[Ruby-GNOME2 Project Website] create - tut-gtk2-txtw-ttags (ruby-gnome2-doc-cvs) - Ruby-GNOME2

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TITLE       = tut-gtk2-txtw-ttags
KEYWORD     = 
= The Text View Widget
{{link "tut-gtk2-txtw-itrsmrks", "tut-gtk2-txtw", "tut-gtk", "tut-gtk2-txtw-iimgs"}}

== Text Tags

There are many methods provided for changing properties of the entire text within the text buffer. But as already mentioned, it is also possible to change the display properties only of a portion of text in the text buffer. You do this with a new class Gtk::TextTag. 

Text tag objects allow you to create documents with varying styles in different parts of the text, which is commonly known as rich text editing. Text tags are very simple context to apply. The following listing represents an application where multiple styles can be added or removed all together from the selection.

{{br}}
{{image_left("txtw-ttags.png")}}

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((*texttags.rb*))

 #!/usr/bin/env ruby
 require 'gtk2'

 # Retrieve the tag from the "tag" object data and apply it
 # to the selection.
 def format(b, txtvu)
   s, e = txtvu.buffer.selection_bounds

   # Our buttons contain Gtk::Stock#Items. Their label values
   # begin with "gtk-", ie: gtk-bold, gtk-italic, ... We need
   # the word after "gtk-" ie.: bold, italic ... which are used
   # as tag property names; Hence Ruby's gsub (sub-string) 
   # extracts the 2nd string
   tag_property_name = b.label.gsub(/(gtk-)([a-z]+)/, '\2')

   txtvu.buffer.apply_tag(tag_property_name, s, e)
 end

 # Apply the selected text size property as the tag.
 def scale_changed(combo, txtvu)
   return if combo.active == -1
   s, e = txtvu.buffer.selection_bounds
   txtvu.buffer.apply_tag(combo.active_text, s, e)
   combo.active = -1
 end

 # Remove all of the tags from the selected text.
 def clear_clicked(txtvu) 
   s, e = txtvu.buffer.selection_bounds
   txtvu.buffer.remove_all_tags(s, e)
 end

 class TextToDouble
   attr_accessor :str, :scale
   def initialize(str, scale)
     @str, @scale = str, scale
   end
 end

 ts = Array.new
 ts[0] = TextToDouble.new("Quarter Sized",      0.25)
 ts[1] = TextToDouble.new("Double Extra Small", Pango::SCALE_XX_SMALL)
 ts[2] = TextToDouble.new("Extra Small",        Pango::SCALE_X_SMALL)
 ts[3] = TextToDouble.new("Small",              Pango::SCALE_SMALL)
 ts[4] = TextToDouble.new("Medium",             Pango::SCALE_MEDIUM)
 ts[5] = TextToDouble.new("Large",              Pango::SCALE_LARGE)
 ts[6] = TextToDouble.new("Extra Large",        Pango::SCALE_X_LARGE)
 ts[7] = TextToDouble.new("Double Extra Large", Pango::SCALE_XX_LARGE)
 ts[8] = TextToDouble.new("Double Sized",       2.0)

 window = Gtk::Window.new(Gtk::Window::TOPLEVEL)
 window.resizable = true
 window.title = "Text Tags"
 window.border_width = 10
 window.signal_connect('delete_event') { Gtk.main_quit }
 window.set_size_request(500, -1)

 textview = Gtk::TextView.new

 buffer = textview.buffer

 # Note: the tag names are stored with buttons in their labels, where
 # each label has string form "gtk-bold", "gtk-italic", ...
 buffer.create_tag("bold",          {"weight"        => Pango::WEIGHT_BOLD})
 buffer.create_tag("italic",        {"style"         => Pango::STYLE_ITALIC})
 buffer.create_tag("strikethrough", {"strikethrough" => true})
 buffer.create_tag("underline",     {"underline"     => Pango::UNDERLINE_SINGLE})

 bold      = Gtk::Button.new(Gtk::Stock::BOLD)
 italic    = Gtk::Button.new(Gtk::Stock::ITALIC)
 underline = Gtk::Button.new(Gtk::Stock::UNDERLINE)
 strike    = Gtk::Button.new(Gtk::Stock::STRIKETHROUGH)
 clear     = Gtk::Button.new(Gtk::Stock::CLEAR)
 scale     = Gtk::ComboBox.new      # (text=true)

 # Add choices to the GtkComboBox widget.
 ts.each do |e|
   scale.append_text(e.str)
   buffer.create_tag(e.str, { "scale" => e.scale } )
 end

 # Connect each of the buttons and the combo box to the necessary signals.
 bold.signal_connect("clicked")      { |w| format(w, textview) }
 italic.signal_connect("clicked")    { |w| format(w, textview) }
 underline.signal_connect("clicked") { |w| format(w, textview) }
 strike.signal_connect("clicked")    { |w| format(w, textview) }
 scale.signal_connect("changed")     { |w| scale_changed(w, textview) }
 clear.signal_connect("clicked")     {     clear_clicked(textview) }

 # Pack the widgets into a GtkVBox, GtkHBox, and then into the window. */
 vbox = Gtk::VBox.new(true, 5)
 vbox.pack_start(bold,      false, false, 0)
 vbox.pack_start(italic,    false, false, 0)
 vbox.pack_start(underline, false, false, 0)
 vbox.pack_start(strike,    false, false, 0)
 vbox.pack_start(scale,     false, false, 0)
 vbox.pack_start(clear,     false, false, 0)

 scrolled_win = Gtk::ScrolledWindow.new
 scrolled_win.border_width = 5
 scrolled_win.add(textview)
 scrolled_win.set_policy(Gtk::POLICY_AUTOMATIC, Gtk::POLICY_ALWAYS)

 hbox = Gtk::HBox.new(false, 5)
 hbox.pack_start(scrolled_win, true,  true, 0)
 hbox.pack_start(vbox,         false, true, 0)

 window.add(hbox)
 window.show_all
 Gtk.main

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[ruby-gnome2-doc-cvs] [Ruby-GNOME2 Project Website] create - tut-gtk2-txtw-ttags