`class Slide`

A single slide parsed from a Markdown file.

Each slide has YAML front_matter for metadata (template, duration, focus), a Markdown document, and optional presenter notes separated by ---.

Nested Classes and Modules

class Fragment: A fragment of a Markly AST document.
module Parser: Parses a Markdown slide file into structured data for class Presently::Slide.

Definitions

`def self.load(presentation, path)`

Load and parse a slide from a Markdown file.

Signature

parameter　presentation　Presentation: The presentation which owns the slide.
parameter　path　String: The slide path relative to the presentation root.
returns　Slide

Implementation

def self.load(presentation, path)
	Parser.load(presentation, path)
end

`def initialize(presentation, path, front_matter: nil, document: nil, notes: nil, scripts: [])`

Initialize a slide with pre-parsed data.

Signature

parameter　presentation　Presentation: The presentation which owns the slide.
parameter　path　String: The slide path relative to the presentation root.
parameter　front_matter　Hash | Nil: The parsed YAML front_matter.
parameter　document　Fragment | Nil: The complete slide document.
parameter　notes　Fragment | Nil: The presenter notes as a Markly AST fragment.
parameter　scripts　Array(String): JavaScript sources to execute after the slide renders.

Implementation

def initialize(presentation, path, front_matter: nil, document: nil, notes: nil, scripts: [])
	@presentation = presentation
	@path = path
	@front_matter = front_matter
	@document = document || Fragment.new(Markly::Node.new(:document))
	@notes = notes
	@scripts = scripts.dup
end

`attr :presentation`

Signature

attribute　Presentation: The presentation which owns the slide.

`attr :path`

Signature

attribute　String: The slide path relative to the presentation root.

`def source_path`

The absolute path of the slide source file.

Signature

returns　String

Implementation

def source_path
	File.join(@presentation.root, @path)
end

`attr :front_matter`

Signature

attribute　Hash | Nil: The parsed YAML front_matter.

`attr :document`

Signature

attribute　Fragment: The complete slide document.

`attr :notes`

Signature

attribute　Fragment | Nil: The presenter notes as a Markly AST fragment.

`attr :scripts`

Signature

attribute　Array(String): JavaScript sources to execute after the slide renders on the display.

`def template`

The template to use for rendering this slide.

Signature

returns　String: The template name from front_matter, or "default".

Implementation

def template
	@front_matter&.fetch("template", "default") || "default"
end

`def background`

The background image URL, resolved relative to this slide's source file.

Signature

returns　String | Nil: The URL, or nil when no image is specified.

Implementation

def background
	value = @front_matter&.fetch("background", nil)
	return unless value.is_a?(String) && !value.strip.empty?
	
	Parser.resolve_image_url(value, source_path, @presentation.root)
end

`def background_size`

How the background image is sized within the full slide surface.

Signature

returns　String: "cover", "contain", or "auto", defaulting to "cover".

Implementation

def background_size
	value = @front_matter&.fetch("background-size", nil)
	["cover", "contain", "auto"].include?(value) ? value : "cover"
end

`def duration`

The expected duration of this slide in seconds. Negative, invalid, or non-finite values are treated as zero.

Signature

returns　Float: A finite duration of at least 0.0, defaulting to 0.0 when unspecified or null.

Implementation

def duration
	if value = @front_matter&.fetch("duration", nil)
		duration = Float(value, exception: false)
		if duration&.finite?
			return duration.clamp(0.0, nil)
		end
	end
	
	return 0.0
end

`def timer`

The timer action to apply when advancing from this slide.

Signature

returns　String | Nil: "start", "pause", "resume", or nil when unspecified.

Implementation

def timer
	@front_matter&.fetch("timer", nil)
end

`def update_duration!(duration)`

Update the expected duration in the slide's YAML front matter. Preserves the remainder of the source file rather than reserializing it.

Signature

parameter　duration　Integer: The new positive duration in seconds.
returns　Integer: The persisted duration.

Implementation

def update_duration!(duration)
	duration = Integer(duration)
	raise ArgumentError, "Duration must be positive!" unless duration.positive?
	
	path = source_path
	source = File.read(path)
	newline = source.include?("\r\n") ? "\r\n" : "\n"
	
	front_matter_pattern = /\A---[ \t]*(?<newline>\r?\n)(?<body>.*?)(?<closing>^---[ \t]*(?:\r?\n|\z))/m
	if match = front_matter_pattern.match(source)
		body = match[:body]
		
		if line = /^duration:[^#\r\n]*(?<comment>[ \t]+#[^\r\n]*)?(?<newline>\r?\n|\z)/.match(body)
			replacement = "duration: #{duration}#{line[:comment]}#{line[:newline]}"
			body = body[0...line.begin(0)] + replacement + body[line.end(0)..]
		else
			body += match[:newline] unless body.empty? || body.end_with?("\n")
			body += "duration: #{duration}#{match[:newline]}"
		end
		
		source = source[0...match.begin(:body)] + body + source[match.end(:body)..]
	else
		source = "---#{newline}duration: #{duration}#{newline}---#{newline}#{source}"
	end
	
	stat = File.stat(path)
	Tempfile.create([".presently-slide", ".md"], File.dirname(path), binmode: true) do |file|
		file.chmod(stat.mode & 0o7777)
		file.write(source)
		file.flush
		File.rename(file.path, path)
	end
	
	(@front_matter ||= {})["duration"] = duration
	return duration
end

`def title`

The title of this slide.

Signature

returns　String: The H1 text, front matter title, or filename without extension.

Implementation

def title
	@document.heading_text(1) || @front_matter&.fetch("title", nil) || File.basename(@path, ".md")
end

`def section`

The section name for this slide.

Signature

returns　String | Nil: The section from front matter, or nil when it was not specified.

Implementation

def section
	@front_matter&.fetch("section", nil)
end

`def skip?`

Whether this slide should be skipped in the presentation.

Signature

returns　Boolean

Implementation

def skip?
	@front_matter&.fetch("skip", false) || false
end

`def marker`

The navigation marker for this slide, used in the presenter's jump-to dropdown.

Signature

returns　String | Nil: The marker label, or nil if not marked.

Implementation

def marker
	@front_matter&.fetch("marker", nil)
end

`def transition`

The transition type for animating into this slide.

Signature

returns　String | Nil: The transition name (e.g. "fade", "slide-left", "slide-right"), or nil for instant swap.

Implementation

def transition
	@front_matter&.fetch("transition", nil)
end

`def speaker`

The name of the speaker presenting this slide.

Signature

returns　String | Nil: The speaker name from front_matter, or nil if not specified.

Implementation

def speaker
	@front_matter&.fetch("speaker", nil)
end

`def focus`

The line range to focus on for code slides.

Signature

returns　Array(Integer, Integer) | Nil: The [start, end] line numbers (1-based), or nil.

Implementation

def focus
	if range = @front_matter&.fetch("focus", nil)
		parts = range.to_s.split("-").map(&:to_i)
		parts.length == 2 ? parts : nil
	end
end