Windows Objects

Windows Objects

Many of the API functions create objects of some sort, which you then manipulate and destroy with other API functions. For example you could create a window, move it, resize it and destroy it. Generally the function that creates the object returns a handle to it, which you pass to the other functions that use this object. There are really two kinds of objects: kernel objects and non-kernel objects. Non kernel objects are usually grouped into user objects and GDI objects.

• Kernel Objects. These are owned and managed by the kernel, not by individual processes. All kernel objects have a name, security descriptor and a usage count. Other attributes are specific to a kind of kernel object; processes have process IDs and a base priority, semaphores have a maximum count, etc.
  Examples:

  Process              File Mapping  Event
  Thread               Heap          Timer
  Module               Pipe          Communications Device
  File                 Mailslot      Update Resource
  Change Notification  Mutex         Event Log
  Find file            Semaphore
  

• User Objects. These objects are user-interface related. They are owned by a process, except for Windows and Hooks, which are owned by threads.
  Examples:

  Window           Accelerator Table  Hook
  Window Position  Icon               Desktop
  Window Station   Cursor             DDE Conversation
  Menu             Caret
  

• GDI Objects: These objects deal primarily with drawing.
  Examples:

  Pen       Region              DC
  Brush     Font                Memory DC
  Palette   Metafile            Metafile DC
  Bitmap    Enhanced Metafile   Enhanced Metafile DC