Add file selection screen

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();
+}