feat: bug fixes and optimizations

- fix double-free
- safe int/float parse
- grid division guard
- list string allocations
- label vector reserve
- skip second layout pass for hstack/vstack

lib/ThemeEngine/include/BasicElements.h

@@ -11,6 +11,22 @@
 
 namespace ThemeEngine {
 
+// Safe integer parsing (no exceptions)
+inline int parseIntSafe(const std::string& s, int defaultVal = 0) {
+  if (s.empty()) return defaultVal;
+  char* end;
+  long val = strtol(s.c_str(), &end, 10);
+  return (end != s.c_str()) ? static_cast<int>(val) : defaultVal;
+}
+
+// Safe float parsing (no exceptions)
+inline float parseFloatSafe(const std::string& s, float defaultVal = 0.0f) {
+  if (s.empty()) return defaultVal;
+  char* end;
+  float val = strtof(s.c_str(), &end);
+  return (end != s.c_str()) ? val : defaultVal;
+}
+
 // --- Container ---
 class Container : public UIElement {
  protected:
@@ -263,8 +279,8 @@ class ProgressBar : public UIElement {
     std::string valStr = context.evaluatestring(valueExpr);
     std::string maxStr = context.evaluatestring(maxExpr);
 
-    int value = valStr.empty() ? 0 : std::stoi(valStr);
-    int maxVal = maxStr.empty() ? 100 : std::stoi(maxStr);
+    int value = parseIntSafe(valStr, 0);
+    int maxVal = parseIntSafe(maxStr, 100);
     if (maxVal <= 0) maxVal = 100;
 
     float ratio = static_cast<float>(value) / static_cast<float>(maxVal);
@@ -367,7 +383,7 @@ class BatteryIcon : public UIElement {
     if (!isVisible(context)) return;
 
     std::string valStr = context.evaluatestring(valueExpr);
-    int percentage = valStr.empty() ? 0 : std::stoi(valStr);
+    int percentage = parseIntSafe(valStr, 0);
 
     std::string colStr = context.evaluatestring(colorExpr);
     uint8_t color = Color::parse(colStr).value;

lib/ThemeEngine/include/LayoutElements.h

@@ -85,7 +85,11 @@ class HStack : public Container {
       // Add child's own Y offset to the calculated position
       childY += childYOffset;
 
-      child->layout(context, currentX, childY, childW, childH);
+      // Only do second layout pass if position changed from first pass
+      int firstPassY = child->getAbsY();
+      if (childY != firstPassY) {
+        child->layout(context, currentX, childY, childW, childH);
+      }
       currentX += childW + spacing;
       availableW -= (childW + spacing);
       if (availableW < 0) availableW = 0;
@@ -168,7 +172,11 @@ class VStack : public Container {
       // Add child's own X offset to the calculated position
       childX += childXOffset;
 
-      child->layout(context, childX, currentY, childW, childH);
+      // Only do second layout pass if position changed from first pass
+      int firstPassX = child->getAbsX();
+      if (childX != firstPassX) {
+        child->layout(context, childX, currentY, childW, childH);
+      }
       currentY += childH + spacing;
       availableH -= (childH + spacing);
       if (availableH < 0) availableH = 0;
@@ -211,8 +219,10 @@ class Grid : public Container {
 
     if (children.empty()) return;
 
-    int availableW = absW - 2 * padding - (columns - 1) * colSpacing;
-    int cellW = availableW / columns;
+    // Guard against division by zero
+    int cols = columns > 0 ? columns : 1;
+    int availableW = absW - 2 * padding - (cols - 1) * colSpacing;
+    int cellW = availableW / cols;
     int availableH = absH - 2 * padding;
 
     int row = 0, col = 0;
@@ -228,7 +238,7 @@ class Grid : public Container {
       if (childH > maxRowHeight) maxRowHeight = childH;
 
       col++;
-      if (col >= columns) {
+      if (col >= cols) {
         col = 0;
         row++;
         currentY += maxRowHeight + rowSpacing;
@@ -587,15 +597,7 @@ class TabBar : public Container {
     // Draw selection indicator
     if (showIndicator && !children.empty()) {
       std::string selStr = context.evaluatestring(selectedExpr);
-      int selectedIdx = 0;
-      if (!selStr.empty()) {
-        // Try to parse as number
-        try {
-          selectedIdx = std::stoi(selStr);
-        } catch (...) {
-          selectedIdx = 0;
-        }
-      }
+      int selectedIdx = parseIntSafe(selStr, 0);
 
       if (selectedIdx >= 0 && selectedIdx < static_cast<int>(children.size())) {
         UIElement* tab = children[selectedIdx];
@@ -686,9 +688,9 @@ class ScrollIndicator : public UIElement {
     std::string totalStr = context.evaluatestring(totalExpr);
     std::string visStr = context.evaluatestring(visibleExpr);
 
