ruby-****@sourc*****
ruby-****@sourc*****
2012年 9月 5日 (水) 09:15:12 JST
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REMOTE_ADDR = 70.49.49.99
REMOTE_HOST =
URL = http://ruby-gnome2.sourceforge.jp/hiki.cgi?tut-gtk2-txtw-textview
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@@ -44,6 +44,44 @@
Here the buffer component is the Gtk::TextBuffer. Text buffers hold text, images, child widgets, text tags and other information necessary for rendering the documents. A Gtk::TextBuffer buffer is an independent object and can be displayed by many text view widgets. However any text view has only a single text buffer associated with it. Most programmers do not take advantage of this feature, but it will become important latter when you learn how to embed child widgets into a text buffer.
+
+:Short D-tour:
+
+ If you are not exactly sure what was just said, following is a short demonstration simulating how Gtk::TextView and Gtk::TextBuffer are implemented, and how you can exploit this design to create some Gtk::TextViews that share the same Gtk::TextBuffer and some that do not:
+
+ In tv-N-tb-example.rb sample program pay attention to three different ((*tview_instance_#*)) TextView instances. The first one, designated with number zero (0) has its own (not shared) TextBuffer, however, the other two (#1 and #2) share the TextBuffer instance:
+
+ ((*tv-N-tb-example.rb*))
+ #!/usr/bin/env ruby
+ class TextView
+ attr_accessor :buffer
+ def initialize(buffer); @buffer = buffer; end
+ end
+ class TextBuffer
+ attr_accessor :text
+ def initialize(text); @text = text; end
+ def to_s; "Class TextBuffer: text=#@text"; end
+ end
+ def show_text_views_buffer(id, tv_inst)
+ puts "Buffer ID=#{id} - #{tv_inst.class}: #{tv_inst.buffer.to_s}"
+ end
+
+ tview_instance_0 = TextView.new(nil)
+ show_text_views_buffer(0, tview_instance_0)
+ tb=TextBuffer.new("Some initial text")
+ tview_instance_1 = TextView.new(tb)
+ tview_instance_2 = TextView.new(tb)
+ show_text_views_buffer(1, tview_instance_1)
+ tview_instance_2.buffer.text = "Override the initial text with new text."
+ puts "----- after overriding text buffer -------"
+ show_text_views_buffer(0, tview_instance_0)
+ show_text_views_buffer(1, tview_instance_1)
+ show_text_views_buffer(2, tview_instance_2)
+
+
+
+
+
Most new text views are created with the Gtk::TextView.new(buffer=nil). When using this method with the default nil argument an empty Gtk::TextBuffer is created for you. This empty text buffer can be replaced or retrieved by "Gtk::TextView#buffer=(buff)", or "Gtk::TextView#set_buffer(buff)", and "buff = Gtk::TextView#buffer" respectively. With the former two methods the contents of the buffer gets completely replaced. However, as we will see in the following page((*Text Iterators and Marks,*))one can also cause changes to a text buffer only partially.
Recall that we have pointed out that a few widgets provide native scrolling support. Well, Gtk::TextView is one of them. This means you should use Gtk::Container#add method, rather than Gtk::ScrolledWindow#add_with_viewport(child), to add Gtk::TextView to the scrolled windows.