] {
     selectedIndex = ButtonNavigator::previousIndex(selectedIndex, static_cast<int>(suggestions.size()));
-    updateRequired = true;
+    requestUpdate();
   });
 
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
@@ -81,10 +55,13 @@ void DictionarySuggestionsActivity::loop() {
     std::string definition = Dictionary::lookup(selected);
 
     if (definition.empty()) {
-      GUI.drawPopup(renderer, "Not found");
+      {
-      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+        Activity::RenderLock lock(*this);
+        GUI.drawPopup(renderer, "Not found");
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      }
       vTaskDelay(1000 / portTICK_PERIOD_MS);
-      updateRequired = true;
+      requestUpdate();
       return;
     }
 
@@ -100,7 +77,7 @@ void DictionarySuggestionsActivity::loop() {
   }
 }
 
-void DictionarySuggestionsActivity::renderScreen() {
+void DictionarySuggestionsActivity::render(Activity::RenderLock&&) {
   renderer.clearScreen();
 
   const auto orient = renderer.getOrientation();

src/activities/reader/DictionarySuggestionsActivity.h

@@ -1,8 +1,4 @@
 #pragma once
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
-#include <freertos/task.h>
-
 #include <functional>
 #include <string>
 #include <vector>
@@ -28,6 +24,7 @@ class DictionarySuggestionsActivity final : public ActivityWithSubactivity {
   void onEnter() override;
   void onExit() override;
   void loop() override;
+  void render(Activity::RenderLock&&) override;
 
  private:
   std::string originalWord;
@@ -39,15 +36,7 @@ class DictionarySuggestionsActivity final : public ActivityWithSubactivity {
   const std::function<void()> onDone;
 
   int selectedIndex = 0;
-  bool updateRequired = false;
   bool pendingBackFromDef = false;
   bool pendingExitToReader = false;
   ButtonNavigator buttonNavigator;
-
-  TaskHandle_t displayTaskHandle = nullptr;
-  SemaphoreHandle_t renderingMutex = nullptr;
-
-  void renderScreen();
-  static void taskTrampoline(void* param);
-  [[noreturn]] void displayTaskLoop();
 };

src/activities/reader/DictionaryWordSelectActivity.cpp

@@ -14,45 +14,19 @@
 #include "util/Dictionary.h"
 #include "util/LookupHistory.h"
 
-void DictionaryWordSelectActivity::taskTrampoline(void* param) {
-  auto* self = static_cast<DictionaryWordSelectActivity*>(param);
-  self->displayTaskLoop();
-}
-
-void DictionaryWordSelectActivity::displayTaskLoop() {
-  while (true) {
-    if (updateRequired && !subActivity) {
-      updateRequired = false;
-      xSemaphoreTake(renderingMutex, portMAX_DELAY);
-      renderScreen();
-      xSemaphoreGive(renderingMutex);
-    }
-    vTaskDelay(10 / portTICK_PERIOD_MS);
-  }
-}
-
 void DictionaryWordSelectActivity::onEnter() {
   ActivityWithSubactivity::onEnter();
-  renderingMutex = xSemaphoreCreateMutex();
   extractWords();
   mergeHyphenatedWords();
   if (!rows.empty()) {
     currentRow = static_cast<int>(rows.size()) / 3;
     currentWordInRow = 0;
   }
-  updateRequired = true;
+  requestUpdate();
-  xTaskCreate(&DictionaryWordSelectActivity::taskTrampoline, "DictWordSelTask", 4096, this, 1, &displayTaskHandle);
 }
 
 void DictionaryWordSelectActivity::onExit() {
   ActivityWithSubactivity::onExit();
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  if (displayTaskHandle) {
-    vTaskDelete(displayTaskHandle);
-    displayTaskHandle = nullptr;
-  }
-  vSemaphoreDelete(renderingMutex);
-  renderingMutex = nullptr;
 }
 
