Initial patterm project

internal/app/layout.go

@@ -0,0 +1,73 @@
+package app
+
+// terminalLayout is the single source of truth for host chrome and the
+// child PTY viewport.
+type terminalLayout struct {
+	hostCols uint16
+	hostRows uint16
+
+	mainLeft uint16
+	mainTop  uint16
+	mainCols uint16
+	mainRows uint16
+
+	sidebarVisible bool
+	sidebarLeft    uint16
+	sidebarWidth   uint16
+
+	statusRow uint16
+}
+
+func newTerminalLayout(cols, rows uint16) terminalLayout {
+	if cols == 0 {
+		cols = 1
+	}
+	if rows == 0 {
+		rows = 1
+	}
+
+	l := terminalLayout{
+		hostCols:  cols,
+		hostRows:  rows,
+		mainLeft:  1,
+		mainTop:   tabBarRows + 1,
+		mainCols:  cols,
+		mainRows:  1,
+		statusRow: rows,
+	}
+
+	if int(cols) > sidebarCols+10 {
+		l.sidebarVisible = true
+		l.sidebarWidth = sidebarCols
+		l.sidebarLeft = cols - sidebarCols + 1
+		l.mainCols = cols - sidebarCols
+	}
+
+	reservedRows := tabBarRows + statusRows
+	if int(rows) > reservedRows {
+		l.mainRows = rows - uint16(reservedRows)
+	}
+	return l
+}
+
+func (l terminalLayout) childCols() uint16 {
+	if l.mainCols == 0 {
+		return 1
+	}
+	return l.mainCols
+}
+
+func (l terminalLayout) childRows() uint16 {
+	if l.mainRows == 0 {
+		return 1
+	}
+	return l.mainRows
+}
+
+func ptyRows(hostRows uint16) uint16 {
+	return newTerminalLayout(1, hostRows).childRows()
+}
+
+func ptyCols(hostCols uint16) uint16 {
+	return newTerminalLayout(hostCols, 1).childCols()
+}