XFA: a script's time starts when its context is ready, and a value reaches every field bound to its data node (#1589)

Two follow-ups the maintainer asked for after #1355.

The script session's worker now says when the engine is ready for the
script it was sent (its JavaScript context built; FormCalc at once),
and the script's time limit runs from then, with the engine's own
start limit before it, as the one-shot path always did: building a
context is not charged to the script, which matters on a busy machine.

A field inside an area shares its data node with a field of the same
name outside it (areas are left out of data paths). The in-place
refresh of the live form now follows the data path through the tree
and gives every field bound to the node the value the tree builder
would, each by its own template field (an exclusion group there means
a rebuild), and the engine's value setter, with an index of widgets by
data node, gives every widget bound to the node the value by its own
kind, hidden fields included, writing the data whenever the node's
text differs. The script's time now also starts after its host and
globals are set up. A stale parity note (choosing a picture for an
image field, delivered in #1175) is removed.

parity/acrobat-features.toml

@@ -5197,7 +5197,7 @@ status = "partial"
 commands = ["file.open"]
 tools = ["doc_open", "doc_info", "form_fields", "form_fill", "js_run"]
 evidence = ["crates/xfa/src/tests.rs::layout_places_captions_fields_and_sizes_containers_to_their_content", "crates/xfa/src/tests.rs::tables_break_across_pages_and_repeat_their_header_row", "crates/xfa/src/tests.rs::rendering_into_the_pdf_replaces_the_placeholder_page_and_adds_fields", "crates/engine/src/tests.rs::dynamic_xfa_forms_are_laid_out_on_open_filled_and_saved_incrementally", "crates/automation/tests/automation.rs::dynamic_xfa_forms_open_render_fill_and_save_through_tools", "crates/ui-egui/tests/ui_group/xfa.rs::a_dynamic_xfa_form_is_laid_out_and_filled", "crates/xfa/src/tests.rs::nested_width_less_subforms_lay_out_in_polynomial_time", "crates/js/src/tests.rs::instance_managers_add_remove_and_count", "crates/xfa/src/tests.rs::the_form_tree_carries_values_presence_instances_and_the_events", "crates/engine/src/tests.rs::xfa_scripts_initialize_calculate_validate_toggle_and_add_rows", "crates/automation/tests/automation.rs::xfa_scripts_run_for_buttons_and_field_changes_through_tools", "crates/ui-egui/tests/ui_group/xfa.rs::xfa_buttons_run_their_scripts_in_the_app", "crates/engine/src/tests.rs::hostile_xfa_open_scripts_are_merged_capped_kept_from_printing_and_noted", "crates/engine/src/tests.rs::runaway_xfa_calculations_at_open_end_quickly_with_a_report", "crates/ui-egui/tests/ui_group/xfa.rs::a_form_whose_scripts_were_turned_off_at_open_says_so", "crates/ui-egui/tests/ui_group/xfa.rs::scripts_turned_off_by_a_click_bring_a_closed_notice_bar_back", "crates/automation/tests/automation.rs::doc_info_says_when_a_runaway_script_turned_the_forms_scripts_off", "crates/xfa/src/tests.rs::the_live_form_of_nested_repeating_subforms_stops_at_its_node_budget", "crates/xfa/src/tests.rs::data_ops_of_one_event_are_one_datasets_rewrite", "crates/xfa/src/tests.rs::choice_lists_signatures_passwords_and_pictures_become_fields_and_images", "crates/xfa/src/tests.rs::choice_values_come_from_the_data_as_saved_values_and_several_for_lists", "crates/xfa/src/tests.rs::pictures_are_sized_from_their_headers_and_hostile_ones_are_refused_unallocated", "crates/engine/src/tests.rs::xfa_choice_lists_signature_and_picture_fields_open_fill_script_and_save", "crates/xfa/src/tests.rs::repeating_subforms_inside_positioned_content_get_their_instances", "crates/engine/src/tests.rs::xfa_rows_in_areas_are_laid_out_read_calculated_and_written_where_adobe_binds_them"]