 bool DictionaryWordSelectActivity::isLandscape() const {
@@ -231,7 +205,7 @@ void DictionaryWordSelectActivity::loop() {
     if (pendingBackFromDef) {
       pendingBackFromDef = false;
       exitActivity();
-      updateRequired = true;
+      requestUpdate();
     }
     if (pendingExitToReader) {
       pendingExitToReader = false;
@@ -353,25 +327,28 @@ void DictionaryWordSelectActivity::loop() {
     std::string cleaned = Dictionary::cleanWord(rawWord);
 
     if (cleaned.empty()) {
-      GUI.drawPopup(renderer, "No word");
+      {
-      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+        Activity::RenderLock lock(*this);
+        GUI.drawPopup(renderer, "No word");
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      }
       vTaskDelay(1000 / portTICK_PERIOD_MS);
-      updateRequired = true;
+      requestUpdate();
       return;
     }
 
-    // Show looking up popup, then release mutex so display task can run
+    Rect popupLayout;
-    xSemaphoreTake(renderingMutex, portMAX_DELAY);
+    {
-    Rect popupLayout = GUI.drawPopup(renderer, "Looking up...");
+      Activity::RenderLock lock(*this);
-    xSemaphoreGive(renderingMutex);
+      popupLayout = GUI.drawPopup(renderer, "Looking up...");
+    }
 
     bool cancelled = false;
     std::string definition = Dictionary::lookup(
         cleaned,
         [this, &popupLayout](int percent) {
-          xSemaphoreTake(renderingMutex, portMAX_DELAY);
+          Activity::RenderLock lock(*this);
           GUI.fillPopupProgress(renderer, popupLayout, percent);
-          xSemaphoreGive(renderingMutex);
         },
         [this, &cancelled]() -> bool {
           mappedInput.update();
@@ -383,7 +360,7 @@ void DictionaryWordSelectActivity::loop() {
         });
 
     if (cancelled) {
-      updateRequired = true;
+      requestUpdate();
       return;
     }
 
@@ -417,10 +394,13 @@ void DictionaryWordSelectActivity::loop() {
       return;
     }
 
-    GUI.drawPopup(renderer, "Not found");
+    {
-    renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      Activity::RenderLock lock(*this);
+      GUI.drawPopup(renderer, "Not found");
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+    }
     vTaskDelay(1500 / portTICK_PERIOD_MS);
-    updateRequired = true;
+    requestUpdate();
     return;
   }
 
@@ -430,11 +410,11 @@ void DictionaryWordSelectActivity::loop() {
   }
 
   if (changed) {
-    updateRequired = true;
+    requestUpdate();
   }
 }
 
-void DictionaryWordSelectActivity::renderScreen() {
+void DictionaryWordSelectActivity::render(Activity::RenderLock&&) {
   renderer.clearScreen();
 
   // Render the page content

src/activities/reader/DictionaryWordSelectActivity.h

@@ -1,8 +1,5 @@
 #pragma once
 #include <Epub/Page.h>
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
-#include <freertos/task.h>
 
 #include <functional>
 #include <memory>
@@ -31,6 +28,7 @@ class DictionaryWordSelectActivity final : public ActivityWithSubactivity {
   void onEnter() override;
   void onExit() override;
   void loop() override;
+  void render(Activity::RenderLock&&) override;
 
  private:
   struct WordInfo {
@@ -64,19 +62,12 @@ class DictionaryWordSelectActivity final : public ActivityWithSubactivity {
   std::vector<Row> rows;
   int currentRow = 0;
   int currentWordInRow = 0;
-  bool updateRequired = false;
   bool pendingBackFromDef = false;
   bool pendingExitToReader = false;
 
