Class: PSD::ChannelImage
- Includes:
- ImageFormat::LayerRAW, ImageFormat::LayerRLE
- Defined in:
- lib/psd/channel_image.rb
Overview
Represents an image for a single layer, which differs slightly in format from the full size preview image.
Constant Summary
Constants inherited from Image
Instance Attribute Summary collapse
-
#height ⇒ Object
readonly
Returns the value of attribute height.
-
#mask_data ⇒ Object
readonly
Returns the value of attribute mask_data.
-
#width ⇒ Object
readonly
Returns the value of attribute width.
Attributes inherited from Image
#has_mask, #opacity, #pixel_data
Instance Method Summary collapse
- #channels ⇒ Object
-
#initialize(file, header, layer) ⇒ ChannelImage
constructor
A new instance of ChannelImage.
- #parse ⇒ Object
- #parse_image_data! ⇒ Object
- #parse_user_mask ⇒ Object
- #skip ⇒ Object
Methods included from Image::Export::PNG
Constructor Details
#initialize(file, header, layer) ⇒ ChannelImage
Returns a new instance of ChannelImage.
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# File 'lib/psd/channel_image.rb', line 12 def initialize(file, header, layer) @layer = layer @width = @layer.width @height = @layer.height super(file, header) @channels_info = @layer.channels_info @has_mask = @channels_info.any? { |chan| chan[:id] == -2 } @opacity = @layer.opacity / 255.0 @mask_data = [] end |
Instance Attribute Details
#height ⇒ Object (readonly)
Returns the value of attribute height.
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# File 'lib/psd/channel_image.rb', line 10 def height @height end |
#mask_data ⇒ Object (readonly)
Returns the value of attribute mask_data.
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# File 'lib/psd/channel_image.rb', line 10 def mask_data @mask_data end |
#width ⇒ Object (readonly)
Returns the value of attribute width.
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# File 'lib/psd/channel_image.rb', line 10 def width @width end |
Instance Method Details
#channels ⇒ Object
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# File 'lib/psd/channel_image.rb', line 33 def channels @layer.channels end |
#parse ⇒ Object
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# File 'lib/psd/channel_image.rb', line 37 def parse PSD.logger.debug "Layer = #{@layer.name}, Size = #{width}x#{height}" PSD.logger.debug @channels_info @chan_pos = 0 @channels_info.each do |ch_info| @ch_info = ch_info if ch_info[:length] <= 0 parse_compression! and next end # If the ID of this current channel is -2, then we assume the dimensions # of the layer mask. if ch_info[:id] < -1 @width = @layer.mask.width @height = @layer.mask.height else @width = @layer.width @height = @layer.height end @length = @width * @height start = @file.tell PSD.logger.debug "Channel ##{ch_info[:id]}, length = #{ch_info[:length]}" parse_image_data! finish = @file.tell if finish != start + ch_info[:length] PSD.logger.error "Read incorrect number of bytes for channel ##{ch_info[:id]}. Expected = #{ch_info[:length]}, Actual = #{finish - start}" @file.seek start + ch_info[:length] end end if @channel_data.length != (@length * @channels_info.length) PSD.logger.error "#{@channel_data.length} read; expected #{@length}" end @width = @layer.width @height = @layer.height parse_user_mask process_image_data end |
#parse_image_data! ⇒ Object
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# File 'lib/psd/channel_image.rb', line 84 def parse_image_data! @compression = parse_compression! case @compression when 0 then parse_raw! when 1 then parse_rle! when 2, 3 then parse_zip! else PSD.logger.error "Unknown image compression: #{@compression}. Attempting to skip." @file.seek(@end_pos) end end |
#parse_user_mask ⇒ Object
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# File 'lib/psd/channel_image.rb', line 97 def parse_user_mask return unless has_mask? mask_id = -2 PSD.logger.debug "Using mask in channel #{mask_id}" channel = @channels_info.select { |c| c[:id] == mask_id }.first index = @channels_info.index { |c| c[:id] == mask_id } return if channel.nil? start = @channel_length * index length = @layer.mask.width * @layer.mask.height PSD.logger.debug "Copying user mask: #{length} bytes at #{start}" @mask_data = @channel_data[start, length] if @mask_data.length != length PSD.logger.error "Mask length is incorrect. Expected = #{length}, Actual = #{@mask_data.length}" end end |
#skip ⇒ Object
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# File 'lib/psd/channel_image.rb', line 26 def skip PSD.logger.debug "Skipping channel image data. Layer = #{@layer.name}" @channels_info.each do |ch| @file.seek ch[:length], IO::SEEK_CUR end end |