-notes = "laid out from the template on open by the xfa crate (positioned, tb, lr-tb, table/row, page masters, breaks, repeated header rows, captions, rich text, JPEG/PNG/GIF images) into real pages and AcroForm fields (text, password, date with AFDate formats, check boxes, radio groups, drop-downs and list boxes with shown/saved item pairs and multi-select, signature fields, image fields showing their picture (pictures decoded once per document, at most 20 million pixels, and reused across re-layouts), buttons with reset/print/save/URL), filled from the datasets packet (including rows another viewer added), saved as an incremental revision with the values merged into the datasets so Adobe's viewers show them; doc_info reports xfa_layout. XFA JavaScript and FormCalc (form.xfa-formcalc) run in the js crate's XFA object model (xfa.form, SOM resolution, rawValue, presence, access, instance managers, xfa.host, xfa.layout, xfa.event): initialize and calculate on open, exit, validate and calculate after a field changes, click for buttons (through js_run and the app), with rows added and removed, subforms shown and hidden, and the form laid out again, all as one undo step and kept in the file. All the scripts of one event run on one thread, each in a fresh context on the form as the engine holds it then (nothing shared between scripts; the live form kept up to date in place for values, rebuilt only when the structure changed), so hundreds of calculations run within the open budget. Hostile scripts are bounded per event (merged and capped effects, messages and console lines, lower loop limits and a time budget on open and calculate, one datasets rewrite per event, print/save/links/focus from clicks only, a runaway script abandoned and the form's scripts turned off, which the app says in a toast and on the notice bar, with a button to the JavaScript console, and doc_info reports as xfa_scripts_off) and what open-time scripts changed is noted. Missing: loops inside nested calls are only stopped by abandoning their thread, and script memory is not capped; the change event per keystroke; xfa.template, connections and data descriptions; a hidden instance of a repeating subform hides them all; choosing a new picture for an image field; barcodes are drawn as their text, not bars; keep rules; metrics are approximate and Acrobat fidelity is eyeballed on real forms, not measured (#60)"
+notes = "laid out from the template on open by the xfa crate (positioned, tb, lr-tb, table/row, page masters, breaks, repeated header rows, captions, rich text, JPEG/PNG/GIF images) into real pages and AcroForm fields (text, password, date with AFDate formats, check boxes, radio groups, drop-downs and list boxes with shown/saved item pairs and multi-select, signature fields, image fields showing their picture (pictures decoded once per document, at most 20 million pixels, and reused across re-layouts), buttons with reset/print/save/URL), filled from the datasets packet (including rows another viewer added), saved as an incremental revision with the values merged into the datasets so Adobe's viewers show them; doc_info reports xfa_layout. XFA JavaScript and FormCalc (form.xfa-formcalc) run in the js crate's XFA object model (xfa.form, SOM resolution, rawValue, presence, access, instance managers, xfa.host, xfa.layout, xfa.event): initialize and calculate on open, exit, validate and calculate after a field changes, click for buttons (through js_run and the app), with rows added and removed, subforms shown and hidden, and the form laid out again, all as one undo step and kept in the file. All the scripts of one event run on one thread, each in a fresh context on the form as the engine holds it then (nothing shared between scripts; the live form kept up to date in place for values, rebuilt only when the structure changed), so hundreds of calculations run within the open budget. Hostile scripts are bounded per event (merged and capped effects, messages and console lines, lower loop limits and a time budget on open and calculate, one datasets rewrite per event, print/save/links/focus from clicks only, a runaway script abandoned and the form's scripts turned off, which the app says in a toast and on the notice bar, with a button to the JavaScript console, and doc_info reports as xfa_scripts_off) and what open-time scripts changed is noted. Missing: loops inside nested calls are only stopped by abandoning their thread, and script memory is not capped; the change event per keystroke; xfa.template, connections and data descriptions; a hidden instance of a repeating subform hides them all; barcodes are drawn as their text, not bars; keep rules; metrics are approximate and Acrobat fidelity is eyeballed on real forms, not measured (#60)"
 
 [[feature]]
 id = "form.xfa-formcalc"