-  TaskHandle_t displayTaskHandle = nullptr;
-  SemaphoreHandle_t renderingMutex = nullptr;
-
   bool isLandscape() const;
   bool isInverted() const;
   void extractWords();
   void mergeHyphenatedWords();
-  void renderScreen();
   void drawHints();
-  static void taskTrampoline(void* param);
-  [[noreturn]] void displayTaskLoop();
 };

src/activities/reader/EpubReaderBookmarkSelectionActivity.cpp

@@ -42,36 +42,13 @@ std::string EpubReaderBookmarkSelectionActivity::getPageSuffix(const Bookmark& b
   return " - Page " + std::to_string(bookmark.pageNumber + 1);
 }
 
-void EpubReaderBookmarkSelectionActivity::taskTrampoline(void* param) {
-  auto* self = static_cast<EpubReaderBookmarkSelectionActivity*>(param);
-  self->displayTaskLoop();
-}
-
 void EpubReaderBookmarkSelectionActivity::onEnter() {
   ActivityWithSubactivity::onEnter();
-
+  requestUpdate();
-  renderingMutex = xSemaphoreCreateMutex();
-
-  // Trigger first update
-  updateRequired = true;
-  xTaskCreate(&EpubReaderBookmarkSelectionActivity::taskTrampoline, "BookmarkSelTask",
-              4096,               // Stack size
-              this,               // Parameters
-              1,                  // Priority
-              &displayTaskHandle  // Task handle
-  );
 }
 
 void EpubReaderBookmarkSelectionActivity::onExit() {
   ActivityWithSubactivity::onExit();
-
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  if (displayTaskHandle) {
-    vTaskDelete(displayTaskHandle);
-    displayTaskHandle = nullptr;
-  }
-  vSemaphoreDelete(renderingMutex);
-  renderingMutex = nullptr;
 }
 
 void EpubReaderBookmarkSelectionActivity::loop() {
@@ -83,7 +60,6 @@ void EpubReaderBookmarkSelectionActivity::loop() {
   const int totalItems = getTotalItems();
 
   if (totalItems == 0) {
-    // All bookmarks deleted, go back
     if (mappedInput.wasReleased(MappedInputManager::Button::Back) ||
         mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
       onGoBack();
@@ -91,14 +67,11 @@ void EpubReaderBookmarkSelectionActivity::loop() {
     return;
   }
 
-  // Delete confirmation mode: wait for confirm (delete) or back (cancel)
   if (deleteConfirmMode) {
     if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
       if (ignoreNextConfirmRelease) {
-        // Ignore the release from the initial long press
         ignoreNextConfirmRelease = false;
       } else {
-        // Confirm delete
         BookmarkStore::removeBookmark(cachePath, bookmarks[pendingDeleteIndex].spineIndex,
                                       bookmarks[pendingDeleteIndex].pageNumber);
         bookmarks.erase(bookmarks.begin() + pendingDeleteIndex);
@@ -106,25 +79,24 @@ void EpubReaderBookmarkSelectionActivity::loop() {
           selectorIndex = std::max(0, static_cast<int>(bookmarks.size()) - 1);
         }
         deleteConfirmMode = false;
-        updateRequired = true;
+        requestUpdate();
       }
     }
     if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
       deleteConfirmMode = false;
       ignoreNextConfirmRelease = false;
-      updateRequired = true;
+      requestUpdate();
     }
     return;
   }
 
-  // Detect long press on Confirm to trigger delete
   constexpr unsigned long DELETE_HOLD_MS = 700;
   if (mappedInput.isPressed(MappedInputManager::Button::Confirm) && mappedInput.getHeldTime() >= DELETE_HOLD_MS) {
     if (totalItems > 0 && selectorIndex >= 0 && selectorIndex < totalItems) {
       deleteConfirmMode = true;
       ignoreNextConfirmRelease = true;
       pendingDeleteIndex = selectorIndex;
-      updateRequired = true;
+      requestUpdate();
     }
     return;
   }
@@ -144,38 +116,26 @@ void EpubReaderBookmarkSelectionActivity::loop() {
 
   buttonNavigator.onNextRelease([this, totalItems] {
     selectorIndex = ButtonNavigator::nextIndex(selectorIndex, totalItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onPreviousRelease([this, totalItems] {
     selectorIndex = ButtonNavigator::previousIndex(selectorIndex, totalItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onNextContinuous([this, totalItems, pageItems] {
     selectorIndex = ButtonNavigator::nextPageIndex(selectorIndex, totalItems, pageItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onPreviousContinuous([this, totalItems, pageItems] {
     selectorIndex = ButtonNavigator::previousPageIndex(selectorIndex, totalItems, pageItems);
-    updateRequired = true;
+    requestUpdate();
   });
 }
 
