class GD2::Image
Introduction¶ ↑
Image
is the abstract base class for Image::IndexedColor
and Image::TrueColor
.
Creating and Importing¶ ↑
Image
objects are created either as a blank array of pixels:
image = Image::IndexedColor.new(width, height) image = Image::TrueColor.new(width, height)
or by loading image data from a file or a string containing one of the supported image formats:
image = Image.load(file) image = Image.load(string)
or by importing image data from a file given by its pathname:
image = Image.import(filename)
Exporting¶ ↑
After manipulating an image, it can be exported to a string in one of the supported image formats:
image.jpeg(quality = nil) image.png(level = nil) image.gif image.wbmp(fgcolor) image.gd image.gd2(fmt = FMT_COMPRESSED)
or to a file in a format determined by the filename extension:
image.export(filename, options = {})
Attributes
The Palette
object for this image
Public Class Methods
# File lib/gd2/image.rb, line 135 def self.extract_format(filename_or_io, options) format = options[:format] if !format case filename_or_io when String md = filename_or_io.match(/\.([^.]+)\z/) format = md ? md[1].downcase : nil else magic = filename_or_io.read(4) filename_or_io.seek(-magic.bytes.length, IO::SEEK_CUR) format = data_type(magic.strip) end end format = format.to_sym if format format end
Import an image from a file with the given filename
. The :format option or the file extension is used to determine the image type (jpeg, png, gif, wbmp, gd, gd2, xbm, or xpm). The resulting image will be either of class Image::TrueColor
or Image::IndexedColor
.
If the file format is gd2, it is optionally possible to extract only a part of the image. Use options :x, :y, :width, and :height to specify the part of the image to import.
# File lib/gd2/image.rb, line 162 def self.import(filename_or_io, options = {}) format = extract_format(filename_or_io, options) ptr = # TODO: implement xpm and xbm imports #if format == :xpm #raise ArgumentError, "Unexpected options #{options.inspect}" unless options.empty? #::GD2::GD2FFI.send(:gdImageCreateFromXpm, filename) #elsif format == :xbm #::GD2::GD2FFI.send(:gdImageCreateFromXbm, filename) if format == :gd2 && !options.empty? x, y, width, height = options.delete(:x) || 0, options.delete(:y) || 0, options.delete(:width) || options.delete(:w), options.delete(:height) || options.delete(:h) raise ArgumentError, "Unexpected options #{options.inspect}" unless options.empty? raise ArgumentError, 'Missing required option :width' if width.nil? raise ArgumentError, 'Missing required option :height' if height.nil? # TODO: ptr = File.open(filename, 'rb') do |file| ::GD2::GD2FFI.send(:gdImageCreateFromGd2Part, file, x.to_i, y.to_i, width.to_i, height.to_i) end else raise ArgumentError, "Unexpected options #{options.inspect}" unless options.empty? create_sym = { :jpeg => :gdImageCreateFromJpegPtr, :jpg => :gdImageCreateFromJpegPtr, :png => :gdImageCreateFromPngPtr, :gif => :gdImageCreateFromGifPtr, :wbmp => :gdImageCreateFromWBMPPtr, :gd => :gdImageCreateFromGdPtr, :gd2 => :gdImageCreateFromGd2Ptr }[format] raise UnrecognizedImageTypeError, 'Format (or file extension) is not recognized' unless create_sym output = case filename_or_io when String File.open(filename_or_io, 'rb').read else filename_or_io.read end output = output.force_encoding("ASCII-8BIT") if output.respond_to? :force_encoding file_ptr = FFI::MemoryPointer.new(output.size, 1, false) file_ptr.put_bytes(0, output) ::GD2::GD2FFI.send(create_sym, output.size, file_ptr) end raise LibraryError if ptr.null? ptr = FFIStruct::ImagePtr.new(ptr) image = (image_true_color?(ptr) ? TrueColor : IndexedColor).allocate.init_with_image(ptr) block_given? ? yield(image) : image end
Load an image from a file or a string. The image type is detected automatically (JPEG, PNG, GIF, WBMP, or GD2
). The resulting image will be either of class Image::TrueColor
or Image::IndexedColor
.
