browseforfolder.rb

# ★ BrowseForFolder
# ★★★★★★★★★★★★★
#
# Author/s : cremno
# RGSS ver : 1 to 3
module BrowseForFolder

  class BrowseForFolderError < StandardError
  end

  HWND = Win32API.new('user32', 'GetActiveWindow', 'V', 'L').call

  SHBrowseForFolder = Win32API.new('shell32', 'SHBrowseForFolderW', 'P', 'L')
  SHGetPathFromIDList =
    Win32API.new('shell32', 'SHGetPathFromIDListW', 'LP', 'L')
  CoTaskMemFree = Win32API.new('ole32', 'CoTaskMemFree', 'L', 'V')
  MultiByteToWideChar =
    Win32API.new('kernel32', 'MultiByteToWideChar', 'LLPLPL', 'L')
  WideCharToMultiByte =
    Win32API.new('kernel32', 'WideCharToMultiByte', 'LLPLPLPP', 'L')

  BIF_RETURNONLYFSDIRS = 0x0000_0001
  BIF_EDITBOX = 0x0000_0010
  BIF_NEWDIALOGSTYLE = 0x0000_0040
  BIF_USENEWUI = BIF_EDITBOX | BIF_NEWDIALOGSTYLE

  CP_UTF8 = 65_001

  MAX_PATH = 260

  SIZEOF_WCHAR_T = 2

  def self.alloc_buffer(size)
    "\0" * size
  end

  def self.str_to_wcs(str)
    len = MultiByteToWideChar.call(CP_UTF8, 0, str, -1, 0, 0)
    if len <= 0
      fail(BrowseForFolderError, "MultiByteToWideChar returned #{len}")
    end
    wcs = alloc_buffer(len * SIZEOF_WCHAR_T)
    MultiByteToWideChar.call(CP_UTF8, 0, str, -1, wcs, len)
    wcs
  end

  def self.wcs_to_str(wcs)
    len = WideCharToMultiByte.call(CP_UTF8, 0, wcs, -1, 0, 0, 0, 0)
    if len <= 0
      fail(BrowseForFolderError, "WideCharToMultiByte returned #{len}")
    end
    str = alloc_buffer(len - 1)
    WideCharToMultiByte.call(CP_UTF8, 0, wcs, -1, str, len, 0, 0)
    str
  end

  def self.select(title = 'Select a folder:', default_if_cancelled = '')
    flags = BIF_RETURNONLYFSDIRS | BIF_USENEWUI
    bi = [HWND, 0, 0, str_to_wcs(title), flags, 0, 0, 0].pack('LLLpLLl')
    pidlist = SHBrowseForFolder.call(bi)
    if pidlist == 0
      default_if_cancelled
    else
      path = alloc_buffer(MAX_PATH * SIZEOF_WCHAR_T)
      r = SHGetPathFromIDList.call(pidlist, path)
      r == 0 && fail(BrowseForFolderError, "SHGetPathFromIDList returned #{r}")
      wcs_to_str(path)
    end
  ensure
    CoTaskMemFree.call(pidlist)
  end
end