Add proper icon and bitmap support for Windows menu items

Implements handling of menu item icons with transparency by converting images to HICON and drawing them onto a 32-bit ARGB bitmap with system menu background color. Ensures cleanup of icon and bitmap resources, and sets the bitmap on the menu item for correct display in Windows menus.

Author: lijy91

src/platform/windows/menu_windows.cpp

@@ -1,4 +1,5 @@
 #include <windows.h>
+#include <cstring>
 #include <functional>
 #include <iostream>
 #include <memory>
@@ -13,6 +14,8 @@
 
 namespace nativeapi {
 
+HICON ImageToHICON(const Image* image, int width, int height);
+
 // Helper function to convert KeyboardAccelerator to Windows accelerator
 std::pair<UINT, UINT> ConvertAccelerator(const KeyboardAccelerator& accelerator) {
   UINT key = 0;
@@ -95,6 +98,8 @@ class MenuItem::Impl {
   MenuItemType type_;
   std::optional<std::string> label_;
   std::shared_ptr<Image> image_;
+  HICON menu_icon_;  // Stored icon for menu item with transparency support
+  HBITMAP menu_bitmap_;  // Stored bitmap with icon drawn on menu background
   std::optional<std::string> tooltip_;
   KeyboardAccelerator accelerator_;
   bool has_accelerator_;
@@ -110,6 +115,8 @@ class MenuItem::Impl {
       : id_(id),
         parent_menu_(parent_menu),
         type_(type),
+        menu_icon_(nullptr),
+        menu_bitmap_(nullptr),
         accelerator_("", KeyboardAccelerator::None),
         has_accelerator_(false),
         state_(MenuItemState::Unchecked),
@@ -134,6 +141,18 @@ class MenuItem::Impl {
       submenu_closed_listener_id_ = 0;
     }
 
+    // Clean up menu icon
+    if (menu_icon_) {
+      DestroyIcon(menu_icon_);
+      menu_icon_ = nullptr;
+    }
+    
+    // Clean up menu bitmap
+    if (menu_bitmap_) {
+      DeleteObject(menu_bitmap_);
+      menu_bitmap_ = nullptr;
+    }
+
     // Windows menu items are automatically cleaned up when the menu is
     // destroyed
   }
@@ -225,9 +244,77 @@ std::optional<std::string> MenuItem::GetLabel() const {
 }
 
 void MenuItem::SetIcon(std::shared_ptr<Image> image) {
+  // Clean up previous resources
+  if (pimpl_->menu_icon_) {
+    DestroyIcon(pimpl_->menu_icon_);
+    pimpl_->menu_icon_ = nullptr;
+  }
+  if (pimpl_->menu_bitmap_) {
+    DeleteObject(pimpl_->menu_bitmap_);
+    pimpl_->menu_bitmap_ = nullptr;
+  }
+
   pimpl_->image_ = image;
-  // Windows menu icons would require HBITMAP handling
-  // This is a placeholder implementation
+
+  if (image && pimpl_->parent_menu_) {
+    // Use 32x32 for menu icons
+    const int iconSize = 32;
+    
+    // Convert image to HICON first for proper transparency support
+    HICON hIcon = ImageToHICON(image.get(), iconSize, iconSize);
+    
+    if (hIcon) {
+      pimpl_->menu_icon_ = hIcon;
+      
+      // Create a 32-bit ARGB bitmap
+      HDC hdc = GetDC(nullptr);
+      
+      // Create BITMAPINFO for 32-bit ARGB
+      BITMAPINFO bmi = {};
+      bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
+      bmi.bmiHeader.biWidth = iconSize;
+      bmi.bmiHeader.biHeight = -iconSize;  // Negative for top-down DIB
+      bmi.bmiHeader.biPlanes = 1;
+      bmi.bmiHeader.biBitCount = 32;
+      bmi.bmiHeader.biCompression = BI_RGB;
+      
+      void* pBits = nullptr;
+      HBITMAP hBmp = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, &pBits, nullptr, 0);
+      
+      if (hBmp && pBits) {
+        // Fill with system menu background color
+        COLORREF bgColor = GetSysColor(COLOR_MENU);
+        DWORD bgPixel = (0xFF << 24) | (GetRValue(bgColor) << 16) | (GetGValue(bgColor) << 8) | GetBValue(bgColor);
+        
+        DWORD* pixels = static_cast<DWORD*>(pBits);
+        for (int i = 0; i < iconSize * iconSize; i++) {
+          pixels[i] = bgPixel;  // System menu background color (ARGB)
+        }
+        
+        // Draw the icon on the bitmap
+        HDC hdcMem = CreateCompatibleDC(hdc);
+        HBITMAP hOldBmp = (HBITMAP)SelectObject(hdcMem, hBmp);
+        
+        // Draw icon with proper blending
+        DrawIconEx(hdcMem, 0, 0, hIcon, iconSize, iconSize, 0, nullptr, DI_NORMAL);
+        
+        SelectObject(hdcMem, hOldBmp);
+        DeleteDC(hdcMem);
+        
+        // Store the bitmap for cleanup
+        pimpl_->menu_bitmap_ = hBmp;
+        
+        // Set the bitmap on the menu item
+        MENUITEMINFOW mii = {};
+        mii.cbSize = sizeof(MENUITEMINFOW);
+        mii.fMask = MIIM_BITMAP;
+        mii.hbmpItem = hBmp;
+        SetMenuItemInfoW(pimpl_->parent_menu_, pimpl_->id_, FALSE, &mii);
+      }
+      
+      ReleaseDC(nullptr, hdc);
+    }
+  }
 }
 
 std::shared_ptr<Image> MenuItem::GetIcon() const {