Add automatic presentation refresh when terminal screen size changes

lib/slideck/presenter.rb

@@ -5,6 +5,14 @@ module Slideck
   #
   # @api private
   class Presenter
+    # Terminal screen size change signal
+    #
+    # @return [String]
+    #
+    # @api private
+    TERM_SCREEN_SIZE_CHANGE_SIG = "WINCH"
+    private_constant :TERM_SCREEN_SIZE_CHANGE_SIG
+
     # Create a Presenter
     #
     # @param [TTY::Reader] reader
@@ -13,16 +21,19 @@ class Presenter
     #   the slides renderer
     # @param [Slideck::Tracker] tracker
     #   the tracker for slides
+    # @param [TTY::Screen] screen
+    #   the terminal screen size
     # @param [IO] output
     #   the output stream for the slides
     # @param [Proc] reloader
     #   the metadata and slides reloader
     #
     # @api public
-    def initialize(reader, renderer, tracker, output, &reloader)
+    def initialize(reader, renderer, tracker, screen, output, &reloader)
       @reader = reader
       @renderer = renderer
       @tracker = tracker
+      @screen = screen
       @output = output
       @reloader = reloader
       @stop = false
@@ -55,6 +66,7 @@ def start
       reload
       @reader.subscribe(self)
       hide_cursor
+      subscribe_to_screen_resize { resize.render }
 
       until @stop
         render
@@ -79,9 +91,12 @@ def stop
 
     # Render presentation on cleared screen
     #
+    # @example
+    #   presenter.render
+    #
     # @return [void]
     #
-    # @api private
+    # @api public
     def render
       clear_screen
       render_slide
@@ -127,6 +142,30 @@ def show_cursor
       @output.print @renderer.cursor.show
     end
 
+    # Subscribe to the terminal screen size change signal
+    #
+    # @param [Proc] resizer
+    #   the presentation resizer
+    #
+    # @return [void]
+    #
+    # @api private
+    def subscribe_to_screen_resize(&resizer)
+      return if @screen.windows?
+
+      Signal.trap(TERM_SCREEN_SIZE_CHANGE_SIG, &resizer)
+    end
+
+    # Resize presentation
+    #
+    # @return [Slideck::Presenter]
+    #
+    # @api private
+    def resize
+      @renderer = @renderer.resize(@screen.width, @screen.height)
+      self
+    end
+
     # Handle a keypress event
     #
     # @param [TTY::Reader::KeyEvent] event

lib/slideck/renderer.rb

@@ -39,6 +39,23 @@ def initialize(converter, ansi, cursor, width: nil, height: nil)
       freeze
     end
 
+    # Create a Renderer with a new screen size
+    #
+    # @example
+    #   renderer.resize(200, 50)
+    #
+    # @param [Integer] width
+    #   the screen width
+    # @param [Integer] height
+    #   the screen height
+    #
+    # @return [Slideck::Renderer]
+    #
+    # @api public
+    def resize(width, height)
+      self.class.new(@converter, @ansi, @cursor, width: width, height: height)
+    end
+
     # Render a slide
     #
     # @example

lib/slideck/runner.rb

@@ -170,7 +170,7 @@ def build_presenter(color, &reloader)
       renderer = Renderer.new(converter, Strings::ANSI, TTY::Cursor,
                               width: @screen.width, height: @screen.height)
       tracker = Tracker.for(0)
-      Presenter.new(reader, renderer, tracker, @output, &reloader)
+      Presenter.new(reader, renderer, tracker, @screen, @output, &reloader)
     end
 
