Class: Tuile::Screen

Inherits:
Object
  • Object
show all
Defined in:
lib/tuile/screen.rb

Overview

The TTY screen. There is exactly one screen per app.

A screen runs the event loop; call #run_event_loop to do that.

A screen holds the screen lock; any UI modifications must be called from the event queue.

All UI lives under a single ScreenPane owned by the screen. Set tiled content via #content=; the pane fills the entire terminal and is responsible for laying out its children.

Modal popups are supported too, via Component::Popup#open. They auto-size to their wrapped content and are drawn centered over the tiled content.

The drawing procedure is very simple: when a window needs repaint, it invalidates itself, but won’t draw immediately. After the keyboard press event processing is done in the event loop, #repaint is called which then repaints all invalidated windows. This prevents repeated paintings.

Direct Known Subclasses

FakeScreen

Constant Summary collapse

@@instance =

Class variable (not class instance var) so the singleton survives subclassing — ‘FakeScreen < Screen` and `Screen.instance` see the same slot.

nil

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Screen

rubocop:disable Style/ClassVars



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# File 'lib/tuile/screen.rb', line 28

def initialize
  @@instance = self # rubocop:disable Style/ClassVars
  @event_queue = EventQueue.new
  @size = EventQueue::TTYSizeEvent.create.size
  @invalidated = Set.new
  # Components being repainted right now. A component may invalidate its
  # children during its repaint phase; this prevents double-draw.
  @repainting = Set.new
  # Until the event loop is run, we pretend we're in the UI thread.
  @pretend_ui_lock = true
  @scheme = detect_scheme
  @theme_def = ThemeDef.default
  @theme = @theme_def.for(@scheme)
  # Structural root of the component tree: holds tiled content, popup
  # stack and status bar.
  @pane = ScreenPane.new
  @on_error = ->(e) { raise e }
  # App-level keyboard shortcuts dispatched by {#handle_key} before keys
  # reach the pane. See {#register_global_shortcut}.
  @global_shortcuts = {}
  # The back buffer components paint into. {#repaint} flushes its diff to
  # the terminal, so only changed cells are emitted (flicker-free on any
  # terminal). Sized to the current viewport; {#layout} resizes it.
  @buffer = Buffer.new(@size)
end

Instance Attribute Details

#buffer ⇒ Buffer (readonly)

Returns the back buffer components paint into (Buffer#set_line / Buffer#fill / Buffer#set_char).

Returns:



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# File 'lib/tuile/screen.rb', line 65

def buffer
  @buffer
end

#event_queue ⇒ EventQueue (readonly)

Returns the event queue.

Returns:



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# File 'lib/tuile/screen.rb', line 172

def event_queue
  @event_queue
end

#focused ⇒ Component?

Returns currently focused component.

Returns:

  • (Component, nil) —

    currently focused component.



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# File 'lib/tuile/screen.rb', line 203

def focused
  @focused
end

#on_error ⇒ Proc

Handler invoked when a StandardError escapes an event handler inside the event loop (e.g. a Component::TextField‘s `on_change` raises).

The default re-raises, so the exception propagates out of #run_event_loop and crashes the script with a stacktrace — unhandled exceptions are bugs and should be surfaced loudly.

Replace it when the host has somewhere visible to put errors, e.g. a Component::LogWindow wired to Tuile.logger:

screen.on_error = lambda do |e|
  Tuile.logger.error("#{e.class}: #{e.message}\n#{e.backtrace&.join("\n")}")
end

The handler runs on the event-loop thread with the UI lock held. Returning normally keeps the loop alive; raising from within the handler tears the loop down and propagates out of #run_event_loop.

Returns:

  • (Proc) —

    one-arg callable receiving the StandardError instance.



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# File 'lib/tuile/screen.rb', line 85

def on_error
  @on_error
end

#pane ⇒ ScreenPane (readonly)

Returns the structural root of the component tree.

