My tool and problem with bind ALT in Windows

Developers Ruby API
1

In Windows, the ALT key takes you to the top menu.
When you create your own tool and want to add actions to ALT (onKeyUp func), problems appear

I solved this problem, but in an aggressive way.

How I implemented it: using fiddle and WinApi I put a global interceptor (Hook) on the keyboard (WH_KEYBOARD_LL), catch ALT and replace it with my function

Attention: If my tool is active, then ALT does not work in other windows programs. I think you can put another type of interceptor that will perform the same role, but only when the Sketchup window is active. But that is another story…

Maybe I’m a fool and there is a more cultural method, because there is no such problem with standard tools (Move tool & etc).

I wrote some code for demonstration. Paste into Console. Return to the model. Don’t change the tool. Don’t move your mouse. press ALT. The cursor will change.

require 'fiddle/import'

class Alt_key
 def activate
	@dll = Fiddle.dlopen('user32')
	setWindowsHookEx = Fiddle::Function.new(@dll['SetWindowsHookExA'], [Fiddle::TYPE_INT, Fiddle::TYPE_VOIDP, Fiddle::TYPE_VOIDP, Fiddle::TYPE_INT], Fiddle::TYPE_VOIDP)
	callback = Fiddle::Closure::BlockCaller.new(Fiddle::TYPE_VOIDP, [Fiddle::TYPE_INT, Fiddle::TYPE_INTPTR_T, Fiddle::TYPE_VOIDP]) do |code, wparam, lparam|
		if lparam[0]==-92 then #left ALT, right ALT=-91
			hook_alt() if wparam==257 # on WM_KEYUP
			1 
		else
			0
		end
	end
	@hook = setWindowsHookEx.call(13, callback, nil, 0)	# WH_KEYBOARD_LL=13
	puts "ALT will be intercepted"
 end
 
 def deactivate(view)
     Fiddle::Function.new(@dll['UnhookWindowsHookEx'], [Fiddle::TYPE_VOIDP], Fiddle::TYPE_INT).call(@hook)
	 puts "ALT will NOT be intercepted"
 end
	  
 def hook_alt() #visual test
		if @i.inspect=="1"
			UI.set_cursor(631)
			@i=0		
		else
			UI.set_cursor(634)
			@i=1		
		end
 end
 
end

Sketchup.active_model.select_tool(Alt_key.new)
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