-void EpubReaderBookmarkSelectionActivity::displayTaskLoop() {
+void EpubReaderBookmarkSelectionActivity::render(Activity::RenderLock&&) {
-  while (true) {
-    if (updateRequired && !subActivity) {
-      updateRequired = false;
-      xSemaphoreTake(renderingMutex, portMAX_DELAY);
-      renderScreen();
-      xSemaphoreGive(renderingMutex);
-    }
-    vTaskDelay(10 / portTICK_PERIOD_MS);
-  }
-}
-
-void EpubReaderBookmarkSelectionActivity::renderScreen() {
   renderer.clearScreen();
 
   const auto pageWidth = renderer.getScreenWidth();
@@ -191,7 +151,6 @@ void EpubReaderBookmarkSelectionActivity::renderScreen() {
   const int pageItems = getPageItems();
   const int totalItems = getTotalItems();
 
-  // Title
   const int titleX =
       contentX + (contentWidth - renderer.getTextWidth(UI_12_FONT_ID, "Go to Bookmark", EpdFontFamily::BOLD)) / 2;
   renderer.drawText(UI_12_FONT_ID, titleX, 15 + contentY, "Go to Bookmark", true, EpdFontFamily::BOLD);
@@ -213,7 +172,6 @@ void EpubReaderBookmarkSelectionActivity::renderScreen() {
       const std::string suffix = getPageSuffix(bookmarks[itemIndex]);
       const int suffixWidth = renderer.getTextWidth(UI_10_FONT_ID, suffix.c_str());
 
-      // Truncate the prefix (chapter + snippet) to leave room for the page suffix
       const std::string prefix = getBookmarkPrefix(bookmarks[itemIndex]);
       const std::string truncatedPrefix =
           renderer.truncatedText(UI_10_FONT_ID, prefix.c_str(), maxLabelWidth - suffixWidth);
@@ -225,7 +183,6 @@ void EpubReaderBookmarkSelectionActivity::renderScreen() {
   }
 
   if (deleteConfirmMode && pendingDeleteIndex < static_cast<int>(bookmarks.size())) {
-    // Draw delete confirmation overlay
     const std::string suffix = getPageSuffix(bookmarks[pendingDeleteIndex]);
     std::string msg = "Delete bookmark" + suffix + "?";
 

src/activities/reader/EpubReaderBookmarkSelectionActivity.h

@@ -1,8 +1,5 @@
 #pragma once
 #include <Epub.h>
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
-#include <freertos/task.h>
 
 #include <memory>
 #include <vector>
@@ -15,32 +12,19 @@ class EpubReaderBookmarkSelectionActivity final : public ActivityWithSubactivity
   std::shared_ptr<Epub> epub;
   std::vector<Bookmark> bookmarks;
   std::string cachePath;
-  TaskHandle_t displayTaskHandle = nullptr;
-  SemaphoreHandle_t renderingMutex = nullptr;
   ButtonNavigator buttonNavigator;
   int selectorIndex = 0;
-  bool updateRequired = false;
   bool deleteConfirmMode = false;
   bool ignoreNextConfirmRelease = false;
   int pendingDeleteIndex = 0;
   const std::function<void()> onGoBack;
   const std::function<void(int newSpineIndex, int newPage)> onSelectBookmark;
 
