class HexaPDF::Type::Page
Represents a page of a PDF document.
A page object contains the meta information for a page. Most of the fields are independent from the page's content like the /Dur field. However, some of them (like /Resources or /UserUnit) influence how or if the page's content can be rendered correctly.
A number of field values can also be inherited: /Resources, /MediaBox, /CropBox, /Rotate. Field inheritance means that if a field is not set on the page object itself, the value is taken from the nearest page tree ancestor that has this value set.
See: PDF1.7 s7.7.3.3, s7.7.3.4, Pages
Constants
- INHERITABLE_FIELDS
The inheritable fields.
- PAPER_SIZE
The predefined paper sizes in points (1/72 inch):
-
ISO sizes: A0x4, A0x2, A0-A10, B0-B10, C0-C10
-
Letter, Legal, Ledger, Tabloid, Executive
-
- REQUIRED_INHERITABLE_FIELDS
The required inheritable fields.
Public Class Methods
Returns the media box for the given paper size. See PAPER_SIZE
for the defined paper sizes.
# File lib/hexapdf/type/page.rb, line 107 def self.media_box(paper_size, orientation: :portrait) unless PAPER_SIZE.key?(paper_size) raise HexaPDF::Error, "Invalid paper size specified: #{paper_size}" end media_box = PAPER_SIZE[paper_size].dup media_box[2], media_box[3] = media_box[3], media_box[2] if orientation == :landscape media_box end
Public Instance Methods
Returns the value for the entry name
.
If name
is an inheritable value and the value has not been set on the page object, its value is retrieved from the ancestor page tree nodes.
See: Dictionary#[]
HexaPDF::Dictionary#[]
# File lib/hexapdf/type/page.rb, line 167 def [](name) if value[name].nil? && INHERITABLE_FIELDS.include?(name) node = self node = node[:Parent] while node.value[name].nil? && node[:Parent] node == self || node.value[name].nil? ? super : node[name] else super end end
Returns all parent nodes of the page up to the root of the page tree.
The direct parent is the first node in the array and the root node the last.
# File lib/hexapdf/type/page.rb, line 358 def ancestor_nodes parent = self[:Parent] result = [parent] result << parent while (parent = parent[:Parent]) result end
If no rectangle
is given, returns the rectangle defining a certain kind of box for the page. Otherwise sets the value for the given box type to rectangle
(an array with four values or a HexaPDF::Rectangle
).
This method should be used instead of directly accessing any of /MediaBox, /CropBox, /BleedBox, /ArtBox or /TrimBox because it also takes the fallback values into account!
The following types are allowed:
- :media
-
The media box defines the boundaries of the medium the page is to be printed on.
- :crop
-
The crop box defines the region to which the contents of the page should be clipped when it is displayed or printed. The default is the media box.
- :bleed
-
The bleed box defines the region to which the contents of the page should be clipped when output in a production environment. The default is the crop box.
- :trim
-
The trim box defines the intended dimensions of the page after trimming. The default value is the crop box.
- :art
-
The art box defines the region of the page's meaningful content as intended by the author. The default is the crop box.
See: PDF1.7 s14.11.2
# File lib/hexapdf/type/page.rb, line 221 def box(type = :media, rectangle = nil) if rectangle case type when :media, :crop, :bleed, :trim, :art self["#{type.capitalize}Box".to_sym] = rectangle else raise ArgumentError, "Unsupported page box type provided: #{type}" end else case type when :media then self[:MediaBox] when :crop then self[:CropBox] || self[:MediaBox] when :bleed then self[:BleedBox] || self[:CropBox] || self[:MediaBox] when :trim then self[:TrimBox] || self[:CropBox] || self[:MediaBox] when :art then self[:ArtBox] || self[:CropBox] || self[:MediaBox] else raise ArgumentError, "Unsupported page box type provided: #{type}" end end end
Returns the requested type of canvas for the page.
The canvas object is cached once it is created so that its graphics state is correctly retained without the need for parsing its contents.
If the media box of the page doesn't have its origin at (0, 0), the canvas origin is translated into the bottom left corner so that this detail doesn't matter when using the canvas. This means that the canvas' origin is always at the bottom left corner of the media box.
