Cthulhu is no longer a fork. Now it is a screen reader written in Golang.

internal/atspi/document_line.go

@@ -0,0 +1,131 @@
+package atspi
+
+import (
+	"context"
+	"errors"
+	"math"
+)
+
+var ErrNoDocumentCaret = errors.New("document caret line unavailable")
+
+type DocumentContent struct {
+	Reference ObjectReference
+	Snapshot  Snapshot
+	Start     int
+	End       int
+	Text      string
+	RawText   string
+	// Separator is display spacing before this object, outside its native range.
+	Separator string
+	Bounds    Rectangle
+}
+
+type DocumentLine struct {
+	Context  []Snapshot
+	Document ObjectReference
+	Contents []DocumentContent
+}
+
+func (tree *AccessibleTree) DocumentLineAtOffset(ctx context.Context, reference ObjectReference, offset int) (DocumentLine, error) {
+	document, err := tree.Document(ctx, reference)
+	if err != nil {
+		return DocumentLine{}, err
+	}
+
+	caretIndex := -1
+	if reference.Valid() {
+		for index, node := range document.Nodes {
+			if node.Reference == reference {
+				caretIndex = index
+				break
+			}
+		}
+	}
+	if caretIndex < 0 {
+		for index, node := range document.Nodes {
+			if node.Text.CaretKnown {
+				caretIndex = index
+				break
+			}
+		}
+	}
+	if caretIndex < 0 {
+		return DocumentLine{}, ErrNoDocumentCaret
+	}
+
+	caretNode := document.Nodes[caretIndex]
+	if offset < 0 {
+		offset = caretNode.Text.CaretOffset
+	}
+	if offset < 0 {
+		return DocumentLine{}, ErrNoDocumentCaret
+	}
+
+	caretRange, found := textRangeAtOffset(caretNode.Text, offset)
+	if !found || !caretRange.Bounds.Valid() {
+		return DocumentLine{}, ErrNoDocumentCaret
+	}
+
+	ancestors := document.Context.Ancestors
+	if len(ancestors) > 0 && ancestors[0].ID() == reference.ID() {
+		ancestors = ancestors[1:]
+	}
+	line := DocumentLine{Document: document.Context.TopLevel, Context: ancestors}
+	for _, node := range document.Nodes {
+		if node.Hidden {
+			continue
+		}
+		for _, textRange := range node.Text.Ranges {
+			if !boundsAreOnSameLine(caretRange.Bounds, textRange.Bounds) {
+				continue
+			}
+			if textRange.Text == "" {
+				continue
+			}
+			line.Contents = append(line.Contents, DocumentContent{
+				Reference: node.Reference,
+				Snapshot:  node.Snapshot,
+				Start:     textRange.Start,
+				End:       textRange.End,
+				Text:      textRange.Text,
+				RawText:   textRange.Text,
+				Bounds:    textRange.Bounds,
+			})
+		}
+	}
+	if len(line.Contents) == 0 {
+		return DocumentLine{}, ErrNoDocumentCaret
+	}
+	return line, nil
+}
+
+func textRangeAtOffset(text VisibleText, offset int) (TextRange, bool) {
+	for _, textRange := range text.Ranges {
+		if textRange.Start <= offset && offset < textRange.End {
+			return textRange, true
+		}
+	}
+	for _, textRange := range text.Ranges {
+		if textRange.Start <= offset && offset <= textRange.End {
+			return textRange, true
+		}
+	}
+	return TextRange{}, false
+}
+
+func boundsAreOnSameLine(first, second Rectangle) bool {
+	if first == second {
+		return true
+	}
+	if !first.Valid() || !second.Valid() {
+		return false
+	}
+	top := max(first.Y, second.Y)
+	bottom := min(first.Y+first.Height, second.Y+second.Height)
+	if bottom <= top {
+		return false
+	}
+	firstCenter := first.Y + first.Height/2
+	secondCenter := second.Y + second.Height/2
+	return math.Abs(float64(firstCenter-secondCenter)) <= 5
+}