* ext/tk/sample/tktextio.rb: add show_mode which means that see where

when changing file position.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@8126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/tk/sample/tktextio.rb

@@ -21,11 +21,13 @@ class TkTextIO < TkText
     ovwt = false
     text = nil
     wrap = 'char'
+    show = :pos
 
     if keys.kind_of?(Hash)
       mode = keys.delete('mode')
       ovwt = keys.delete('overwrite')
       text = keys.delete('text')
+      show = keys.delete('show') if keys.has_key?('show')
       wrap = keys.delete('wrap') || 'char'
     end
 
@@ -37,6 +39,8 @@ class TkTextIO < TkText
     @txtpos = TkTextMark.new(self, '1.0')
     @txtpos.gravity = :left
 
+    self.show_mode = show
+
     @sync = true
     @overwrite = (ovwt)? true: false
 
@@ -168,6 +172,7 @@ class TkTextIO < TkText
     return nil if eof?
     c = get(@txtpos)
     @txtpos.set(@txtpos + '1 char')
+    _see_pos
     c
   end
 
@@ -217,6 +222,7 @@ class TkTextIO < TkText
   def index_pos=(idx)
     @txtpos.set(idx)
     @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
+    _see_pos
     idx
   end
 
@@ -294,6 +300,7 @@ class TkTextIO < TkText
     s = get(@txtpos, epos)
     @txtpos.set(epos)
     @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
+    _see_pos
     s
   end
   private :_read
@@ -307,6 +314,7 @@ class TkTextIO < TkText
     else
       s = get(@txtpos, 'end - 1 char')
       @txtpos.set('end - 1 char')
+      _see_pos
     end
     buf.replace(s) if buf.kind_of?(String)
     s
@@ -317,6 +325,7 @@ class TkTextIO < TkText
     fail EOFError if eof?
     c = get(@txtpos)
     @txtpos.set(@txtpos + '1 char')
+    _see_pos
     c
   end
 
@@ -340,12 +349,14 @@ class TkTextIO < TkText
       if idx
         s = get(@txtpos, "#{idx} + #{@count_var.value} char")
         @txtpos.set("#{idx} + #{@count_var.value} char")
+        @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
       else
         s = get(@txtpos, 'end - 1 char')
         @txtpos.set('end - 1 char')
       end
     end
 
+    _see_pos
     @lineno += 1
     $_ = s
   end
@@ -380,6 +391,7 @@ class TkTextIO < TkText
 
   def rewind
     @txtpos.set('1.0')
+    _see_pos
     @lineno = 0
     @line_offset = 0
     self
@@ -404,11 +416,48 @@ class TkTextIO < TkText
     end
 
     @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
+    _see_pos
 
     0
   end
   alias sysseek seek
 
+  def _see_pos
+    see(@show) if @show
+  end
+  private :_see_pos
+
+  def show_mode
+    (@show == @txtpos)? :pos : @show
+  end
+
+  def show_mode=(mode)
+    # define show mode  when file position is changed. 
+    #  mode == :pos or "pos" or true :: see current file position. 
+    #  mode == :insert or "insert"   :: see insert cursor position. 
+    #  mode == nil or false          :: do nothing
+    #  else see 'mode' position ('mode' should be text index or mark)
+    case mode
+    when :pos, 'pos', true
+      @show = @txtpos
+    when :insert, 'insert'
+      @show = :insert
+    when nil, false
+      @show = false
+    else
+      begin
+        index(mode)
+      rescue
+        fail ArgumentError, 'invalid show-position'
+      end
+      @show = mode
+    end
+
+    _see_pos
+
+    mode
+  end
+
   def stat
     fail NotImplementedError, 'stat is not implemented on TkTextIO'
   end
@@ -450,6 +499,7 @@ class TkTextIO < TkText
       delete(@txtpos)
       insert(@txtpos, tk_call('string', 'range', c, 0, 1))
       @txtpos.set(@txtpos - '1 char') if @txtpos.gravity == 'right'
+      _see_pos
     else
       fail IOError, 'cannot ungetc at head of stream'
     end
@@ -462,6 +512,8 @@ class TkTextIO < TkText
     delete(@txtpos, @txtpos + "#{n} char") if @overwrite
     self.insert(@txtpos, s)
     @txtpos.set(@txtpos + "#{n} char")
+    @txtpos.set('end - 1 char') if compare(@txtpos, '>=', :end)
+    _see_pos
     Tk.update if @sync
     n
   end
@@ -478,7 +530,8 @@ end
 ####################
 if __FILE__ == $0
   f = TkFrame.new.pack
-  tio = TkTextIO.new(f, :text=>">>> This is an initial text line. <<<\n\n"){
+  tio = TkTextIO.new(f, :show=>:pos, 
+                     :text=>">>> This is an initial text line. <<<\n\n"){
     yscrollbar(TkScrollbar.new(f).pack(:side=>:right, :fill=>:y))
     pack(:side=>:left, :fill=>:both, :expand=>true)
   }
@@ -498,12 +551,21 @@ if __FILE__ == $0
   puts "On this sample, a text widget works as if it is a I/O stream."
   puts "Please see the code."
   puts
-  printf("printf message: %d %X\n", 123456, 255);
+  printf("printf message: %d %X\n", 123456, 255)
   puts
+  printf("(output by 'p' method) This TkTextIO object is ...\n")
   p tio
+  print(" [ Current wrap mode of this object is 'char'. ]\n")
   puts
   warn("This is a warning message generated by 'warn' method.")
   puts
+  puts "current show_mode is #{tio.show_mode}."
+  if tio.show_mode == :pos
+    puts "So, you can see the current file position on this text widget."
+  else
+    puts "So, you can see the position '#{tio.show_mode}' on this text widget."
+  end
+  print("Please scroll up this text widget to see the head of lines.\n")
   print("---------------------------------------------------------\n")
 
   STDOUT.print("\n=============== TkTextIO#readlines =============\n\n")