Class: OdroidLCD::LCD

Inherits:
Object
  • Object
show all
Defined in:
lib/odroid_lcd/lcd.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(mocks: {}) ⇒ LCD

Returns a new instance of LCD.



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# File 'lib/odroid_lcd/lcd.rb', line 12

def initialize(mocks: {})
  @hw = if mocks[:odroidlcd_hw]
          mocks[:odroidlcd_hw]
        else
          require 'odroid_lcd/hw'
          OdroidLCD::HW.new
        end

  @max_column = @hw.max_column
  @max_row = @hw.max_row
  freeze()
end

Instance Attribute Details

#max_column ⇒ Object (readonly)

The main interface to the LCD screen.



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# File 'lib/odroid_lcd/lcd.rb', line 9

def max_column
  @max_column
end

#max_row ⇒ Object (readonly)

Returns the value of attribute max_row.



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# File 'lib/odroid_lcd/lcd.rb', line 10

def max_row
  @max_row
end

Instance Method Details

#clear ⇒ Object

Clear the display



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# File 'lib/odroid_lcd/lcd.rb', line 26

def clear
  @hw.clear
end

#set_character(row:, column:, character:) ⇒ Object

set_character

Sets a single character at a particular position on the display.

Note that the display uses a Japanese display driver, so the following quirks / features are present:

“" is displayed as the yen character ”~“ is displayed as a right arrow delete (or rubout) is displayed as a left arrow

Row 0 is the top row, row 1 is the bottom row.



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# File 'lib/odroid_lcd/lcd.rb', line 43

def set_character(row:, column:, character:)
  begin
    # It's a Japanese display, seemingly using Windows-31J
    #
    # Note that \ displays as a yen sign, ~ displays as a right arrow, DEL displays as a left arrow
    chr = character.encode("Windows-31J")
    @hw.set_character(row, column, chr)
  rescue Encoding::UndefinedConversionError => e
    raise OdroidLCD::LCDError, "Could not display character: #{character}, the display uses Japanese Windows-31J"
  end
end

#set_lines(lines:, align: "left") ⇒ Object

::lines::

["line one", "line two"]
["line one", "line two", "line three"]

::align::

Optional, either "left", "right", or "center"
Defaults to: "left"



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# File 'lib/odroid_lcd/lcd.rb', line 93

def set_lines(lines:, align: "left")
  if lines.length >= @max_row
    set_string(row: 0, string: lines[0].to_s, align: align)
    set_string(row: 1, string: lines[1].to_s, align: align)
  else
    set_string(row: 0, string: lines[0].to_s, align: align)
  end
end

#set_string(row: 0, string:, align: "left") ⇒ Object

set_string

Sets a string on the display.

::row::

Which row of the display to update.
Row 0 is the top row, row 1 is the bottom row.

::string::

The string to send to the display.

::align::

Optional, either "left", "right", or "center"
Defaults to: "left"



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# File 'lib/odroid_lcd/lcd.rb', line 70

def set_string(row: 0, string:, align: "left")
  column = 0
  str = case align
        when "left"   then string[0, @max_column].ljust(@max_column)
        when "right"  then string[0, @max_column].rjust(@max_column)
        when "center" then string[0, @max_column].center(@max_column)
        else string[0, @max_column].ljust(@max_column)
        end

  str.chars do |chr|
    set_character(row: row, column: column, character: chr)
    column += 1
  end
end