# Tk mouse events and keys **URL:** \ **Category:** ruby-talk\ **Created:** [3 December 2004 12:05 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122 "2004-12-03T12:05:09Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Mark\_Volkmann](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Mark\_Volkmann](https://rubytalk.org/u/Mark_Volkmann)\ **Post date:** [3 December 2004 12:05 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/1 "2004-12-03T12:05:09Z")
I'm using the following code to detect a left mouse click.     canvas.bind('1', proc {|event| doPress(event)}) Inside my doPress method, is there a way I can ask the event object whether the ctrl key was down when the mouse button was pressed? Is proc what I should be using in my bind call? ---
**Author:** ![Hidetoshi\_NAGAI](https://avatars.discourse-cdn.com/v4/letter/h/49beb7/32.png) [@Hidetoshi\_NAGAI](https://rubytalk.org/u/Hidetoshi_NAGAI)\ **Post date:** [3 December 2004 14:23 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/2 "2004-12-03T14:23:33Z")
Hi, > **路路路** > > From: "R. Mark Volkmann" \ > Subject: Tk mouse events and keys > Date: Fri, 3 Dec 2004 21:05:09 +0900 > Message-ID: \<01be01c4d930$52e58e50$0200a8c0@MarkDesktop\> > > > I'm using the following code to detect a left mouse click. > > > >     canvas.bind('1', proc {|event| doPress(event)}) > > > > Inside my doPress method, is there a way I can ask the event object whether > > the ctrl key was down when the mouse button was pressed? > > Please see Tcl/Tk's "bind" manual. 馃檪 > Modifiers of event sequence are required. > When a widget has 'Shift-Button-1' and 'Button-1' binding and > the button 1 is pressed \*WITHOUT\* Shift-key on the widget, > both of the sequences can mathe the event. > Then, the binding which is called for the event is decided > based on the following rules. > >   Rule1: Only one binding is called on each bindtag (NOT each widget). >   Rule2: More detailed sequence description has higher priority. >   Rule3: The binding defined at last has highest priority. > > The following is a test script. I think the script will help you. > ------------------------------------------------------------------- > #!/usr/bin/env ruby > require 'tk' > > root = Tk.root > > $ctrl\_st = false > $shift\_st = false > $alt\_st = false > > def p\_st(btn, x, y, ctrl, shift, alt) >     puts "btn#{btn}(#{x},#{y}) ctrl=\>[#{$ctrl\_st},#{ctrl}] shift=\>[#{$shift\_st},#{shift}] alt=\>[#{$alt\_st},#{alt}]" > end > > root.bind('KeyPress-Control\_L', proc{puts 'press ctrl'; $ctrl\_st = true}) > root.bind('KeyRelease-Control\_L', proc{puts 'release ctrl'; $ctrl\_st = false}) > root.bind('KeyPress-Control\_R', proc{puts 'press ctrl'; $ctrl\_st = true}) > root.bind('KeyRelease-Control\_R', proc{puts 'release ctrl'; $ctrl\_st = false}) > > root.bind('KeyPress-Shift\_L', proc{puts 'press shift'; $shift\_st = true}) > root.bind('KeyRelease-Shift\_L', proc{puts 'release shift'; $shift\_st = false}) > root.bind('KeyPress-Shift\_R', proc{puts 'press shift'; $shift\_st = true}) > root.bind('KeyRelease-Shift\_R', proc{puts 'release shift'; $shift\_st = false}) > > root.bind('KeyPress-Alt\_L', proc{puts 'press alt'; $alt\_st = true}) > root.bind('KeyRelease-Alt\_L', proc{puts 'release alt'; $alt\_st = false}) > root.bind('KeyPress-Alt\_R', proc{puts 'press alt'; $alt\_st = true}) > root.bind('KeyRelease-Alt\_R', proc{puts 'release alt'; $alt\_st = false}) > > root.bind('Button', >           proc{|b, x, y| p\_st(b, x, y, false, false, false) }, '%b', '%x','%y') > root.bind('Control-Button', >           proc{|b, x, y| p\_st(b, x, y, true, false, false) }, '%b', '%x','%y') > root.bind('Shift-Button', >           proc{|b, x, y| p\_st(b, x, y, false, true, false) }, '%b', '%x','%y') > root.bind('Alt-Button', >           proc{|b, x, y| p\_st(b, x, y, false, false, true) }, '%b', '%x','%y') > root.bind('Shift-Alt-Button', >           proc{|b, x, y| p\_st(b, x, y, false, true, true) }, '%b', '%x','%y') > root.bind('Control-Alt-Button', >           proc{|b, x, y| p\_st(b, x, y, true, false, true) }, '%b', '%x','%y') > root.bind('Control-Shift-Button', >           proc{|b, x, y| p\_st(b, x, y, true, true, false) }, '%b', '%x','%y') > root.bind('Control-Shift-Alt-Button', >           proc{|b, x, y| p\_st(b, x, y, true, true, true) }, '%b', '%x','%y') > > Tk.mainloop > ------------------------------------------------------------------- > -- >                                   Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp) ---
