Merge 66e69e750e into e5c0ddc9fa

## Summary

* **What is the goal of this PR?**
Add a debugging script to help developers monitor the ESP32 serial port
directly from a PC.

* **What changes are included?**
Added a new script: scripts/debugging_monitor.py

## Additional Context

While working on a new Crosspoint-Reader feature, it quickly became
clear that watching the ESP32 serial output without any visual cues was
inconvenient and easy to mess up.

This script improves the debugging experience by reading data from the
serial port and providing:

1. A timestamp prefix for every log line (instead of milliseconds since
power-up)
2. Color-coded output for different message types
3. A secondary window displaying a live graph of RAM usage, which is
especially useful for tracking the memory impact of new features

<img width="1916" height="1049" alt="Screenshot_20260126_183811"
src="https://github.com/user-attachments/assets/6291887f-ac17-43ac-9e43-f5dec8a7097e"
/>

---

### AI Usage

Did you use AI tools to help write this code? _**< PARTIALLY >**_
I wrote the initial version of the script. Gemini was used to help add
the Matplotlib-based graphing and threading logic.

README.md

@@ -95,6 +95,20 @@ Connect your Xteink X4 to your computer via USB-C and run the following command.
 ```sh
 pio run --target upload
 ```
+### Debugging
+
+After flashing the new features, it’s recommended to capture detailed logs from the serial port.
+
+First, make sure all required Python packages are installed:
+
+```python
+python3 -m pip install serial colorama matplotlib
+```
+after that run the script:
+```sh
+python3 scripts/debugging_monitor.py
+```
+This was tested on Debian and should work on most Linux systems. Minor adjustments may be required for Windows or macOS.
 
 ## Internals
 

lib/GfxRenderer/GfxRenderer.cpp

@@ -415,13 +415,21 @@ void GfxRenderer::displayBuffer(const HalDisplay::RefreshMode refreshMode) const
 
 std::string GfxRenderer::truncatedText(const int fontId, const char* text, const int maxWidth,
                                        const EpdFontFamily::Style style) const {
+  if (!text || maxWidth <= 0) return "";
+
   std::string item = text;
-  int itemWidth = getTextWidth(fontId, item.c_str(), style);
-  while (itemWidth > maxWidth && item.length() > 8) {
-    item.replace(item.length() - 5, 5, "...");
-    itemWidth = getTextWidth(fontId, item.c_str(), style);
+  const char* ellipsis = "...";
+  int textWidth = getTextWidth(fontId, item.c_str(), style);
+  if (textWidth <= maxWidth) {
+    // Text fits, return as is
+    return item;
   }
-  return item;
+
+  while (!item.empty() && getTextWidth(fontId, (item + ellipsis).c_str(), style) >= maxWidth) {
+    utf8RemoveLastChar(item);
+  }
+
+  return item.empty() ? ellipsis : item + ellipsis;
 }
 
 // Note: Internal driver treats screen in command orientation; this library exposes a logical orientation

lib/Utf8/Utf8.cpp

@@ -29,3 +29,20 @@ uint32_t utf8NextCodepoint(const unsigned char** string) {
 
   return cp;
 }
+
+size_t utf8RemoveLastChar(std::string& str) {
+  if (str.empty()) return 0;
+  size_t pos = str.size() - 1;
+  while (pos > 0 && (static_cast<unsigned char>(str[pos]) & 0xC0) == 0x80) {
+    --pos;
+  }
+  str.resize(pos);
+  return pos;
+}
+
+// Truncate string by removing N UTF-8 characters from the end
+void utf8TruncateChars(std::string& str, const size_t numChars) {
+  for (size_t i = 0; i < numChars && !str.empty(); ++i) {
+    utf8RemoveLastChar(str);
+  }
+}

lib/Utf8/Utf8.h

@@ -1,7 +1,11 @@
 #pragma once
 
 #include <cstdint>
-
+#include <string>
 #define REPLACEMENT_GLYPH 0xFFFD
 
 uint32_t utf8NextCodepoint(const unsigned char** string);
+// Remove the last UTF-8 codepoint from a std::string and return the new size.
+size_t utf8RemoveLastChar(std::string& str);
+// Truncate string by removing N UTF-8 codepoints from the end.
+void utf8TruncateChars(std::string& str, size_t numChars);