Returns:

  • (ScreenPane) —

    the structural root of the component tree.



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# File 'lib/tuile/screen.rb', line 61

def pane
  @pane
end

#size ⇒ Size (readonly)

Returns current screen size.

Returns:

  • (Size) —

    current screen size.



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# File 'lib/tuile/screen.rb', line 105

def size
  @size
end

#theme ⇒ Theme

The color Theme built-in components read at paint time: the member of #theme_def matching the terminal background detected at construction (see TerminalBackground.detect; inconclusive means dark). While the event loop runs, terminals supporting mode 2031 push OS appearance changes (EventQueue::ColorSchemeEvent) and the screen re-picks from #theme_def.

Returns:



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# File 'lib/tuile/screen.rb', line 114

def theme
  @theme
end

#theme_def ⇒ ThemeDef

The app’s ThemeDef — the dark/light Theme pair the screen picks #theme from, at startup and on every OS appearance flip. Starts as ThemeDef.default (ThemeDef::DEFAULT unless reassigned — tests do, see ThemeDef.default=). Assigning a custom definition is the durable way to theme an app: unlike a bare #theme=, it survives the user toggling the OS appearance.

Returns:



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# File 'lib/tuile/screen.rb', line 123

def theme_def
  @theme_def
end

Class Method Details

.close ⇒ void

This method returns an undefined value.



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# File 'lib/tuile/screen.rb', line 456

def self.close
  @@instance&.close
end

.fake ⇒ FakeScreen

Testing only — creates new screen, locks the UI, and prevents any redraws, so that test TTY is not painted over. FakeScreen#initialize self-installs as the singleton, so subsequent instance calls return the same object.

Returns:



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# File 'lib/tuile/screen.rb', line 446

def self.fake = FakeScreen.new

.instance ⇒ Screen

Returns the singleton instance.

Returns:

  • (Screen) —

    the singleton instance.

Raises:



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# File 'lib/tuile/screen.rb', line 88

def self.instance
  raise Tuile::Error, "Screen not initialized; call Screen.new first" if @@instance.nil?

  @@instance
end

Instance Method Details

#active_window ⇒ Component?

Returns current active tiled component.

Returns:

  • (Component, nil) —

    current active tiled component.



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# File 'lib/tuile/screen.rb', line 397

def active_window
  check_locked
  result = nil
  @pane.content&.on_tree { result = _1 if _1.is_a?(Component::Window) && _1.active? }
  result
end

#add_popup(window) ⇒ void

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

This method returns an undefined value.

Internal — use Component::Popup#open instead. Adds the popup to #pane, centers and focuses it.

Parameters:



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# File 'lib/tuile/screen.rb', line 276

def add_popup(window)
  check_locked
  @pane.add_popup(window)
  # No need to fully repaint the scene: a popup simply paints over the
  # current screen contents.
end

#check_locked ⇒ void

This method returns an undefined value.

Checks that the UI lock is held and the current code runs in the “UI thread”.

Raises:



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# File 'lib/tuile/screen.rb', line 177

def check_locked
  return if @pretend_ui_lock || @event_queue.locked?

  raise Tuile::Error,
        "UI lock not held: UI mutations must run on the event-loop thread; " \
        "marshal via screen.event_queue.submit { ... }"
end

#clear ⇒ void

This method returns an undefined value.

Clears the TTY screen.



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# File 'lib/tuile/screen.rb', line 187

def clear
  print TTY::Cursor.move_to(0, 0), TTY::Cursor.clear_screen
end

#close ⇒ void

This method returns an undefined value.



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# File 'lib/tuile/screen.rb', line 449

def close
  clear
  @pane = nil
  @@instance = nil # rubocop:disable Style/ClassVars
end

#content ⇒ Component?

Returns tiled content (forwarded to Tuile::ScreenPane).

Returns:



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# File 'lib/tuile/screen.rb', line 95

def content = @pane.content

#content=(content) ⇒ void

This method returns an undefined value.

