From 9a28db40c4acc6e7944da31a0a2a5e6bb5c7560e Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 20 May 2022 02:50:33 +0200
Subject: [PATCH 01/44] new struct type sixel

---
 ui.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/ui.go b/ui.go
index 951c91b5..4ed3acf6 100644
--- a/ui.go
+++ b/ui.go
@@ -461,8 +461,15 @@ func (win *win) printDir(screen tcell.Screen, dir *dir, selections map[string]in
 	}
 }
 
+type sixel struct {
+	x   int
+	y   int
+	str string
+}
+
 type ui struct {
 	screen       tcell.Screen
+	sixels       []sixel
 	polling      bool
 	wins         []*win
 	promptWin    *win

From 5b10351c0129625e5c4105f44743c2691e415786 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 20 May 2022 02:52:20 +0200
Subject: [PATCH 02/44] add sixel detection logic in printReg

---
 ui.go | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/ui.go b/ui.go
index 4ed3acf6..57fd39ca 100644
--- a/ui.go
+++ b/ui.go
@@ -252,7 +252,7 @@ func (win *win) printRight(screen tcell.Screen, y int, st tcell.Style, s string)
 	win.print(screen, win.w-printLength(s), y, st, s)
 }
 
-func (win *win) printReg(screen tcell.Screen, reg *reg) {
+func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 	if reg == nil {
 		return
 	}
@@ -270,6 +270,15 @@ func (win *win) printReg(screen tcell.Screen, reg *reg) {
 			break
 		}
 
+		if a := strings.Index(l, "\x1bP"); a >= 0 {
+			if b := strings.Index(l[a+1:len(l)], "\x1b\\"); b >= 0 {
+				sixel := sixel{str: l[a : b+3], x: win.x + 2, y: win.y + i}
+				*sixels = append(*sixels, sixel)
+
+				l = l[:a] + l[b+3:]
+			}
+		}
+
 		st = win.print(screen, 2, i, st, l)
 	}
 }
@@ -891,7 +900,7 @@ func (ui *ui) draw(nav *nav) {
 			if curr.IsDir() {
 				preview.printDir(ui.screen, ui.dirPrev, nav.selections, nav.saves, nav.tags, ui.styles, ui.icons)
 			} else if curr.Mode().IsRegular() {
-				preview.printReg(ui.screen, ui.regPrev)
+				preview.printReg(ui.screen, &ui.sixels, ui.regPrev)
 			}
 		}
 	}

From 93edee3b08e4d102bb0170df5df56ca75f643a2b Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 20 May 2022 02:53:44 +0200
Subject: [PATCH 03/44] new ShowSixels that prints sixels to the screen

---
 ui.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/ui.go b/ui.go
index 57fd39ca..361c273b 100644
--- a/ui.go
+++ b/ui.go
@@ -930,6 +930,7 @@ func (ui *ui) draw(nav *nav) {
 	}
 
 	ui.screen.Show()
+	ui.ShowSixels()
 }
 
 func findBinds(keys map[string]expr, prefix string) (binds map[string]expr, ok bool) {
@@ -1306,3 +1307,10 @@ func listMatchesMenu(ui *ui, matches []string) error {
 	ui.menuBuf = b
 	return nil
 }
+
+func (ui *ui) ShowSixels() {
+	for _, sixel := range ui.sixels {
+		moveCursor := fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1)
+		os.Stdin.WriteString(moveCursor + sixel.str)
+	}
+}

From c8c5b640a5b1d8b70724ef39f3d6c378088654ff Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 20 May 2022 02:54:33 +0200
Subject: [PATCH 04/44] placeholder function UnshowSixels

---
 nav.go | 2 ++
 ui.go  | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/nav.go b/nav.go
index 37fa540d..7200fcb4 100644
--- a/nav.go
+++ b/nav.go
@@ -619,6 +619,8 @@ func (nav *nav) previewLoop(ui *ui) {
 			if err := cmd.Run(); err != nil {
 				log.Printf("cleaning preview: %s", err)
 			}
+			ui.UnshowSixels()
+			ui.sixels = nil
 			nav.volatilePreview = false
 		}
 		if len(path) != 0 {
diff --git a/ui.go b/ui.go
index 361c273b..d28bebcc 100644
--- a/ui.go
+++ b/ui.go
@@ -1314,3 +1314,11 @@ func (ui *ui) ShowSixels() {
 		os.Stdin.WriteString(moveCursor + sixel.str)
 	}
 }
+
+// Placeholder
+func (ui *ui) UnshowSixels() {
+	for _, sixel := range ui.sixels {
+		x, y := sixel.x, sixel.y
+		ui.screen.SetContent(x, y, '\u2800', nil, tcell.StyleDefault)
+	}
+}

From d782c580b17847b4f06a153c5aa3bb7607cc57ea Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 20 May 2022 02:57:26 +0200
Subject: [PATCH 05/44] run `ui.ShowSixels` after `ui.screen.Sync`

---
 eval.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/eval.go b/eval.go
index 77de6891..30bace9d 100644
--- a/eval.go
+++ b/eval.go
@@ -1198,6 +1198,7 @@ func (e *callExpr) eval(app *app, args []string) {
 		}
 		app.ui.renew()
 		app.ui.screen.Sync()
+		app.ui.ShowSixels()
 		if app.nav.height != app.ui.wins[0].h {
 			app.nav.height = app.ui.wins[0].h
 			app.nav.regCache = make(map[string]*reg)

From 3642375454667db7db6b89fe9fbe7f8baee8d92b Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 20 May 2022 16:09:37 +0200
Subject: [PATCH 06/44] fix sixel placed on wrong coordinates

---
 ui.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/ui.go b/ui.go
index d28bebcc..d5ababc3 100644
--- a/ui.go
+++ b/ui.go
@@ -271,11 +271,11 @@ func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 		}
 
 		if a := strings.Index(l, "\x1bP"); a >= 0 {
-			if b := strings.Index(l[a+1:len(l)], "\x1b\\"); b >= 0 {
-				sixel := sixel{str: l[a : b+3], x: win.x + 2, y: win.y + i}
+			if b := strings.Index(l[a+2:], "\x1b\\"); b >= 0 {
+				sixel := sixel{str: l[a : a+b+4], x: win.x + a + 2, y: win.y + i}
 				*sixels = append(*sixels, sixel)
 
-				l = l[:a] + l[b+3:]
+				l = l[:a] + l[a+b+4:]
 			}
 		}
 

From d8c1df26ac4cda65c444bd4fb57a6f85c39e3799 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Sat, 21 May 2022 00:32:30 +0200
Subject: [PATCH 07/44] change sixel termination sequence to prevent other
 escape sequence being run inside it

---
 ui.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ui.go b/ui.go
index d5ababc3..7789e58d 100644
--- a/ui.go
+++ b/ui.go
@@ -271,7 +271,7 @@ func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 		}
 
 		if a := strings.Index(l, "\x1bP"); a >= 0 {
-			if b := strings.Index(l[a+2:], "\x1b\\"); b >= 0 {
+			if b := strings.Index(l[a+2:], "\x1b"); b >= 0 && l[a+b+3] == '\\' {
 				sixel := sixel{str: l[a : a+b+4], x: win.x + a + 2, y: win.y + i}
 				*sixels = append(*sixels, sixel)
 

From 4f68fd35f2f3df89fd3b9ef262a008d008b1eae7 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Sat, 21 May 2022 02:45:55 +0200
Subject: [PATCH 08/44] process multi-line sixel sequence