scripts/debugging_monitor.py

@@ -0,0 +1,214 @@
+import sys
+import argparse
+import re
+import threading
+from datetime import datetime
+from collections import deque
+import time
+
+# Try to import potentially missing packages
+try:
+    import serial
+    from colorama import init, Fore, Style
+    import matplotlib.pyplot as plt
+    import matplotlib.animation as animation
+except ImportError as e:
+    missing_package = e.name
+    print("\n" + "!" * 50)
+    print(f" Error: The required package '{missing_package}' is not installed.")
+    print("!" * 50)
+
+    print(f"\nTo fix this, please run the following command in your terminal:\n")
+
+    install_cmd = "pip install "
+    packages = []
+    if 'serial' in str(e): packages.append("pyserial")
+    if 'colorama' in str(e): packages.append("colorama")
+    if 'matplotlib' in str(e): packages.append("matplotlib")
+
+    print(f"    {install_cmd}{' '.join(packages)}")
+
+    print("\nExiting...")
+    sys.exit(1)
+
+# --- Global Variables for Data Sharing ---
+# Store last 50 data points
+MAX_POINTS = 50
+time_data = deque(maxlen=MAX_POINTS)
+free_mem_data = deque(maxlen=MAX_POINTS)
+total_mem_data = deque(maxlen=MAX_POINTS)
+data_lock = threading.Lock() # Prevent reading while writing
+
+# Initialize colors
+init(autoreset=True)
+
+def get_color_for_line(line):
+    """
+    Classify log lines by type and assign appropriate colors.
+    """
+    line_upper = line.upper()
+
+    if any(keyword in line_upper for keyword in ["ERROR", "[ERR]", "[SCT]", "FAILED", "WARNING"]):
+        return Fore.RED
+    if "[MEM]" in line_upper or "FREE:" in line_upper:
+        return Fore.CYAN
+    if any(keyword in line_upper for keyword in ["[GFX]", "[ERS]", "DISPLAY", "RAM WRITE", "RAM COMPLETE", "REFRESH", "POWERING ON", "FRAME BUFFER", "LUT"]):
+        return Fore.MAGENTA
+    if any(keyword in line_upper for keyword in ["[EBP]", "[BMC]", "[ZIP]", "[PARSER]", "[EHP]", "LOADING EPUB", "CACHE", "DECOMPRESSED", "PARSING"]):
+        return Fore.GREEN
+    if "[ACT]" in line_upper or "ENTERING ACTIVITY" in line_upper or "EXITING ACTIVITY" in line_upper:
+        return Fore.YELLOW
+    if any(keyword in line_upper for keyword in ["RENDERED PAGE", "[LOOP]", "DURATION", "WAIT COMPLETE"]):
+        return Fore.BLUE
+    if any(keyword in line_upper for keyword in ["[CPS]", "SETTINGS", "[CLEAR_CACHE]"]):
+        return Fore.LIGHTYELLOW_EX
+    if any(keyword in line_upper for keyword in ["ESP-ROM", "BUILD:", "RST:", "BOOT:", "SPIWP:", "MODE:", "LOAD:", "ENTRY", "[SD]", "STARTING CROSSPOINT", "VERSION"]):
+        return Fore.LIGHTBLACK_EX
+    if "[RBS]" in line_upper:
+        return Fore.LIGHTCYAN_EX
+    if "[KRS]" in line_upper:
+        return Fore.LIGHTMAGENTA_EX
+    if any(keyword in line_upper for keyword in ["EINKDISPLAY:", "STATIC FRAME", "INITIALIZING", "SPI INITIALIZED", "GPIO PINS", "RESETTING", "SSD1677", "E-INK"]):
+        return Fore.LIGHTMAGENTA_EX
+    if any(keyword in line_upper for keyword in ["[FNS]", "FOOTNOTE"]):
+        return Fore.LIGHTGREEN_EX
+    if any(keyword in line_upper for keyword in ["[CHAP]", "[OPDS]", "[COF]"]):
+        return Fore.LIGHTYELLOW_EX
+
+    return Fore.WHITE
+
+def parse_memory_line(line):
+    """
+    Extracts Free and Total bytes from the specific log line.
+    Format: [MEM] Free: 196344 bytes, Total: 226412 bytes, Min Free: 112620 bytes
+    """
+    # Regex to find 'Free: <digits>' and 'Total: <digits>'
+    match = re.search(r"Free:\s*(\d+).*Total:\s*(\d+)", line)
+    if match:
+        try:
+            free_bytes = int(match.group(1))
+            total_bytes = int(match.group(2))
+            return free_bytes, total_bytes
+        except ValueError:
+            return None, None
+    return None, None
+
+def serial_worker(port, baud):
+    """
+    Runs in a background thread. Handles reading serial, printing to console,
+    and updating the data lists.
+    """
+    print(f"{Fore.CYAN}--- Opening {port} at {baud} baud ---{Style.RESET_ALL}")
+
+    try:
+        ser = serial.Serial(port, baud, timeout=0.1)
+        ser.dtr = False
+        ser.rts = False
+    except serial.SerialException as e:
+        print(f"{Fore.RED}Error opening port: {e}{Style.RESET_ALL}")
+        return
+
+    try:
+        while True:
+            try:
+                raw_data = ser.readline().decode('utf-8', errors='replace')
+
+                if not raw_data:
+                    continue
+
+                clean_line = raw_data.strip()
+                if not clean_line:
+                    continue
+
+                # Add PC timestamp
+                pc_time = datetime.now().strftime("%H:%M:%S")
+                formatted_line = re.sub(r"^\[\d+\]", f"[{pc_time}]", clean_line)
+
+                # Check for Memory Line
+                if "[MEM]" in formatted_line:
+                    free_val, total_val = parse_memory_line(formatted_line)
+                    if free_val is not None:
+                        with data_lock:
+                            time_data.append(pc_time)
+                            free_mem_data.append(free_val / 1024) # Convert to KB
+                            total_mem_data.append(total_val / 1024) # Convert to KB
+
+                # Print to console
+                line_color = get_color_for_line(formatted_line)
+                print(f"{line_color}{formatted_line}")
+
+            except OSError:
+                print(f"{Fore.RED}Device disconnected.{Style.RESET_ALL}")
+                break
+    except Exception as e:
+        # If thread is killed violently (e.g. main exit), silence errors
+        pass
+    finally:
+        if 'ser' in locals() and ser.is_open:
+            ser.close()
+
+def update_graph(frame):
+    """
+    Called by Matplotlib animation to redraw the chart.
+    """
+    with data_lock:
+        if not time_data:
+            return
+
+        # Convert deques to lists for plotting
+        x = list(time_data)
+        y_free = list(free_mem_data)
+        y_total = list(total_mem_data)
+
+    plt.cla() # Clear axis
+
+    # Plot Total RAM
+    plt.plot(x, y_total, label='Total RAM (KB)', color='red', linestyle='--')
+
+    # Plot Free RAM
+    plt.plot(x, y_free, label='Free RAM (KB)', color='green', marker='o')
+
+    # Fill area under Free RAM
+    plt.fill_between(x, y_free, color='green', alpha=0.1)
+
+    plt.title("ESP32 Memory Monitor")
+    plt.ylabel("Memory (KB)")
+    plt.xlabel("Time")
+    plt.legend(loc='upper left')
+    plt.grid(True, linestyle=':', alpha=0.6)
+
+    # Rotate date labels
+    plt.xticks(rotation=45, ha='right')
+    plt.tight_layout()
+
+def main():
+    parser = argparse.ArgumentParser(description="ESP32 Monitor with Graph")
+    parser.add_argument("port", nargs="?", default="/dev/ttyACM0", help="Serial port")
+    parser.add_argument("--baud", type=int, default=115200, help="Baud rate")
+    args = parser.parse_args()
+
+    # 1. Start the Serial Reader in a separate thread
+    # Daemon=True means this thread dies when the main program closes
+    t = threading.Thread(target=serial_worker, args=(args.port, args.baud), daemon=True)
+    t.start()
+
+    # 2. Set up the Graph (Main Thread)
+    try:
+        plt.style.use('light_background')
+    except:
+        pass
+
+    fig = plt.figure(figsize=(10, 6))
+
+    # Update graph every 1000ms
+    ani = animation.FuncAnimation(fig, update_graph, interval=1000)
+
+    try:
+        print(f"{Fore.YELLOW}Starting Graph Window... (Close window to exit){Style.RESET_ALL}")
+        plt.show()
+    except KeyboardInterrupt:
+        print(f"\n{Fore.YELLOW}Exiting...{Style.RESET_ALL}")
+        plt.close('all') # Force close any lingering plot windows
+
+if __name__ == "__main__":
+    main()

src/activities/browser/OpdsBookBrowserActivity.cpp

@@ -17,7 +17,6 @@
 
 namespace {
 constexpr int PAGE_ITEMS = 23;
-constexpr int SKIP_PAGE_MS = 700;
 }  // namespace
 
 void OpdsBookBrowserActivity::taskTrampoline(void* param) {
@@ -118,12 +117,6 @@ void OpdsBookBrowserActivity::loop() {
 