- type
-
Can either be
-
:page for getting the canvas for the page itself (only valid for initially empty pages)
-
:overlay for getting the canvas for drawing over the page contents
-
:underlay for getting the canvas for drawing unter the page contents
-
# File lib/hexapdf/type/page.rb, line 380 def canvas(type: :page) unless [:page, :overlay, :underlay].include?(type) raise ArgumentError, "Invalid value for 'type', expected: :page, :underlay or :overlay" end cache_key = "#{type}_canvas".intern return cache(cache_key) if cached?(cache_key) if type == :page && key?(:Contents) raise HexaPDF::Error, "Cannot get the canvas for a page with contents" end create_canvas = lambda do Content::Canvas.new(self).tap do |canvas| media_box = box(:media) if media_box.left != 0 || media_box.bottom != 0 canvas.translate(media_box.left, media_box.bottom) end end end contents = self[:Contents] if contents.nil? page_canvas = cache(:page_canvas, create_canvas.call) self[:Contents] = document.add({Filter: :FlateDecode}, stream: page_canvas.stream_data) end if type == :overlay || type == :underlay underlay_canvas = cache(:underlay_canvas, create_canvas.call) overlay_canvas = cache(:overlay_canvas, create_canvas.call) stream = HexaPDF::StreamData.new do Fiber.yield(" q ") fiber = underlay_canvas.stream_data.fiber while fiber.alive? && (data = fiber.resume) Fiber.yield(data) end " Q q " end underlay = document.add({Filter: :FlateDecode}, stream: stream) stream = HexaPDF::StreamData.new do Fiber.yield(" Q q ") fiber = overlay_canvas.stream_data.fiber while fiber.alive? && (data = fiber.resume) Fiber.yield(data) end " Q " end overlay = document.add({Filter: :FlateDecode}, stream: stream) self[:Contents] = [underlay, *self[:Contents], overlay] end cache(cache_key) end
Returns the concatenated stream data from the content streams as binary string.
Note: Any modifications done to the returned value *won't* be reflected in any of the streams' data!
# File lib/hexapdf/type/page.rb, line 303 def contents Array(self[:Contents]).each_with_object("".b) do |content_stream, content| content << " " unless content.empty? content << content_stream.stream end end
Replaces the contents of the page with the given string.
This is done by deleting all but the first content stream and reusing this content stream; or by creating a new one if no content stream exists.
# File lib/hexapdf/type/page.rb, line 314 def contents=(data) first, *rest = self[:Contents] rest.each {|stream| document.delete(stream) } if first self[:Contents] = first document.deref(first).stream = data else self[:Contents] = document.add({Filter: :FlateDecode}, stream: data) end end
Copies the page's inherited values from the ancestor page tree nodes into a hash and returns the hash.
The hash can then be used to update the page itself (e.g. when moving a page from one position to another) or another page (e.g. when importing a page from another document).
# File lib/hexapdf/type/page.rb, line 182 def copy_inherited_values INHERITABLE_FIELDS.each_with_object({}) do |name, hash| hash[name] = HexaPDF::Object.deep_copy(self[name]) if value[name].nil? end end
Flattens all or the given annotations of the page. Returns an array with all the annotations that couldn't be flattened because they don't have an appearance stream.
Flattening means making the appearances of the annotations part of the content stream of the page and deleting the annotations themselves. Invisible and hidden fields are deleted but not rendered into the content stream.
If an annotation is a form field widget, only the widget will be deleted but not the form field itself.
# File lib/hexapdf/type/page.rb, line 476 def flatten_annotations(annotations = self[:Annots]) return [] unless key?(:Annots) not_flattened = annotations.to_ary annotations = not_flattened & self[:Annots] if annotations != self[:Annots] return not_flattened if annotations.empty? canvas = self.canvas(type: :overlay) canvas.save_graphics_state media_box = box(:media) if media_box.left != 0 || media_box.bottom != 0 canvas.translate(-media_box.left, -media_box.bottom) # revert initial translation of origin end to_delete = [] not_flattened -= annotations annotations.each do |annotation| annotation = document.wrap(annotation, type: :Annot) appearance = annotation.appearance if annotation.flagged?(:hidden) || annotation.flagged?(:invisible) to_delete << annotation next elsif !appearance not_flattened << annotation next end rect = annotation[:Rect] box = appearance.box matrix = appearance[:Matrix] # Adjust position based on matrix pos = [rect.left - matrix[4], rect.bottom - matrix[5]] # In case of a rotation we need to counter the default translation in #xobject by adding # box.left and box.bottom, and then translate the origin for the rotation angle = (-Math.atan2(matrix[2], matrix[0]) * 180 / Math::PI).to_i case angle when 0 # Nothing to do, no rotation when 90 pos[0] += box.top + box.left pos[1] += -box.left + box.bottom when -90 pos[0] += -box.bottom + box.left pos[1] += box.right + box.bottom when 180, -180 pos[0] += box.right + box.left pos[1] += box.top + box.bottom else not_flattened << annotation next end width, height = (angle.abs == 90 ? [rect.height, rect.width] : [rect.width, rect.height]) canvas.xobject(appearance, at: pos, width: width, height: height) to_delete << annotation end canvas.restore_graphics_state to_delete.each do |annotation| if annotation[:Subtype] == :Widget annotation.form_field.delete_widget(annotation) else self[:Annots].delete(annotation) document.delete(annotation) end end not_flattened end
Returns the index of the page in the page tree.
