# Changing screen resolution through Ruby **URL:** \ **Category:** Ruby\ **Created:** [November 10, 2009, 7:31pm UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751 "2009-11-10T19:31:09Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Saturn](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e19b73/32.png) [@Saturn](https://www.ruby-forum.com/u/Saturn)\ **Post date:** [November 10, 2009, 7:31pm UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751/1 "2009-11-10T19:31:09Z")
Hi All, Thanks in advance to all the helpers. I want to change screen resolution using ruby or selenium. Please help me and let me know if it is possible in either way. ---
**Author:** ![Saturn](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e19b73/32.png) [@Saturn](https://www.ruby-forum.com/u/Saturn)\ **Post date:** [November 10, 2009, 8:18pm UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751/2 "2009-11-10T20:18:43Z")
Saturn wrote: > Hi All, > Thanks in advance to all the helpers. > > I want to change screen resolution using ruby or selenium. > > Please help me and let me know if it is possible in either way. ## Do you need to change screen resolution, or simply window size? Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid ---
**Author:** ![Saturn](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e19b73/32.png) [@Saturn](https://www.ruby-forum.com/u/Saturn)\ **Post date:** [November 10, 2009, 8:26pm UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751/3 "2009-11-10T20:26:07Z")
Saturn wrote: > Hi All, > Thanks in advance to all the helpers. > > I want to change screen resolution using ruby or selenium. > > Please help me and let me know if it is possible in either way. For Windows, there’s a WinAPI function I think, but I don’t know about Linux or Mac OS. Btw. is there any good reference on how to manipulate the X server? I’d like to add some more automation functions to my xdo gem, but I wasn’t able to find out how to interact directly with X… Marvin ---
**Author:** ![Saturn](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e19b73/32.png) [@Saturn](https://www.ruby-forum.com/u/Saturn)\ **Post date:** [November 11, 2009, 7:29am UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751/4 "2009-11-11T07:29:52Z")
On Nov 11, 12:26 am, Marvin Gülker [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Btw. is there any good reference on how to manipulate the X server? I’d > like to add some more automation functions to my xdo gem, but I wasn’t > able to find out how to interact directly with X… > > ## Marvin > > Posted viahttp://www.ruby-forum.com/. Yes I need to change screen resolution itself like from 1280 X 800 to 800 X 600. I can read the resolutions through win API but can’t write If you any way to change please let me know - thanks ---
**Author:** ![Saturn](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e19b73/32.png) [@Saturn](https://www.ruby-forum.com/u/Saturn)\ **Post date:** [November 11, 2009, 11:49am UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751/5 "2009-11-11T11:49:49Z")
Saturn wrote: > On Nov 11, 12:26�am, Marvin G�lker [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > Btw. is there any good reference on how to manipulate the X server? I’d > > like to add some more automation functions to my xdo gem, but I wasn’t > > able to find out how to interact directly with X… > > > > ## Marvin > > > > Posted viahttp://www.ruby-forum.com/. > > Yes I need to change screen resolution itself like from 1280 X 800 to > 800 X 600. > I can read the resolutions through win API but can’t write > If you any way to change please let me know > > - thanks I’ve searched through Google and the Windows API, and found that this function can do the trick: ChangeDisplaySettings > **[ChangeDisplaySettingsA function (winuser.h) - Win32 apps](https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-changedisplaysettingsa?redirectedfrom=MSDN)** > > The ChangeDisplaySettings function changes the settings of the default display device to the specified graphics mode. (ANSI) An article on how to use it I found here: > **[Changing Screen Orientation Programmatically](https://learn.microsoft.com/en-us/previous-versions/ms812499(v=msdn.10)?redirectedfrom=MSDN)** You could use the function itself easily, but building up the DEVMODE struct seems to be very complex (note that I’m using the win32-api gem for such tasks). In C, you only have to change the values of a DEVMODE you want to change, but since you can’t access a struct from within Ruby, you have to build up the whole struct and then use Array#pack to turn it into a string which you can pass into the WinAPI function. That’s no problem with easy structs like the POINT struct - just do [0, 0].pack(‘LL’) - but I’ve never found out how to manage that with complex ones, especially with ones containing other structs. If someone knows how to simplify that (besides a C extension written for the MSVC-compiled Ruby version), please let me know. Marvin ---
**Author:** ![Saturn](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e19b73/32.png) [@Saturn](https://www.ruby-forum.com/u/Saturn)\ **Post date:** [November 11, 2009, 1:20pm UTC](https://www.ruby-forum.com/t/changing-screen-resolution-through-ruby/178751/6 "2009-11-11T13:20:28Z")
Thanks Marvin, As you said problem is same here, I am unable to make it’s arguments: I tried following: require ‘Win32API’ @e = Win32API.new(“user32”,“ChangeDisplaySettings”, [‘I’,‘I’], ‘I’ ) p @e.call(800, 600) it’s giving me error Or nothing if I remove p from the last line. If any body has a clean solution like initialized all other DEVMODE settings with default and changing only resolution part please let me know. Thanks for helping me.