89 lines
3.8 KiB
Go
89 lines
3.8 KiB
Go
// Cthulhu screen reader.
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// Copyright (c) 2026 Storm Dragon
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// Authors: Storm Dragon, Angus Kola
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// SPDX-License-Identifier: GPL-3.0-or-later
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package app
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import (
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"strings"
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"git.stormux.org/storm/cthulhu/internal/atspi"
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"git.stormux.org/storm/cthulhu/internal/input"
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)
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func should_ignore_terminal_scrollback(event atspi.Event) bool {
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// VTE can remove old lines at the start of its accessible text while
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// appending output at a different offset. A deletion entirely before
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// the caret line is not an edit to the prompt. VTE wrapped rows have
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// no trailing newline, so do not require one. This event pattern
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// occurs on both X11 and Wayland.
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return event.Type == atspi.TextDeletedEvent &&
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event.Source.Role == "terminal" && event.Detail1 == 0 &&
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event.Source.TextCaretKnown && event.Source.BrailleLineStart > 0 &&
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event.TextChangeLength > 0 &&
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event.TextChangeLength <= event.Source.BrailleLineStart
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}
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// is_user_terminal_deletion identifies a deletion the user just caused at
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// the caret on its own line: a Backspace or Delete edit. The deleted text
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// is the user's confirmation that the edit took, so repaint coalescing
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// must not swallow it. Program repaints start above the caret line, and
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// deletions without a preceding delete key are program output churn.
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func is_user_terminal_deletion(event atspi.Event, intent input.Intent) bool {
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return intent == input.DeleteIntent &&
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event.Type == atspi.TextDeletedEvent && event.Source.Role == "terminal" &&
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event.Source.TextCaretKnown &&
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event.Detail1 >= event.Source.BrailleLineStart &&
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event.Detail1 <= event.Source.BrailleCaret
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}
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// is_latest_wins_terminal_repaint identifies an in-place rewrite: an
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// insertion that replaced a just-deleted range. Status regions update
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// this way several times a second and only the newest state is worth
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// hearing. Editing feedback on the caret line after a typing or delete
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// key stays immediate; appended output has no preceding deletion and
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// never qualifies.
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func is_latest_wins_terminal_repaint(event atspi.Event, intent input.Intent, replacedDeletion bool) bool {
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if !replacedDeletion || event.Type != atspi.TextInsertedEvent || event.Source.Role != "terminal" {
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return false
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}
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if (intent == input.TypingIntent || intent == input.DeleteIntent) &&
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event.Source.TextCaretKnown && event.Detail1 >= event.Source.BrailleLineStart {
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return false
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}
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return true
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}
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// Blank repaints carry no speech. Short nonblank updates can still be
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// meaningful ("OK", a count, or one Unicode character) and must survive.
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func is_trivial_terminal_repaint(event atspi.Event) bool {
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return event.Type == atspi.TextInsertedEvent && event.Source.Role == "terminal" &&
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strings.TrimSpace(event.Payload) == ""
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}
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// terminalReplacementOverlap reports whether an insertion rewrites any of
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// the range a pending deletion removed. Offsets are not compared exactly:
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// a scroll shift at the start of the buffer between the deletion and its
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// replacement insertion moves the insertion's offset, and a repainted
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// region is routinely rewritten at a neighboring offset.
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func terminalReplacementOverlap(deletion, insertion atspi.Event) bool {
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if deletion.Source.Role != "terminal" || insertion.Source.Role != "terminal" ||
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deletion.Source.Path == "" || deletion.Source.ID() != insertion.Source.ID() {
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return false
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}
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deletionEnd := deletion.Detail1 + max(deletion.TextChangeLength, 1)
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insertionEnd := insertion.Detail1 + max(insertion.TextChangeLength, 1)
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return insertion.Detail1 < deletionEnd && deletion.Detail1 < insertionEnd
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}
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// Preserve the first deadline so a continuously redrawn status still speaks
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// its latest value. The event loop owns both the event and the timer.
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func (pending *pendingPresentation) coalesce_terminal_repaint(event atspi.Event) {
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if pending.event.Type == "" {
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pending.schedule(event, input.NoIntent, terminalRepaintDebounce)
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return
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}
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pending.event = event
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}
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