# File lib/gd2/image.rb, line 73 def self.load(src) src = src.force_encoding("ASCII-8BIT") if src.respond_to? :force_encoding case src when File pos = src.pos magic = src.read(4) src.pos = pos data = if FFI::Platform.windows? File.open(src.path, 'rb').read[pos..-1] else data = src.read end data = data.force_encoding("ASCII-8BIT") if data.respond_to? :force_encoding args = [ data.length, data ] when String magic = src.slice(0, 4) args = [ src.length, src ] else raise TypeError, 'Unexpected argument type' end create = { :jpeg => :gdImageCreateFromJpegPtr, :png => :gdImageCreateFromPngPtr, :gif => :gdImageCreateFromGifPtr, :wbmp => :gdImageCreateFromWBMPPtr, :gd2 => :gdImageCreateFromGd2Ptr } type = data_type(magic) or raise UnrecognizedImageTypeError, 'Image data format is not recognized' ptr = ::GD2::GD2FFI.send(create[type], *args) raise LibraryError if ptr.null? ptr = FFIStruct::ImagePtr.new(ptr) image = (image_true_color?(ptr) ? TrueColor : IndexedColor).allocate.init_with_image(ptr) block_given? ? yield(image) : image end
Create a new image of the specified dimensions. The default image class is Image::TrueColor
; call this method on Image::IndexedColor
instead if a palette image is desired.
# File lib/gd2/image.rb, line 59 def self.new(w, h) image = (self == Image) ? TrueColor.new(w, h) : allocate.init_with_size(w, h) block_given? ? yield(image) : image end
Private Class Methods
# File lib/gd2/image.rb, line 117 def self.data_type(magic) case magic when /^\xff\xd8/ :jpeg when /^\x89PNG/ :png when /^GIF8/ :gif when /^\x00/ :wbmp when /^gd2/ :gd2 when /^\xff\xff/ :gd end end
# File lib/gd2/image.rb, line 224 def self.image_true_color?(ptr) not ptr[:trueColor].zero? end
Public Instance Methods
Compare this image with another image. Returns false if the images are not identical.
# File lib/gd2/image.rb, line 279 def ==(other) (compare(other) & CMP_IMAGE).zero? end
Return the color of the pixel at image location (x
, y
).
# File lib/gd2/image.rb, line 325 def [](x, y) pixel2color(get_pixel(x, y)) end
Set the color of the pixel at image location (x
, y
).
# File lib/gd2/image.rb, line 330 def []=(x, y, color) set_pixel(x, y, color2pixel(color)) end
Set whether colors should be alpha blended with existing colors when pixels are modified. Alpha blending is not available for IndexedColor
images.
# File lib/gd2/image.rb, line 378 def alpha_blending=(bool) ::GD2::GD2FFI.send(:gdImageAlphaBlending, image_ptr, bool ? 1 : 0) end
Return true if colors will be alpha blended into the image when pixels are modified. Returns false if colors will be copied verbatim into the image without alpha blending when pixels are modified.
# File lib/gd2/image.rb, line 371 def alpha_blending? not image_ptr[:alphaBlendingFlag].zero? end
Return the aspect ratio of this image, as a floating point ratio of the width to the height.
# File lib/gd2/image.rb, line 308 def aspect width.to_f / height end
Return the current clipping rectangle. Use Image#with_clipping
to temporarily modify the clipping rectangle.
# File lib/gd2/image.rb, line 409 def clipping x1 = FFI::MemoryPointer.new(:pointer) y1 = FFI::MemoryPointer.new(:pointer) x2 = FFI::MemoryPointer.new(:pointer) y2 = FFI::MemoryPointer.new(:pointer) ::GD2::GD2FFI.send(:gdImageGetClip, image_ptr, x1, y1, x2, y2) [ x1.read_int, y1.read_int, x2.read_int, y2.read_int ] end
Return true if the current clipping rectangle excludes the given point.