     # Build a listener for changes in a filename

spec/unit/cli_spec.rb

@@ -5,7 +5,9 @@
   let(:output) { StringIO.new("".dup, "w+") }
   let(:error_output) { StringIO.new("".dup, "w+") }
   let(:env) { {"TTY_TEST" => true} }
-  let(:screen) { class_double(TTY::Screen, width: 40, height: 20) }
+  let(:windows?) { RSpec::Support::OS.windows? }
+  let(:screen_methods) { {width: 40, height: 20, windows?: windows?} }
+  let(:screen) { class_double(TTY::Screen, **screen_methods) }
   let(:runner) { Slideck::Runner.new(screen, input, output, env) }
 
   it "starts with a slides file and --color=always option and quits" do

spec/unit/presenter_spec.rb

@@ -15,6 +15,9 @@
   let(:meta_defaults) { Slideck::MetadataDefaults.new(alignment, margin) }
   let(:metadata) { Slideck::Metadata.from(meta_converter, {}, meta_defaults) }
   let(:slide_metadata) { Slideck::Metadata.from(meta_converter, {}, {}) }
+  let(:windows?) { RSpec::Support::OS.windows? }
+  let(:screen_methods) { {width: 20, height: 8, windows?: windows?} }
+  let(:screen) { class_double(TTY::Screen, **screen_methods) }
 
   def build_metadata(custom_metadata)
     Slideck::Metadata.from(meta_converter, custom_metadata, meta_defaults)
@@ -26,11 +29,12 @@ def build_metadata(custom_metadata)
         {content: "slide#{i + 1}", metadata: slide_metadata}
       end
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
       reloaded_metadata = build_metadata({theme: {strong: :cyan}})
       reloaded_slides = [{content: "**Reloaded**", metadata: slide_metadata}]
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         [reloaded_metadata, reloaded_slides]
       end
 
@@ -50,9 +54,10 @@ def build_metadata(custom_metadata)
                 {content: "slide2", metadata: slide_metadata},
                 {content: "slide3", metadata: slide_metadata}]
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         [metadata, slides]
       end
       input << "q"
@@ -73,9 +78,10 @@ def build_metadata(custom_metadata)
                 {content: "slide2", metadata: slide_metadata},
                 {content: "slide3", metadata: slide_metadata}]
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         [metadata, slides]
       end
       input << "n" << "l" << "p" << "h" << ?\C-x
@@ -108,9 +114,10 @@ def build_metadata(custom_metadata)
                 {content: "slide2", metadata: slide_metadata},
                 {content: "slide3", metadata: slide_metadata}]
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         [metadata, slides]
       end
       reader.on(:keypress) do |event|
@@ -156,9 +163,10 @@ def build_metadata(custom_metadata)
                 {content: "slide2", metadata: slide_metadata},
                 {content: "slide3", metadata: slide_metadata}]
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         [metadata, slides]
       end
       input << "$" << "^" << "\e"
@@ -185,9 +193,10 @@ def build_metadata(custom_metadata)
         {content: "slide#{i + 1}", metadata: slide_metadata}
       end
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         [metadata, slides]
       end
       input << "1" << "3" << "g" << "q" << ?\C-c
@@ -216,10 +225,11 @@ def build_metadata(custom_metadata)
       slides = [{content: "slide1", metadata: slide_metadata},
                 {content: "slide2", metadata: slide_metadata}]
       tracker = Slideck::Tracker.for(slides.size)
-      renderer = Slideck::Renderer.new(converter, ansi, cursor,
-                                       width: 20, height: 8)
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
       i = -1
-      presenter = described_class.new(reader, renderer, tracker, output) do
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
         if (i += 1).zero?
           [metadata, slides]
         else
@@ -244,5 +254,53 @@ def build_metadata(custom_metadata)
         "\e[2J\e[1;1H\e[?25h"
       ].join.inspect)
     end
+
+    it "refreshes the slides when the screen size changes",
+       unless: RSpec::Support::OS.windows? do
+      slides = Array.new(5) do |i|
+        {content: "slide#{i + 1}", metadata: slide_metadata}
+      end
+      tracker = Slideck::Tracker.for(slides.size)
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      allow(Signal).to receive(:trap).with("WINCH").and_yield
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
+        [metadata, slides]
+      end
+      input << "q"
+      input.rewind
+
+      presenter.start
+
+      expect(output.string.inspect).to eq([
+        "\e[?25l\e[2J\e[1;1H",
+        "\e[1;1Hslide1\n",
+        "\e[8;16H1 / 5",
+        "\e[2J\e[1;1H",
+        "\e[1;1Hslide1\n",
+        "\e[8;16H1 / 5",
+        "\e[2J\e[1;1H\e[?25h"
+      ].join.inspect)
+    end
+
+    it "doesn't subscribe to the screen size change signal on Windows" do
+      slides = []
+      tracker = Slideck::Tracker.for(slides.size)
+      screen = class_double(TTY::Screen, width: 20, height: 8, windows?: true)
+      renderer = Slideck::Renderer.new(
+        converter, ansi, cursor, width: screen.width, height: screen.height)
+      allow(Signal).to receive(:trap)
+      presenter = described_class.new(
+        reader, renderer, tracker, screen, output) do
+        [metadata, slides]
+      end
+      input << "q"
+      input.rewind
+
+      presenter.start
+
+      expect(Signal).not_to have_received(:trap)
+    end
   end
 end

