v0.1.0 initial commit

tui/scroll.go

@@ -0,0 +1,76 @@
+package tui
+
+// --- Scroll position calculation ---
+
+// AdjustScroll returns new scroll offset keeping cursor visible
+func AdjustScroll(cursor, scroll, visible, total int) int {
+	if total <= visible {
+		return 0
+	}
+	if cursor < scroll {
+		return cursor
+	}
+	if cursor >= scroll+visible {
+		return cursor - visible + 1
+	}
+	return scroll
+}
+
+// ScrollPercent returns scroll position as 0-100 percentage
+func ScrollPercent(scroll, visible, total int) int {
+	if total <= visible {
+		return 0
+	}
+	maxScroll := total - visible
+	if maxScroll <= 0 {
+		return 0
+	}
+	pct := (scroll * 100) / maxScroll
+	if pct > 100 {
+		pct = 100
+	}
+	if pct < 0 {
+		pct = 0
+	}
+	return pct
+}
+
+// --- Clamping utilities ---
+
+// ClampScroll ensures scroll offset is within valid range
+func ClampScroll(scroll, visible, total int) int {
+	if total <= visible {
+		return 0
+	}
+	maxScroll := total - visible
+	if scroll < 0 {
+		return 0
+	}
+	if scroll > maxScroll {
+		return maxScroll
+	}
+	return scroll
+}
+
+// ClampCursor ensures cursor is within valid range
+func ClampCursor(cursor, total int) int {
+	if total <= 0 {
+		return 0
+	}
+	if cursor < 0 {
+		return 0
+	}
+	if cursor >= total {
+		return total - 1
+	}
+	return cursor
+}
+
+// PageDelta returns recommended page scroll amount
+func PageDelta(visible int) int {
+	delta := visible / 2
+	if delta < 1 {
+		delta = 1
+	}
+	return delta
+}