# File lib/gd2/image.rb, line 434 def clips?(x, y) ::GD2::GD2FFI.send(:gdImageBoundsSafe, image_ptr, x.to_i, y.to_i).zero? end
Return a pixel value for the given color
object.
# File lib/gd2/image.rb, line 352 def color2pixel(color) color.rgba end
Compare this image with another image. Returns 0 if the images are identical, otherwise a bit field indicating the differences. See the GD2::CMP_* constants for individual bit flags.
# File lib/gd2/image.rb, line 273 def compare(other) ::GD2::GD2FFI.send(:gdImageCompare, image_ptr, other.image_ptr) end
Copy a portion of another image to this image. If src_w
and src_h
are specified, the indicated portion of the source image will be resized (and resampled) to fit the indicated dimensions of the destination.
# File lib/gd2/image.rb, line 577 def copy_from(other, dst_x, dst_y, src_x, src_y, dst_w, dst_h, src_w = nil, src_h = nil) raise ArgumentError unless src_w.nil? == src_h.nil? if src_w ::GD2::GD2FFI.send(:gdImageCopyResampled, image_ptr, other.image_ptr, dst_x.to_i, dst_y.to_i, src_x.to_i, src_y.to_i, dst_w.to_i, dst_h.to_i, src_w.to_i, src_h.to_i) else ::GD2::GD2FFI.send(:gdImageCopy, image_ptr, other.image_ptr, dst_x.to_i, dst_y.to_i, src_x.to_i, src_y.to_i, dst_w.to_i, dst_h.to_i) end self end
Copy a portion of another image to this image, rotating the source portion first by the indicated angle
(in radians). The dst_x
and dst_y
arguments indicate the center of the desired destination, and may be floating point.
# File lib/gd2/image.rb, line 594 def copy_from_rotated(other, dst_x, dst_y, src_x, src_y, w, h, angle) ::GD2::GD2FFI.send(:gdImageCopyRotated, image_ptr, other.image_ptr, dst_x.to_f, dst_y.to_f, src_x.to_i, src_y.to_i, w.to_i, h.to_i, angle.to_degrees.round.to_i) self end
Like Image#crop!
except a new image is returned.
# File lib/gd2/image.rb, line 633 def crop(x, y, w, h) clone.crop!(x, y, w, h) end
Crop this image to the specified dimensions, such that (x
, y
) becomes (0, 0).
# File lib/gd2/image.rb, line 626 def crop!(x, y, w, h) ptr = self.class.create_image_ptr(w, h, alpha_blending?) ::GD2::GD2FFI.send(:gdImageCopy, ptr, image_ptr, 0, 0, x.to_i, y.to_i, w.to_i, h.to_i) init_with_image(ptr) end
Provide a drawing environment for a block. See GD2::Canvas
.
# File lib/gd2/image.rb, line 439 def draw #:yields: canvas yield Canvas.new(self) self end
Duplicate this image, copying all pixels to a new image. Contrast with Image#clone which produces a shallow copy and shares internal pixel data.
# File lib/gd2/image.rb, line 266 def dup self.class.superclass.load(gd2(FMT_RAW)) end
Iterate over each row of pixels in the image, returning an array of pixel values.
# File lib/gd2/image.rb, line 336 def each (0...height).each do |y| row = (0...width).inject(Array.new(width)) do |r, x| r[x] = get_pixel(x, y) r end yield row end end
Export this image to a file or stream with the given filename
. The image format is determined by the :format option, or by the file extension (jpeg, png, gif, wbmp, gd, or gd2). Returns the size of the written image data. Additional options
are as arguments for the Image#jpeg
, Image#png
, Image#wbmp
, or Image#gd2
methods.
