add separate render path when sleep.bmp is found in root of sd card

src/activities/boot_sleep/SleepActivity.cpp

@@ -3,10 +3,23 @@
 #include <GfxRenderer.h>
 
 #include "CrossPointSettings.h"
+#include "SD.h"
 #include "config.h"
 #include "images/CrossLarge.h"
 
 void SleepActivity::onEnter() {
+  // Look for sleep.bmp on the root of the sd card to determine if we should
+  // render a custom sleep screen instead of the default.
+  auto file = SD.open("/sleep.bmp");
+  if (file) {
+    renderCustomSleepScreen(file);
+    return;
+  }
+
+  renderDefaultSleepScreen();
+}
+
+void SleepActivity::renderDefaultSleepScreen() {
   const auto pageWidth = GfxRenderer::getScreenWidth();
   const auto pageHeight = GfxRenderer::getScreenHeight();
 
@@ -22,3 +35,16 @@ void SleepActivity::onEnter() {
 
   renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
 }
+
+void SleepActivity::renderCustomSleepScreen(File file) {
+  Serial.println("Rendering custom sleep screen from sleep.bmp");
+
+  const auto pageWidth = GfxRenderer::getScreenWidth();
+  const auto pageHeight = GfxRenderer::getScreenHeight();
+
+  renderer.clearScreen();
+
+  renderer.drawCenteredText(UI_FONT_ID, pageHeight / 2 + 70, "CUSTOM SLEEP SCREEN", true, BOLD);
+
+  renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+}

src/activities/boot_sleep/SleepActivity.h

@@ -1,8 +1,13 @@
 #pragma once
 #include "../Activity.h"
+#include "SD.h"
 
 class SleepActivity final : public Activity {
  public:
   explicit SleepActivity(GfxRenderer& renderer, InputManager& inputManager) : Activity(renderer, inputManager) {}
   void onEnter() override;
+
+ private:
+  void renderDefaultSleepScreen();
+  void renderCustomSleepScreen(File file);
 };