   // Handle browsing state
   if (state == BrowserState::BROWSING) {
-    const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::Up) ||
-                              mappedInput.wasReleased(MappedInputManager::Button::Left);
-    const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::Down) ||
-                              mappedInput.wasReleased(MappedInputManager::Button::Right);
-    const bool skipPage = mappedInput.getHeldTime() > SKIP_PAGE_MS;
-
     if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
       if (!entries.empty()) {
         const auto& entry = entries[selectorIndex];
@@ -135,20 +128,29 @@ void OpdsBookBrowserActivity::loop() {
       }
     } else if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
       navigateBack();
-    } else if (prevReleased && !entries.empty()) {
-      if (skipPage) {
-        selectorIndex = ((selectorIndex / PAGE_ITEMS - 1) * PAGE_ITEMS + entries.size()) % entries.size();
-      } else {
-        selectorIndex = (selectorIndex + entries.size() - 1) % entries.size();
-      }
-      updateRequired = true;
-    } else if (nextReleased && !entries.empty()) {
-      if (skipPage) {
-        selectorIndex = ((selectorIndex / PAGE_ITEMS + 1) * PAGE_ITEMS) % entries.size();
-      } else {
-        selectorIndex = (selectorIndex + 1) % entries.size();
-      }
-      updateRequired = true;
+    }
+
+    // Handle navigation
+    if (!entries.empty()) {
+      buttonNavigator.onNextRelease([this] {
+        selectorIndex = ButtonNavigator::nextIndex(selectorIndex, entries.size());
+        updateRequired = true;
+      });
+
+      buttonNavigator.onPreviousRelease([this] {
+        selectorIndex = ButtonNavigator::previousIndex(selectorIndex, entries.size());
+        updateRequired = true;
+      });
+
+      buttonNavigator.onNextContinuous([this] {
+        selectorIndex = ButtonNavigator::nextPageIndex(selectorIndex, entries.size(), PAGE_ITEMS);
+        updateRequired = true;
+      });
+
+      buttonNavigator.onPreviousContinuous([this] {
+        selectorIndex = ButtonNavigator::previousPageIndex(selectorIndex, entries.size(), PAGE_ITEMS);
+        updateRequired = true;
+      });
     }
   }
 }

src/activities/browser/OpdsBookBrowserActivity.h

@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "../ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 /**
  * Activity for browsing and downloading books from an OPDS server.
@@ -37,6 +38,7 @@ class OpdsBookBrowserActivity final : public ActivityWithSubactivity {
  private:
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
 
   BrowserState state = BrowserState::LOADING;

src/activities/home/HomeActivity.cpp

@@ -4,6 +4,7 @@
 #include <Epub.h>
 #include <GfxRenderer.h>
 #include <SDCardManager.h>
+#include <Utf8.h>
 #include <Xtc.h>
 
 #include <cstring>
@@ -161,13 +162,18 @@ void HomeActivity::freeCoverBuffer() {
 }
 
 void HomeActivity::loop() {
-  const bool prevPressed = mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-                           mappedInput.wasPressed(MappedInputManager::Button::Left);
-  const bool nextPressed = mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-                           mappedInput.wasPressed(MappedInputManager::Button::Right);
-
   const int menuCount = getMenuItemCount();
 
+  buttonNavigator.onNext([this, menuCount] {
+    selectorIndex = ButtonNavigator::nextIndex(selectorIndex, menuCount);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPrevious([this, menuCount] {
+    selectorIndex = ButtonNavigator::previousIndex(selectorIndex, menuCount);
+    updateRequired = true;
+  });
+
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
     // Calculate dynamic indices based on which options are available
     int idx = 0;
@@ -188,12 +194,6 @@ void HomeActivity::loop() {
     } else if (selectorIndex == settingsIdx) {
       onSettingsOpen();
     }
-  } else if (prevPressed) {
-    selectorIndex = (selectorIndex + menuCount - 1) % menuCount;
-    updateRequired = true;
-  } else if (nextPressed) {
-    selectorIndex = (selectorIndex + 1) % menuCount;
-    updateRequired = true;
   }
 }
 
@@ -366,7 +366,7 @@ void HomeActivity::render() {
         while (!lines.back().empty() && renderer.getTextWidth(UI_12_FONT_ID, lines.back().c_str()) > maxLineWidth) {
           // Remove "..." first, then remove one UTF-8 char, then add "..." back
           lines.back().resize(lines.back().size() - 3);  // Remove "..."
-          StringUtils::utf8RemoveLastChar(lines.back());
+          utf8RemoveLastChar(lines.back());
           lines.back().append("...");
         }
         break;
@@ -375,7 +375,7 @@ void HomeActivity::render() {
       int wordWidth = renderer.getTextWidth(UI_12_FONT_ID, i.c_str());
       while (wordWidth > maxLineWidth && !i.empty()) {
         // Word itself is too long, trim it (UTF-8 safe)
-        StringUtils::utf8RemoveLastChar(i);
+        utf8RemoveLastChar(i);
         // Check if we have room for ellipsis
         std::string withEllipsis = i + "...";
         wordWidth = renderer.getTextWidth(UI_12_FONT_ID, withEllipsis.c_str());
@@ -428,7 +428,7 @@ void HomeActivity::render() {
       if (!lastBookAuthor.empty()) {
         std::string trimmedAuthor = lastBookAuthor;
         while (renderer.getTextWidth(UI_10_FONT_ID, trimmedAuthor.c_str()) > maxLineWidth && !trimmedAuthor.empty()) {
-          StringUtils::utf8RemoveLastChar(trimmedAuthor);
+          utf8RemoveLastChar(trimmedAuthor);
         }
         if (renderer.getTextWidth(UI_10_FONT_ID, trimmedAuthor.c_str()) <
             renderer.getTextWidth(UI_10_FONT_ID, lastBookAuthor.c_str())) {
@@ -462,14 +462,14 @@ void HomeActivity::render() {
       // Trim author if too long (UTF-8 safe)
       bool wasTrimmed = false;
       while (renderer.getTextWidth(UI_10_FONT_ID, trimmedAuthor.c_str()) > maxLineWidth && !trimmedAuthor.empty()) {
-        StringUtils::utf8RemoveLastChar(trimmedAuthor);
+        utf8RemoveLastChar(trimmedAuthor);
         wasTrimmed = true;
       }
       if (wasTrimmed && !trimmedAuthor.empty()) {
         // Make room for ellipsis
         while (renderer.getTextWidth(UI_10_FONT_ID, (trimmedAuthor + "...").c_str()) > maxLineWidth &&
                !trimmedAuthor.empty()) {
-          StringUtils::utf8RemoveLastChar(trimmedAuthor);
+          utf8RemoveLastChar(trimmedAuthor);
         }
         trimmedAuthor.append("...");
       }

src/activities/home/HomeActivity.h

@@ -6,10 +6,12 @@
 #include <functional>
 
 #include "../Activity.h"
+#include "util/ButtonNavigator.h"
 
 class HomeActivity final : public Activity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   int selectorIndex = 0;
   bool updateRequired = false;
   bool hasContinueReading = false;

src/activities/home/MyLibraryActivity.cpp

@@ -21,7 +21,6 @@ constexpr int LEFT_MARGIN = 20;
 constexpr int RIGHT_MARGIN = 40;  // Extra space for scroll indicator
 