# File lib/gd2/image.rb, line 456 def export(filename_or_io, options = {}) format = self.class.extract_format(filename_or_io, options) size = FFI::MemoryPointer.new(:pointer) case format when :jpeg, :jpg write_sym = :gdImageJpegPtr args = [ size, options.delete(:quality) || -1 ] when :png write_sym = :gdImagePngPtrEx args = [ size, options.delete(:level) || -1 ] when :gif write_sym = :gdImageGifPtr args = [ size ] when :wbmp write_sym = :gdImageWBMPPtr fgcolor = options.delete(:fgcolor) raise ArgumentError, 'Missing required option :fgcolor' if fgcolor.nil? args = [size, color2pixel(fgcolor)] when :gd write_sym = :gdImageGdPtr args = [ size ] when :gd2 write_sym = :gdImageGd2Ptr args = [ options.delete(:chunk_size) || 0, options.delete(:fmt) || FMT_COMPRESSED, size ] else raise UnrecognizedImageTypeError, 'Format (or file extension) is not recognized' end output = case filename_or_io when String File.open(filename_or_io, 'wb') else filename_or_io end begin img = ::GD2::GD2FFI.send(write_sym, image_ptr, *args) output.write(img.get_bytes(0, size.get_int(0))) ensure ::GD2::GD2FFI.gdFree(img) end output.flush output.rewind output end
Encode and return data for this image in “.gd” format. This is an internal format used by the gd library to quickly read and write images.
# File lib/gd2/image.rb, line 555 def gd size = FFI::MemoryPointer.new(:pointer) ptr = ::GD2::GD2FFI.send(:gdImageGdPtr, image_ptr, size) ptr.get_bytes(0, size.get_int(0)) ensure ::GD2::GD2FFI.send(:gdFree, ptr) end
Encode and return data for this image in “.gd2” format. This is an internal format used by the gd library to quickly read and write images. The specified fmt
may be either GD2::FMT_RAW or GD2::FMT_COMPRESSED.
# File lib/gd2/image.rb, line 566 def gd2(fmt = FMT_COMPRESSED, chunk_size = 0) size = FFI::MemoryPointer.new(:pointer) ptr = ::GD2::GD2FFI.send(:gdImageGd2Ptr, image_ptr, chunk_size.to_i, fmt.to_i, size) ptr.get_bytes(0, size.get_int(0)) ensure ::GD2::GD2FFI.send(:gdFree, ptr) end
Return the pixel value at image location (x
, y
).
# File lib/gd2/image.rb, line 313 def get_pixel(x, y) ::GD2::GD2FFI.send(:gdImageGetPixel, @image_ptr, x.to_i, y.to_i) end
Encode and return data for this image in GIF format. Note that GIF only supports palette images; TrueColor
images will be automatically converted to IndexedColor
internally in order to create the GIF. Use Image#to_indexed_color
to control this conversion more precisely.
# File lib/gd2/image.rb, line 533 def gif size = FFI::MemoryPointer.new(:pointer) ptr = ::GD2::GD2FFI.send(:gdImageGifPtr, image_ptr, size) ptr.get_bytes(0, size.get_int(0)) ensure ::GD2::GD2FFI.send(:gdFree, ptr) end
Return the height of this image, in pixels.
# File lib/gd2/image.rb, line 296 def height image_ptr[:sy] end
Set whether this image will be stored in interlaced form when output as PNG or JPEG.
# File lib/gd2/image.rb, line 364 def interlaced=(bool) ::GD2::GD2FFI.send(:gdImageInterlace, image_ptr, bool ? 1 : 0) end
Return true if this image will be stored in interlaced form when output as PNG or JPEG.
# File lib/gd2/image.rb, line 358 def interlaced? not image_ptr[:interlace].zero? end
Encode and return data for this image in JPEG format. The quality
argument should be in the range 0–95, with higher quality values usually implying both higher quality and larger sizes.
# File lib/gd2/image.rb, line 510 def jpeg(quality = nil) size = FFI::MemoryPointer.new(:pointer) ptr = ::GD2::GD2FFI.send(:gdImageJpegPtr, image_ptr, size, quality || -1) ptr.get_bytes(0, size.get_int(0)) ensure ::GD2::GD2FFI.send(:gdFree, ptr) end
Merge a portion of another image into this one by the amount specified as pct
(a percentage). A percentage of 1.0 is identical to Image#copy_from
; a percentage of 0.0 is a no-op. Note that alpha channel information from the source image is ignored.