Parameters:



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# File 'lib/tuile/screen.rb', line 99

def content=(content)
  @pane.content = content
  layout
end

#cursor_position ⇒ Point?

Returns the absolute screen coordinates where the hardware cursor should sit, or nil if it should be hidden. Only the #focused component owns the cursor: there can be multiple active components (the focus path), but only one focused.

Returns:



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# File 'lib/tuile/screen.rb', line 547

def cursor_position = @focused&.cursor_position

#focus_next ⇒ Boolean

Advances focus to the next Component#tab_stop? in tree order, wrapping around. Scope is the topmost popup if one is open, otherwise #content — this keeps Tab confined inside a modal popup. No-op (returns false) if the modal scope has no tab stops or no content at all.

Returns:

  • (Boolean) —

    true if focus moved.



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# File 'lib/tuile/screen.rb', line 317

def focus_next = cycle_focus(forward: true)

#focus_previous ⇒ Boolean

Mirror of #focus_next that walks backwards through the tab order.

Returns:

  • (Boolean) —

    true if focus moved.



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# File 'lib/tuile/screen.rb', line 321

def focus_previous = cycle_focus(forward: false)

#has_popup?(window) ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Internal — use Component::Popup#open? instead.

Parameters:

Returns:

  • (Boolean) —

    true if this popup is currently mounted.



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# File 'lib/tuile/screen.rb', line 436

def has_popup?(window) # rubocop:disable Naming/PredicatePrefix
  check_locked
  @pane.has_popup?(window)
end

#invalidate(component) ⇒ void

This method returns an undefined value.

Invalidates a component: causes the component to be repainted on next call to #repaint.

Parameters:

Raises:

  • (TypeError) 


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# File 'lib/tuile/screen.rb', line 195

def invalidate(component)
  check_locked
  raise TypeError, "expected Component, got #{component.inspect}" unless component.is_a? Component

  @invalidated << component unless @repainting.include? component
end

#needs_full_repaint ⇒ void

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

This method returns an undefined value.

Invalidates the entire attached tree, forcing every component to repaint on the next cycle. Needed whenever something overdraws the scene without clipping and then exposes what was underneath — a closing popup (#remove_popup), or a popup that shrinks or moves so its new #rect no longer covers the cells it previously painted (Component::Popup#rect=). The popup-only fast path in #repaint can’t clear those vacated cells on its own, so we accept the cost of a full repaint.



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# File 'lib/tuile/screen.rb', line 428

def needs_full_repaint
  @pane&.on_tree { invalidate _1 }
end

#popups ⇒ Array<Component>

Returns currently active popup components (forwarded to Tuile::ScreenPane). The array must not be modified!.

Returns:



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# File 'lib/tuile/screen.rb', line 169

def popups = @pane.popups

#print(*args) ⇒ void

This method returns an undefined value.

Writes terminal-housekeeping escapes straight to stdout: #clear, mouse-tracking start/stop, the color-scheme notify toggles, cursor-show on teardown. Component painting does not go through here anymore — it writes into #buffer, which #repaint diffs and #emits. FakeScreen overrides this (and #emit) to capture into ‘@prints` instead of the test runner’s stdout.

Parameters:

  • args (String) —

    stuff to print.



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# File 'lib/tuile/screen.rb', line 468

def print(*args)
  Kernel.print(*args)
end

#register_global_shortcut(key, over_popups: false, hint: nil) { ... } ⇒ void

This method returns an undefined value.

Registers an app-level keyboard shortcut. When ‘key` arrives, the block is invoked on the event-loop thread (so it may freely mutate UI) before the key reaches any component. Re-registering the same key replaces the previous binding; use #unregister_global_shortcut to remove one.