-  // Number of items that fit on a page, derived from logical screen height.
   int getPageItems() const;
-
   int getTotalItems() const;
-
-  // Build the prefix portion of a bookmark label (chapter + snippet, without page suffix)
   std::string getBookmarkPrefix(const Bookmark& bookmark) const;
-
-  // Build the page suffix (e.g. " - Page 5")
   static std::string getPageSuffix(const Bookmark& bookmark);
 
-  static void taskTrampoline(void* param);
-  [[noreturn]] void displayTaskLoop();
-  void renderScreen();
-
  public:
   explicit EpubReaderBookmarkSelectionActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                                                const std::shared_ptr<Epub>& epub,
@@ -57,4 +41,5 @@ class EpubReaderBookmarkSelectionActivity final : public ActivityWithSubactivity
   void onEnter() override;
   void onExit() override;
   void loop() override;
+  void render(Activity::RenderLock&&) override;
 };

src/activities/reader/EpubReaderMenuActivity.h

@@ -82,7 +82,6 @@ class EpubReaderMenuActivity final : public ActivityWithSubactivity {
 
   const std::function<void(uint8_t)> onBack;
   const std::function<void(MenuAction)> onAction;
-<<<<<<< HEAD
 
   // Map the internal override value to an index into letterboxFillLabels.
   int letterboxFillToIndex() const {

src/activities/reader/LookedUpWordsActivity.cpp

@@ -12,41 +12,15 @@
 #include "util/Dictionary.h"
 #include "util/LookupHistory.h"
 
-void LookedUpWordsActivity::taskTrampoline(void* param) {
-  auto* self = static_cast<LookedUpWordsActivity*>(param);
-  self->displayTaskLoop();
-}
-
-void LookedUpWordsActivity::displayTaskLoop() {
-  while (true) {
-    if (updateRequired && !subActivity) {
-      updateRequired = false;
-      xSemaphoreTake(renderingMutex, portMAX_DELAY);
-      renderScreen();
-      xSemaphoreGive(renderingMutex);
-    }
-    vTaskDelay(10 / portTICK_PERIOD_MS);
-  }
-}
-
 void LookedUpWordsActivity::onEnter() {
   ActivityWithSubactivity::onEnter();
-  renderingMutex = xSemaphoreCreateMutex();
   words = LookupHistory::load(cachePath);
   std::reverse(words.begin(), words.end());
-  updateRequired = true;
+  requestUpdate();
-  xTaskCreate(&LookedUpWordsActivity::taskTrampoline, "LookedUpTask", 4096, this, 1, &displayTaskHandle);
 }
 
 void LookedUpWordsActivity::onExit() {
   ActivityWithSubactivity::onExit();
-  xSemaphoreTake(renderingMutex, portMAX_DELAY);
-  if (displayTaskHandle) {
-    vTaskDelete(displayTaskHandle);
-    displayTaskHandle = nullptr;
-  }
-  vSemaphoreDelete(renderingMutex);
-  renderingMutex = nullptr;
 }
 
 void LookedUpWordsActivity::loop() {
@@ -55,7 +29,7 @@ void LookedUpWordsActivity::loop() {
     if (pendingBackFromDef) {
       pendingBackFromDef = false;
       exitActivity();
-      updateRequired = true;
+      requestUpdate();
     }
     if (pendingExitToReader) {
       pendingExitToReader = false;
@@ -87,13 +61,13 @@ void LookedUpWordsActivity::loop() {
           selectedIndex = std::max(0, static_cast<int>(words.size()) - 1);
         }
         deleteConfirmMode = false;
-        updateRequired = true;
+        requestUpdate();
       }
     }
     if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
       deleteConfirmMode = false;
       ignoreNextConfirmRelease = false;
-      updateRequired = true;
+      requestUpdate();
     }
     return;
   }
@@ -104,7 +78,7 @@ void LookedUpWordsActivity::loop() {
     deleteConfirmMode = true;
     ignoreNextConfirmRelease = true;
     pendingDeleteIndex = selectedIndex;
-    updateRequired = true;
+    requestUpdate();
     return;
   }
 