---
 nav.go | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/nav.go b/nav.go
index 7200fcb4..1183254d 100644
--- a/nav.go
+++ b/nav.go
@@ -700,13 +700,36 @@ func (nav *nav) preview(path string, win *win) {
 
 	buf := bufio.NewScanner(reader)
 
-	for i := 0; i < win.h && buf.Scan(); i++ {
+	var sixel strings.Builder
+	sixelCont := false
+	for i := 0; (sixelCont || i < win.h) && buf.Scan(); i++ {
 		for _, r := range buf.Text() {
 			if r == 0 {
 				reg.lines = []string{"\033[7mbinary\033[0m"}
 				return
 			}
 		}
+		if a := strings.Index(buf.Text(), "\x1bP"); a >= 0 {
+			if b := strings.Index(buf.Text()[a+2:], "\x1b\\"); b >= 0 {
+				reg.lines = append(reg.lines, buf.Text())
+				continue
+			}
+			sixel.WriteString(buf.Text()[a:])
+			sixelCont = true
+			continue
+		}
+		if sixelCont {
+			if b := strings.Index(buf.Text(), "\x1b\\"); b >= 0 {
+				sixel.WriteString(buf.Text()[:b+2])
+				reg.lines = append(reg.lines, sixel.String(), buf.Text()[b+2:])
+				log.Printf("found multiline: %s", reg.lines[len(reg.lines)-1])
+				sixel.Reset()
+				sixelCont = false
+				continue
+			}
+			sixel.WriteString(buf.Text())
+			continue
+		}
 		reg.lines = append(reg.lines, buf.Text())
 	}
 

From 934e58907644f36a834e2c7d3259065ccda6cd6a Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Sat, 21 May 2022 02:58:20 +0200
Subject: [PATCH 09/44] fixed bug where string before sixel image is not
 printed

---
 nav.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nav.go b/nav.go
index 1183254d..6caf5e05 100644
--- a/nav.go
+++ b/nav.go
@@ -714,7 +714,7 @@ func (nav *nav) preview(path string, win *win) {
 				reg.lines = append(reg.lines, buf.Text())
 				continue
 			}
-			sixel.WriteString(buf.Text()[a:])
+			sixel.WriteString(buf.Text())
 			sixelCont = true
 			continue
 		}

From e53e6324715cdff3c7f26a71e3ba4a38f3499328 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 25 May 2022 14:42:38 +0200
Subject: [PATCH 10/44] add sixelDimPx and pxToCells

---
 misc.go | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/misc.go b/misc.go
index 7083cd7a..d0e84023 100644
--- a/misc.go
+++ b/misc.go
@@ -299,6 +299,57 @@ func mod(a, b int) int {
 	return (a%b + b) % b
 }
 
+var reNumber = regexp.MustCompile(`^[0-9]+`)
+
+// needs some testing
+func sixelDimPx(s string) (w int, h int) {
+	// TODO maybe take into account pixel aspect ratio (")
+	// TODO handle macro parameters P1 to P3
+	// `DCS P1;P2;P3;q...`
+	a := strings.Index(s, "q") + 1
+	if a == 0 {
+		//syntax error
+	}
+	var wi int
+	for i := a; i < len(s)-2; i++ {
+		c := s[i]
+		switch {
+		case '?' <= c && c <= '~':
+			wi++
+		case c == '-':
+			w = max(w, wi)
+			wi = 0
+			h++
+		case c == '$':
+			w = max(w, wi)
+			wi = 0
+		case c == '!':
+			m := reNumber.FindString(s[i+1:])
+			if m == "" {
+				// syntax error
+			}
+			if s[i+1+len(m)] < '?' || s[i+1+len(m)] > '~' {
+				// syntax error
+			}
+			n, _ := strconv.Atoi(m)
+			wi += n - 1
+		default:
+		}
+	}
+	if s[len(s)-3] != '-' {
+		w = max(w, wi)
+		wi = 0
+		h++ // add newline on last row
+	}
+	return w, h * 6
+}
+
+func pxToCells(x, y, wc, hc, wpx, hpx int) (int, int) {
+	var fw int = wpx / wc
+	var fh int = hpx / hc
+	return x/fw + 1, y/fh + 1 // TODO should probably use ceiling instead of +1
+}
+
 // We don't need no generic code
 // We don't need no type control
 // No dark templates in compiler

From eadab5e22aa971dffe4158fded094ac8f18b8da5 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 25 May 2022 14:44:43 +0200
Subject: [PATCH 11/44] add getTermPixels for unix

---
 os.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/os.go b/os.go
index 3dd9b1f9..cc02c3f0 100644
--- a/os.go
+++ b/os.go
@@ -220,3 +220,11 @@ func exportFiles(f string, fs []string, pwd string) {
 		os.Setenv("fx", envFiles)
 	}
 }
+
+func getTermPixels(fd int) (w, h int, err error) {
+	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
+	if err != nil {
+		return -1, -1, err
+	}
+	return int(ws.Xpixel), int(ws.Ypixel), nil
+}

From 34838131ea87cf66ff6a1c799215b8566b757db6 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 16:25:00 +0200
Subject: [PATCH 12/44] remove unused method UnshowSixels

---
 nav.go | 2 --
 ui.go  | 8 --------
 2 files changed, 10 deletions(-)

diff --git a/nav.go b/nav.go
index 6caf5e05..787db51f 100644
--- a/nav.go
+++ b/nav.go
@@ -619,8 +619,6 @@ func (nav *nav) previewLoop(ui *ui) {
 			if err := cmd.Run(); err != nil {
 				log.Printf("cleaning preview: %s", err)
 			}
-			ui.UnshowSixels()
-			ui.sixels = nil
 			nav.volatilePreview = false
 		}
 		if len(path) != 0 {
diff --git a/ui.go b/ui.go
index 7789e58d..f51633ad 100644
--- a/ui.go
+++ b/ui.go
@@ -1314,11 +1314,3 @@ func (ui *ui) ShowSixels() {
 		os.Stdin.WriteString(moveCursor + sixel.str)
 	}
 }
-
-// Placeholder
-func (ui *ui) UnshowSixels() {
-	for _, sixel := range ui.sixels {
-		x, y := sixel.x, sixel.y
-		ui.screen.SetContent(x, y, '\u2800', nil, tcell.StyleDefault)
-	}
-}

From d977957370f644a3048179e812415a1e32ac181e Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 16:38:40 +0200
Subject: [PATCH 13/44] fix: remove unneeded ShowSixels

---
 eval.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/eval.go b/eval.go
index 30bace9d..77de6891 100644
--- a/eval.go
+++ b/eval.go
@@ -1198,7 +1198,6 @@ func (e *callExpr) eval(app *app, args []string) {
 		}
 		app.ui.renew()
 		app.ui.screen.Sync()
-		app.ui.ShowSixels()
 		if app.nav.height != app.ui.wins[0].h {
 			app.nav.height = app.ui.wins[0].h
 			app.nav.regCache = make(map[string]*reg)

From 1d93785caa2142984da93a2d6b4b73bc930ee1f8 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 16:48:13 +0200
Subject: [PATCH 14/44] add new fields sixel.wPx,hPx and reg.sixels

