feat: allow last content to display in sleep mode

USER_GUIDE.md

@@ -90,6 +90,7 @@ The Settings screen allows you to configure the device's behavior. There are a f
   - "Custom" - Custom images from the SD card; see [Sleep Screen](#36-sleep-screen) below for more information
   - "Cover" - The book cover image (Note: this is experimental and may not work as expected)
   - "None" - A blank screen
+  - "Last" - Preserve the last content displayed on the screen
 - **Sleep Screen Cover Mode**: How to display the book cover when "Cover" sleep screen is selected:
   - "Fit" (default) - Scale the image down to fit centered on the screen, padding with white borders as necessary
   - "Crop" - Scale the image down and crop as necessary to try to to fill the screen (Note: this is experimental and may not work as expected)

src/CrossPointSettings.h

@@ -16,7 +16,7 @@ class CrossPointSettings {
   CrossPointSettings& operator=(const CrossPointSettings&) = delete;
 
   // Should match with SettingsActivity text
-  enum SLEEP_SCREEN_MODE { DARK = 0, LIGHT = 1, CUSTOM = 2, COVER = 3, BLANK = 4 };
+  enum SLEEP_SCREEN_MODE { DARK = 0, LIGHT = 1, CUSTOM = 2, COVER = 3, BLANK = 4, LAST = 5 };
   enum SLEEP_SCREEN_COVER_MODE { FIT = 0, CROP = 1 };
 
   // Status bar display type enum

src/activities/boot_sleep/SleepActivity.cpp

@@ -14,6 +14,11 @@
 
 void SleepActivity::onEnter() {
   Activity::onEnter();
+
+  if (SETTINGS.sleepScreen == CrossPointSettings::SLEEP_SCREEN_MODE::LAST) {
+    return renderLastSleepScreen();
+  }
+
   renderPopup("Entering Sleep...");
 
   if (SETTINGS.sleepScreen == CrossPointSettings::SLEEP_SCREEN_MODE::BLANK) {
@@ -272,3 +277,16 @@ void SleepActivity::renderBlankSleepScreen() const {
   renderer.clearScreen();
   renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
 }
+
+void SleepActivity::renderLastSleepScreen() const {
+  const char * text = "SLEEPING";
+  const int textWidth = renderer.getTextWidth(UI_10_FONT_ID, text, EpdFontFamily::BOLD);
+  constexpr int margin = 5;
+  const int x = (renderer.getScreenWidth() - textWidth - margin * 2) / 2;
+  const int y = (renderer.getScreenHeight() - renderer.getLineHeight(UI_10_FONT_ID) - 20);
+  const int w = textWidth + margin * 2;
+  const int h = renderer.getLineHeight(UI_10_FONT_ID) + margin * 2;
+  renderer.fillRect(x, y, w, h, true);
+  renderer.drawText(UI_10_FONT_ID, x + margin, y + margin, text, false, EpdFontFamily::BOLD);
+  renderer.displayBuffer();
+}

src/activities/boot_sleep/SleepActivity.h

@@ -16,4 +16,5 @@ class SleepActivity final : public Activity {
   void renderCoverSleepScreen() const;
   void renderBitmapSleepScreen(const Bitmap& bitmap) const;
   void renderBlankSleepScreen() const;
+  void renderLastSleepScreen() const;
 };

src/activities/settings/SettingsActivity.cpp

@@ -14,7 +14,7 @@ namespace {
 constexpr int displaySettingsCount = 5;
 const SettingInfo displaySettings[displaySettingsCount] = {
     // Should match with SLEEP_SCREEN_MODE
-    SettingInfo::Enum("Sleep Screen", &CrossPointSettings::sleepScreen, {"Dark", "Light", "Custom", "Cover", "None"}),
+    SettingInfo::Enum("Sleep Screen", &CrossPointSettings::sleepScreen, {"Dark", "Light", "Custom", "Cover", "None", "Last"}),
     SettingInfo::Enum("Sleep Screen Cover Mode", &CrossPointSettings::sleepScreenCoverMode, {"Fit", "Crop"}),
     SettingInfo::Enum("Status Bar", &CrossPointSettings::statusBar, {"None", "No Progress", "Full"}),
     SettingInfo::Enum("Hide Battery %", &CrossPointSettings::hideBatteryPercentage, {"Never", "In Reader", "Always"}),