spec/unit/renderer_spec.rb

@@ -18,6 +18,22 @@ def build_slide_metadata(custom_metadata)
     Slideck::Metadata.from(meta_converter, custom_metadata, {})
   end
 
+  describe "#resize" do
+    it "creates an instance with a new screen size" do
+      metadata = build_metadata({})
+      slide = {content: "content", metadata: build_slide_metadata({})}
+      renderer = described_class.new(converter, ansi, cursor,
+                                     width: 20, height: 8)
+
+      new_renderer = renderer.resize(40, 16)
+
+      expect(new_renderer.render(metadata, slide, 1, 1).inspect).to eq([
+        "\e[1;1Hcontent\n",
+        "\e[16;36H1 / 1"
+      ].join.inspect)
+    end
+  end
+
   describe "#render" do
     it "renders page number without slide content" do
       metadata = build_metadata({})

spec/unit/runner_spec.rb

@@ -4,9 +4,11 @@
   let(:output) { StringIO.new("".dup, "w+") }
   let(:input) { StringIO.new("".dup, "w+") }
   let(:env) { {"TTY_TEST" => true} }
+  let(:windows?) { RSpec::Support::OS.windows? }
+  let(:screen_methods) { {width: 40, height: 10, windows?: windows?} }
+  let(:screen) { class_double(TTY::Screen, **screen_methods) }
 
   it "displays no slides and quits" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     runner = described_class.new(screen, input, output, env)
     input << "q"
     input.rewind
@@ -21,7 +23,6 @@
   end
 
   it "displays slides with color and quits" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     runner = described_class.new(screen, input, output, env)
     input << "q"
     input.rewind
@@ -43,7 +44,6 @@
   end
 
   it "displays slides without color and quits" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     runner = described_class.new(screen, input, output, env)
     input << "q"
     input.rewind
@@ -65,7 +65,6 @@
   end
 
   it "reloads slides from watched file and quits" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     listener = instance_spy(Listen::Listener)
     slides_file = fixtures_path("empty.md")
     allow(Listen).to receive(:to).and_yield([slides_file], [], [])
@@ -86,7 +85,6 @@
   end
 
   it "doesn't reload slides from an unchanged file and quits" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     listener = instance_spy(Listen::Listener)
     allow(Listen).to receive(:to).and_yield([], [], []).and_return(listener)
     runner = described_class.new(screen, input, output, env)
@@ -103,7 +101,6 @@
   end
 
   it "stops the listener before quitting" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     listener = instance_spy(Listen::Listener)
     allow(Listen).to receive(:to).and_return(listener)
     runner = described_class.new(screen, input, output, env)
@@ -116,7 +113,6 @@
   end
 
   it "doesn't watch for changes in file with slides" do
-    screen = class_double(TTY::Screen, width: 40, height: 10)
     allow(Listen).to receive(:to)
     runner = described_class.new(screen, input, output, env)
     input << "q"