Sixel Part 2. Ignore embedded by Windows CSI and OSC sequences. (#132)

* Sixel Part 2. Ignore embedded by Windows CSI and OSC sequences.

* Sixel Step 3. Recover original Sixel sequence from Windows formatting

matrix/automatrix.go

@@ -0,0 +1,69 @@
+package matrix
+
+// AutoMatrix -- automatically growing matrix
+type AutoMatrix struct {
+	lines [][]rune
+}
+
+// NewAutoMatrix creates a new auto-matrix
+func NewAutoMatrix() *AutoMatrix {
+	m := &AutoMatrix{
+		lines: make([][]rune, 0),
+	}
+	return m
+}
+
+// ExtractFrom extracts from (x1, y1) until the end
+func (matrix *AutoMatrix) ExtractFrom(x1, y1 int) []rune {
+	result := make([]rune, 0)
+	y := y1
+	for y < len(matrix.lines) {
+		if matrix.lines[y] != nil {
+			xMin := 0
+			if y == y1 {
+				xMin = x1
+			}
+			result = append(result, matrix.lines[y][xMin:]...)
+		}
+		y++
+	}
+	return result
+}
+
+// Extract from (x1, y1) until (x2, y2)
+func (matrix *AutoMatrix) Extract(x1, y1, x2, y2 int) []rune {
+	result := make([]rune, 0)
+	y := y1
+	for y <= y2 && y < len(matrix.lines) {
+		xMin := 0
+		if y == y1 {
+			xMin = x1
+		}
+		if matrix.lines[y] != nil {
+			xMax := x2
+			if y != y2 {
+				xMax = len(matrix.lines[y]) - 1
+			}
+			result = append(result, matrix.lines[y][xMin:xMax]...)
+		}
+		y++
+	}
+	return result
+}
+
+func (matrix *AutoMatrix) setAtLine(value rune, x int, line []rune) []rune {
+	if x >= len(line) {
+		line = append(line, make([]rune, x-len(line)+1)...)
+	}
+	line[x] = value
+	return line
+}
+
+// SetAt sets a value at (x, y) growing the matrix as necessary
+func (matrix *AutoMatrix) SetAt(value rune, x int, y int) {
+
+	if y >= len(matrix.lines) {
+		matrix.lines = append(matrix.lines, make([][]rune, y-len(matrix.lines)+1)...)
+	}
+	matrix.lines[y] = matrix.setAtLine(value, x, matrix.lines[y])
+}

terminal/csi.go

@@ -49,11 +49,17 @@ var csiSequences = []csiMapping{
 	{id: '@', handler: csiInsertBlankCharactersHandler, description: "Insert Ps (Blank) Character(s) (default = 1) (ICH)"},
 }
 
-func csiHandler(pty chan rune, terminal *Terminal) error {
-	var final rune
+type runeRange struct {
+	min rune
+	max rune
+}
+
+var csiTerminators = runeRange{0x40, 0x7e}
+
+func loadCSI(pty chan rune) (final rune, param string, intermediate string) {
 	var b rune
-	param := ""
-	intermediate := ""
+	param = ""
+	intermediate = ""
 CSI:
 	for {
 		b = <-pty
@@ -63,16 +69,27 @@ CSI:
 		case b >= 0x20 && b <= 0x2F:
 			//intermediate? useful?
 			intermediate += string(b)
-		case b >= 0x40 && b <= 0x7e:
+		case b >= csiTerminators.min && b <= csiTerminators.max:
 			final = b
 			break CSI
 		}
 	}
 
-	params := strings.Split(param, ";")
-	if param == "" {
+	return final, param, intermediate
+}
+
+func splitParams(paramString string) []string {
+	params := strings.Split(paramString, ";")
+	if paramString == "" {
 		params = []string{}
 	}
+	return params
+}
+
+func csiHandler(pty chan rune, terminal *Terminal) error {
+	final, param, intermediate := loadCSI(pty)
+
+	params := splitParams(param)
 
 	for _, sequence := range csiSequences {
 		if sequence.id == final {
@@ -221,8 +238,8 @@ func csiCursorCharacterAbsoluteHandler(params []string, intermediate string, ter
 	return nil
 }
 
-func csiCursorPositionHandler(params []string, intermediate string, terminal *Terminal) error {
-	x, y := 1, 1
+func parseCursorPosition(params []string) (x, y int) {
+	x, y = 1, 1
 	if len(params) == 2 {
 		var err error
 		if params[0] != "" {
@@ -238,6 +255,11 @@ func csiCursorPositionHandler(params []string, intermediate string, terminal *Te
 			}
 		}
 	}
+	return x, y
+}
+
+func csiCursorPositionHandler(params []string, intermediate string, terminal *Terminal) error {
+	x, y := parseCursorPosition(params)
 
 	terminal.ActiveBuffer().SetPosition(uint16(x-1), uint16(y-1))
 	return nil

terminal/sixel.go

@@ -7,32 +7,130 @@ import (
 	"math"
 	"strings"
 
