M7: a form edit reads the document's fields once (form.fill-text)

The fields of a document are kept with the state they were read from
(pdfcraft_cos::ReadState), and a document that still reads as that state
gets a copy instead of a new walk. One value edit read them four times
on an AcroForm (fill, recalculate, refresh, display) and seven on a
laid-out XFA form (plus the data sync twice and the scripts), mostly with
nothing changed in between; it now walks them once, and twice on an XFA
form (once more after its data is written).

parity/acrobat-features.toml

@@ -4638,7 +4638,7 @@ milestone = "M6"
 status = "shipped"
 commands = ["form.fields"]
 tools = ["form_fill", "form_fields"]
-evidence = ["crates/ui-egui/tests/it/forms.rs::typing_into_a_text_field_and_tabbing_on", "crates/ui-egui/tests/it/forms.rs::auto_size_fields_shrink_and_wrap_typed_text_to_fit_their_box", "crates/forms/src/tests.rs::text_fields_get_new_appearances", "crates/engine/src/tests.rs::filling_a_form_shows_saves_and_undoes", "crates/automation/tests/it/automation.rs::orphan_form_fields_through_tools", "crates/forms/src/tests.rs::fields_sharing_a_name_take_the_same_value", "crates/ui-egui/tests/it/forms.rs::hovering_a_field_shows_its_tooltip", "crates/forms/src/tests.rs::zero_max_len_is_unlimited_and_overrides_inherited_limit", "crates/engine/src/tests.rs::password_field_values_are_kept_in_memory_but_written_to_no_file", "crates/forms/src/tests.rs::a_cleared_password_field_returns_to_its_default_value", "crates/forms/src/tests.rs::a_text_field_says_what_fits_it_as_its_appearance_draws_it", "crates/forms/src/tests.rs::an_edit_to_a_full_field_keeps_what_fits", "crates/ui-egui/tests/it/forms.rs::a_field_that_doesnt_scroll_stops_taking_text_when_full", "crates/ui-egui/tests/it/forms.rs::a_multi_line_auto_sized_field_that_doesnt_scroll_stops_when_full", "crates/engine/src/tests.rs::an_xfa_field_that_doesnt_scroll_opens_with_do_not_scroll_and_a_text_box", "crates/xfa/src/tests.rs::fields_that_dont_scroll_are_written_with_do_not_scroll", "crates/forms/src/tests.rs::comb_fields_show_their_cells", "crates/forms/src/tests.rs::thai_a_field_font_cannot_hold_is_drawn_from_the_thai_face", "crates/automation/tests/it/automation.rs::thai_in_fill_sign_text_comments_fields_and_page_marks_is_drawn_and_found"]
+evidence = ["crates/ui-egui/tests/it/forms.rs::typing_into_a_text_field_and_tabbing_on", "crates/ui-egui/tests/it/forms.rs::auto_size_fields_shrink_and_wrap_typed_text_to_fit_their_box", "crates/forms/src/tests.rs::text_fields_get_new_appearances", "crates/engine/src/tests.rs::filling_a_form_shows_saves_and_undoes", "crates/automation/tests/it/automation.rs::orphan_form_fields_through_tools", "crates/forms/src/tests.rs::fields_sharing_a_name_take_the_same_value", "crates/ui-egui/tests/it/forms.rs::hovering_a_field_shows_its_tooltip", "crates/forms/src/tests.rs::zero_max_len_is_unlimited_and_overrides_inherited_limit", "crates/engine/src/tests.rs::password_field_values_are_kept_in_memory_but_written_to_no_file", "crates/forms/src/tests.rs::a_cleared_password_field_returns_to_its_default_value", "crates/forms/src/tests.rs::a_text_field_says_what_fits_it_as_its_appearance_draws_it", "crates/forms/src/tests.rs::an_edit_to_a_full_field_keeps_what_fits", "crates/ui-egui/tests/it/forms.rs::a_field_that_doesnt_scroll_stops_taking_text_when_full", "crates/ui-egui/tests/it/forms.rs::a_multi_line_auto_sized_field_that_doesnt_scroll_stops_when_full", "crates/engine/src/tests.rs::an_xfa_field_that_doesnt_scroll_opens_with_do_not_scroll_and_a_text_box", "crates/xfa/src/tests.rs::fields_that_dont_scroll_are_written_with_do_not_scroll", "crates/forms/src/tests.rs::comb_fields_show_their_cells", "crates/forms/src/tests.rs::thai_a_field_font_cannot_hold_is_drawn_from_the_thai_face", "crates/automation/tests/it/automation.rs::thai_in_fill_sign_text_comments_fields_and_page_marks_is_drawn_and_found", "crates/engine/tests/form_edit_reads.rs::a_form_edit_reads_the_fields_once_however_many_the_form_holds"]
 notes = "in-place editor; Thai the field's /DA font can't hold is drawn from the craft-fonts Thai face as Add text draws it (Type 3 glyphs with a ToUnicode map beside the field's font, /DA kept, no /NeedAppearances asked for; the ink of stacked marks and descenders kept inside the border, an automatic size shrinking for it), and refused, saying what to do, in a build without a Thai face (#2354); comb and list fields still draw Thai as `?`, marked; Enter or clicking away commits, Escape cancels; auto-size (0 Tf) fields shrink, and multiline ones wrap, the text being typed to fit the box, on screen as on the page (the screen measures in the interface font, so its size can be a little smaller than the page's Helvetica fit); fixed sizes are kept and clip, as in Acrobat; a field that doesn't scroll (DoNotScroll, ISO 32000-2 Table 228, and XFA's hScrollPolicy/vScrollPolicy=\"off\", written as it) takes no more text than its appearance shows, measured in the field's own font, padding and size (the smallest automatic size, 4 pt, for 0 Tf): typing into a full field adds nothing, and a paste or a replaced selection keeps what fits (form_fill isn't interactive and still takes any value); no format/keystroke JavaScript yet (M6.4); resting the pointer on any field shows its tooltip (/TU), as Acrobat does (#3854); imported MaxLen 0 permits text input and overrides inherited limits; positive limits remain enforced. A text field with the Password flag is saved as Acrobat saves it (#3926, black-box test): the typed value is written to no file (Save, Save As, Reduce File Size, recovery, Extract/Split/Combine, signing); the field gets back its default value (/DV) or is left empty, and its asterisks are redrawn from that value. /DV and the field's scripts stay. Known limits, which Acrobat shares: a script that copies the password into an ordinary field saves it there (Acrobat recalculates a Calculate copy on save, PdfCraft does not), and an incremental save leaves a password stored by an earlier revision in that revision. A comb field with a border colour shows its MaxLen cells as lines in that colour, in the appearances PdfCraft saves and in display-only ones (up to 500 cells)."
 
 [[feature]]