Only unprintable keys are accepted — control characters (Ctrl+letter, ESC, BACKSPACE, ENTER, …) and multi-character escape sequences (arrows, F-keys, …). Printable keys raise ArgumentError: they’d hijack typing into a Component::TextField and should be expressed as Component#key_shortcut instead, which the dispatcher suppresses while a text widget owns the hardware cursor. TAB and SHIFT_TAB are also rejected because #handle_key intercepts them for focus navigation before the global registry is consulted, so a binding on them would silently never fire.

Pass ‘hint:` to surface the shortcut in the status bar. It’s a preformatted string the caller fully owns (so colors and the key label style stay consistent with whatever the host app uses elsewhere). The framework splices it in like any other status hint: in the tiled case, right after ‘q quit` and before the active window’s own hint; while a popup is open, only hints from ‘over_popups: true` shortcuts are shown, and they’re prepended before the popup’s ‘q Close`.

Example — open a log popup with Ctrl+L from anywhere, even while a popup is already on screen:

screen.register_global_shortcut(Keys::CTRL_L,
                                over_popups: true,
                                hint: "^L #{screen.theme.hint("log")}") do
  log_popup.open
end

Parameters:

  • key (String) —

    unprintable key (e.g. Keys::CTRL_L, Keys::ESC, Keys::PAGE_UP).

  • over_popups (Boolean) (defaults to: false) —

    when true, fires even while a modal popup is open (pre-empting the popup’s own key handling). When false (default), the shortcut is suppressed while any popup is open and the popup gets the key instead.

  • hint (String, nil) (defaults to: nil) —

    preformatted status-bar hint (e.g. ‘“^L #Tuile::Screen.screenscreen.themescreen.theme.hint(”log“)”`). When nil (default) the shortcut is silent in the status bar. The colors are baked into the string, so a later #theme= does not restyle it — re-register if needed.

Yields:

  • invoked with no arguments when ‘key` is pressed.

Raises:

  • (ArgumentError) 


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# File 'lib/tuile/screen.rb', line 367

def register_global_shortcut(key, over_popups: false, hint: nil, &block)
  raise ArgumentError, "block required" if block.nil?
  raise ArgumentError, "key must be a String, got #{key.inspect}" unless key.is_a?(String)
  raise ArgumentError, "key cannot be empty" if key.empty?
  if Keys.printable?(key)
    raise ArgumentError,
          "global shortcut key must be unprintable; got #{key.inspect}. " \
          "Use Component#key_shortcut for printable keys (it's suppressed " \
          "while a text widget owns the cursor, so it won't hijack typing)."
  end
  if [Keys::TAB, Keys::SHIFT_TAB].include?(key)
    raise ArgumentError,
          "#{key == Keys::TAB ? "TAB" : "SHIFT_TAB"} is reserved for focus navigation"
  end
  raise ArgumentError, "hint must be a String or nil, got #{hint.inspect}" unless hint.nil? || hint.is_a?(String)

  @global_shortcuts[key] = Shortcut.new(block: block, over_popups: over_popups, hint: hint)
  refresh_status_bar
end

#remove_popup(window) ⇒ void

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

This method returns an undefined value.

Internal — use Component::Popup#close instead. Removes the popup from #pane, repairs focus, and repaints the scene.

Does nothing if the window is not open on this screen.

Parameters:



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# File 'lib/tuile/screen.rb', line 411

def remove_popup(window)
  check_locked
  return unless @pane.has_popup?(window)

  @pane.remove_popup(window)
  needs_full_repaint
end

#repaint ⇒ void

This method returns an undefined value.

Repaints the screen; tries to be as effective as possible, by only considering invalidated windows.



