Class: Axon::Cropper
- Inherits:
-
Object
- Object
- Axon::Cropper
- Defined in:
- lib/axon/cropper.rb
Overview
An Image Cropper
Axon::Crop allows you to crop images and extract regions.
Example
image_in = Axon::Solid.new(100, 200)
c = Axon::Crop.new(image_in, 50, 75, 10, 20)
c.width # => 50
c.height # => 75
c.gets # => String
Example of Cropping Past the Boundaries of the Original Image
image_in = Axon::Solid.new(100, 200)
c = Axon::Crop.new(image_in, 50, 75, 60, 20)
c.width # => 40
Instance Attribute Summary collapse
-
#lineno ⇒ Object
readonly
The index of the next line that will be fetched by gets, starting at 0.
Instance Method Summary collapse
-
#color_model ⇒ Object
Gets the color model of the cropped image.
-
#components ⇒ Object
Gets the components in the cropped image.
-
#gets ⇒ Object
Gets the next scanline from the cropped image.
-
#height ⇒ Object
Calculates the height of the cropped image.
-
#initialize(source, width, height, x_offset = nil, y_offset = nil) ⇒ Cropper
constructor
:call-seq: Cropper.new(image_in, width, height, x_offset = 0, y_offset = 0).
-
#width ⇒ Object
Calculates the width of the cropped image.
Constructor Details
#initialize(source, width, height, x_offset = nil, y_offset = nil) ⇒ Cropper
:call-seq:
Cropper.new(image_in, width, height, x_offset = 0, y_offset = 0)
Crops image_in
to the size width
x height
. Optionally, x_offset
and y_offset
can be used to shift the upper left corner of the cropped area.
If the cropped image extends beyond the boundaries of image_in
then the cropped image will be truncated at the boundary.
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# File 'lib/axon/cropper.rb', line 35 def initialize(source, width, height, x_offset=nil, y_offset=nil) raise ArgumentError if width < 1 || height < 1 raise ArgumentError if x_offset && x_offset < 1 || y_offset && y_offset < 1 @source = source @width = width @height = height @x_offset = x_offset || 0 @y_offset = y_offset || 0 @lineno = 0 end |
Instance Attribute Details
#lineno ⇒ Object (readonly)
The index of the next line that will be fetched by gets, starting at 0.
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# File 'lib/axon/cropper.rb', line 23 def lineno @lineno end |
Instance Method Details
#color_model ⇒ Object
Gets the color model of the cropped image. Same as the color model of the source image.
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# File 'lib/axon/cropper.rb', line 77 def color_model @source.color_model end |
#components ⇒ Object
Gets the components in the cropped image. Same as the components of the source image.
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# File 'lib/axon/cropper.rb', line 70 def components @source.components end |
#gets ⇒ Object
Gets the next scanline from the cropped image.
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# File 'lib/axon/cropper.rb', line 83 def gets return nil if @lineno >= height || width < 1 || height < 1 while @source.lineno < @y_offset break unless @source.gets end @lineno += 1 sl_width = width * components sl_offset = @x_offset * components @source.gets[sl_offset, sl_width] end |
#height ⇒ Object
Calculates the height of the cropped image.
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# File 'lib/axon/cropper.rb', line 49 def height if @y_offset + @height > @source.height [@source.height - @y_offset, 0].max else @height end end |
#width ⇒ Object
Calculates the width of the cropped image.
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# File 'lib/axon/cropper.rb', line 59 def width if @x_offset + @width > @source.width [@source.width - @x_offset, 0].max else @width end end |