Add file selection screen

src/screens/EpubReaderScreen.cpp

@@ -41,6 +41,7 @@ void EpubReaderScreen::onEnter() {
 
 void EpubReaderScreen::onExit() {
   vTaskDelete(displayTaskHandle);
+  displayTaskHandle = nullptr;
   xSemaphoreTake(sectionMutex, portMAX_DELAY);
   vSemaphoreDelete(sectionMutex);
   sectionMutex = nullptr;
@@ -91,6 +92,8 @@ void EpubReaderScreen::handleInput(const Input input) {
     }
 
     updateRequired = true;
+  } else if (input.button == BACK) {
+    onGoHome();
   }
 }
 

src/screens/EpubReaderScreen.h

@@ -15,6 +15,7 @@ class EpubReaderScreen final : public Screen {
   int currentSpineIndex = 0;
   int nextPageNumber = 0;
   bool updateRequired = false;
+  const std::function<void()> onGoHome;
 
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
@@ -22,7 +23,8 @@ class EpubReaderScreen final : public Screen {
   void renderStatusBar() const;
 
  public:
-  explicit EpubReaderScreen(EpdRenderer* renderer, Epub* epub) : Screen(renderer), epub(epub) {}
+  explicit EpubReaderScreen(EpdRenderer* renderer, Epub* epub, const std::function<void()>& onGoHome)
+      : Screen(renderer), epub(epub), onGoHome(onGoHome) {}
   ~EpubReaderScreen() override { free(section); }
   void onEnter() override;
   void onExit() override;

src/screens/FileSelectionScreen.cpp

@@ -0,0 +1,87 @@
+#include "FileSelectionScreen.h"
+
+#include <EpdRenderer.h>
+#include <SD.h>
+
+void FileSelectionScreen::taskTrampoline(void* param) {
+  auto* self = static_cast<FileSelectionScreen*>(param);
+  self->displayTaskLoop();
+}
+
+void FileSelectionScreen::onEnter() {
+  files.clear();
+  auto root = SD.open("/");
+  File file;
+  while ((file = root.openNextFile())) {
+    if (file.isDirectory()) {
+      file.close();
+      continue;
+    }
+
+    auto filename = std::string(file.name());
+    if (filename.substr(filename.length() - 5) != ".epub" || filename[0] == '.') {
+      file.close();
+      continue;
+    }
+
+    files.emplace_back(filename);
+    file.close();
+  }
+  root.close();
+
+  // Trigger first update
+  updateRequired = true;
+
+  xTaskCreate(&FileSelectionScreen::taskTrampoline, "FileSelectionScreenTask",
+              1024,               // Stack size
+              this,               // Parameters
+              1,                  // Priority
+              &displayTaskHandle  // Task handle
+  );
+}
+
+void FileSelectionScreen::onExit() {
+  vTaskDelete(displayTaskHandle);
+  displayTaskHandle = nullptr;
+}
+
+void FileSelectionScreen::handleInput(const Input input) {
+  if (input.button == VOLUME_DOWN) {
+    selectorIndex = (selectorIndex + 1) % files.size();
+    updateRequired = true;
+  } else if (input.button == VOLUME_UP) {
+    selectorIndex = (selectorIndex + files.size() - 1) % files.size();
+    updateRequired = true;
+  } else if (input.button == CONFIRM) {
+    Serial.printf("Selected file: %s\n", files[selectorIndex].c_str());
+    onSelect("/" + files[selectorIndex]);
+  }
+}
+
+void FileSelectionScreen::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      render();
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void FileSelectionScreen::render() const {
+  renderer->clearScreen();
+
+  const auto pageWidth = renderer->getPageWidth();
+  const auto titleWidth = renderer->getTextWidth("CrossPoint Reader", true);
+  renderer->drawText((pageWidth - titleWidth) / 2, 0, "CrossPoint Reader", true);
+
+  // Draw selection
+  renderer->fillRect(0, 50 + selectorIndex * 20 + 2, pageWidth - 1, 20, 1);
+
+  for (size_t i = 0; i < files.size(); i++) {
+    const auto file = files[i];
+    renderer->drawSmallText(50, 50 + i * 20, file.c_str(), i == selectorIndex ? 0 : 1);
+  }
+
+  renderer->flushDisplay();
+}

src/screens/FileSelectionScreen.h

@@ -0,0 +1,28 @@
+#pragma once
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+
+#include <functional>
+#include <string>
+#include <vector>
+
+#include "Screen.h"
+
+class FileSelectionScreen final : public Screen {
+  TaskHandle_t displayTaskHandle = nullptr;
+  std::vector<std::string> files;
+  int selectorIndex = 0;
+  bool updateRequired = false;
+  const std::function<void(const std::string&)> onSelect;
+
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  void render() const;
+
+ public:
+  explicit FileSelectionScreen(EpdRenderer* renderer, const std::function<void(const std::string&)>& onSelect)
+      : Screen(renderer), onSelect(onSelect) {}
+  void onEnter() override;
+  void onExit() override;
+  void handleInput(Input input) override;
+};