---
 ui.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/ui.go b/ui.go
index f51633ad..b7b376e2 100644
--- a/ui.go
+++ b/ui.go
@@ -473,6 +473,8 @@ func (win *win) printDir(screen tcell.Screen, dir *dir, selections map[string]in
 type sixel struct {
 	x   int
 	y   int
+	wPx int
+	hPx int
 	str string
 }
 
@@ -646,6 +648,7 @@ type reg struct {
 	loadTime time.Time
 	path     string
 	lines    []string
+	sixels   []sixel
 }
 
 func (ui *ui) loadFile(nav *nav, volatile bool) {

From ad88770227e557c41d767c9cc790ec8d8ba557a5 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 16:37:01 +0200
Subject: [PATCH 15/44] modify sixel processing logic

detecting sixels in preview script now fills corresponding area with braille blank `\u2800` and saves sixel to reg.sixels
---
 nav.go | 47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/nav.go b/nav.go
index 787db51f..d3fab0b8 100644
--- a/nav.go
+++ b/nav.go
@@ -15,6 +15,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/gdamore/tcell/v2"
 	times "gopkg.in/djherbis/times.v1"
 )
 
@@ -623,7 +624,7 @@ func (nav *nav) previewLoop(ui *ui) {
 		}
 		if len(path) != 0 {
 			win := ui.wins[len(ui.wins)-1]
-			nav.preview(path, win)
+			nav.preview(path, ui.screen, win)
 			prev = path
 		}
 	}
@@ -644,7 +645,7 @@ func matchPattern(pattern, name, path string) bool {
 	return matched
 }
 
-func (nav *nav) preview(path string, win *win) {
+func (nav *nav) preview(path string, screen tcell.Screen, win *win) {
 	reg := &reg{loadTime: time.Now(), path: path}
 	defer func() { nav.regChan <- reg }()
 
@@ -698,9 +699,8 @@ func (nav *nav) preview(path string, win *win) {
 
 	buf := bufio.NewScanner(reader)
 
-	var sixel strings.Builder
-	sixelCont := false
-	for i := 0; (sixelCont || i < win.h) && buf.Scan(); i++ {
+	sixelFrom := -1
+	for i := 0; (sixelFrom != -1 || len(reg.lines) < win.h) && buf.Scan(); i++ {
 		for _, r := range buf.Text() {
 			if r == 0 {
 				reg.lines = []string{"\033[7mbinary\033[0m"}
@@ -708,25 +708,27 @@ func (nav *nav) preview(path string, win *win) {
 			}
 		}
 		if a := strings.Index(buf.Text(), "\x1bP"); a >= 0 {
-			if b := strings.Index(buf.Text()[a+2:], "\x1b\\"); b >= 0 {
-				reg.lines = append(reg.lines, buf.Text())
+			if b := strings.Index(buf.Text()[a:], "\x1b\\"); b >= 0 {
+				addSixel(screen, reg, buf.Text()[a:a+b+2], win.x, win.y+len(reg.lines))
+				reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
 				continue
 			}
-			sixel.WriteString(buf.Text())
-			sixelCont = true
+			reg.lines = append(reg.lines, buf.Text()[:a] /*TODO skip empty line*/, buf.Text()[a:])
+			sixelFrom = len(reg.lines) - 1
 			continue
 		}
-		if sixelCont {
+		if sixelFrom != -1 {
 			if b := strings.Index(buf.Text(), "\x1b\\"); b >= 0 {
-				sixel.WriteString(buf.Text()[:b+2])
-				reg.lines = append(reg.lines, sixel.String(), buf.Text()[b+2:])
+				reg.lines = append(reg.lines, buf.Text()[:b+2])
+				sx := strings.Join(reg.lines[sixelFrom:], "")
+				reg.lines = reg.lines[:sixelFrom]
+				addSixel(screen, reg, sx, win.x+2, win.y+len(reg.lines))
+
+				reg.lines = append(reg.lines, buf.Text()[b+2:])
 				log.Printf("found multiline: %s", reg.lines[len(reg.lines)-1])
-				sixel.Reset()
-				sixelCont = false
+				sixelFrom = -1
 				continue
 			}
-			sixel.WriteString(buf.Text())
-			continue
 		}
 		reg.lines = append(reg.lines, buf.Text())
 	}
@@ -736,6 +738,19 @@ func (nav *nav) preview(path string, win *win) {
 	}
 }
 
+func addSixel(screen tcell.Screen, reg *reg, sx string, x, y int) {
+	Wc, Hc := screen.Size()
+	Wpx, Hpx, _ := getTermPixels(int(os.Stdin.Fd())) //TODO do this elsewhere
+	w, h := sixelDimPx(sx)
+	wc, hc := pxToCells(w, h, Wc, Hc, Wpx, Hpx)
+
+	reg.sixels = append(reg.sixels, sixel{x, y, w, h, sx})
+	fill := strings.Repeat("\u2800", wc)
+	for j := 0; j < hc; j++ {
+		reg.lines = append(reg.lines, fill)
+	}
+}
+
 func (nav *nav) loadReg(path string, volatile bool) *reg {
 	r, ok := nav.regCache[path]
 	if !ok || (volatile && r.volatile) {

From 2cf0a365ac53e8bd2582d97a7c592fc3ec6afcf9 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 16:40:07 +0200
Subject: [PATCH 16/44] modify sixel processing logic

printReg doesn't process sixels directly anymore
---
 ui.go | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/ui.go b/ui.go
index b7b376e2..56b6ae81 100644
--- a/ui.go
+++ b/ui.go
@@ -270,17 +270,9 @@ func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 			break
 		}
 
-		if a := strings.Index(l, "\x1bP"); a >= 0 {
-			if b := strings.Index(l[a+2:], "\x1b"); b >= 0 && l[a+b+3] == '\\' {
-				sixel := sixel{str: l[a : a+b+4], x: win.x + a + 2, y: win.y + i}
-				*sixels = append(*sixels, sixel)
-
-				l = l[:a] + l[a+b+4:]
-			}
-		}
-
 		st = win.print(screen, 2, i, st, l)
 	}
+	*sixels = reg.sixels
 }
 
 var gThisYear = time.Now().Year()

From 9e9b80677bb1a5ce094055ae0846f05e4d2a232f Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 16:58:32 +0200
Subject: [PATCH 17/44] reset sixels buffer at the start of `draw`

---
 ui.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ui.go b/ui.go
index 56b6ae81..dc100fd2 100644
--- a/ui.go
+++ b/ui.go
@@ -846,6 +846,7 @@ func (ui *ui) draw(nav *nav) {
 			ui.screen.SetContent(i, j, ' ', nil, st)
 		}
 	}
+	ui.sixels = nil
 
 	ui.drawPromptLine(nav)
 

From 5487a6322fa7685480937ab3438f08d733c6602a Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 26 May 2022 17:02:19 +0200
Subject: [PATCH 18/44] rename `ui.ShowSixels` to `showSixels`

---
 ui.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ui.go b/ui.go
index dc100fd2..960922f8 100644
--- a/ui.go
+++ b/ui.go
@@ -926,7 +926,7 @@ func (ui *ui) draw(nav *nav) {
 	}
 
 	ui.screen.Show()
-	ui.ShowSixels()
+	ui.showSixels()
 }
 
 func findBinds(keys map[string]expr, prefix string) (binds map[string]expr, ok bool) {
@@ -1304,7 +1304,7 @@ func listMatchesMenu(ui *ui, matches []string) error {
 	return nil
 }
 