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# File 'lib/tuile/screen.rb', line 475

def repaint
  check_locked
  # This simple TUI framework doesn't support window clipping since tiled
  # windows are not expected to overlap. If there rarely is a popup, we
  # just repaint all windows in correct order — sure they will paint over
  # other windows, but if this is done in the right order, the final
  # drawing will look okay. Not the most effective algorithm, but very
  # simple and very fast in common cases.

  did_paint = false
  until @invalidated.empty?
    # Defensive filter: a component can become detached between enqueue
    # and drain (popup close, sibling removed mid-event-handling, focus
    # repair). Detached components have no place on the screen and must
    # never paint, even though Component#invalidate already gates them
    # out — this catches the case where attachment changed since.
    @invalidated.delete_if { |c| !c.attached? }
    break if @invalidated.empty?

    did_paint = true
    popups = @pane.popups

    # Build the repaint list in z-order, leaning on the tree itself rather
    # than a depth sort. The pane's pre-order traversal already orders the
    # tiled layer (content subtree + status bar) parent-before-child; the
    # popups are the top layer and must paint last. The status bar is a
    # *late* pane child yet sits under the popups, so a single pane.on_tree
    # walk won't do — we collect the tiled layer first, then append popups.
    popup_members = Set.new
    popups.each { |p| p.on_tree { popup_members << _1 } }

    # Tiled layer: invalidated non-popup components, in tree order.
    repaint = []
    tiled_invalidated = false
    @pane.on_tree do |c|
      next if popup_members.include?(c)
      next unless @invalidated.include?(c)

      repaint << c
      tiled_invalidated = true
    end

    # Popups on top: the whole stack when a tiled repaint may have clobbered
    # cells they share in the buffer, else just the invalidated popup
    # components. Overdraw into the buffer is free (only net-visible cell
    # changes reach the terminal), so reasserting the stack is cheap.
    popups.each do |p|
      p.on_tree { |c| repaint << c if tiled_invalidated || @invalidated.include?(c) }
    end

    @repainting = repaint.to_set
    @invalidated.clear

    # Components write into @buffer; overdraw is free and correct here
    # because the buffer only diffs net-visible changes to the terminal.
    repaint.each(&:repaint)

    # Repaint done, mark all components as up-to-date.
    @repainting.clear
  end
  return unless did_paint

  # Flush only the changed cells, then reposition the cursor — all inside
  # one synchronized-output batch so the terminal composites it atomically.
  emit("#{Ansi::SYNC_BEGIN}#{@buffer.flush}#{cursor_sequence}#{Ansi::SYNC_END}")
end

#run_event_loop(capture_mouse: true) ⇒ void

This method returns an undefined value.

Runs event loop – waits for keys and sends them to active window. The function exits when the ‘ESC’ or ‘q’ key is pressed.

Parameters:

  • capture_mouse (Boolean) (defaults to: true) —

    when true (default), enables xterm mouse tracking so clicks and scroll wheel arrive as MouseEvents and feed Component#handle_mouse. When false, no tracking escape sequence is written: the terminal keeps its native click handling, which is what you want if the app benefits more from select-to-copy than from click-to-focus. Components’ ‘handle_mouse` is simply never invoked from the loop in that mode (the terminal stops sending the bytes).



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# File 'lib/tuile/screen.rb', line 294

def run_event_loop(capture_mouse: true)
  @pretend_ui_lock = false
  $stdin.echo = false
  print MouseEvent.start_tracking if capture_mouse
  # Follow OS light/dark flips live: terminals supporting mode 2031
  # push color-scheme reports that the key thread turns into
  # {EventQueue::ColorSchemeEvent}s.
  print TerminalBackground::NOTIFY_ON
  $stdin.raw do
    event_loop
  end
ensure
  print TerminalBackground::NOTIFY_OFF
  print MouseEvent.stop_tracking if capture_mouse
  print TTY::Cursor.show
  $stdin.echo = true
end

#unregister_global_shortcut(key) ⇒ void

This method returns an undefined value.

Removes a shortcut previously installed by #register_global_shortcut. No-op if ‘key` was not registered.

Parameters:

  • key (String) 


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# File 'lib/tuile/screen.rb', line 391

def unregister_global_shortcut(key)
  @global_shortcuts.delete(key)
  refresh_status_bar
end