 // Timing thresholds
-constexpr int SKIP_PAGE_MS = 700;
 constexpr unsigned long GO_HOME_MS = 1000;
 
 void sortFileList(std::vector<std::string>& strs) {
@@ -178,13 +177,9 @@ void MyLibraryActivity::loop() {
     return;
   }
 
-  const bool upReleased = mappedInput.wasReleased(MappedInputManager::Button::Up);
-  const bool downReleased = mappedInput.wasReleased(MappedInputManager::Button::Down);
   const bool leftReleased = mappedInput.wasReleased(MappedInputManager::Button::Left);
   const bool rightReleased = mappedInput.wasReleased(MappedInputManager::Button::Right);
 
-  const bool skipPage = mappedInput.getHeldTime() > SKIP_PAGE_MS;
-
   // Confirm button - open selected item
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
     if (currentTab == Tab::Recent) {
@@ -249,24 +244,28 @@ void MyLibraryActivity::loop() {
   }
 
   // Navigation: Up/Down moves through items only
-  const bool prevReleased = upReleased;
-  const bool nextReleased = downReleased;
+  constexpr auto upButton = MappedInputManager::Button::Up;
+  constexpr auto downButton = MappedInputManager::Button::Down;
 
-  if (prevReleased && itemCount > 0) {
-    if (skipPage) {
-      selectorIndex = ((selectorIndex / pageItems - 1) * pageItems + itemCount) % itemCount;
-    } else {
-      selectorIndex = (selectorIndex + itemCount - 1) % itemCount;
-    }
+  buttonNavigator.onRelease({downButton}, [this, itemCount] {
+    selectorIndex = ButtonNavigator::nextIndex(selectorIndex, itemCount);
     updateRequired = true;
-  } else if (nextReleased && itemCount > 0) {
-    if (skipPage) {
-      selectorIndex = ((selectorIndex / pageItems + 1) * pageItems) % itemCount;
-    } else {
-      selectorIndex = (selectorIndex + 1) % itemCount;
-    }
+  });
+
+  buttonNavigator.onRelease({upButton}, [this, itemCount] {
+    selectorIndex = ButtonNavigator::previousIndex(selectorIndex, itemCount);
     updateRequired = true;
-  }
+  });
+
+  buttonNavigator.onContinuous({downButton}, [this, itemCount, pageItems] {
+    selectorIndex = ButtonNavigator::nextPageIndex(selectorIndex, itemCount, pageItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onContinuous({upButton}, [this, itemCount, pageItems] {
+    selectorIndex = ButtonNavigator::previousPageIndex(selectorIndex, itemCount, pageItems);
+    updateRequired = true;
+  });
 }
 
 void MyLibraryActivity::displayTaskLoop() {

src/activities/home/MyLibraryActivity.h

@@ -9,6 +9,7 @@
 
 #include "../Activity.h"
 #include "RecentBooksStore.h"
+#include "util/ButtonNavigator.h"
 
 class MyLibraryActivity final : public Activity {
  public:
@@ -17,6 +18,7 @@ class MyLibraryActivity final : public Activity {
  private:
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
 
   Tab currentTab = Tab::Recent;
   int selectorIndex = 0;

src/activities/network/NetworkModeSelectionActivity.cpp

@@ -72,18 +72,15 @@ void NetworkModeSelectionActivity::loop() {
   }
 
   // Handle navigation
-  const bool prevPressed = mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-                           mappedInput.wasPressed(MappedInputManager::Button::Left);
-  const bool nextPressed = mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-                           mappedInput.wasPressed(MappedInputManager::Button::Right);
+  buttonNavigator.onNext([this] {
+    selectedIndex = ButtonNavigator::nextIndex(selectedIndex, MENU_ITEM_COUNT);
+    updateRequired = true;
+  });
 
-  if (prevPressed) {
-    selectedIndex = (selectedIndex + MENU_ITEM_COUNT - 1) % MENU_ITEM_COUNT;
+  buttonNavigator.onPrevious([this] {
+    selectedIndex = ButtonNavigator::previousIndex(selectedIndex, MENU_ITEM_COUNT);
     updateRequired = true;
-  } else if (nextPressed) {
-    selectedIndex = (selectedIndex + 1) % MENU_ITEM_COUNT;
-    updateRequired = true;
-  }
+  });
 }
 
 void NetworkModeSelectionActivity::displayTaskLoop() {

src/activities/network/NetworkModeSelectionActivity.h

@@ -6,6 +6,7 @@
 #include <functional>
 
 #include "../Activity.h"
+#include "util/ButtonNavigator.h"
 
 // Enum for network mode selection
 enum class NetworkMode { JOIN_NETWORK, CONNECT_CALIBRE, CREATE_HOTSPOT };
@@ -22,6 +23,8 @@ enum class NetworkMode { JOIN_NETWORK, CONNECT_CALIBRE, CREATE_HOTSPOT };
 class NetworkModeSelectionActivity final : public Activity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
+
   int selectedIndex = 0;
   bool updateRequired = false;
   const std::function<void(NetworkMode)> onModeSelected;

src/activities/network/WifiSelectionActivity.cpp

@@ -419,20 +419,16 @@ void WifiSelectionActivity::loop() {
       return;
     }
 
-    // Handle UP/DOWN navigation
-    if (mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-        mappedInput.wasPressed(MappedInputManager::Button::Left)) {
-      if (selectedNetworkIndex > 0) {
-        selectedNetworkIndex--;
-        updateRequired = true;
-      }
-    } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-               mappedInput.wasPressed(MappedInputManager::Button::Right)) {
-      if (!networks.empty() && selectedNetworkIndex < static_cast<int>(networks.size()) - 1) {
-        selectedNetworkIndex++;
-        updateRequired = true;
-      }
-    }
+    // Handle navigation
+    buttonNavigator.onNext([this] {
+      selectedNetworkIndex = ButtonNavigator::nextIndex(selectedNetworkIndex, networks.size());
+      updateRequired = true;
+    });
+
+    buttonNavigator.onPrevious([this] {
+      selectedNetworkIndex = ButtonNavigator::previousIndex(selectedNetworkIndex, networks.size());
+      updateRequired = true;
+    });
   }
 }
 

