Class: FileViewer

Inherits:
Object
  • Object
show all
Defined in:
view2.rb

Overview

A curses based file viewer

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ FileViewer

Create a new fileviewer, and view the file.


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# File 'view2.rb', line 10

def initialize(filename)
  @data_lines = []
  @screen = nil
  @top = nil
  init_curses
  load_file(filename)
  interact
end

Instance Method Details

#init_cursesObject

Perform the curses setup


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# File 'view2.rb', line 20

def init_curses  # signal(SIGINT, finish)


  Curses.init_screen
  Curses.nonl
  Curses.cbreak
  Curses.noecho

  @screen = Curses.stdscr

  @screen.scrollok(true)  #$screen.keypad(true)

end

#interactObject

Allow the user to interact with the display. This uses EMACS-like keybindings, and also vi-like keybindings as well, except that left and right move to the beginning and end of the file, respectively.


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# File 'view2.rb', line 92

def interact
  while true
    result = true
    c = Curses.getch
    case c
    when Curses::KEY_DOWN, Curses::KEY_CTRL_N, ?j
      result = scroll_down
    when Curses::KEY_UP, Curses::KEY_CTRL_P, ?k
      result = scroll_up
    when Curses::KEY_NPAGE, ?\s  # white space
      for i in 0..(@screen.maxy - 2)
        if( ! scroll_down )
          if( i == 0 )
            result = false
          end
          break
        end
      end
    when Curses::KEY_PPAGE
      for i in 0..(@screen.maxy - 2)
        if( ! scroll_up )
          if( i == 0 )
            result = false
          end
          break
        end
      end
    when Curses::KEY_LEFT, Curses::KEY_CTRL_T, ?h
      while( scroll_up )
      end
    when Curses::KEY_RIGHT, Curses::KEY_CTRL_B, ?l
      while( scroll_down )
      end
    when ?q
      break
    else
      @screen.setpos(0,0)
      @screen.addstr("[unknown key `#{Curses.keyname(c)}'=#{c}] ")
    end
    if( !result )
      Curses.beep
    end
    @screen.setpos(0,0)
  end
  Curses.close_screen
end

#load_file(filename) ⇒ Object

Load the file into memory, and put the first part on the curses display.


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# File 'view2.rb', line 36

def load_file(filename)
  fp = open(filename, "r") do |fp|
  # slurp the file
  fp.each_line { |l|
    @data_lines.push(l.chop)
  }
  end
  @top = 0
  @data_lines[0..@screen.maxy-1].each_with_index{|line, idx|
    @screen.setpos(idx, 0)
    @screen.addstr(line)
  }
  @screen.setpos(0,0)
  @screen.refresh
rescue
  raise "cannot open file '#{filename}' for reading"
end

#scroll_downObject

Scroll the display down by one line


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# File 'view2.rb', line 72

def scroll_down
  if( @top + @screen.maxy < @data_lines.length )
    @screen.scrl(1)
    @top += 1
    str = @data_lines[@top + @screen.maxy - 1]
    if( str )
      @screen.setpos(@screen.maxy - 1, 0)
      @screen.addstr(str)
    end
    return true
  else
    return false
  end
end

#scroll_upObject

Scroll the display up by one line


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# File 'view2.rb', line 56

def scroll_up
  if( @top > 0 )
    @screen.scrl(-1)
    @top -= 1
    str = @data_lines[@top]
    if( str )
      @screen.setpos(0, 0)
      @screen.addstr(str)
    end
    return true
  else
    return false
  end
end