Re: refreshing a ruby tk window/scrollbox

On Apr 22, 2007, at 6:51 PM, DBH wrote:

> I have a TkScrollBox object that displays a list of records.  I  
> want to
> sort the list and filter it in various ways, but the only way I've
> figured out how to do this is to get rid of the old window and  
> create a
> new window with the sorting option.  My question is, is there a way to
> refresh a TkScrollBox or the window itself so I don't have to create a
> new window each time?

What I do in situations similar to what you describe is to delete the  
contents of the list box and repopulate it with new contents. The  
following is a rather long example demonstrating this technique. I'm  
sorry I don't have a shorter one. The technique is coded into  
X11ColorBrowser#category_selected_action.

Hope this helps.

Regards, Morton

<code>
#! /usr/bin/ruby -w
# Author: Morton Goldberg
# Date: August 26, 2006
# X11 color browser

require 'tk'

class X11ColorCategory

    # Full path name of the X11 colors file.
    RGB_TXT = "/usr/X11R6/lib/X11/rgb.txt"

    #Dictionary of rgb values keyed by color name.
    COLORS = {}

    def X11ColorCategory.read_rgb_table
       # read and parse the X11 colors file.
       File.foreach(RGB_TXT) do |rgb|
          next if rgb =~ /^!/ # skip header line
          rgb = rgb.lstrip.split(/\s+/)
          r = rgb.shift
          g = rgb.shift
          b = rgb.shift
          key = rgb.join(' ')
          COLORS[key] = "r:#{r} g:#{g} b:#{b}"
       end
       COLORS
    end

    def X11ColorCategory.all
       ALL_CATEGORIES
    end

    def X11ColorCategory.rgb(color_name)
       COLORS[color_name]
    end

    def extract(pattern)
       @members, OTHER.members =
          OTHER.members.partition { |m| m =~ pattern }
       self
    end

    def initialize(name)
       @name = name
       @members = []
    end

    attr_accessor :name, :members

    ALL = X11ColorCategory.new('ALL')
    X11ColorCategory.read_rgb_table.each {|key,| ALL.members << key}
    ALL.members.sort!
    OTHER = X11ColorCategory.new('OTHER')
    ALL.members.each {|m| OTHER.members << m}
    REDS = X11ColorCategory.new('REDS').
       extract(/red|rose|pink|salmon|fire/i)
    GREENS = X11ColorCategory.new('GREENS').
       extract(/green|chartreuse|olive|honeydew/i)
    BLUES = X11ColorCategory.new('BLUES').
       extract(/blue|navy/i)
    CYANS = X11ColorCategory.new('CYANS').
       extract(/cyan|aqua|azure|turquoise/i)
    MAGENTAS = X11ColorCategory.new('MAGENTAS').
       extract(/magenta|maroon|violet|plum|purple|orchid|thistle/i)
    YELLOWS = X11ColorCategory.new('YELLOWS').
       extract(/yellow|gold|lemon|corn/i)
    ORANGES = X11ColorCategory.new('ORANGES').
       extract(/orange|tomato|peach|coral/i)
    BROWNS = X11ColorCategory.new('BROWNS').
       extract(/brown|tan|wood|choc|sienna|wheat|peru/i)
    WHITES = X11ColorCategory.new('WHITES').
       extract(/white|ivory|snow|lace/i)
    GRAYS = X11ColorCategory.new('GRAYS').
       extract(/gr[ae]y|gainsboro/i)

    ALL_CATEGORIES = [
       REDS,
       ORANGES,
       YELLOWS,
       GREENS,
       CYANS,
       BLUES,
       MAGENTAS,
       BROWNS,
       WHITES,
       GRAYS,
       OTHER
    ]

end

class X11ColorBrowser

    # Action performed when category selection is made.
    def category_selected_action
       @category_names.focus
       @selected_category =
          X11ColorCategory.all[@category_names.curselection[0]]
       @color_names.delete(0, 'end')
       @selected_category.members.each { |m| @color_names.insert 
("end", m) }
       @color_names.selection_set(0)
       color_selected_action
    end