**Author:** ![Mark\_Volkmann](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Mark\_Volkmann](https://rubytalk.org/u/Mark_Volkmann)\ **Post date:** [4 December 2004 02:11 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/3 "2004-12-04T02:11:28Z")
If I have an item on a TkCanvas such as a Rectangle, is there a way to hide it temporarily and then show it later? Hopefully I don't have to delete it and recreate it later. ---
**Author:** ![Hidetoshi\_NAGAI](https://avatars.discourse-cdn.com/v4/letter/h/49beb7/32.png) [@Hidetoshi\_NAGAI](https://rubytalk.org/u/Hidetoshi_NAGAI)\ **Post date:** [4 December 2004 03:36 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/4 "2004-12-04T03:36:14Z")
Hi, > **路路路** > > From: "R. Mark Volkmann" \ > Subject: hide/show items on TkCanvas? > Date: Sat, 4 Dec 2004 11:11:28 +0900 > Message-ID: \<039d01c4d9a6$8e9e8b10$0200a8c0@MarkDesktop\> > > > If I have an item on a TkCanvas such as a Rectangle, is there a way to hide > > it temporarily and then show it later? > > Hopefully I don't have to delete it and recreate it later. > > Probably, the simplest way is to move the item to out of > the canvas's scrollregion. > For exampke, when the scrollregion of the canvas is > (min\_x, min\_y, max\_x, max\_y), you can hide the item by > item.move(-(max\_x - min\_x), -(max\_y - min\_y)) and show > it by item.move(max\_x - min\_x, max\_y - min\_y). > Of course, if the part of the item exists on the out of > the scrollregion, you never forget the out\_of\_range part > when decide the moving delta. > Then, bbox method (and canvas tags) may be useful. > -- > Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp) ---
**Author:** ![Martin\_S\_Weber](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Martin\_S\_Weber](https://rubytalk.org/u/Martin_S_Weber)\ **Post date:** [4 December 2004 08:17 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/5 "2004-12-04T08:17:18Z")
I don't know Ruby/Tk, but I do know Tk, and the canvas supports this via itemconfigure -state {normal, hidden}. For mental guidance, the equivalent tcl code would be sth like ..   # ....   canvas .c   set id [.c create rectangle 50 50 200 200]   .c itemconfigure $id -state hidden   # .. lateron:   .c itemconfigure $id -state normal Of course if you're using tags etc. you can have whole groups disappear at once and reappear later etc. I suggest reading the canvas manpage, it's huge but has a lot of info too 馃檪 Hth, -Martin > **路路路** > > On Sat, Dec 04, 2004 at 11:11:28AM +0900, R. Mark Volkmann wrote: > > > If I have an item on a TkCanvas such as a Rectangle, is there a way to hide > > it temporarily and then show it later? ---
**Author:** ![Hidetoshi\_NAGAI](https://avatars.discourse-cdn.com/v4/letter/h/49beb7/32.png) [@Hidetoshi\_NAGAI](https://rubytalk.org/u/Hidetoshi_NAGAI)\ **Post date:** [4 December 2004 08:37 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/6 "2004-12-04T08:37:20Z")
Hi, > **路路路** > > From: "Martin S. Weber" \ > Subject: Re: hide/show items on TkCanvas? > Date: Sat, 4 Dec 2004 17:17:18 +0900 > Message-ID: \<20041204081507.GA3290@circe.entropie.net\> > > > I don't know Ruby/Tk, but I do know Tk, and the canvas supports this via > > itemconfigure -state {normal, hidden}. For mental guidance, the equivalent > > tcl code would be sth like .. > > You are right. 'state' option is supported on Tk8.3+ (is it right?). > > # I'd forgotten the option. And I checked the manual of Tk8.0. (^\_^; > > >   # .... > >   canvas .c > >   set id [.c create rectangle 50 50 200 200] > >   .c itemconfigure $id -state hidden > >   # .. lateron: > >   .c itemconfigure $id -state normal > > In Ruby/Tk, > >   # .... >   c = TkCanvas.new >   id = TkcRectangle.new(c, 50, 50, 200, 200) >   id.state(:hiden) >   # .. lateron: >   id.state(:normal) > > -- > Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp) ---
**Author:** ![Martin\_S\_Weber](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Martin\_S\_Weber](https://rubytalk.org/u/Martin_S_Weber)\ **Post date:** [4 December 2004 08:57 UTC](https://rubytalk.org/t/tk-mouse-events-and-keys/15122/7 "2004-12-04T08:57:50Z")
> Hi, Moin, > \> (... me suggesting item's 'state' option ...) > You are right. 'state' option is supported on Tk8.3+ (is it right?). Dunno, it's been there ever since I've needed it 馃檪 Regards, -Martin > **路路路** > > On Sat, Dec 04, 2004 at 05:37:20PM +0900, Hidetoshi NAGAI wrote: