After commit c018f5fd29 Fenrir is being switched over to go. If you do not want to be part of the testing process, please switch to master.

internal/screen/region.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2026 Storm Dragon
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package screen
+
+import "strings"
+
+// Region uses inclusive screen-cell coordinates, independently of text width
+// in bytes. ToLineEnd follows the current right edge when the terminal resizes.
+// Other coordinates stay fixed and are clipped only while reading/filtering.
+type Region struct {
+	Left, Top, Right, Bottom int
+	ToLineEnd                bool
+}
+
+func (r Region) Right_edge(cols int) int {
+	if r.ToLineEnd {
+		return cols - 1
+	}
+	return min(r.Right, cols-1)
+}
+
+func (r Region) Contains(x, y, cols int) bool {
+	return x >= r.Left && x <= r.Right_edge(cols) && y >= r.Top && y <= r.Bottom
+}
+
+func (r Region) Text(s Snapshot) string {
+	right := r.Right_edge(s.Cols)
+	if r.Left > right || r.Top >= s.Rows {
+		return ""
+	}
+	var lines []string
+	for row := r.Top; row <= min(r.Bottom, s.Rows-1); row++ {
+		lines = append(lines, strings.TrimRight(string(s.Line(row)[r.Left:right+1]), " \x00"))
+	}
+	return strings.Join(lines, "\n")
+}