+	"github.com/liamg/aminal/matrix"
 	"github.com/liamg/aminal/sixel"
 )
 
-func sixelHandler(pty chan rune, terminal *Terminal) error {
-
-	data := []rune{}
+type boolFormRuneFunc func(rune) bool
 
+func swallowByFunction(pty chan rune, isTerminator boolFormRuneFunc) {
 	for {
 		b := <-pty
-		if b == 0x1b { // terminated by ESC bell or ESC \
+		if isTerminator(b) {
+			break
+		}
+	}
+}
+
+func filter(src []rune) []rune {
+	result := make([]rune, 0, len(src))
+	for _, v := range src {
+		if v >= 33 {
+			result = append(result, v)
+		}
+	}
+	return result
+}
+
+func sixelHandler(pty chan rune, terminal *Terminal) error {
+	debug := ""
+
+	// data := []rune{}
+
+	// track for Windows formatting workaround
+	scrollOffset := uint16(terminal.GetScrollOffset())
+	x := terminal.ActiveBuffer().CursorColumn() + 2 // reserve two bytes for Sixel prefix (ESC P)
+	y := terminal.ActiveBuffer().CursorLine()
+	scrollingLine := terminal.ActiveBuffer().ViewHeight() - 1
+	xStart := x
+	yStartWithOffset := y + scrollOffset
+	matrix := matrix.NewAutoMatrix() // a simplified version of Buffer
+	for {
+		b := <-pty
+		if b == 0x1b {
 			t := <-pty
+			if t == '[' { // Windows injected a CSI sequence
+				final, param, _ := loadCSI(pty)
+
+				if final == 'H' {
+					// position cursor
+					params := splitParams(param)
+					{
+						xT, yT := parseCursorPosition(params) // 1 based
+						x = uint16(xT - 1)                    // 0 based
+						y = uint16(yT - 1)                    // 0 based
+					}
+				}
+				debug += "[CSI " + param + string(final) + "]"
+				continue
+			}
+			if t == ']' { // Windows injected an OSC sequence
+				// TODO: pass through as if it came via normal stream
+				swallowByFunction(pty, terminal.IsOSCTerminator)
+				debug += "[OSC]"
+				continue
+			}
+			// if re-drawing a region beforethe start of sixel sequencce,
+			// ignore all possible ESC pairs (including ESC P)
+			if y+scrollOffset < yStartWithOffset || (y+scrollOffset == yStartWithOffset && x < xStart) {
+				x += 2
+				continue
+			}
 			if t != 0x07 && t != 0x5c {
 				return fmt.Errorf("Incorrect terminator in sixel sequence: 0x%02X [%c]", t, t)
 			}
-			break
+			break // terminated by ESC bell or ESC \
 		}
-		if b >= 33 {
-			data = append(data, b)
+
+		if b == 0x0d {
+			// skip
+		} else if b == 0x0a {
+			terminal.logger.Debugf("Sixel line: %s", debug)
+			debug = ""
+			if y == scrollingLine {
+				scrollOffset++
+			} else {
+				y++
+			}
+			x = 0
+		} else if y+scrollOffset < yStartWithOffset || (y+scrollOffset == yStartWithOffset && x < xStart) {
+			x++
+		} else if b < 32 {
+			x++ // always?
+		} else {
+			debug += string(b)
+			matrix.SetAt(b, int(x), int(y+scrollOffset-yStartWithOffset))
+			x++
 		}
+		/*
+			if b >= 33 {
+				data = append(data, b)
+			}
+		*/
 	}
 
-	six, err := sixel.ParseString(string(data))
+	if debug != "" {
+		terminal.logger.Debugf("Sixel last line: %s", debug)
+	}
+
+	newData := matrix.ExtractFrom(int(xStart), 0) // , int(x), int(y+scrollOffset))
+
+	terminal.logger.Debugf("Sixel data: %s", string(newData))
+
+	filteredData := filter(newData)
+
+	six, err := sixel.ParseString(string(filteredData))
+
 	if err != nil {
 		return fmt.Errorf("Failed to parse sixel data: %s", err)
 	}
 
+	drawSixel(six, terminal)
+
+	return nil
+}
+
+func drawSixel(six *sixel.Sixel, terminal *Terminal) {
 	originalImage := six.RGBA()
 
 	w := originalImage.Bounds().Size().X
@@ -70,6 +168,4 @@ func sixelHandler(pty chan rune, terminal *Terminal) error {
 			cell.SetImage(rgba)
 		}
 	}
-
-	return nil
 }