    # Action performed when color selection is made.
    def color_selected_action
       color = @selected_category.members[@color_names.curselection[0]]
       @color_rect.background(color)
       @rgb_lbl.text(X11ColorCategory.rgb(color))
    end

    # Action performed when browser window is mapped.
    def window_mapped_action
       return if @mapped
       @mapped = true
       X11ColorCategory.all.each do |category|
          @category_names.insert("end", category.name)
       end
       @category_names.selection_set(0)
       category_selected_action
    end

    def initialize
       # Flag indicating that window has been mapped at least once.
       @mapped = false
       # Holder for currently selected color category
       @selected_category = nil
       # Set up the browser window.
       root = TkRoot.new {title 'Color Browser'}
       # Panel at top of browser containing scrolling list of X11  
colors and
       # label displaying selected color.
       top_pnl = TkFrame.new(root)
          # List box displaying names of X11 color categories.
          @category_names = TkListbox.new(top_pnl)
          # Scroll bar for the color names list.
          vbar1 = TkScrollbar.new(top_pnl)
          @category_names.yscrollbar(vbar1)
          # List box displaying names of X11 colors within selected  
category.
          @color_names = TkListbox.new(top_pnl)
          # Scroll bar for the color names list.
          vbar2 = TkScrollbar.new(top_pnl)
          @color_names.yscrollbar(vbar2)
          # Label displaying selected color.
          @color_rect = TkLabel.new(top_pnl, 'width'=>25)
       # Request layout of top panel.
       @category_names.pack("side"=>"left", "fill"=>"both",  
"expand"=>true,
                            "padx"=>5)
       vbar1.pack("side"=>"left", "after"=>@category_names, "fill"=>"y")
       @color_names.pack("side"=>"left", "after"=>vbar1, "fill"=>"both",
                         "expand"=>true, "padx"=>5)
       vbar2.pack("side"=>"left", "after"=>@color_names, "fill"=>"y")
       @color_rect.pack("side"=>"right", "fill"=>"both", "expand"=>true,
                        "padx"=>5)
       top_pnl.pack("side"=>"top", "fill"=>"both", "expand"=>true,
                    "padx"=>5, "pady"=>8)
       # Panel at bottom of browser containing exit button and label
       # displaying RGB values of selected color.
       btm_pnl = TkFrame.new(root)
          # Label displaying rgb values of selected color.
          @rgb_lbl = TkLabel.new(btm_pnl) {
             text "r:xxx g:xxx b:xxx"
          }
          # Exit button.
          @quit_btn = TkButton.new(btm_pnl) {
             text "Exit"
             command { Tk.root.destroy }
          }
       # Request layout of bottom panel.
       @rgb_lbl.pack("side"=>"left", "anchor"=>"w")
       @quit_btn.pack("side"=>"right")
       btm_pnl.pack("side"=>"bottom", "fill"=>"x", "padx"=>10,  
"pady"=>8)
       # Set initial window geometry; i.e., size and placement.
       win_w, win_h = 750, 300
       root.minsize(win_w, win_h)
       win_x = (root.winfo_screenwidth - win_w) / 2
       root.geometry("#{win_w}x#{win_h}+#{win_x}+50")
       # Make Cmnd+Q work as expected (for Mac OS X).
       root.bind('Command-q') { @quit_btn.invoke }
       # Bind mouse button-1, space bar, window map event to their  
actions.
       @category_names.bind('Map') { window_mapped_action }
       ev = TkVirtualEvent.new('ButtonRelease-1', 'space')
       @category_names.bind(ev) { category_selected_action }
       @color_names.bind(ev) { color_selected_action }
       Tk.mainloop
    end

end

X11ColorBrowser.new
</code>