-func (ui *ui) ShowSixels() {
+func (ui *ui) showSixels() {
 	for _, sixel := range ui.sixels {
 		moveCursor := fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1)
 		os.Stdin.WriteString(moveCursor + sixel.str)

From 3ba360bc7837db323340374604b5ad9503a1f7f0 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Sat, 28 May 2022 16:02:03 +0200
Subject: [PATCH 19/44] add constants `gSixelBegin` and `gSixelTerminate`

---
 nav.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/nav.go b/nav.go
index d3fab0b8..0b41fae8 100644
--- a/nav.go
+++ b/nav.go
@@ -19,6 +19,11 @@ import (
 	times "gopkg.in/djherbis/times.v1"
 )
 
+const (
+	gSixelBegin     = "\033P"
+	gSixelTerminate = "\033\\"
+)
+
 type linkState byte
 
 const (

From fe8c1d5ed18b87947582bdb8c6c64bea50e83d0c Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 2 Jun 2022 13:37:21 +0200
Subject: [PATCH 20/44] add check to prevent arbitrary escape code being passed
 to stdin

---
 nav.go | 47 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/nav.go b/nav.go
index 0b41fae8..3a007ba9 100644
--- a/nav.go
+++ b/nav.go
@@ -712,32 +712,45 @@ func (nav *nav) preview(path string, screen tcell.Screen, win *win) {
 				return
 			}
 		}
-		if a := strings.Index(buf.Text(), "\x1bP"); a >= 0 {
-			if b := strings.Index(buf.Text()[a:], "\x1b\\"); b >= 0 {
-				addSixel(screen, reg, buf.Text()[a:a+b+2], win.x, win.y+len(reg.lines))
-				reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
+		if a := strings.Index(buf.Text(), gSixelBegin); a >= 0 {
+			if b := strings.IndexByte(buf.Text()[a+2:], gEscapeCode); b >= 0 {
+				if buf.Text()[a+b+1] == '\\' {
+					addSixel(screen, reg, buf.Text()[a:a+b+2], win.x, win.y+len(reg.lines))
+					reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
+					continue
+				} else {
+					reg.lines = append(reg.lines, buf.Text())
+					continue
+				}
+			} else {
+				reg.lines = append(reg.lines, buf.Text()[:a] /*TODO skip empty line*/, buf.Text()[a:])
+				sixelFrom = len(reg.lines) - 1
 				continue
 			}
-			reg.lines = append(reg.lines, buf.Text()[:a] /*TODO skip empty line*/, buf.Text()[a:])
-			sixelFrom = len(reg.lines) - 1
-			continue
 		}
 		if sixelFrom != -1 {
-			if b := strings.Index(buf.Text(), "\x1b\\"); b >= 0 {
-				reg.lines = append(reg.lines, buf.Text()[:b+2])
-				sx := strings.Join(reg.lines[sixelFrom:], "")
-				reg.lines = reg.lines[:sixelFrom]
-				addSixel(screen, reg, sx, win.x+2, win.y+len(reg.lines))
-
-				reg.lines = append(reg.lines, buf.Text()[b+2:])
-				log.Printf("found multiline: %s", reg.lines[len(reg.lines)-1])
-				sixelFrom = -1
-				continue
+			if b := strings.IndexByte(buf.Text(), gEscapeCode); b >= 0 {
+				if buf.Text()[b+1] == '\\' {
+					reg.lines = append(reg.lines, buf.Text()[:b+2])
+					sx := strings.Join(reg.lines[sixelFrom:], "")
+					reg.lines = reg.lines[:sixelFrom]
+					addSixel(screen, reg, sx, win.x+2, win.y+len(reg.lines))
+
+					reg.lines = append(reg.lines, buf.Text()[b+2:])
+					sixelFrom = -1
+					continue
+				} else {
+					sixelFrom = -1
+				}
 			}
 		}
 		reg.lines = append(reg.lines, buf.Text())
 	}
 
+	if len(reg.lines) > win.h {
+		reg.lines = reg.lines[:win.h]
+	}
+
 	if buf.Err() != nil {
 		log.Printf("loading file: %s", buf.Err())
 	}

From c87c639a766a91ca66b61281390e13de42996873 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Thu, 2 Jun 2022 13:40:33 +0200
Subject: [PATCH 21/44] fix cursor out of place in command line mode

---
 ui.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/ui.go b/ui.go
index 960922f8..e64515d0 100644
--- a/ui.go
+++ b/ui.go
@@ -926,7 +926,10 @@ func (ui *ui) draw(nav *nav) {
 	}
 
 	ui.screen.Show()
-	ui.showSixels()
+	if len(ui.sixels) > 0 {
+		ui.showSixels()
+	}
+
 }
 
 func findBinds(keys map[string]expr, prefix string) (binds map[string]expr, ok bool) {
@@ -1305,8 +1308,10 @@ func listMatchesMenu(ui *ui, matches []string) error {
 }
 
 func (ui *ui) showSixels() {
+	os.Stdin.WriteString("\0337")
 	for _, sixel := range ui.sixels {
 		moveCursor := fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1)
 		os.Stdin.WriteString(moveCursor + sixel.str)
 	}
+	os.Stdin.WriteString("\0338")
 }

From 16f8e5bf7f9f0d0dc3262fb41cb774971adf206d Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 14 Jun 2022 17:24:43 +0200
Subject: [PATCH 22/44] fix bug where sixel in drawn at old location after
 horizontal resize

---
 nav.go | 4 ++--
 ui.go  | 8 +++++++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/nav.go b/nav.go
index 3a007ba9..8a976331 100644
--- a/nav.go
+++ b/nav.go
@@ -715,7 +715,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, win *win) {
 		if a := strings.Index(buf.Text(), gSixelBegin); a >= 0 {
 			if b := strings.IndexByte(buf.Text()[a+2:], gEscapeCode); b >= 0 {
 				if buf.Text()[a+b+1] == '\\' {
-					addSixel(screen, reg, buf.Text()[a:a+b+2], win.x, win.y+len(reg.lines))
+					addSixel(screen, wPx, hPx, reg, buf.Text()[a:a+b+2], 2, win.y+len(reg.lines))
 					reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
 					continue
 				} else {
@@ -734,7 +734,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, win *win) {
 					reg.lines = append(reg.lines, buf.Text()[:b+2])
 					sx := strings.Join(reg.lines[sixelFrom:], "")
 					reg.lines = reg.lines[:sixelFrom]
-					addSixel(screen, reg, sx, win.x+2, win.y+len(reg.lines))
+					addSixel(screen, wPx, hPx, reg, sx, 2, len(reg.lines))
 
 					reg.lines = append(reg.lines, buf.Text()[b+2:])
 					sixelFrom = -1
diff --git a/ui.go b/ui.go
index e64515d0..9d400c07 100644
--- a/ui.go
+++ b/ui.go
@@ -272,7 +272,13 @@ func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 
 		st = win.print(screen, 2, i, st, l)
 	}
-	*sixels = reg.sixels
+
+   for _, sx := range reg.sixels {
+      s := sx
+      s.x += win.x
+      s.y += win.y
+      *sixels = append(*sixels, s)
+   }
 }
 
 var gThisYear = time.Now().Year()

From 18efee8a19081d0c350cd02c172027bc4fb08771 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 14 Jun 2022 17:28:37 +0200
Subject: [PATCH 23/44] add ui.wPx and ui.hPx

