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
#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;
}