如何在Windows系统中使用Ruby获取当前屏幕方向？Ruby 3.0单屏幕场景下检测屏幕是否翻转纵向（倒置）

Hey there! Let's figure out how to get your screen orientation and detect inverted portrait mode on Windows using Ruby 3.0. Since Ruby doesn't have built-in utilities for this, we'll need to hook into Windows' native APIs—don't worry, it's straightforward with a couple of gems.

Option 1: Using the win32-api Gem #

This gem lets you call Windows API functions directly from Ruby. First, install it:

gem install win32-api

Then use this code to fetch orientation and check for inverted states:

require 'win32/api'

# Windows API constants we'll need
DM_DISPLAYORIENTATION = 0x00000080
DMDO_DEFAULT = 0       # Normal landscape
DMDO_90 = 1            # 90° clockwise (portrait)
DMDO_180 = 2           # 180° rotation (inverted landscape)
DMDO_270 = 3           # 270° clockwise (inverted portrait)

# Define the EnumDisplaySettingsA function from user32.dll
EnumDisplaySettings = Win32API.new('user32', 'EnumDisplaySettingsA', ['P', 'L', 'P'], 'L')

# Initialize the DEVMODE structure (holds display settings)
DEVMODE_SIZE = 156
devmode = "\x00" * DEVMODE_SIZE
devmode[0, 2] = [DEVMODE_SIZE].pack('S')  # Set the dmSize field

# Fetch current display settings
if EnumDisplaySettings.call(nil, -1, devmode) != 0
  dm_fields = devmode[40, 4].unpack('L')[0]
  
  # Check if orientation data is available
  if dm_fields & DM_DISPLAYORIENTATION != 0
    orientation = devmode[44, 4].unpack('L')[0]
    
    # Translate orientation code to human-readable text
    orientation_label = case orientation
                        when DMDO_DEFAULT then "Default (normal landscape)"
                        when DMDO_90 then "90° clockwise (portrait)"
                        when DMDO_180 then "180° rotation (inverted landscape)"
                        when DMDO_270 then "270° clockwise (inverted portrait)"
                        else "Unknown orientation"
                        end
    
    puts "Current screen orientation: #{orientation_label}"
    
    # Check for inverted states
    is_inverted_landscape = orientation == DMDO_180
    is_inverted_portrait = orientation == DMDO_270
    
    puts "\nDetection results:"
    puts "Is screen in inverted landscape? #{is_inverted_landscape}"
    puts "Is screen in inverted portrait? #{is_inverted_portrait}"
  else
    puts "Could not retrieve orientation information from display settings."
  end
else
  puts "Failed to fetch current display settings."
end

Option 2: Using the ffi Gem (Modern Alternative) #

ffi is a more flexible, cross-platform way to call native APIs. Install it first:

gem install ffi

Here's the equivalent code using ffi:

require 'ffi'

module User32
  extend FFI::Library
  ffi_lib 'user32'
  ffi_convention :stdcall

  # Define the DEVMODE structure that holds display settings
  class DEVMODE < FFI::Struct
    layout(
      :dmDeviceName, [:char, 32],
      :dmSpecVersion, :word,
      :dmDriverVersion, :word,
      :dmSize, :word,
      :dmDriverExtra, :word,
      :dmFields, :dword,
      :union, [:union, {
        :dmOrientation, :short,
        :dmPosition, :pointl,
        :dmDisplayOrientation, :dword,
        :dmDisplayFixedOutput, :dword
      }]
    )
  end

  # Constants for display settings and orientation
  ENUM_CURRENT_SETTINGS = -1
  DM_DISPLAYORIENTATION = 0x00000080
  DMDO_DEFAULT = 0
  DMDO_90 = 1
  DMDO_180 = 2
  DMDO_270 = 3

  # Attach the EnumDisplaySettingsA function
  attach_function :EnumDisplaySettingsA, [:pointer, :long, :pointer], :bool
end

# Initialize and populate the DEVMODE structure
devmode = User32::DEVMODE.new
devmode[:dmSize] = User32::DEVMODE.size

if User32.EnumDisplaySettingsA(nil, User32::ENUM_CURRENT_SETTINGS, devmode)
  if (devmode[:dmFields] & User32::DM_DISPLAYORIENTATION) != 0
    orientation = devmode[:union][:dmDisplayOrientation]
    
    # Map orientation code to readable label
    orientation_label = case orientation
                        when User32::DMDO_DEFAULT then "Default (normal landscape)"
                        when User32::DMDO_90 then "90° clockwise (portrait)"
                        when User32::DMDO_180 then "180° rotation (inverted landscape)"
                        when User32::DMDO_270 then "270° clockwise (inverted portrait)"
                        else "Unknown orientation"
                        end
    
    puts "Current screen orientation: #{orientation_label}"
    
    # Check for inverted states
    is_inverted_landscape = orientation == User32::DMDO_180
    is_inverted_portrait = orientation == User32::DMDO_270
    
    puts "\nDetection results:"
    puts "Is screen in inverted landscape? #{is_inverted_landscape}"
    puts "Is screen in inverted portrait? #{is_inverted_portrait}"
  else
    puts "Display orientation data not available."
  end
else
  puts "Failed to query display settings."
end

Key Notes for Single-Screen Scenarios #

Both examples above target your primary display, which works perfectly for single-screen setups. If you ever need to handle multi-screen setups later, you'd use EnumDisplayDevices to iterate over connected monitors, but that's unnecessary here.

What Do the Orientation Values Mean? #

• DMDO_DEFAULT: Normal landscape (your screen's default position)
• DMDO_90: Clockwise 90° rotation (standard portrait mode)
• DMDO_180: 180° rotation (inverted landscape, upside-down)
• DMDO_270: Clockwise 270° (equivalent to counter-clockwise 90°, which is inverted portrait)

Based on your question, DMDO_270 is the "flipped portrait (inverted)" state you're looking to detect.

内容的提问来源于stack exchange，提问作者GT Baka