---
 eval.go | 6 ++++++
 nav.go  | 9 ++++-----
 os.go   | 3 ++-
 ui.go   | 9 +++++++++
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/eval.go b/eval.go
index 77de6891..aae02cca 100644
--- a/eval.go
+++ b/eval.go
@@ -1196,6 +1196,12 @@ func (e *callExpr) eval(app *app, args []string) {
 		if !app.nav.init {
 			return
 		}
+   var err error
+	app.ui.wPx, app.ui.hPx, err = getTermPixels()
+	if err != nil {
+		app.ui.wPx, app.ui.hPx = -1, -1
+		log.Printf("getting terminal pixel size: %s", err)
+	}
 		app.ui.renew()
 		app.ui.screen.Sync()
 		if app.nav.height != app.ui.wins[0].h {
diff --git a/nav.go b/nav.go
index 8a976331..8a94de66 100644
--- a/nav.go
+++ b/nav.go
@@ -629,7 +629,7 @@ func (nav *nav) previewLoop(ui *ui) {
 		}
 		if len(path) != 0 {
 			win := ui.wins[len(ui.wins)-1]
-			nav.preview(path, ui.screen, win)
+			nav.preview(path, ui.screen, ui.wPx, ui.hPx, win)
 			prev = path
 		}
 	}
@@ -650,7 +650,7 @@ func matchPattern(pattern, name, path string) bool {
 	return matched
 }
 
-func (nav *nav) preview(path string, screen tcell.Screen, win *win) {
+func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win) {
 	reg := &reg{loadTime: time.Now(), path: path}
 	defer func() { nav.regChan <- reg }()
 
@@ -756,11 +756,10 @@ func (nav *nav) preview(path string, screen tcell.Screen, win *win) {
 	}
 }
 
-func addSixel(screen tcell.Screen, reg *reg, sx string, x, y int) {
+func addSixel(screen tcell.Screen, wPx, hPx int, reg *reg, sx string, x, y int) {
 	Wc, Hc := screen.Size()
-	Wpx, Hpx, _ := getTermPixels(int(os.Stdin.Fd())) //TODO do this elsewhere
 	w, h := sixelDimPx(sx)
-	wc, hc := pxToCells(w, h, Wc, Hc, Wpx, Hpx)
+	wc, hc := pxToCells(w, h, Wc, Hc, wPx, hPx)
 
 	reg.sixels = append(reg.sixels, sixel{x, y, w, h, sx})
 	fill := strings.Repeat("\u2800", wc)
diff --git a/os.go b/os.go
index cc02c3f0..0dba33f7 100644
--- a/os.go
+++ b/os.go
@@ -221,7 +221,8 @@ func exportFiles(f string, fs []string, pwd string) {
 	}
 }
 
-func getTermPixels(fd int) (w, h int, err error) {
+func getTermPixels() (w, h int, err error) {
+	fd := int(os.Stdin.Fd())
 	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
 	if err != nil {
 		return -1, -1, err
diff --git a/ui.go b/ui.go
index 9d400c07..1d040a91 100644
--- a/ui.go
+++ b/ui.go
@@ -479,6 +479,7 @@ type sixel struct {
 type ui struct {
 	screen       tcell.Screen
 	sixels       []sixel
+	wPx, hPx     int
 	polling      bool
 	wins         []*win
 	promptWin    *win
@@ -549,6 +550,7 @@ func getWins(screen tcell.Screen) []*win {
 }
 
 func newUI(screen tcell.Screen) *ui {
+	var err error
 	wtot, htot := screen.Size()
 
 	ui := &ui{
@@ -567,6 +569,13 @@ func newUI(screen tcell.Screen) *ui {
 		menuSelected: -2,
 	}
 
+	ui.wPx, ui.hPx, err = getTermPixels()
+   // TODO getting pixel size does not gurantee sixel support
+	if err != nil {
+		ui.wPx, ui.hPx = -1, -1
+		log.Printf("getting terminal pixel size: %s", err)
+	}
+
 	go ui.pollEvents()
 
 	return ui

From c37274d19ae0b21d537f94b7491f877eb16e464a Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 14 Jun 2022 22:40:34 +0200
Subject: [PATCH 24/44] buffer sixel sequences before printing

---
 ui.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/ui.go b/ui.go
index 1d040a91..97ab1b17 100644
--- a/ui.go
+++ b/ui.go
@@ -1323,10 +1323,12 @@ func listMatchesMenu(ui *ui, matches []string) error {
 }
 
 func (ui *ui) showSixels() {
-	os.Stdin.WriteString("\0337")
+   var buf strings.Builder
+	buf.WriteString("\0337")
 	for _, sixel := range ui.sixels {
-		moveCursor := fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1)
-		os.Stdin.WriteString(moveCursor + sixel.str)
+		buf.WriteString(fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1))
+      buf.WriteString(sixel.str)
 	}
-	os.Stdin.WriteString("\0338")
+	buf.WriteString("\0338")
+   fmt.Print(buf.String())
 }

From 150dd79103ab140660c2f61d56bc54b32daa8267 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 17 Jun 2022 13:21:34 +0200
Subject: [PATCH 25/44] add check for valid terminal size(px) before previewing
 sixel

---
 nav.go | 52 +++++++++++++++++++++++++++-------------------------
 1 file changed, 27 insertions(+), 25 deletions(-)

diff --git a/nav.go b/nav.go
index 8a94de66..257e7087 100644
--- a/nav.go
+++ b/nav.go
@@ -712,35 +712,37 @@ func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win
 				return
 			}
 		}
-		if a := strings.Index(buf.Text(), gSixelBegin); a >= 0 {
-			if b := strings.IndexByte(buf.Text()[a+2:], gEscapeCode); b >= 0 {
-				if buf.Text()[a+b+1] == '\\' {
-					addSixel(screen, wPx, hPx, reg, buf.Text()[a:a+b+2], 2, win.y+len(reg.lines))
-					reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
-					continue
+		if wPx > 0 && hPx > 0 {
+			if a := strings.Index(buf.Text(), gSixelBegin); a >= 0 {
+				if b := strings.IndexByte(buf.Text()[a+2:], gEscapeCode); b >= 0 {
+					if buf.Text()[a+b+1] == '\\' {
+						addSixel(screen, wPx, hPx, reg, buf.Text()[a:a+b+2], 2, win.y+len(reg.lines))
+						reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
+						continue
+					} else {
+						reg.lines = append(reg.lines, buf.Text())
+						continue
+					}
 				} else {
-					reg.lines = append(reg.lines, buf.Text())
+					reg.lines = append(reg.lines, buf.Text()[:a] /*TODO skip empty line*/, buf.Text()[a:])
+					sixelFrom = len(reg.lines) - 1
 					continue
 				}
-			} else {
-				reg.lines = append(reg.lines, buf.Text()[:a] /*TODO skip empty line*/, buf.Text()[a:])
-				sixelFrom = len(reg.lines) - 1
-				continue
 			}
-		}
-		if sixelFrom != -1 {
-			if b := strings.IndexByte(buf.Text(), gEscapeCode); b >= 0 {
-				if buf.Text()[b+1] == '\\' {
-					reg.lines = append(reg.lines, buf.Text()[:b+2])
-					sx := strings.Join(reg.lines[sixelFrom:], "")
-					reg.lines = reg.lines[:sixelFrom]
-					addSixel(screen, wPx, hPx, reg, sx, 2, len(reg.lines))
-
-					reg.lines = append(reg.lines, buf.Text()[b+2:])
-					sixelFrom = -1
-					continue
-				} else {
-					sixelFrom = -1
+			if sixelFrom != -1 {
+				if b := strings.IndexByte(buf.Text(), gEscapeCode); b >= 0 {
+					if buf.Text()[b+1] == '\\' {
+						reg.lines = append(reg.lines, buf.Text()[:b+2])
+						sx := strings.Join(reg.lines[sixelFrom:], "")
+						reg.lines = reg.lines[:sixelFrom]
+						addSixel(screen, wPx, hPx, reg, sx, 2, len(reg.lines))
+
+						reg.lines = append(reg.lines, buf.Text()[b+2:])
+						sixelFrom = -1
+						continue
+					} else {
+						sixelFrom = -1
+					}
 				}
 			}
 		}