# File lib/gd2/image.rb, line 604 def merge_from(other, dst_x, dst_y, src_x, src_y, w, h, pct) ::GD2::GD2FFI.send(:gdImageCopyMerge, image_ptr, other.image_ptr, dst_x.to_i, dst_y.to_i, src_x.to_i, src_y.to_i, w.to_i, h.to_i, pct.to_percent.round.to_i) self end
Consolidate duplicate colors in this image, and eliminate all unused palette entries. This only has an effect on IndexedColor
images, and is rather expensive. Returns the number of palette entries deallocated.
# File lib/gd2/image.rb, line 447 def optimize_palette # implemented by subclass end
Return a Color
object for the given pixel
value.
# File lib/gd2/image.rb, line 347 def pixel2color(pixel) Color.new_from_rgba(pixel) end
Encode and return data for this image in PNG format. The level
argument should be in the range 0–9 indicating the level of lossless compression (0 = none, 1 = minimal but fast, 9 = best but slow).
# File lib/gd2/image.rb, line 521 def png(level = nil) size = FFI::MemoryPointer.new(:pointer) ptr = ::GD2::GD2FFI.send(:gdImagePngPtrEx, image_ptr, size, level.to_i || -1) ptr.get_bytes(0, size.get_int(0)) ensure ::GD2::GD2FFI.send(:gdFree, ptr) end
Like Image#polar_transform!
except a new image is returned.
# File lib/gd2/image.rb, line 681 def polar_transform(radius) clone.polar_transform!(radius) end
Transform this image into a new image of width and height radius
× 2, in which the X axis of the original has been remapped to θ (angle) and the Y axis of the original has been remapped to ρ (distance from center). Note that the original image must be square.
# File lib/gd2/image.rb, line 673 def polar_transform!(radius) raise 'Image must be square' unless width == height ptr = ::GD2::GD2FFI.send(:gdImageSquareToCircle, image_ptr, radius.to_i) raise LibraryError if ptr.null? init_with_image(ptr) end
Like Image#resize!
except a new image is returned.
# File lib/gd2/image.rb, line 665 def resize(w, h, resample = true) clone.resize!(w, h, resample) end
Resize this image to the given dimensions. If resample
is true, the image pixels will be resampled; otherwise they will be stretched or shrunk as necessary without resampling.
# File lib/gd2/image.rb, line 654 def resize!(w, h, resample = true) ptr = self.class.create_image_ptr(w, h, false) ::GD2::GD2FFI.send(resample ? :gdImageCopyResampled : :gdImageCopyResized, ptr, image_ptr, 0, 0, 0, 0, w.to_i, h.to_i, width.to_i, height.to_i) alpha_blending = alpha_blending? init_with_image(ptr) self.alpha_blending = alpha_blending self end
Like Image#rotate!
except a new image is returned.
# File lib/gd2/image.rb, line 620 def rotate(angle, axis_x = width / 2.0, axis_y = height / 2.0) clone.rotate!(angle, axis_x, axis_y) end
Rotate this image by the given angle
(in radians) about the given axis coordinates. Note that some of the edges of the image may be lost.
# File lib/gd2/image.rb, line 612 def rotate!(angle, axis_x = width / 2.0, axis_y = height / 2.0) ptr = self.class.create_image_ptr(width, height, alpha_blending?) ::GD2::GD2FFI.send(:gdImageCopyRotated, ptr, image_ptr, axis_x.to_f, axis_y.to_f, 0, 0, width.to_i, height.to_i, angle.to_degrees.round.to_i) init_with_image(ptr) end
Set whether this image will be stored with full alpha channel information when output as PNG.
# File lib/gd2/image.rb, line 390 def save_alpha=(bool) ::GD2::GD2FFI.send(:gdImageSaveAlpha, image_ptr, bool ? 1 : 0) end
Return true if this image will be stored with full alpha channel information when output as PNG.
