c++ - Ruby win32 API 接口(interface)

Question

我需要访问 ruby​​ 中 win32 库的一些函数。我在网上发现关于 Win32API 类的信息非常稀少，所以我在这里问一下。

我知道你可以这样做:

function = Win32API.new('user32','MessageBox',['L', 'P', 'P', 'L'],'I')

但我似乎无法使用当前的 win32 绑定(bind)调用此函数:

http://msdn.microsoft.com/en-us/library/bb762108%28VS.85%29.aspx

问题出在它的原型(prototype)上:

UINT_PTR SHAppBarMessage(      
    DWORD dwMessage,
    PAPPBARDATA pData
);

我将能够使用 win32 ruby​​ 绑定(bind)来获取返回类型和第一个参数，但是，第二个参数需要一个结构。结构体定义如下:

typedef struct _AppBarData {
    DWORD cbSize;
    HWND hWnd;
    UINT uCallbackMessage;
    UINT uEdge;
    RECT rc;
    LPARAM lParam;
} APPBARDATA, *PAPPBARDATA;

我尝试使用这两种方法定义此 api 方法:

api = Win32API.new('shell32','SHAppBarMessage',['L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L'],'I') 

和

api = Win32API.new('shell32','SHAppBarMessage',['L', 'LLLLLLLL'],'I')

但第一个在“call”方法期间出现段错误，第二个由于在“call”方法调用中指定的参数数量错误而无法运行。有什么方法可以公开此 api 函数而无需求助于在 C++ 中创建外部模块？

谢谢。

Answer 1

诀窍是使用“P”作为所有指针参数的格式说明符。您必须提供一个字符串作为指向区域。

当然，您必须确保这些字符串具有正确的预期大小，否则会发生不好的事情。

你可以直接创建这些字符串

# Mostly useful when the area will be totally overwritten
pointed_to_area = "\0" * n

或者使用更文明的Array#pack

# Allows you to control how ruby values get encoded in the buffer
pointed_to_area = [1, 2, 3, 4].pack('SsLI')

希望这对您有所帮助。

---

以下在我的 XP 盒子上使用旧的 ruby​​ 1.8.2 工作:

require 'Win32API'


module Win32
  # This method is only here for test purposes
  # Be careful to use the ascii version
  FindWindow = Win32API.new('user32', 'FindWindowA', ['P', 'P'], 'L')
  def self.findWindow(lpClassName, lpWindowName)
    h = FindWindow.call(lpClassName, lpWindowName)
    raise "FindWindow failed" if h == 0
    h
  end

  # From winddef.h
  RECT = Struct.new(:left, :top, :right, :bottom)
  RECT.class_eval do
    def pack
      [left, top, right, bottom].pack('l4')
    end
    def self.unpack(s)
      new(*s.unpack('l4'))
    end
  end

  # From shellapi.h
  APPBARDATA = Struct.new(:cbSize, :hWnd, :uCallbackMessage, :uEdge, :rc, :lParam)
  APPBARDATA.class_eval do
    def pack
      unless rc.is_a? RECT
        raise ArgumentError, ":rc must be an instance of Win32::RECT, got #{rc.inspect}"
      end
      # DWORD + HWND + UINT + UINT + RECT + LPARAM
      cbSize = 4 + 4 + 4 + 4 + 16 + 4
      [cbSize, hWnd, uCallbackMessage, uEdge, rc.pack, lParam].pack('L2I2a16L')
    end
    def self.unpack(s)
      tmp = self.new(*s.unpack('L2I2a16L'))
      tmp.rc = RECT.unpack(tmp.rc)
      tmp
    end
  end
  SHAppBarMessage = Win32API.new('shell32', 'SHAppBarMessage', ['L', 'P'], 'L')

  # Calls SHAppBarMessage and returns the altered APPBARDATA
  def self.shAppBarMessage(dwMessage, appBarData)
    s = appBarData.pack
    ok = (SHAppBarMessage.call(dwMessage, s) != 0)
    raise "SHAppBarMessage failed" unless ok
    APPBARDATA.unpack(s)
  end

  ABM_NEW              = 0x00000000
  ABM_REMOVE           = 0x00000001
  ABM_QUERYPOS         = 0x00000002
  ABM_SETPOS           = 0x00000003
  ABM_GETSTATE         = 0x00000004
  ABM_GETTASKBARPOS    = 0x00000005
  ABM_ACTIVATE         = 0x00000006
  ABM_GETAUTOHIDEBAR   = 0x00000007
  ABM_SETAUTOHIDEBAR   = 0x00000008
  ABM_WINDOWPOSCHANGED = 0x00000009
  ABM_SETSTATE         = 0x0000000a

  ABE_LEFT   = 0
  ABE_TOP    = 1
  ABE_RIGHT  = 2
  ABE_BOTTOM = 3
end




if __FILE__ == $0
  require 'test/unit'
  class SHAppBarMessageTest < Test::Unit::TestCase
    include Win32

    def test_pack_unpack
      a = APPBARDATA.new(-1, 0, 0, ABE_TOP, RECT.new(1, 2, 3, 4), 0)
      b = APPBARDATA.unpack(a.pack)
      a.cbSize = b.cbSize
      assert_equal(a.values, b.values)
    end
    def test_simple_pos_query
      h = Win32.findWindow("Shell_TrayWnd", nil)
      a = APPBARDATA.new(-1, 0, 0, ABE_TOP, RECT.new(0, 0, 0, 0), 0)
      result = Win32.shAppBarMessage(ABM_GETTASKBARPOS, a)
      assert(result.rc.left < result.rc.right)
      assert(result.rc.top < result.rc.bottom)
      puts result.rc.inspect
    end
  end
end