From a6bfeaeefae98463917199cd39e8b29f03ca2691 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 17 Jun 2022 13:59:20 +0200
Subject: [PATCH 26/44] clean up

---
 eval.go | 12 ++++++------
 ui.go   | 27 ++++++++++++---------------
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/eval.go b/eval.go
index aae02cca..b4f21d83 100644
--- a/eval.go
+++ b/eval.go
@@ -1196,12 +1196,12 @@ func (e *callExpr) eval(app *app, args []string) {
 		if !app.nav.init {
 			return
 		}
-   var err error
-	app.ui.wPx, app.ui.hPx, err = getTermPixels()
-	if err != nil {
-		app.ui.wPx, app.ui.hPx = -1, -1
-		log.Printf("getting terminal pixel size: %s", err)
-	}
+		var err error
+		app.ui.wPx, app.ui.hPx, err = getTermPixels()
+		if err != nil {
+			app.ui.wPx, app.ui.hPx = -1, -1
+			log.Printf("getting terminal pixel size: %s", err)
+		}
 		app.ui.renew()
 		app.ui.screen.Sync()
 		if app.nav.height != app.ui.wins[0].h {
diff --git a/ui.go b/ui.go
index 97ab1b17..c1bfa134 100644
--- a/ui.go
+++ b/ui.go
@@ -273,12 +273,12 @@ func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 		st = win.print(screen, 2, i, st, l)
 	}
 
-   for _, sx := range reg.sixels {
-      s := sx
-      s.x += win.x
-      s.y += win.y
-      *sixels = append(*sixels, s)
-   }
+	for _, sx := range reg.sixels {
+		s := sx
+		s.x += win.x
+		s.y += win.y
+		*sixels = append(*sixels, s)
+	}
 }
 
 var gThisYear = time.Now().Year()
@@ -469,11 +469,8 @@ func (win *win) printDir(screen tcell.Screen, dir *dir, selections map[string]in
 }
 
 type sixel struct {
-	x   int
-	y   int
-	wPx int
-	hPx int
-	str string
+	x, y, wPx, hPx int
+	str            string
 }
 
 type ui struct {
@@ -570,7 +567,7 @@ func newUI(screen tcell.Screen) *ui {
 	}
 
 	ui.wPx, ui.hPx, err = getTermPixels()
-   // TODO getting pixel size does not gurantee sixel support
+	// TODO getting pixel size does not gurantee sixel support
 	if err != nil {
 		ui.wPx, ui.hPx = -1, -1
 		log.Printf("getting terminal pixel size: %s", err)
@@ -1323,12 +1320,12 @@ func listMatchesMenu(ui *ui, matches []string) error {
 }
 
 func (ui *ui) showSixels() {
-   var buf strings.Builder
+	var buf strings.Builder
 	buf.WriteString("\0337")
 	for _, sixel := range ui.sixels {
 		buf.WriteString(fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1))
-      buf.WriteString(sixel.str)
+		buf.WriteString(sixel.str)
 	}
 	buf.WriteString("\0338")
-   fmt.Print(buf.String())
+	fmt.Print(buf.String())
 }

From 3cccb8368d5233b111bef87a0a5bc9e39312b419 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 1 Jul 2022 14:02:57 +0200
Subject: [PATCH 27/44] placeholder function getTermPixels for windows

---
 os_windows.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/os_windows.go b/os_windows.go
index 1852c869..380acc43 100644
--- a/os_windows.go
+++ b/os_windows.go
@@ -181,3 +181,7 @@ func exportFiles(f string, fs []string, pwd string) {
 		os.Setenv("fx", envFiles)
 	}
 }
+
+func getTermPixels() (w, h int, err error) {
+	return -1, -1, nil
+}

From f8bfef0a05f48bfaca47f78b9af0451f13e7471f Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Sun, 3 Jul 2022 01:39:50 +0200
Subject: [PATCH 28/44] function sixelDimPx now considers image size given in
 the optional raster attributes field

---
 misc.go | 53 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 47 insertions(+), 6 deletions(-)

diff --git a/misc.go b/misc.go
index d0e84023..eff62919 100644
--- a/misc.go
+++ b/misc.go
@@ -303,15 +303,55 @@ var reNumber = regexp.MustCompile(`^[0-9]+`)
 
 // needs some testing
 func sixelDimPx(s string) (w int, h int) {
-	// TODO maybe take into account pixel aspect ratio (")
+	// TODO maybe take into account pixel aspect ratio
 	// TODO handle macro parameters P1 to P3
 	// `DCS P1;P2;P3;q...`
-	a := strings.Index(s, "q") + 1
-	if a == 0 {
-		//syntax error
+
+	// General sixel sequence:
+	//    DCS <P1>;<P2>;<P3>;	q  [" <raster_attributes>];   <main_body> ST
+	// DCS is "ESC P"
+	// We are not interested in P1~P3
+	// the optional raster attributes may contain the image size in pixels
+	// ST is the terminating string "ESC \"
+	i := strings.Index(s, "q") + 1
+	if i == 0 {
+		// syntax error
+		return -1, -1
+	}
+
+	// Start of (optional) Raster Attributes
+	//    "	Pan	;	Pad;	Ph;	Pv
+	// pixel aspect ratio = Pan/Pad
+	// We are only interested in Ph and Pv (horizontal and vertical size in px)
+	if s[i] == '"' {
+		i++
+		b := strings.Index(s[i:], ";")
+		// pan := strconv.Atoi(s[a:b])
+		i += b + 1
+		b = strings.Index(s[i:], ";")
+		// pad := strconv.Atoi(s[a:b])
+
+		i += b + 1
+		b = strings.Index(s[i:], ";")
+		ph, err1 := strconv.Atoi(s[i : i+b])
+
+		i += b + 1
+		b = strings.Index(s[i:], ";")
+		pv, err2 := strconv.Atoi(s[i : i+b])
+
+		if err1 != nil || err2 != nil {
+			goto main_body // keep trying
+		}
+
+		// TODO
+		// ph and pv are more like suggestions, it's still possible to go over the
+		// reported size, so we might need to parse the entire main body anyway
+		return ph, pv
 	}
+
+main_body:
 	var wi int
-	for i := a; i < len(s)-2; i++ {
+	for ; i < len(s)-2; i++ {
 		c := s[i]
 		switch {
 		case '?' <= c && c <= '~':
@@ -327,9 +367,11 @@ func sixelDimPx(s string) (w int, h int) {
 			m := reNumber.FindString(s[i+1:])
 			if m == "" {
 				// syntax error
+				return -1, -1
 			}
 			if s[i+1+len(m)] < '?' || s[i+1+len(m)] > '~' {
 				// syntax error
+				return -1, -1
 			}
 			n, _ := strconv.Atoi(m)
 			wi += n - 1
@@ -338,7 +380,6 @@ func sixelDimPx(s string) (w int, h int) {
 	}
 	if s[len(s)-3] != '-' {
 		w = max(w, wi)
-		wi = 0
 		h++ // add newline on last row
 	}
 	return w, h * 6

