ruby - 在 ruby​​ 中使用 GetDIBits 函数时遇到问题

Question

我有下面的 Ruby 代码，我正在使用 Windows API 调用，我应该能够使用函数 GetDIBits 从我创建的位图中检索 RGB 值数组，用于 AI 处理。我需要为 GetDIBits 函数提供一个 BITMAPINFO 结构以及一些其他变量。我应该可以接受其他变量，但是如何在 ruby​​ 中创建一个可用于该函数的结构(使用 Windows API)？

请看下面的代码

如果您能完成 GetDIBits 函数以便我可以检索一组 RGB 值，我将不胜感激。

谢谢 马丁

def getscreen()

width = Win32API.new("User32.dll","GetSystemMetrics",["L"],"L").call(0)
height = Win32API.new("User32.dll","GetSystemMetrics",["L"],"L").call(1)

#Get desktop DC, create a compatible dc, create a comaptible bitmap and select into compatible dc.
hddc = Win32API.new("User32.dll","GetDC",["L"],"L").call(Win32API.new("User32.dll","GetDesktopWindow",[],"L").call)
hcdc = Win32API.new("Gdi32.dll","CreateCompatibleDC",["L"],"L").call(hddc)
hbitmap = Win32API.new("Gdi32.dll","CreateCompatibleBitmap",["L","L","L"],"L").call(hddc,width,height)
Win32API.new("Gdi32.dll","SelectObject",["L","L"],"L").call(hcdc,hbitmap)
Win32API.new("Gdi32.dll","BitBlt",["L","L","L","L","L","L","L","L","P"],"L").call(hcdc,0,0,width,height,hddc,0,0,"SRCCOPY|CAPTUREBLT")

#save hbitmap to stream of byte as you mentioned
Win32API.new("Gdi32.dll","GetDIBits",["L","L","L","L","L","L","P"],"L").call(hcdc,hbitmap,1,1200,0,"DIB_RGB_COLORS")

pixelarray = Array.new
#Need a .call to fill the pixelarray array

Win32API.new("User32.dll","ReleaseDC",["L","L"],"L").call(Win32API.new("User32.dll","GetDesktopWindow",[],"L").call,hddc)
Win32API.new("Gdi32.dll","DeleteDC",["L"],"L").call(hcdc)
Win32API.new("Gdi32.dll","DeleteObject",["L"],"L").call(hbitmap)

#Print screen width and height
puts "Screen width: #{width}"
puts "Screen height: #{height}"

end

Answer 1

这段代码似乎得到了一些数据，虽然我没有仔细观察以判断它是否是来自屏幕的颜色:

require 'Win32API'

module Foo
  GetSystemMetrics = Win32API.new "User32.dll", "GetSystemMetrics", ["L"], "L"
  GetDC = Win32API.new "User32.dll", "GetDC", ["L"], "L"
  GetDesktopWindow = Win32API.new "User32.dll", "GetDesktopWindow", [], "L"
  CreateCompatibleDC = Win32API.new "Gdi32.dll", "CreateCompatibleDC", ["L"], "L"
  CreateCompatibleBitmap = Win32API.new "Gdi32.dll", "CreateCompatibleBitmap", ["L","L","L"], "L"
  SelectObject = Win32API.new "Gdi32.dll","SelectObject", ["L","L"], "L"
  BitBlt = Win32API.new "Gdi32.dll","BitBlt", ["L","L","L","L","L","L","L","L","L"], "L"
  CAPTUREBLT = 0x40000000 
  SRCCOPY = 0x00CC0020
  GetDIBits = Win32API.new "Gdi32.dll","GetDIBits", ["L","L","L","L","P","P","L"], "L"
  DIB_RGB_COLORS = 0
  BI_RGB = 0

  def self.getscreen
    width = GetSystemMetrics.call 0
    height = GetSystemMetrics.call 1    
    puts "Screen width: #{width}"
    puts "Screen height: #{height}"

    desktop_handle = GetDesktopWindow.call
    raise "GetDesktopWindow failed" if desktop_handle == 0
    hddc = GetDC.call desktop_handle
    raise "Get DC failed." if hddc == 0
    hcdc = CreateCompatibleDC.call hddc
    raise "CreateCompatibleDC failed" if hcdc == 0

    hbitmap = CreateCompatibleBitmap.call hddc, width, height
    raise "CreateCompatibleBitmap failed" if hbitmap == 0
    result = SelectObject.call hcdc, hbitmap
    raise "SelectObject failed" if result == 0   # not sure if this is right

    result = BitBlt.call hcdc, 0, 0, width, height, hddc, 0, 0, SRCCOPY | CAPTUREBLT
    raise "BitBlt failed" if result == 0

    SelectObject.call hcdc, 0   # attempt to deselect the bitmap because GetDIBits requires it?

    size_in_bytes = width*height*4
    bitmap_info = [40, #biSize
      width,
      height,
      1, #biPlanes
      32, #biBitCount
      BI_RGB, #biCompression
      size_in_bytes,
      2000, #biXPelsPerMeter: not used?
      2000, #biYPelsPerMeter: not used?
      0, # biClrUsed
      0 # biClrImportant
    ].pack("LLLSSLLLLLL") #+ [0,0,0,0].pack("LLLL")

    buffer = (" " * size_in_bytes).force_encoding("BINARY")

    result = GetDIBits.call hcdc, hbitmap, 0, height, buffer, bitmap_info, DIB_RGB_COLORS
    raise "GetDIBits failed." if result == 0
    puts "Number of scan lines copied: #{result}"
    puts "buffer contents: " + buffer.strip.inspect[0,100] + " ..."
    puts "First pixel = %02x,%02x,%02x,%02x" % [buffer[0].ord, buffer[1].ord, buffer[2].ord, buffer[3].ord]

    return buffer
  end
end

Foo.getscreen

当我在 Windows 中使用 ruby​​ 1.9.2p180 运行它时的输出是:

Screen width: 1366
Screen height: 768
Number of scan lines copied: 768
buffer contents: "\x0F\f\a\xFF\x0F\f\a\xFF\x0F\f\a\xFF\x0F\f\a\xFF\x0F\f\a\xFF\x
0F\f\a\xFF\x0F\f\a\xFF\x0F\f\a\xFF\x0 ...
First pixel = 0f,0c,07,ff

如果您对我在这里所做的事情有任何疑问，请告诉我。