src/activities/network/WifiSelectionActivity.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "activities/ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 // Structure to hold WiFi network information
 struct WifiNetworkInfo {
@@ -45,6 +46,7 @@ enum class WifiSelectionState {
 class WifiSelectionActivity final : public ActivityWithSubactivity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
   WifiSelectionState state = WifiSelectionState::SCANNING;
   int selectedNetworkIndex = 0;

src/activities/reader/EpubReaderActivity.cpp

@@ -570,8 +570,8 @@ void EpubReaderActivity::renderStatusBar(const int orientedMarginRight, const in
         availableTitleSpace = rendererableScreenWidth - titleMarginLeft - titleMarginRight;
         titleMarginLeftAdjusted = titleMarginLeft;
       }
-      while (titleWidth > availableTitleSpace && title.length() > 11) {
-        title.replace(title.length() - 8, 8, "...");
+      if (titleWidth > availableTitleSpace) {
+        title = renderer.truncatedText(SMALL_FONT_ID, title.c_str(), availableTitleSpace);
         titleWidth = renderer.getTextWidth(SMALL_FONT_ID, title.c_str());
       }
     }

src/activities/reader/EpubReaderChapterSelectionActivity.cpp

@@ -7,11 +7,6 @@
 #include "MappedInputManager.h"
 #include "fontIds.h"
 
-namespace {
-// Time threshold for treating a long press as a page-up/page-down
-constexpr int SKIP_PAGE_MS = 700;
-}  // namespace
-
 bool EpubReaderChapterSelectionActivity::hasSyncOption() const { return KOREADER_STORE.hasCredentials(); }
 
 int EpubReaderChapterSelectionActivity::getTotalItems() const {
@@ -119,12 +114,6 @@ void EpubReaderChapterSelectionActivity::loop() {
     return;
   }
 
-  const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::Up) ||
-                            mappedInput.wasReleased(MappedInputManager::Button::Left);
-  const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::Down) ||
-                            mappedInput.wasReleased(MappedInputManager::Button::Right);
-
-  const bool skipPage = mappedInput.getHeldTime() > SKIP_PAGE_MS;
   const int pageItems = getPageItems();
   const int totalItems = getTotalItems();
 
@@ -145,21 +134,27 @@ void EpubReaderChapterSelectionActivity::loop() {
     }
   } else if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
     onGoBack();
-  } else if (prevReleased) {
-    if (skipPage) {
-      selectorIndex = ((selectorIndex / pageItems - 1) * pageItems + totalItems) % totalItems;
-    } else {
-      selectorIndex = (selectorIndex + totalItems - 1) % totalItems;
-    }
-    updateRequired = true;
-  } else if (nextReleased) {
-    if (skipPage) {
-      selectorIndex = ((selectorIndex / pageItems + 1) * pageItems) % totalItems;
-    } else {
-      selectorIndex = (selectorIndex + 1) % totalItems;
-    }
-    updateRequired = true;
   }
+
+  buttonNavigator.onNextRelease([this, totalItems] {
+    selectorIndex = ButtonNavigator::nextIndex(selectorIndex, totalItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPreviousRelease([this, totalItems] {
+    selectorIndex = ButtonNavigator::previousIndex(selectorIndex, totalItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onNextContinuous([this, totalItems, pageItems] {
+    selectorIndex = ButtonNavigator::nextPageIndex(selectorIndex, totalItems, pageItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPreviousContinuous([this, totalItems, pageItems] {
+    selectorIndex = ButtonNavigator::previousPageIndex(selectorIndex, totalItems, pageItems);
+    updateRequired = true;
+  });
 }
 
 void EpubReaderChapterSelectionActivity::displayTaskLoop() {

src/activities/reader/EpubReaderChapterSelectionActivity.h

@@ -7,12 +7,14 @@
 #include <memory>
 
 #include "../ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 class EpubReaderChapterSelectionActivity final : public ActivityWithSubactivity {
   std::shared_ptr<Epub> epub;
   std::string epubPath;
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   int currentSpineIndex = 0;
   int currentPage = 0;
   int totalPagesInSpine = 0;

src/activities/reader/TxtReaderActivity.cpp

@@ -533,8 +533,8 @@ void TxtReaderActivity::renderStatusBar(const int orientedMarginRight, const int
 
     std::string title = txt->getTitle();
     int titleWidth = renderer.getTextWidth(SMALL_FONT_ID, title.c_str());
-    while (titleWidth > availableTextWidth && title.length() > 11) {
-      title.replace(title.length() - 8, 8, "...");
+    if (titleWidth > availableTextWidth) {
+      title = renderer.truncatedText(SMALL_FONT_ID, title.c_str(), availableTextWidth);
       titleWidth = renderer.getTextWidth(SMALL_FONT_ID, title.c_str());
     }
 

src/activities/reader/XtcReaderChapterSelectionActivity.cpp

@@ -5,10 +5,6 @@
 #include "MappedInputManager.h"
 #include "fontIds.h"
 
-namespace {
-constexpr int SKIP_PAGE_MS = 700;
-}  // namespace
-
 int XtcReaderChapterSelectionActivity::getPageItems() const {
   constexpr int startY = 60;
   constexpr int lineHeight = 30;
@@ -75,13 +71,8 @@ void XtcReaderChapterSelectionActivity::onExit() {
 }
 
 void XtcReaderChapterSelectionActivity::loop() {
-  const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::Up) ||
-                            mappedInput.wasReleased(MappedInputManager::Button::Left);
-  const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::Down) ||
-                            mappedInput.wasReleased(MappedInputManager::Button::Right);
-
-  const bool skipPage = mappedInput.getHeldTime() > SKIP_PAGE_MS;
   const int pageItems = getPageItems();
+  const int totalItems = static_cast<int>(xtc->getChapters().size());
 