From 2eddca918f92b26b28b910d329541ad70a58194e Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 5 Jul 2022 01:36:17 +0200
Subject: [PATCH 29/44] change sixel image alignment to emulate behavior of a
 terminal - images used to always draw on a new line - images is now placed
 where it starts: ``` printf 'abc <sixel sequence> xyz' ``` would result in:
 ``` abc +------+     | img  |     | here |     +------+ xyz ```

old behavior:
```
abc
+------+
| img  |
| here |
+------+
xyz
```
---
 nav.go | 105 +++++++++++++++++++++++++++++++++------------------------
 1 file changed, 61 insertions(+), 44 deletions(-)

diff --git a/nav.go b/nav.go
index 257e7087..28655732 100644
--- a/nav.go
+++ b/nav.go
@@ -704,8 +704,11 @@ func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win
 
 	buf := bufio.NewScanner(reader)
 
-	sixelFrom := -1
-	for i := 0; (sixelFrom != -1 || len(reg.lines) < win.h) && buf.Scan(); i++ {
+	var sixelBuffer []string
+	processingSixel := false
+	for i := 0; (processingSixel || len(reg.lines) < win.h) && buf.Scan(); i++ {
+		text := buf.Text()
+
 		for _, r := range buf.Text() {
 			if r == 0 {
 				reg.lines = []string{"\033[7mbinary\033[0m"}
@@ -713,44 +716,70 @@ func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win
 			}
 		}
 		if wPx > 0 && hPx > 0 {
-			if a := strings.Index(buf.Text(), gSixelBegin); a >= 0 {
-				if b := strings.IndexByte(buf.Text()[a+2:], gEscapeCode); b >= 0 {
-					if buf.Text()[a+b+1] == '\\' {
-						addSixel(screen, wPx, hPx, reg, buf.Text()[a:a+b+2], 2, win.y+len(reg.lines))
-						reg.lines = append(reg.lines, buf.Text()[:a], buf.Text()[a+b+2:])
-						continue
-					} else {
-						reg.lines = append(reg.lines, buf.Text())
-						continue
-					}
-				} else {
-					reg.lines = append(reg.lines, buf.Text()[:a] /*TODO skip empty line*/, buf.Text()[a:])
-					sixelFrom = len(reg.lines) - 1
-					continue
-				}
+			if a := strings.Index(text, gSixelBegin); a >= 0 {
+				reg.lines = append(reg.lines, text[:a])
+				text = text[a:]
+				processingSixel = true
 			}
-			if sixelFrom != -1 {
-				if b := strings.IndexByte(buf.Text(), gEscapeCode); b >= 0 {
-					if buf.Text()[b+1] == '\\' {
-						reg.lines = append(reg.lines, buf.Text()[:b+2])
-						sx := strings.Join(reg.lines[sixelFrom:], "")
-						reg.lines = reg.lines[:sixelFrom]
-						addSixel(screen, wPx, hPx, reg, sx, 2, len(reg.lines))
-
-						reg.lines = append(reg.lines, buf.Text()[b+2:])
-						sixelFrom = -1
+
+			if processingSixel {
+				var lookFrom int
+				if text[:2] == gSixelBegin {
+					lookFrom = 2
+				}
+				if b := strings.IndexByte(text[lookFrom:], gEscapeCode); b >= 0 {
+					b += lookFrom
+					if len(text) > b && text[b+1] == '\\' {
+						sixelBuffer = append(sixelBuffer, text[:b+2])
+						sx := strings.Join(sixelBuffer, "")
+
+						xoff := runeSliceWidth([]rune(reg.lines[len(reg.lines)-1])) + 2
+						yoff := len(reg.lines) - 1
+						Wc, Hc := screen.Size()
+						w, h := sixelDimPx(sx)
+						if w < 0 || h < 0 {
+							goto discard_sixel
+						}
+						wc, hc := pxToCells(w, h, Wc, Hc, wPx, hPx)
+
+						reg.sixels = append(reg.sixels, sixel{xoff, yoff, w, h, sx})
+						fill := strings.Repeat("\u2800", wc)
+						paddedfill := strings.Repeat(" ", xoff) + fill
+						reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + fill
+						for j := 1; j < hc; j++ {
+							reg.lines = append(reg.lines, paddedfill)
+						}
+
+						reg.lines = append(reg.lines, text[b+2:])
+						processingSixel = false
 						continue
-					} else {
-						sixelFrom = -1
+					} else { // deal with unexpected control sequence
+						goto discard_sixel
 					}
 				}
+				sixelBuffer = append(sixelBuffer, text)
+				continue
+
+			discard_sixel:
+				emptyLines := win.h - len(reg.lines)
+				reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + sixelBuffer[0]
+				if emptyLines > 0 {
+					reg.lines = append(reg.lines, sixelBuffer[1:emptyLines+1]...)
+				}
+				reg.lines = append(reg.lines, text)
+				processingSixel = false
+				continue
 			}
 		}
-		reg.lines = append(reg.lines, buf.Text())
+		reg.lines = append(reg.lines, text)
 	}
 
-	if len(reg.lines) > win.h {
-		reg.lines = reg.lines[:win.h]
+	if processingSixel && len(sixelBuffer) > 0 {
+		emptyLines := win.h - len(reg.lines)
+		reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + sixelBuffer[0]
+		if emptyLines > 0 {
+			reg.lines = append(reg.lines, sixelBuffer[1:emptyLines+1]...)
+		}
 	}
 
 	if buf.Err() != nil {
@@ -758,18 +787,6 @@ func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win
 	}
 }
 
-func addSixel(screen tcell.Screen, wPx, hPx int, reg *reg, sx string, x, y int) {
-	Wc, Hc := screen.Size()
-	w, h := sixelDimPx(sx)
-	wc, hc := pxToCells(w, h, Wc, Hc, wPx, hPx)
-
-	reg.sixels = append(reg.sixels, sixel{x, y, w, h, sx})
-	fill := strings.Repeat("\u2800", wc)
-	for j := 0; j < hc; j++ {
-		reg.lines = append(reg.lines, fill)
-	}
-}
-
 func (nav *nav) loadReg(path string, volatile bool) *reg {
 	r, ok := nav.regCache[path]
 	if !ok || (volatile && r.volatile) {

From 43fb37f2d74cca76c30593b92a1e7b2958403684 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 6 Jul 2022 14:32:47 +0200
Subject: [PATCH 30/44] fix bug where raster attributes are wrongly parsed in
 sixelDimPx

---
 misc.go | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/misc.go b/misc.go
index eff62919..87af887e 100644
--- a/misc.go
+++ b/misc.go
@@ -304,8 +304,6 @@ var reNumber = regexp.MustCompile(`^[0-9]+`)
 // needs some testing
 func sixelDimPx(s string) (w int, h int) {
 	// TODO maybe take into account pixel aspect ratio
-	// TODO handle macro parameters P1 to P3
