Class: Win32::API::Function

Inherits:

Win32::API

• Object
• Win32::API
• Win32::API::Function

Defined in:

ext/win32/api.c

Constant Summary

Constants inherited from Win32::API

VERSION

Instance Attribute Summary

• #address ⇒ Object readonly

Attributes inherited from Win32::API

#dll_name, #effective_function_name, #function_name, #prototype, #return_type

Instance Method Summary

• #API::Function.new(address, prototype = 'V', return_type = 'L') ⇒ Object constructor

  Creates and returns an API::Function object.

Methods inherited from Win32::API

#call

Constructor Details

#API::Function.new(address, prototype = 'V', return_type = 'L') ⇒ Object

Creates and returns an API::Function object. This object is similar to an API object, except that instead of a character function name you pass a function pointer address as the first argument, and there’s no associated DLL file.

Once you have your API::Function object you can then call it the same way you would an API object.

Example:

require 'win32/api'
include Win32

LoadLibrary = API.new('LoadLibrary', 'P', 'L')
GetProcAddress = API.new('GetProcAddress', 'LP', 'L')

# Play a system beep
hlib = LoadLibrary.call('user32')
addr = GetProcAddress.call(hlib, 'MessageBeep')
func = Win32::API::Function.new(addr, 'L', 'L')
func.call(0)

# File 'ext/win32/api.c', line 432

static VALUE func_init(int argc, VALUE* argv, VALUE self){
   Win32API* ptr;
   int i;
   VALUE v_address, v_proto, v_return;

   rb_scan_args(argc, argv, "12", &v_address, &v_proto, &v_return);

   Data_Get_Struct(self, Win32API, ptr);

   // Convert a string prototype to an array of characters
   if(rb_respond_to(v_proto, rb_intern("split")))
      v_proto = rb_str_split(v_proto, "");

   // Convert a nil or empty prototype to 'V' (void) automatically
   if(NIL_P(v_proto) || RARRAY_LEN(v_proto) == 0){
      v_proto = rb_ary_new();
      rb_ary_push(v_proto, rb_str_new2("V"));
   }

   // Set an arbitrary limit of 20 parameters
   if(20 < RARRAY_LEN(v_proto))
      rb_raise(rb_eArgError, "too many parameters: %d\n", RARRAY_LEN(v_proto));

   // Set the default return type to 'L' (DWORD)
   if(NIL_P(v_return))
      v_return = rb_str_new2("L");

   ptr->function = (FARPROC)NUM2LONG(v_address);

   // Push the numeric prototypes onto our int array for later use.

   for(i = 0; i < RARRAY_LEN(v_proto); i++){
      SafeStringValue(RARRAY_PTR(v_proto)[i]);
      switch(*(char*)StringValuePtr(RARRAY_PTR(v_proto)[i])){
         case 'L':
            ptr->prototype[i] = _T_LONG;
            break;
         case 'P':
            ptr->prototype[i] = _T_POINTER;
            break;
         case 'I': case 'B':
            ptr->prototype[i] = _T_INTEGER;
            break;
         case 'V':
            ptr->prototype[i] = _T_VOID;
            break;
         case 'K':
            ptr->prototype[i] = _T_CALLBACK;
            break;
         case 'S':
            ptr->prototype[i] = _T_STRING;
            break;
         default:
            rb_raise(cAPIProtoError, "Illegal prototype '%s'",
               StringValuePtr(RARRAY_PTR(v_proto)[i])
            );
      }
   }

   // Store the return type for later use.

   // Automatically convert empty strings or nil to type void.
   if(NIL_P(v_return) || RSTRING_LEN(v_return) == 0){
      v_return = rb_str_new2("V");
      ptr->return_type = _T_VOID;
   }
   else{
      SafeStringValue(v_return);
      switch(*RSTRING_PTR(v_return)){
         case 'L':
            ptr->return_type = _T_LONG;
            break;
         case 'P':
            ptr->return_type = _T_POINTER;
            break;
         case 'I': case 'B':
            ptr->return_type = _T_INTEGER;
            break;
         case 'V':
            ptr->return_type = _T_VOID;
            break;
         case 'S':
            ptr->return_type = _T_STRING;
            break;
         default:
            rb_raise(cAPIProtoError, "Illegal return type '%s'",
               RSTRING_PTR(v_return)
            );
      }
   }

   rb_iv_set(self, "@address", v_address);
   rb_iv_set(self, "@prototype", v_proto);
   rb_iv_set(self, "@return_type", v_return);

   return self;
}

Instance Attribute Details

#address ⇒ Object (readonly)