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
     const auto& chapters = xtc->getChapters();
@@ -90,29 +81,27 @@ void XtcReaderChapterSelectionActivity::loop() {
     }
   } else if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
     onGoBack();
-  } else if (prevReleased) {
-    const int total = static_cast<int>(xtc->getChapters().size());
-    if (total == 0) {
-      return;
-    }
-    if (skipPage) {
-      selectorIndex = ((selectorIndex / pageItems - 1) * pageItems + total) % total;
-    } else {
-      selectorIndex = (selectorIndex + total - 1) % total;
-    }
-    updateRequired = true;
-  } else if (nextReleased) {
-    const int total = static_cast<int>(xtc->getChapters().size());
-    if (total == 0) {
-      return;
-    }
-    if (skipPage) {
-      selectorIndex = ((selectorIndex / pageItems + 1) * pageItems) % total;
-    } else {
-      selectorIndex = (selectorIndex + 1) % total;
-    }
-    updateRequired = true;
   }
+
+  buttonNavigator.onNextRelease([this, totalItems] {
+    selectorIndex = ButtonNavigator::nextIndex(selectorIndex, totalItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPreviousRelease([this, totalItems] {
+    selectorIndex = ButtonNavigator::previousIndex(selectorIndex, totalItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onNextContinuous([this, totalItems, pageItems] {
+    selectorIndex = ButtonNavigator::nextPageIndex(selectorIndex, totalItems, pageItems);
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPreviousContinuous([this, totalItems, pageItems] {
+    selectorIndex = ButtonNavigator::previousPageIndex(selectorIndex, totalItems, pageItems);
+    updateRequired = true;
+  });
 }
 
 void XtcReaderChapterSelectionActivity::displayTaskLoop() {

src/activities/reader/XtcReaderChapterSelectionActivity.h

@@ -7,11 +7,13 @@
 #include <memory>
 
 #include "../Activity.h"
+#include "util/ButtonNavigator.h"
 
 class XtcReaderChapterSelectionActivity final : public Activity {
   std::shared_ptr<Xtc> xtc;
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   uint32_t currentPage = 0;
   int selectorIndex = 0;
   bool updateRequired = false;

src/activities/settings/CalibreSettingsActivity.cpp

@@ -62,15 +62,16 @@ void CalibreSettingsActivity::loop() {
     return;
   }
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-      mappedInput.wasPressed(MappedInputManager::Button::Left)) {
-    selectedIndex = (selectedIndex + MENU_ITEMS - 1) % MENU_ITEMS;
-    updateRequired = true;
-  } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-             mappedInput.wasPressed(MappedInputManager::Button::Right)) {
+  // Handle navigation
+  buttonNavigator.onNext([this] {
     selectedIndex = (selectedIndex + 1) % MENU_ITEMS;
     updateRequired = true;
-  }
+  });
+
+  buttonNavigator.onPrevious([this] {
+    selectedIndex = (selectedIndex + MENU_ITEMS - 1) % MENU_ITEMS;
+    updateRequired = true;
+  });
 }
 
 void CalibreSettingsActivity::handleSelection() {

src/activities/settings/CalibreSettingsActivity.h

@@ -6,6 +6,7 @@
 #include <functional>
 
 #include "activities/ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 /**
  * Submenu for OPDS Browser settings.
@@ -24,6 +25,7 @@ class CalibreSettingsActivity final : public ActivityWithSubactivity {
  private:
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
 
   int selectedIndex = 0;

src/activities/settings/CategorySettingsActivity.cpp

@@ -62,15 +62,15 @@ void CategorySettingsActivity::loop() {
   }
 
   // Handle navigation
-  if (mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-      mappedInput.wasPressed(MappedInputManager::Button::Left)) {
-    selectedSettingIndex = (selectedSettingIndex > 0) ? (selectedSettingIndex - 1) : (settingsCount - 1);
+  buttonNavigator.onNext([this] {
+    selectedSettingIndex = (selectedSettingIndex + 1) % settingsCount;
     updateRequired = true;
-  } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-             mappedInput.wasPressed(MappedInputManager::Button::Right)) {
-    selectedSettingIndex = (selectedSettingIndex < settingsCount - 1) ? (selectedSettingIndex + 1) : 0;
+  });
+
+  buttonNavigator.onPrevious([this] {
+    selectedSettingIndex = (selectedSettingIndex + settingsCount - 1) % settingsCount;
     updateRequired = true;
-  }
+  });
 }
 
 void CategorySettingsActivity::toggleCurrentSetting() {

src/activities/settings/CategorySettingsActivity.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "activities/ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 class CrossPointSettings;
 
@@ -44,6 +45,7 @@ struct SettingInfo {
 class CategorySettingsActivity final : public ActivityWithSubactivity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
   int selectedSettingIndex = 0;
   const char* categoryName;

src/activities/settings/KOReaderSettingsActivity.cpp

@@ -63,15 +63,16 @@ void KOReaderSettingsActivity::loop() {
     return;
   }
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-      mappedInput.wasPressed(MappedInputManager::Button::Left)) {
-    selectedIndex = (selectedIndex + MENU_ITEMS - 1) % MENU_ITEMS;
-    updateRequired = true;
-  } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-             mappedInput.wasPressed(MappedInputManager::Button::Right)) {
+  // Handle navigation
+  buttonNavigator.onNext([this] {
     selectedIndex = (selectedIndex + 1) % MENU_ITEMS;
     updateRequired = true;
-  }
+  });
+
+  buttonNavigator.onPrevious([this] {
+    selectedIndex = (selectedIndex + MENU_ITEMS - 1) % MENU_ITEMS;
+    updateRequired = true;
+  });
 }
 
 void KOReaderSettingsActivity::handleSelection() {

src/activities/settings/KOReaderSettingsActivity.h

@@ -6,6 +6,7 @@
 #include <functional>
 
 #include "activities/ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 /**
  * Submenu for KOReader Sync settings.
@@ -24,6 +25,7 @@ class KOReaderSettingsActivity final : public ActivityWithSubactivity {
  private:
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
 
   int selectedIndex = 0;

src/activities/settings/SettingsActivity.cpp

@@ -111,17 +111,15 @@ void SettingsActivity::loop() {
   }
 
   // Handle navigation
-  if (mappedInput.wasPressed(MappedInputManager::Button::Up) ||
-      mappedInput.wasPressed(MappedInputManager::Button::Left)) {
-    // Move selection up (with wrap-around)
-    selectedCategoryIndex = (selectedCategoryIndex > 0) ? (selectedCategoryIndex - 1) : (categoryCount - 1);
+  buttonNavigator.onNext([this] {
+    selectedCategoryIndex = (selectedCategoryIndex + 1) % categoryCount;
     updateRequired = true;
-  } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
-             mappedInput.wasPressed(MappedInputManager::Button::Right)) {
-    // Move selection down (with wrap around)
-    selectedCategoryIndex = (selectedCategoryIndex < categoryCount - 1) ? (selectedCategoryIndex + 1) : 0;
+  });
+
+  buttonNavigator.onPrevious([this] {
+    selectedCategoryIndex = (selectedCategoryIndex + categoryCount - 1) % categoryCount;
     updateRequired = true;
-  }
+  });
 }
 