-    float position = posStr.empty() ? 0 : std::stof(posStr);
-    int total = totalStr.empty() ? 1 : std::stoi(totalStr);
-    int visible = visStr.empty() ? 1 : std::stoi(visStr);
+    float position = parseFloatSafe(posStr, 0.0f);
+    int total = parseIntSafe(totalStr, 1);
+    int visible = parseIntSafe(visStr, 1);
 
     if (total <= visible) {
       // No need to show scrollbar

lib/ThemeEngine/include/ThemeManager.h

@@ -26,6 +26,7 @@ struct ScreenCache {
   uint32_t contextHash = 0;  // Hash of context data to detect changes
   bool valid = false;
 
+  ScreenCache() = default;
   ~ScreenCache() {
     if (buffer) {
       free(buffer);
@@ -33,6 +34,37 @@ struct ScreenCache {
     }
   }
 
+  // Prevent double-free from copy
+  ScreenCache(const ScreenCache&) = delete;
+  ScreenCache& operator=(const ScreenCache&) = delete;
+
+  // Allow move
+  ScreenCache(ScreenCache&& other) noexcept
+      : buffer(other.buffer),
+        bufferSize(other.bufferSize),
+        screenName(std::move(other.screenName)),
+        contextHash(other.contextHash),
+        valid(other.valid) {
+    other.buffer = nullptr;
+    other.bufferSize = 0;
+    other.valid = false;
+  }
+
+  ScreenCache& operator=(ScreenCache&& other) noexcept {
+    if (this != &other) {
+      if (buffer) free(buffer);
+      buffer = other.buffer;
+      bufferSize = other.bufferSize;
+      screenName = std::move(other.screenName);
+      contextHash = other.contextHash;
+      valid = other.valid;
+      other.buffer = nullptr;
+      other.bufferSize = 0;
+      other.valid = false;
+    }
+    return *this;
+  }
+
   void invalidate() { valid = false; }
 };
 

lib/ThemeEngine/src/BasicElements.cpp

@@ -126,6 +126,7 @@ void Label::draw(const GfxRenderer& renderer, const ThemeContext& context) {
   int lineHeight = renderer.getLineHeight(fontId);
 
   std::vector<std::string> lines;
+  lines.reserve(maxLines);  // Pre-allocate to avoid reallocations
   if (absW > 0 && textWidth > absW && maxLines > 1) {
     // Logic to wrap text
     std::string remaining = finalStr;
@@ -374,6 +375,13 @@ void List::draw(const GfxRenderer& renderer, const ThemeContext& context) {
   int itemW = getItemWidth();
   int itemH = getItemHeight();
 
+  // Pre-allocate string buffers to avoid repeated allocations
+  std::string prefix;
+  prefix.reserve(source.length() + 16);
+  std::string key;
+  key.reserve(source.length() + 32);
+  char numBuf[12];
+
   // Handle different layout modes
   if (direction == Direction::Horizontal || layoutMode == LayoutMode::Grid) {
     // Horizontal or Grid layout
@@ -389,9 +397,16 @@ void List::draw(const GfxRenderer& renderer, const ThemeContext& context) {
     }
 
     for (int i = 0; i < count; ++i) {
+      // Build prefix efficiently: "source.i."
+      prefix.clear();
+      prefix += source;
+      prefix += '.';
+      snprintf(numBuf, sizeof(numBuf), "%d", i);
+      prefix += numBuf;
+      prefix += '.';
+
       // Create item context with scoped variables
       ThemeContext itemContext(&context);
-      std::string prefix = source + "." + std::to_string(i) + ".";
 
       // Standard list item variables - include all properties for full flexibility
       std::string nameVal = context.getString(prefix + "Name");
@@ -470,9 +485,16 @@ void List::draw(const GfxRenderer& renderer, const ThemeContext& context) {
         break;
       }
 
+      // Build prefix efficiently: "source.i."
+      prefix.clear();
+      prefix += source;
+      prefix += '.';
+      snprintf(numBuf, sizeof(numBuf), "%d", i);
+      prefix += numBuf;
+      prefix += '.';
+
       // Create item context with scoped variables
       ThemeContext itemContext(&context);
-      std::string prefix = source + "." + std::to_string(i) + ".";
 
       // Standard list item variables - include all properties for full flexibility
       std::string nameVal = context.getString(prefix + "Name");

lib/ThemeEngine/src/ThemeManager.cpp

@@ -55,9 +55,6 @@ UIElement* ThemeManager::createElement(const std::string& id, const std::string&
   return nullptr;
 }
 
-// Parse integer safely - returns 0 on error
-static int parseIntSafe(const std::string& val) { return static_cast<int>(std::strtol(val.c_str(), nullptr, 10)); }
-
 void ThemeManager::applyProperties(UIElement* elem, const std::map<std::string, std::string>& props) {
   const auto elemType = elem->getType();