@@ -113,30 +87,37 @@ void LookedUpWordsActivity::loop() {
 
   buttonNavigator.onNextRelease([this, totalItems] {
     selectedIndex = ButtonNavigator::nextIndex(selectedIndex, totalItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onPreviousRelease([this, totalItems] {
     selectedIndex = ButtonNavigator::previousIndex(selectedIndex, totalItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onNextContinuous([this, totalItems, pageItems] {
     selectedIndex = ButtonNavigator::nextPageIndex(selectedIndex, totalItems, pageItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   buttonNavigator.onPreviousContinuous([this, totalItems, pageItems] {
     selectedIndex = ButtonNavigator::previousPageIndex(selectedIndex, totalItems, pageItems);
-    updateRequired = true;
+    requestUpdate();
   });
 
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
     const std::string& headword = words[selectedIndex];
 
-    Rect popupLayout = GUI.drawPopup(renderer, "Looking up...");
+    Rect popupLayout;
+    {
+      Activity::RenderLock lock(*this);
+      popupLayout = GUI.drawPopup(renderer, "Looking up...");
+    }
     std::string definition = Dictionary::lookup(
-        headword, [this, &popupLayout](int percent) { GUI.fillPopupProgress(renderer, popupLayout, percent); });
+        headword, [this, &popupLayout](int percent) {
+          Activity::RenderLock lock(*this);
+          GUI.fillPopupProgress(renderer, popupLayout, percent);
+        });
 
     if (!definition.empty()) {
       enterNewActivity(new DictionaryDefinitionActivity(
@@ -166,10 +147,13 @@ void LookedUpWordsActivity::loop() {
       return;
     }
 
-    GUI.drawPopup(renderer, "Not found");
+    {
-    renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      Activity::RenderLock lock(*this);
+      GUI.drawPopup(renderer, "Not found");
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+    }
     vTaskDelay(1500 / portTICK_PERIOD_MS);
-    updateRequired = true;
+    requestUpdate();
     return;
   }
 
@@ -190,7 +174,7 @@ int LookedUpWordsActivity::getPageItems() const {
   return std::max(1, contentHeight / metrics.listRowHeight);
 }
 
-void LookedUpWordsActivity::renderScreen() {
+void LookedUpWordsActivity::render(Activity::RenderLock&&) {
   renderer.clearScreen();
 
   const auto orient = renderer.getOrientation();

src/activities/reader/LookedUpWordsActivity.h

@@ -1,8 +1,4 @@
 #pragma once
-#include <freertos/FreeRTOS.h>
-#include <freertos/semphr.h>
-#include <freertos/task.h>
-
 #include <functional>
 #include <string>
 #include <vector>
@@ -25,6 +21,7 @@ class LookedUpWordsActivity final : public ActivityWithSubactivity {
   void onEnter() override;
   void onExit() override;
   void loop() override;
+  void render(Activity::RenderLock&&) override;
 
  private:
   std::string cachePath;
@@ -35,7 +32,6 @@ class LookedUpWordsActivity final : public ActivityWithSubactivity {
 
   std::vector<std::string> words;
   int selectedIndex = 0;
-  bool updateRequired = false;
   bool pendingBackFromDef = false;
   bool pendingExitToReader = false;
   ButtonNavigator buttonNavigator;
@@ -45,11 +41,5 @@ class LookedUpWordsActivity final : public ActivityWithSubactivity {
   bool ignoreNextConfirmRelease = false;
   int pendingDeleteIndex = 0;
 
-  TaskHandle_t displayTaskHandle = nullptr;
-  SemaphoreHandle_t renderingMutex = nullptr;
-
   int getPageItems() const;
-  void renderScreen();
-  static void taskTrampoline(void* param);
-  [[noreturn]] void displayTaskLoop();
 };