Class: GDAL::ColorTable

Inherits:
Object
  • Object
show all
Includes:
GDAL::ColorTableMixins::Extensions
Defined in:
lib/gdal/color_table.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from GDAL::ColorTableMixins::Extensions

#color_entries, #color_entries_as_rgb, #color_entries_for

Constructor Details

#initialize(palette_interp_or_pointer) ⇒ ColorTable

Returns a new instance of ColorTable.

Parameters:

  • palette_interp_or_pointer (FFI::GDAL::PaletteInterp, FFI::Pointer)

Raises:



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# File 'lib/gdal/color_table.rb', line 40

def initialize(palette_interp_or_pointer)
  pointer =
    if FFI::GDAL::GDAL::PaletteInterp[palette_interp_or_pointer]
      ptr = FFI::GDAL::GDAL.GDALCreateColorTable(palette_interp_or_pointer)
      ptr.autorelease = false

      ptr
    elsif palette_interp_or_pointer.is_a? FFI::Pointer
      palette_interp_or_pointer
    end

  if !pointer.is_a?(FFI::Pointer) || pointer.null?
    raise GDAL::InvalidColorTable,
          "Unable to create #{self.class.name} from #{palette_interp_or_pointer}"
  end

  @c_pointer = pointer
  @color_entries = []

  case palette_interpretation
  when :GPI_Gray then extend GDAL::ColorTableTypes::Gray
  when :GPI_RGB then extend GDAL::ColorTableTypes::RGB
  when :GPI_CMYK then extend GDAL::ColorTableTypes::CMYK
  when :GPI_HLS then extend GDAL::ColorTableTypes::HLS
  else
    raise "Unknown PaletteInterpretation: #{palette_interpretation}"
  end
end

Instance Attribute Details

#c_pointer ⇒ FFI::Pointer (readonly)

Returns C pointer to the C color table.

Returns:

  • (FFI::Pointer) —

    C pointer to the C color table.



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# File 'lib/gdal/color_table.rb', line 35

def c_pointer
  @c_pointer
end

Class Method Details

.new_pointer(color_table) ⇒ FFI::AutoPointer

Parameters:

Returns:

  • (FFI::AutoPointer) 


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# File 'lib/gdal/color_table.rb', line 21

def self.new_pointer(color_table)
  ptr = GDAL._pointer(GDAL::ColorTable, color_table, autorelease: false)

  FFI::AutoPointer.new(ptr, ColorTable.method(:release))
end

.release(pointer) ⇒ Object

Parameters:

  • pointer (FFI::Pointer) 


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# File 'lib/gdal/color_table.rb', line 28

def self.release(pointer)
  return unless pointer && !pointer.null?

  FFI::GDAL::GDAL.GDALDestroyColorTable(pointer)
end

Instance Method Details

#add_color_entry(index, one = nil, two = nil, three = nil, four = nil) ⇒ GDAL::ColorEntry

Add a new ColorEntry to the ColorTable. Valid values depend on the image type you’re working with (i.e. for Tiff, values can be between 0 and 65535). Values must also be relevant to the PaletteInterp type you’re working with.

rubocop:disable Metrics/ParameterLists

Parameters:

  • index (Integer) —

    The index of the color table’s color entry to set. Must be between 0 and color_entry_count - 1.

  • one (Integer) (defaults to: nil) —

    The ‘c1` value of the GDAL::ColorEntry struct to set.

  • two (Integer) (defaults to: nil) —

    The ‘c2` value of the GDAL::ColorEntry struct to set.

  • three (Integer) (defaults to: nil) —

    The ‘c3` value of the GDAL::ColorEntry struct to set.

  • four (Integer) (defaults to: nil) —

    The ‘c4` value of the GDAL::ColorEntry struct to set.

Returns:



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# File 'lib/gdal/color_table.rb', line 139

def add_color_entry(index, one = nil, two = nil, three = nil, four = nil)
  entry = GDAL::ColorEntry.new
  entry.color1 = one if one
  entry.color2 = two if two
  entry.color3 = three if three
  entry.color4 = four if four

  FFI::GDAL::GDAL.GDALSetColorEntry(@c_pointer, index, entry.c_struct)
  @color_entries.insert(index, entry)

  entry
end

#clone ⇒ GDAL::ColorTable

Clones the ColorTable using the C API.

Returns:



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# File 'lib/gdal/color_table.rb', line 78

def clone
  ct_ptr = FFI::GDAL::GDAL.GDALCloneColorTable(@c_pointer)
  ct_ptr.autorelease = false

  return nil if ct_ptr.null?

  GDAL::ColorTable.new(ct_ptr)
end

#color_entry(index) ⇒ GDAL::ColorEntry

Parameters:

Returns:



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# File 'lib/gdal/color_table.rb', line 101

def color_entry(index)
  @color_entries.fetch(index) do
    color_entry = FFI::GDAL::GDAL.GDALGetColorEntry(@c_pointer, index)
    return nil if color_entry.null?

    GDAL::ColorEntry.new(color_entry)
  end
end

#color_entry_as_rgb(index) ⇒ GDAL::ColorEntry

Parameters:

Returns:



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# File 'lib/gdal/color_table.rb', line 112

def color_entry_as_rgb(index)
  entry = color_entry(index)
  return unless entry

  FFI::GDAL::GDAL.GDALGetColorEntryAsRGB(@c_pointer, index, entry.c_pointer)
  return nil if entry.c_pointer.null?

  entry
end

#color_entry_count ⇒ Integer

Returns:



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# File 'lib/gdal/color_table.rb', line 95

def color_entry_count
  FFI::GDAL::GDAL.GDALGetColorEntryCount(@c_pointer)
end

#create_color_ramp!(start_index, start_color, end_index, end_color) ⇒ Integer

Automatically creates a color ramp from one color entry to another. It can be called several times to create multiple ramps in the same color table.

Parameters:

  • start_index (Integer) —

    Index to start the ramp on (0..255)

  • start_color (GDAL::ColorEntry) —

    Value to start the ramp.

  • end_index (Integer) —

    Index to end the ramp on (0..255)

  • end_color (GDAL::ColorEntry) —

    Value to end the ramp.

Returns:

  • (Integer) —

    The total number of entries. nil or -1 on error.



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# File 'lib/gdal/color_table.rb', line 162

def create_color_ramp!(start_index, start_color, end_index, end_color)
  start_color_ptr = start_color.c_struct
  end_color_ptr = end_color.c_struct

  FFI::GDAL::GDAL.GDALCreateColorRamp(@c_pointer, start_index,
                                      start_color_ptr,
                                      end_index,
                                      end_color_ptr)
end

#destroy! ⇒ Object 



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# File 'lib/gdal/color_table.rb', line 69

def destroy!
  ColorTable.release(@c_pointer)

  @c_pointer = nil
end

#palette_interpretation ⇒ Symbol

Usually :GPI_RGB.

Returns:

  • (Symbol) —

    One of FFI::GDAL::GDAL::PaletteInterp.



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# File 'lib/gdal/color_table.rb', line 90

def palette_interpretation
  FFI::GDAL::GDAL.GDALGetPaletteInterpretation(@c_pointer)
end