v0.1.0 initial commit

ansi.go

@@ -0,0 +1,111 @@
+package terminal
+
+import (
+	"bufio"
+)
+
+// Pre-allocated ANSI sequence fragments (avoid allocations during render)
+var (
+	// CSI sequences
+	csi      = []byte("\x1b[")
+	csiEnd   = []byte("m")
+	csiReset = []byte("\x1b[0m")
+	csiClear = []byte("\x1b[2J\x1b[H")
+	csiHome  = []byte("\x1b[H")
+	csiRIS   = []byte("\x1bc") // Reset to Initial GameState (emergency)
+	csiSGR0  = []byte("\x1b[0m")
+
+	// Cursor control
+	csiCursorHide = []byte("\x1b[?25l")
+	csiCursorShow = []byte("\x1b[?25h")
+	csiCursorPos  = []byte("\x1b[") // followed by row;colH
+
+	// Screen modes
+	csiAltScreenEnter = []byte("\x1b[?1049h")
+	csiAltScreenExit  = []byte("\x1b[?1049l")
+	// DECAWM: Auto-Wrap Mode
+	// ?7l disables wrapping (cursor sticks at right edge), preventing scroll when writing to bottom-right corner
+	csiAutoWrapOn  = []byte("\x1b[?7h")
+	csiAutoWrapOff = []byte("\x1b[?7l")
+
+	// Color prefixes
+	csiFg256     = []byte("\x1b[38;5;") // followed by N;m
+	csiBg256     = []byte("\x1b[48;5;") // followed by N;m
+	csiFgRGB     = []byte("\x1b[38;2;") // followed by R;G;B;m
+	csiBgRGB     = []byte("\x1b[48;2;") // followed by R;G;B;m
+	csiDefaultFg = []byte("\x1b[39m")
+	csiDefaultBg = []byte("\x1b[49m")
+
+	// Attribute sequences
+	csiAttrBold      = []byte("\x1b[1m")
+	csiAttrDim       = []byte("\x1b[2m")
+	csiAttrItalic    = []byte("\x1b[3m")
+	csiAttrUnderline = []byte("\x1b[4m")
+	csiAttrBlink     = []byte("\x1b[5m")
+	csiAttrReverse   = []byte("\x1b[7m")
+
+	// Mouse mode sequences (SGR 1006 for extended coordinates)
+	csiMouseClickOn   = []byte("\x1b[?1000h") // Enable click reporting
+	csiMouseClickOff  = []byte("\x1b[?1000l")
+	csiMouseDragOn    = []byte("\x1b[?1002h") // Enable button-event (drag) tracking
+	csiMouseDragOff   = []byte("\x1b[?1002l")
+	csiMouseMotionOn  = []byte("\x1b[?1003h") // Enable any-event (all motion) tracking
+	csiMouseMotionOff = []byte("\x1b[?1003l")
+	csiMouseSGROn     = []byte("\x1b[?1006h") // Enable SGR extended mode
+	csiMouseSGROff    = []byte("\x1b[?1006l")
+)
+
+// writeInt writes an integer without allocation
+// Optimized for terminal values (0-255 common, 0-999 typical max)
+func writeInt(w *bufio.Writer, n int) {
+	if n < 0 {
+		n = 0
+	}
+	if n < 10 {
+		w.WriteByte(byte(n) + '0')
+		return
+	}
+	if n < 100 {
+		w.WriteByte(byte(n/10) + '0')
+		w.WriteByte(byte(n%10) + '0')
+		return
+	}
+	if n < 1000 {
+		w.WriteByte(byte(n/100) + '0')
+		w.WriteByte(byte(n/10%10) + '0')
+		w.WriteByte(byte(n%10) + '0')
+		return
+	}
+	// Fallback for >999 (rare)
+	var buf [5]byte
+	i := 4
+	for n > 0 {
+		buf[i] = byte(n%10) + '0'
+		n /= 10
+		i--
+	}
+	w.Write(buf[i+1:])
+}
+
+// writeCursorPos writes cursor positioning sequence (0-indexed input)
+func writeCursorPos(w *bufio.Writer, x, y int) {
+	w.Write(csiCursorPos)
+	writeInt(w, y+1)
+	w.WriteByte(';')
+	writeInt(w, x+1)
+	w.WriteByte('H')
+}
+
+// writeCursorForward writes cursor forward N positions
+func writeCursorForward(w *bufio.Writer, n int) {
+	if n <= 0 {
+		return
+	}
+	if n == 1 {
+		w.Write([]byte("\x1b[C"))
+		return
+	}
+	w.Write(csi)
+	writeInt(w, n)
+	w.WriteByte('C')
+}