 void SettingsActivity::enterCategory(int categoryIndex) {

src/activities/settings/SettingsActivity.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "activities/ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
 
 class CrossPointSettings;
 struct SettingInfo;
@@ -15,6 +16,7 @@ struct SettingInfo;
 class SettingsActivity final : public ActivityWithSubactivity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
   int selectedCategoryIndex = 0;  // Currently selected category
   const std::function<void()> onGoHome;

src/activities/util/KeyboardEntryActivity.cpp

@@ -138,37 +138,24 @@ void KeyboardEntryActivity::handleKeyPress() {
 }
 
 void KeyboardEntryActivity::loop() {
-  // Navigation
-  if (mappedInput.wasPressed(MappedInputManager::Button::Up)) {
-    if (selectedRow > 0) {
-      selectedRow--;
-      // Clamp column to valid range for new row
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    } else {
-      // Wrap to bottom row
-      selectedRow = NUM_ROWS - 1;
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    }
-    updateRequired = true;
-  }
+  // Handle navigation
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Up}, [this] {
+    selectedRow = ButtonNavigator::previousIndex(selectedRow, NUM_ROWS);
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Down)) {
-    if (selectedRow < NUM_ROWS - 1) {
-      selectedRow++;
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    } else {
-      // Wrap to top row
-      selectedRow = 0;
-      const int maxCol = getRowLength(selectedRow) - 1;
-      if (selectedCol > maxCol) selectedCol = maxCol;
-    }
+    const int maxCol = getRowLength(selectedRow) - 1;
+    if (selectedCol > maxCol) selectedCol = maxCol;
     updateRequired = true;
-  }
+  });
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Left)) {
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Down}, [this] {
+    selectedRow = ButtonNavigator::nextIndex(selectedRow, NUM_ROWS);
+
+    const int maxCol = getRowLength(selectedRow) - 1;
+    if (selectedCol > maxCol) selectedCol = maxCol;
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Left}, [this] {
     const int maxCol = getRowLength(selectedRow) - 1;
 
     // Special bottom row case
@@ -187,20 +174,14 @@ void KeyboardEntryActivity::loop() {
         // At done button, move to backspace
         selectedCol = BACKSPACE_COL;
       }
-      updateRequired = true;
-      return;
-    }
-
-    if (selectedCol > 0) {
-      selectedCol--;
     } else {
-      // Wrap to end of current row
-      selectedCol = maxCol;
+      selectedCol = ButtonNavigator::previousIndex(selectedCol, maxCol + 1);
     }
-    updateRequired = true;
-  }
 
-  if (mappedInput.wasPressed(MappedInputManager::Button::Right)) {
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPressAndContinuous({MappedInputManager::Button::Right}, [this] {
     const int maxCol = getRowLength(selectedRow) - 1;
 
     // Special bottom row case
@@ -219,18 +200,11 @@ void KeyboardEntryActivity::loop() {
         // At done button, wrap to beginning of row
         selectedCol = SHIFT_COL;
       }
-      updateRequired = true;
-      return;
-    }
-
-    if (selectedCol < maxCol) {
-      selectedCol++;
     } else {
-      // Wrap to beginning of current row
-      selectedCol = 0;
+      selectedCol = ButtonNavigator::nextIndex(selectedCol, maxCol + 1);
     }
     updateRequired = true;
-  }
+  });
 
   // Selection
   if (mappedInput.wasPressed(MappedInputManager::Button::Confirm)) {

src/activities/util/KeyboardEntryActivity.h

@@ -9,6 +9,7 @@
 #include <utility>
 
 #include "../Activity.h"
+#include "util/ButtonNavigator.h"
 
 /**
  * Reusable keyboard entry activity for text input.
@@ -65,6 +66,7 @@ class KeyboardEntryActivity : public Activity {
   bool isPassword;
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
+  ButtonNavigator buttonNavigator;
   bool updateRequired = false;
 
   // Keyboard state

src/main.cpp

@@ -25,6 +25,7 @@
 #include "activities/settings/SettingsActivity.h"
 #include "activities/util/FullScreenMessageActivity.h"
 #include "fontIds.h"
+#include "util/ButtonNavigator.h"
 
 HalDisplay display;
 HalGPIO gpio;
@@ -293,6 +294,7 @@ void setup() {
 
   SETTINGS.loadFromFile();
   KOREADER_STORE.loadFromFile();
+  ButtonNavigator::setMappedInputManager(mappedInputManager);
 
   switch (gpio.getWakeupReason()) {
     case HalGPIO::WakeupReason::PowerButton:

