Flags on onKeyDown?

Jim

Can anyone explain to me the flags argument for the onKeyDown method. I had assumed it would have a certain, predictable value when the one of the modifier keys was being help down, but it doesn't make any sense to me.

I am trying to avoid code like the following:


 if key == VK_SHIFT
   @shift = true
 end
 if key == VK_CONTROL
   @ctrl = true
 end

Chris Fullmer

The flags are (as best as I could ever tell)

1 = left mouse button down
2 = right mouse button down
4 = shift down
8 = ctrl down
16 = ?
32 = alt down

Then add them together to determine if the user has more than one key down. So shift + ctrl would give a flag of 12. Alt + ctrl gives a flag of 40. All of them down together give a flag of 47 (not including 16. I can't find 16, so I can't press it).

Now, I don't know how to use that info in a script though. Sorry, I probably didn't help very much. Can you think of a good way to examine the flag 47 and decide what keys that means are being held down?

Chris

Jim

Well, it's a bit field. So using your information...


47.to_s(2)
101111

Each position in the binary would represent a key state.


1 - left mouse on
0 - right mouse off
1 - shift on
1 - ctrl on
1 - ?
1 - alt on

But my problem is the flag value does not change if I have the SHIFT key down or not, when I think it should. Maybe I'm making bad assumptions.

thomthom

didn't know you could convert to binary that way. neat.

Chris Fullmer

Oh, here's a thought. onKeyDown/Up use the "key" argument, while the others (onMouseMove, onRButtonDown, etc) use the "flag" argument. So with onkeyup, its not really a flag, but a keycode or keyID, whereas the other methods return a flag using the system I described above.

Don't know how that changes things....

tomasz

What would be the best way to read the CTRL key in Win and its corresponding key on MAC. I am writing about a case without creating a new tool.

I would like to read a state of CTRL key when an user presses a toolbar icon.

Tomasz

wikii

if (flags & 4)==4
shift=true
end

Jim

Ah, so maybe that is what these constants are for?


["CONSTRAIN_MODIFIER_KEY", "CONSTRAIN_MODIFIER_MASK", "ALT_MODIFIER_KEY", "ALT_MODIFIER_MASK", "COPY_MODIFIER_KEY", "COPY_MODIFIER_MASK"]

tomasz

@unknownuser said:

.. I am writing about a case without creating a new tool.

@jim said:

["CONSTRAIN_MODIFIER_KEY", "CONSTRAIN_MODIFIER_MASK", "ALT_MODIFIER_KEY", "ALT_MODIFIER_MASK", "COPY_MODIFIER_KEY", "COPY_MODIFIER_MASK"]

Actually creating a tool in not a big deal, but I thought there is a way to omit that.
In SU2KT there is no need for creating the tool and all necessary methods to handle it.
I just need to read a state of CTRL\MENU key upon the start-up of the plugin.

Jim

Can't be done, as far as I know. I agree it would be nice.

tomasz

class SU2KT_key

	def SU2KT_key;;key_pressed?
		@key
	end

	def SU2KT_key;;activate
		@key=false
	end

	def SU2KT_key;;onKeyDown(key, repeat, flags, view)
		@key=(key==COPY_MODIFIER_KEY)
		puts @key
	 end

 end


keytool=SU2KT_key.new
Sketchup.active_model.select_tool SU2KT_key
sleep 1
puts SU2KT_key.key_pressed?

Why does it always give me 'false' on reload of the script? It looks that SU doesn't check the keyboard on creation of a new tool, otherwise I would get the @key value BEFORE sleep 1. Am I right?

Thanks
Tomasz

fredo6

@unknownuser said:

I just need to read a state of CTRL\MENU key upon the start-up of the plugin.

Did you try with the event OnMouseMove, which has a flags argument too?

BTM

@unknownuser said:

@unknownuser said:

I just need to read a state of CTRL\MENU key upon the start-up of the plugin.

Did you try with the event OnMouseMove, which has a flags argument too?

… This is a bit off-topic, but on windows
` class Flagtest

def onMouseMove(flags,x,y,view)
UI.messagebox flags
end
end

Sketchup.active_model.select_tool Flagtest.new`
will come up with 0 on mouse move, if no keys are pressed. on my mac, it's 256. Any idea why?

update:
Also, onMouseMove only activates when the mouse moves in the model area, so it wouldn't activate on startup of the plugin.

Chris Fullmer

ok, I am using the "flags" parameter of the onLButtonUp method to determine ctrl, alt key status. This is my code so far. It works, but I have a feeling it could be optimized. I really don't manipulate strings very well. I nearly turned it all into an array.

` def onLButtonUp(flags, x, y, view)

flag_bin = flags.to_s(2)
flag_bin_to_add = 6 - flag_bin.length
zeros = "0"*flag_bin_to_add
adjusted_flag = (zeros + flag_bin).reverse

ctrlk = true if adjusted_flag[3,1] == "1"
altk = true if adjusted_flag[5,1] == "1"`

So I take the flag, turn it into binary as Jim showed. But a value less than 32 makes a binary with less than 6 digits in it. So if the user is holding alt, then a 6 digit binary is given. If they are holding ctrl, then only a 4 digit binary is given. So I am adding zeros to the binary string, then reversing it because I like the binary to be ordered according to the numerical representations for each key, lowest number key on the left, highest number key on the right.

Then I set my variables to be true if their binary digit is true, indicating that their key was pressed.

I hope that makes sense. Again, this seems to work great. But it feels klunky. Is there an easier way to parse the bit field?

Any optimization ideas?

Chris

ps - I tacked it onto this thread since this thread is what pointed me in the direction of how to work with the "flags" parameter.

thomthom

shift = (flags & CONSTRAIN_MODIFIER_MASK) == CONSTRAIN_MODIFIER_MASK

Use the & for bitwise comparison.

Chris Fullmer

I don't quite understand what that means. What is bitwise?

thomthom

Bitwise operation - Wikipedia

(en.wikipedia.org)

thomthom

Nice little list of Ruby's operators http://www.tutorialspoint.com/ruby/ruby_operators.htm

MartinRinehart

@chris fullmer said:

flag_bin = flags.to_s(2) flag_bin_to_add = 6 - flag_bin.length zeros = "0"*flag_bin_to_add adjusted_flag = (zeros + flag_bin).reverse

Stick in a non-zero bit to the left of the flags.

Quickly: (flags | 128).to_s(2)[2..7].reverse

Slowly:

flags 
        # 00bbbbbb
flags | 128 
        # 10bbbbbb
(flags | 128).to_s(2)
        # 8-char string version
(flags | 128).to_s(2)[2..7] 
        # the 6 chars your really want

thomthom

Converting to string is very inefficient.