View source for WpQueryHandleFromContents

{{DISPLAYTITLE:wpQueryHandleFromContents}}
This method is specific to Version 4, or higher, of the OS/2 operating system.

This instance method returns a handle to a known system data type based on a file's contents. This is an abstract method; subclasses that describe files for which a system handle type exist (such as [[WPIcon]] or [[WPBitmap]]) should subclass this method.

==Syntax==
 _wpQueryHandleFromContents(somSelf)

==Parameters==
;''somSelf'' ([[WPDataFile]] *) - input
:Pointer to the object on which the method is being invoked.
:Points to an object of class [[WPDataFile]].

==Returns==
;''handle'' ([[LHANDLE]]) - returns
:Handle to the data type object (or **NULLHANDLE** if call is unsuccessful).

==How to Override==
This method should be overridden in any subclass of [[WPDataFile]] that can represent its data with a handle.

==Usage==
This method can be called at any time to obtain a handle that represents the data in the data file corresponding to this data file object.

== Remarks ==
The handle returned by this method is data type specific. For example, an Image File object will return a handle to a bitmap (that is, an **HBITMAP**), while an Icon or Pointer might return a handle to a pointer (such as an **HPOINTER**).

==Example Code==
<PRE>
#define INCL_WINWORKPLACE
#include <os2.h>

WPDataFile *somSelf; /* Pointer to the object on which the method is being invoked. */
LHANDLE handle; /* Handle to the data type object (or NULLHANDLE if call is unsuccessful). */

handle = _wpQueryHandleFromContents(somSelf);

/* Example code from the Image File class: */
SOM_Scope LHANDLE SOMLINK img_wpQueryHandleFromContents(WPImageFile
*somSelf)
{
    HBITMAP hBitmap = NULLHANDLE;

    _wpQueryBitmapHandle(somSelf,&hBitmap,NULL,0,0,0,RGB_BLACK,NULL);
    return hBitmap;
}
</PRE>

== Related Methods==
* [[wpQueryPointerFromContents]]
* [[wpSetContentsFromHandle]]
* [[wpSetContentsFromPointer]]

[[Category:Workplace Instance Methods]]