GUID

gistfile1.rb

        class GUID < FFI::Struct
          layout :data1, :int32,
                 :data2, :int16,
                 :data3, :int16,
                 :data4_0, :int8,
                 :data4_1, :int8,
                 :data4_2, :int8,
                 :data4_3, :int8,
                 :data4_4, :int8,
                 :data4_5, :int8,
                 :data4_6, :int8,
                 :data4_7, :int8,
        end

        class IAccessible < FFI::Struct
          layout :lpVtbl, :pointer
        end

        class IAccessibleVtbl < FFI::Struct
          layout  :QueryInterface, :pointer,
            :AddRef, :pointer,
            :Release, :pointer,
            :GetTypeInfoCount, :pointer,
            :GetTypeInfo, :pointer,
            :GetIDsOfNames, :pointer,
            :Invoke, :pointer,
            :get_accParent, :pointer,
            :get_accChildCount, :pointer,
            :get_accChild, :pointer,
            :get_accName, :pointer,
            :get_accValue, :pointer,
            :get_accDescription, :pointer,
            :get_accRole, :pointer,
            :get_accState, :pointer,
            :get_accHelp, :pointer,
            :get_accHelpTopic, :pointer,
            :get_accKeyboardShortcut, :pointer,
            :get_accFocus, :pointer,
            :get_accSelection, :pointer,
            :get_accDefaultAction, :pointer,
            :accSelect, :pointer,
            :accLocation, :pointer,
            :accNavigate, :pointer,
            :accHitTest, :pointer,
            :accDoDefaultAction, :pointer,
            :put_accName, :pointer,
            :put_accValue, :pointer
        end

        class Variant < FFI::Struct
          layout :vt, :long,
              :wReserved1, :uint,
              :wReserved2, :uint,
              :wReserved3, :uint,
              :lVal, :long
        end

        S_OK = 0
        E_INVALIDARG = 0x80070057
        E_NOINTERFACE = 0x80004002

 

          def state_of_accessible_button(hwnd)
            co_initialize nil

            module_handle = load_library "oleacc.dll"
            if (module_handle != 0)
              address_accessible_object_from_window = get_proc_address(module_handle, "AccessibleObjectFromWindow")

                guid = GUID.new
                guid[:data1] = 0x618736e0
                guid[:data2] = 0x3c3d
                guid[:data3] = 0x11cf
                guid[:data4_0] = 0x81
                guid[:data4_1] = 0x0c
                guid[:data4_2] = 0x00
                guid[:data4_3] = 0xaa
                guid[:data4_4] = 0x00
                guid[:data4_5] = 0x38
                guid[:data4_6] = 0x9b
                guid[:data4_7] = 0x71

              i_accessible_ptr =  FFI::MemoryPointer.new(:pointer)
              accessible_object_from_window = FFI::Function.new(:uint32, [:long, :uint32, :pointer, :pointer ], address_accessible_object_from_window)
              hResult = accessible_object_from_window.call(hwnd, 0xFFFFFFFC, guid, i_accessible_ptr)  # for OBJID_CLIENT
              if (hResult == S_OK)
                i_accessible = IAccessible.new(i_accessible_ptr.read_pointer)
                i_accessible_vtbl = IAccessibleVtbl.new(i_accessible[:lpVtbl])

                get_accState = FFI::Function.new(:uint32, [:pointer, :pointer, :pointer], i_accessible_vtbl[:get_accState])

                variant_in = Variant.new
                variant_in[:vt] = 3
                variant_in[:lVal] = 0  # CHILDID_SELF

                variant_out = Variant.new

                result = get_accState.call(i_accessible, variant_in, variant_out)   # segfault
                puts "result" + result.to_s
                puts "variant_out" + variant_out[:lVal]
              end
              if (hResult == E_INVALIDARG)
                puts "E_INVALIDARG"
              end
              if (hResult == E_NOINTERFACE)
                puts "E_NOINTERFACE"
              end
              puts "hResult = 0x" + hResult.to_s(16)
            end
            co_uninitialize
          end