src/util/ButtonNavigator.cpp

@@ -0,0 +1,124 @@
+#include "ButtonNavigator.h"
+
+const MappedInputManager* ButtonNavigator::mappedInput = nullptr;
+
+void ButtonNavigator::onNext(const Callback& callback) {
+  onNextPress(callback);
+  onNextContinuous(callback);
+}
+
+void ButtonNavigator::onPrevious(const Callback& callback) {
+  onPreviousPress(callback);
+  onPreviousContinuous(callback);
+}
+
+void ButtonNavigator::onPressAndContinuous(const Buttons& buttons, const Callback& callback) {
+  onPress(buttons, callback);
+  onContinuous(buttons, callback);
+}
+
+void ButtonNavigator::onNextPress(const Callback& callback) { onPress(getNextButtons(), callback); }
+
+void ButtonNavigator::onPreviousPress(const Callback& callback) { onPress(getPreviousButtons(), callback); }
+
+void ButtonNavigator::onNextRelease(const Callback& callback) { onRelease(getNextButtons(), callback); }
+
+void ButtonNavigator::onPreviousRelease(const Callback& callback) { onRelease(getPreviousButtons(), callback); }
+
+void ButtonNavigator::onNextContinuous(const Callback& callback) { onContinuous(getNextButtons(), callback); }
+
+void ButtonNavigator::onPreviousContinuous(const Callback& callback) { onContinuous(getPreviousButtons(), callback); }
+
+void ButtonNavigator::onPress(const Buttons& buttons, const Callback& callback) {
+  const bool wasPressed = std::any_of(buttons.begin(), buttons.end(), [](const MappedInputManager::Button button) {
+    return mappedInput != nullptr && mappedInput->wasPressed(button);
+  });
+
+  if (wasPressed) {
+    callback();
+  }
+}
+
+void ButtonNavigator::onRelease(const Buttons& buttons, const Callback& callback) {
+  const bool wasReleased = std::any_of(buttons.begin(), buttons.end(), [](const MappedInputManager::Button button) {
+    return mappedInput != nullptr && mappedInput->wasReleased(button);
+  });
+
+  if (wasReleased) {
+    if (lastContinuousNavTime == 0) {
+      callback();
+    }
+
+    lastContinuousNavTime = 0;
+  }
+}
+
+void ButtonNavigator::onContinuous(const Buttons& buttons, const Callback& callback) {
+  const bool isPressed = std::any_of(buttons.begin(), buttons.end(), [this](const MappedInputManager::Button button) {
+    return mappedInput != nullptr && mappedInput->isPressed(button) && shouldNavigateContinuously();
+  });
+
+  if (isPressed) {
+    callback();
+    lastContinuousNavTime = millis();
+  }
+}
+
+bool ButtonNavigator::shouldNavigateContinuously() const {
+  if (!mappedInput) return false;
+
+  const bool buttonHeldLongEnough = mappedInput->getHeldTime() > continuousStartMs;
+  const bool navigationIntervalElapsed = (millis() - lastContinuousNavTime) > continuousIntervalMs;
+
+  return buttonHeldLongEnough && navigationIntervalElapsed;
+}
+
+int ButtonNavigator::nextIndex(const int currentIndex, const int totalItems) {
+  if (totalItems <= 0) return 0;
+
+  // Calculate the next index with wrap-around
+  return (currentIndex + 1) % totalItems;
+}
+
+int ButtonNavigator::previousIndex(const int currentIndex, const int totalItems) {
+  if (totalItems <= 0) return 0;
+
+  // Calculate the previous index with wrap-around
+  return (currentIndex + totalItems - 1) % totalItems;
+}
+
+int ButtonNavigator::nextPageIndex(const int currentIndex, const int totalItems, const int itemsPerPage) {
+  if (totalItems <= 0 || itemsPerPage <= 0) return 0;
+
+  // When items fit on one page, use index navigation instead
+  if (totalItems <= itemsPerPage) {
+    return nextIndex(currentIndex, totalItems);
+  }
+
+  const int lastPageIndex = (totalItems - 1) / itemsPerPage;
+  const int currentPageIndex = currentIndex / itemsPerPage;
+
+  if (currentPageIndex < lastPageIndex) {
+    return (currentPageIndex + 1) * itemsPerPage;
+  }
+
+  return 0;
+}
+
+int ButtonNavigator::previousPageIndex(const int currentIndex, const int totalItems, const int itemsPerPage) {
+  if (totalItems <= 0 || itemsPerPage <= 0) return 0;
+
+  // When items fit on one page, use index navigation instead
+  if (totalItems <= itemsPerPage) {
+    return previousIndex(currentIndex, totalItems);
+  }
+
+  const int lastPageIndex = (totalItems - 1) / itemsPerPage;
+  const int currentPageIndex = currentIndex / itemsPerPage;
+
+  if (currentPageIndex > 0) {
+    return (currentPageIndex - 1) * itemsPerPage;
+  }
+
+  return lastPageIndex * itemsPerPage;
+}

src/util/ButtonNavigator.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <functional>
+#include <vector>
+
+#include "MappedInputManager.h"
+
+class ButtonNavigator final {
+  using Callback = std::function<void()>;
+  using Buttons = std::vector<MappedInputManager::Button>;
+
+  const uint16_t continuousStartMs;
+  const uint16_t continuousIntervalMs;
+  uint32_t lastContinuousNavTime = 0;
+  static const MappedInputManager* mappedInput;
+
+  [[nodiscard]] bool shouldNavigateContinuously() const;
+
+ public:
+  explicit ButtonNavigator(const uint16_t continuousIntervalMs = 500, const uint16_t continuousStartMs = 500)
+      : continuousStartMs(continuousStartMs), continuousIntervalMs(continuousIntervalMs) {}
+
+  static void setMappedInputManager(const MappedInputManager& mappedInputManager) { mappedInput = &mappedInputManager; }
+
+  void onNext(const Callback& callback);
+  void onPrevious(const Callback& callback);
+  void onPressAndContinuous(const Buttons& buttons, const Callback& callback);
+
+  void onNextPress(const Callback& callback);
+  void onPreviousPress(const Callback& callback);
+  void onPress(const Buttons& buttons, const Callback& callback);
+
+  void onNextRelease(const Callback& callback);
+  void onPreviousRelease(const Callback& callback);
+  void onRelease(const Buttons& buttons, const Callback& callback);
+
+  void onNextContinuous(const Callback& callback);
+  void onPreviousContinuous(const Callback& callback);
+  void onContinuous(const Buttons& buttons, const Callback& callback);
+
+  [[nodiscard]] static int nextIndex(int currentIndex, int totalItems);
+  [[nodiscard]] static int previousIndex(int currentIndex, int totalItems);
+
+  [[nodiscard]] static int nextPageIndex(int currentIndex, int totalItems, int itemsPerPage);
+  [[nodiscard]] static int previousPageIndex(int currentIndex, int totalItems, int itemsPerPage);
+
+  [[nodiscard]] static Buttons getNextButtons() {
+    return {MappedInputManager::Button::Down, MappedInputManager::Button::Right};
+  }
+  [[nodiscard]] static Buttons getPreviousButtons() {
+    return {MappedInputManager::Button::Up, MappedInputManager::Button::Left};
+  }
+};

src/util/StringUtils.cpp

@@ -61,23 +61,4 @@ bool checkFileExtension(const String& fileName, const char* extension) {
   return localFile.endsWith(localExtension);
 }
 
-size_t utf8RemoveLastChar(std::string& str) {
-  if (str.empty()) return 0;
-  size_t pos = str.size() - 1;
-  // Walk back to find the start of the last UTF-8 character
-  // UTF-8 continuation bytes start with 10xxxxxx (0x80-0xBF)
-  while (pos > 0 && (static_cast<unsigned char>(str[pos]) & 0xC0) == 0x80) {
-    --pos;
-  }
-  str.resize(pos);
-  return pos;
-}
-
-// Truncate string by removing N UTF-8 characters from the end
-void utf8TruncateChars(std::string& str, const size_t numChars) {
-  for (size_t i = 0; i < numChars && !str.empty(); ++i) {
-    utf8RemoveLastChar(str);
-  }
-}
-
 }  // namespace StringUtils

src/util/StringUtils.h

@@ -19,10 +19,4 @@ std::string sanitizeFilename(const std::string& name, size_t maxLength = 100);
 bool checkFileExtension(const std::string& fileName, const char* extension);
 bool checkFileExtension(const String& fileName, const char* extension);
 
-// UTF-8 safe string truncation - removes one character from the end
-// Returns the new size after removing one UTF-8 character
-size_t utf8RemoveLastChar(std::string& str);
-
-// Truncate string by removing N UTF-8 characters from the end
-void utf8TruncateChars(std::string& str, size_t numChars);
 }  // namespace StringUtils