# File lib/gd2/image.rb, line 384 def save_alpha? not image_ptr[:saveAlphaFlag].zero? end
Set the pixel value at image location (x
, y
).
# File lib/gd2/image.rb, line 319 def set_pixel(x, y, value) ::GD2::GD2FFI.send(:gdImageSetPixel, @image_ptr, x.to_i, y.to_i, value.to_i) nil end
Sharpen this image by pct
(a percentage) which can be greater than 1.0. Transparency/alpha channel are not altered. This has no effect on IndexedColor
images.
# File lib/gd2/image.rb, line 688 def sharpen(pct) self end
Return the size of this image as an array [width, height], in pixels.
# File lib/gd2/image.rb, line 302 def size [width, height] end
Return this image as an IndexedColor
image, creating a copy if necessary. colors
indicates the maximum number of palette colors to use, and dither
controls whether dithering is used.
# File lib/gd2/image.rb, line 700 def to_indexed_color(colors = MAX_COLORS, dither = true) ptr = ::GD2::GD2FFI.send(:gdImageCreatePaletteFromTrueColor, to_true_color.image_ptr, dither ? 1 : 0, colors.to_i) raise LibraryError if ptr.null? obj = IndexedColor.allocate.init_with_image(ptr) # fix for gd bug where image->open[] is not properly initialized (0...obj.image_ptr[:colorsTotal]).each do |i| obj.image_ptr[:open][i] = 0 end obj end
Return this image as a TrueColor
image, creating a copy if necessary.
# File lib/gd2/image.rb, line 693 def to_true_color self end
Return the transparent color for this image, or nil if none has been set.
# File lib/gd2/image.rb, line 396 def transparent pixel = image_ptr[:transparent] pixel == -1 ? nil : pixel2color(pixel) end
Set or unset the transparent color for this image.
# File lib/gd2/image.rb, line 402 def transparent=(color) ::GD2::GD2FFI.send(:gdImageColorTransparent, image_ptr, color.nil? ? -1 : color2pixel(color)) end
Return true if this image is a TrueColor
image.
# File lib/gd2/image.rb, line 284 def true_color? kind_of?(TrueColor) # self.class.image_true_color?(image_ptr) end
Like Image#uncrop!
except a new image is returned.
# File lib/gd2/image.rb, line 647 def uncrop(x1, y1 = x1, x2 = x1, y2 = y1) clone.uncrop!(x1, y1, x2, y2) end
Expand the left, top, right, and bottom borders of this image by the given number of pixels.
# File lib/gd2/image.rb, line 639 def uncrop!(x1, y1 = x1, x2 = x1, y2 = y1) ptr = self.class.create_image_ptr(x1 + width + x2, y1 + height + y2, alpha_blending?) ::GD2::GD2FFI.send(:gdImageCopy, ptr, image_ptr, x1.to_i, y1.to_i, 0, 0, width.to_i, height.to_i) init_with_image(ptr) end
Encode and return data for this image in WBMP format. WBMP currently supports only black and white images; the specified fgcolor
will be used as the foreground color (black), and all other colors will be considered “background” (white).
# File lib/gd2/image.rb, line 545 def wbmp(fgcolor) size = FFI::MemoryPointer.new(:pointer) ptr = ::GD2::GD2FFI.send(:gdImageWBMPPtr, image_ptr, size, color2pixel(fgcolor)) ptr.get_bytes(0, size.get_int(0)) ensure ::GD2::GD2FFI.send(:gdFree, ptr) end
Return the width of this image, in pixels.
# File lib/gd2/image.rb, line 290 def width image_ptr[:sx] end
Temporarily set the clipping rectangle during the execution of a block. Pixels outside this rectangle will not be modified by drawing or copying operations.
# File lib/gd2/image.rb, line 422 def with_clipping(x1, y1, x2, y2) #:yields: image clip = clipping begin ::GD2::GD2FFI.send(:gdImageSetClip, image_ptr, x1.to_i, y1.to_i, x2.to_i, y2.to_i) yield self self ensure ::GD2::GD2FFI.send(:gdImageSetClip, image_ptr, *clip) end end