# File lib/hexapdf/type/page.rb, line 342 def index idx = 0 node = self while (parent_node = node[:Parent]) parent_node[:Kids].each do |kid| break if kid == node idx += (kid.type == :Page ? 1 : kid[:Count]) end node = parent_node end idx end
Returns true
since page objects must always be indirect.
# File lib/hexapdf/type/page.rb, line 157 def must_be_indirect? true end
Returns the orientation of the media box, either :portrait or :landscape.
# File lib/hexapdf/type/page.rb, line 243 def orientation box = self[:MediaBox] rotation = self[:Rotate] if (box.height > box.width && (rotation == 0 || rotation == 180)) || (box.height < box.width && (rotation == 90 || rotation == 270)) :portrait else :landscape end end
Processes the content streams associated with the page with the given processor object.
See: HexaPDF::Content::Processor
# File lib/hexapdf/type/page.rb, line 335 def process_contents(processor) self[:Resources] = {} if self[:Resources].nil? processor.resources = self[:Resources] Content::Parser.parse(contents, processor) end
Returns the, possibly inherited, resource dictionary which is automatically created if it doesn't exist.
# File lib/hexapdf/type/page.rb, line 327 def resources self[:Resources] ||= document.wrap({ProcSet: [:PDF, :Text, :ImageB, :ImageC, :ImageI]}, type: :XXResources) end
Rotates the page angle
degrees counterclockwise where angle
has to be a multiple of 90.
Positive values rotate the page to the left, negative values to the right. If flatten
is true
, the rotation is not done via the page's meta data but by “rotating” the canvas itself.
Note that the :Rotate key of a page object describes the angle in a clockwise orientation but this method uses counterclockwise rotation to be consistent with other rotation methods (e.g. HexaPDF::Content::Canvas#rotate
).
# File lib/hexapdf/type/page.rb, line 263 def rotate(angle, flatten: false) if angle % 90 != 0 raise ArgumentError, "Page rotation has to be multiple of 90 degrees" end cw_angle = (self[:Rotate] - angle) % 360 if flatten delete(:Rotate) return if cw_angle == 0 matrix, llx, lly, urx, ury = \ case cw_angle when 90 [HexaPDF::Content::TransformationMatrix.new(0, -1, 1, 0), box.right, box.bottom, box.left, box.top] when 180 [HexaPDF::Content::TransformationMatrix.new(-1, 0, 0, -1), box.right, box.top, box.left, box.bottom] when 270 [HexaPDF::Content::TransformationMatrix.new(0, 1, -1, 0), box.left, box.top, box.right, box.bottom] end [:MediaBox, :CropBox, :BleedBox, :TrimBox, :ArtBox].each do |box| next unless key?(box) self[box].value = matrix.evaluate(llx, lly).concat(matrix.evaluate(urx, ury)) end before_contents = document.add({}, stream: " q #{matrix.to_a.join(' ')} cm ") after_contents = document.add({}, stream: " Q ") self[:Contents] = [before_contents, *self[:Contents], after_contents] else self[:Rotate] = cw_angle end end
Creates a Form
XObject from the page's dictionary and contents for the given PDF document.
If reference
is true, the page's contents is referenced when possible to avoid unnecessary decoding/encoding.
Note 1: The created Form
XObject is not added to the document automatically!
Note 2: If reference
is false and if a canvas is used on this page (see canvas
), this method should only be called once the contents of the page has been fully defined. The reason is that during the copying of the content stream data the contents may be modified to make it a fully valid content stream.
# File lib/hexapdf/type/page.rb, line 448 def to_form_xobject(reference: true) first, *rest = self[:Contents] stream = if !first nil elsif !reference || !rest.empty? || first.raw_stream.kind_of?(String) contents else first.raw_stream end dict = { Type: :XObject, Subtype: :Form, BBox: HexaPDF::Object.deep_copy(box(:crop)), Resources: HexaPDF::Object.deep_copy(self[:Resources]), Filter: :FlateDecode, } document.wrap(dict, stream: stream) end
Private Instance Methods
Ensures that the required inheritable fields are set.
HexaPDF::Dictionary#perform_validation
# File lib/hexapdf/type/page.rb, line 551 def perform_validation(&block) super REQUIRED_INHERITABLE_FIELDS.each do |name| next if self[name] yield("Inheritable page field #{name} not set", name == :Resources) resources.validate(&block) if name == :Ressources end end