-	// `DCS P1;P2;P3;q...`
 
 	// General sixel sequence:
 	//    DCS <P1>;<P2>;<P3>;	q  [" <raster_attributes>];   <main_body> ST
@@ -336,8 +334,9 @@ func sixelDimPx(s string) (w int, h int) {
 		ph, err1 := strconv.Atoi(s[i : i+b])
 
 		i += b + 1
-		b = strings.Index(s[i:], ";")
-		pv, err2 := strconv.Atoi(s[i : i+b])
+		n := reNumber.FindString(s[i:]) // use stirngs.Index(s[i:], "#") instead?
+		pv, err2 := strconv.Atoi(n)
+		i += len(n)
 
 		if err1 != nil || err2 != nil {
 			goto main_body // keep trying

From 3a6f80742adbce7e1956627ce355130ed363872b Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 6 Jul 2022 14:41:11 +0200
Subject: [PATCH 31/44] prevent drawing sixels while menu is active

---
 ui.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ui.go b/ui.go
index c1bfa134..71f830ca 100644
--- a/ui.go
+++ b/ui.go
@@ -938,7 +938,7 @@ func (ui *ui) draw(nav *nav) {
 	}
 
 	ui.screen.Show()
-	if len(ui.sixels) > 0 {
+	if ui.menuBuf == nil && len(ui.sixels) > 0 {
 		ui.showSixels()
 	}
 

From 6cce131fa0caf32620becf26cfc00de88aed6545 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Fri, 8 Jul 2022 14:25:51 +0200
Subject: [PATCH 32/44] introduce sixelScreen struct and refactor screen
 width,height in px to use new struct

---
 eval.go |  4 ++--
 nav.go  | 12 ++++++++----
 ui.go   | 30 ++++++++++++++++++++----------
 3 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/eval.go b/eval.go
index b4f21d83..876b1b7d 100644
--- a/eval.go
+++ b/eval.go
@@ -1197,9 +1197,9 @@ func (e *callExpr) eval(app *app, args []string) {
 			return
 		}
 		var err error
-		app.ui.wPx, app.ui.hPx, err = getTermPixels()
+		app.ui.sxScreen.wpx, app.ui.sxScreen.hpx, err = getTermPixels()
 		if err != nil {
-			app.ui.wPx, app.ui.hPx = -1, -1
+			app.ui.sxScreen.wpx, app.ui.sxScreen.hpx = -1, -1
 			log.Printf("getting terminal pixel size: %s", err)
 		}
 		app.ui.renew()
diff --git a/nav.go b/nav.go
index 28655732..0ea4eb84 100644
--- a/nav.go
+++ b/nav.go
@@ -24,6 +24,10 @@ const (
 	gSixelTerminate = "\033\\"
 )
 
+var (
+	gSixelFiller = '.'
+)
+
 type linkState byte
 
 const (
@@ -629,7 +633,7 @@ func (nav *nav) previewLoop(ui *ui) {
 		}
 		if len(path) != 0 {
 			win := ui.wins[len(ui.wins)-1]
-			nav.preview(path, ui.screen, ui.wPx, ui.hPx, win)
+			nav.preview(path, ui.screen, ui.sxScreen, win)
 			prev = path
 		}
 	}
@@ -650,7 +654,7 @@ func matchPattern(pattern, name, path string) bool {
 	return matched
 }
 
-func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win) {
+func (nav *nav) preview(path string, screen tcell.Screen, sxScreen sixelScreen, win *win) {
 	reg := &reg{loadTime: time.Now(), path: path}
 	defer func() { nav.regChan <- reg }()
 
@@ -715,7 +719,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win
 				return
 			}
 		}
-		if wPx > 0 && hPx > 0 {
+		if sxScreen.wpx > 0 && sxScreen.hpx > 0 {
 			if a := strings.Index(text, gSixelBegin); a >= 0 {
 				reg.lines = append(reg.lines, text[:a])
 				text = text[a:]
@@ -740,7 +744,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, wPx, hPx int, win *win
 						if w < 0 || h < 0 {
 							goto discard_sixel
 						}
-						wc, hc := pxToCells(w, h, Wc, Hc, wPx, hPx)
+						wc, hc := pxToCells(w, h, Wc, Hc, sxScreen.wpx, sxScreen.hpx)
 
 						reg.sixels = append(reg.sixels, sixel{xoff, yoff, w, h, sx})
 						fill := strings.Repeat("\u2800", wc)
diff --git a/ui.go b/ui.go
index 71f830ca..ece8643a 100644
--- a/ui.go
+++ b/ui.go
@@ -252,7 +252,7 @@ func (win *win) printRight(screen tcell.Screen, y int, st tcell.Style, s string)
 	win.print(screen, win.w-printLength(s), y, st, s)
 }
 
-func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
+func (win *win) printReg(screen tcell.Screen, sxs *sixelScreen, reg *reg) {
 	if reg == nil {
 		return
 	}
@@ -277,7 +277,7 @@ func (win *win) printReg(screen tcell.Screen, sixels *[]sixel, reg *reg) {
 		s := sx
 		s.x += win.x
 		s.y += win.y
-		*sixels = append(*sixels, s)
+		sxs.sx = append(sxs.sx, s)
 	}
 }
 
@@ -473,10 +473,16 @@ type sixel struct {
 	str            string
 }
 
+type sixelScreen struct {
+	wpx, hpx int
+	sx       []sixel
+	lastFile string
+	altFill  bool
+}
+
 type ui struct {
 	screen       tcell.Screen
-	sixels       []sixel
-	wPx, hPx     int
+	sxScreen     sixelScreen
 	polling      bool
 	wins         []*win
 	promptWin    *win
@@ -566,10 +572,10 @@ func newUI(screen tcell.Screen) *ui {
 		menuSelected: -2,
 	}
 
-	ui.wPx, ui.hPx, err = getTermPixels()
+	ui.sxScreen.wpx, ui.sxScreen.hpx, err = getTermPixels()
 	// TODO getting pixel size does not gurantee sixel support
 	if err != nil {
-		ui.wPx, ui.hPx = -1, -1
+		ui.sxScreen.wpx, ui.sxScreen.hpx = -1, -1
 		log.Printf("getting terminal pixel size: %s", err)
 	}
 
@@ -858,7 +864,7 @@ func (ui *ui) draw(nav *nav) {
 			ui.screen.SetContent(i, j, ' ', nil, st)
 		}
 	}
-	ui.sixels = nil
+	ui.sxScreen.clear()
 
 	ui.drawPromptLine(nav)
 
@@ -908,7 +914,7 @@ func (ui *ui) draw(nav *nav) {
 			if curr.IsDir() {
 				preview.printDir(ui.screen, ui.dirPrev, nav.selections, nav.saves, nav.tags, ui.styles, ui.icons)
 			} else if curr.Mode().IsRegular() {
-				preview.printReg(ui.screen, &ui.sixels, ui.regPrev)
+				preview.printReg(ui.screen, &ui.sxScreen, ui.regPrev)
 			}
 		}
 	}
@@ -938,7 +944,7 @@ func (ui *ui) draw(nav *nav) {
 	}
 
 	ui.screen.Show()
-	if ui.menuBuf == nil && len(ui.sixels) > 0 {
+	if ui.menuBuf == nil && len(ui.sxScreen.sx) > 0 {
 		ui.showSixels()
 	}
 
@@ -1319,10 +1325,14 @@ func listMatchesMenu(ui *ui, matches []string) error {
 	return nil
 }
 
+func (sxs *sixelScreen) clear() {
+	sxs.sx = nil
+}
+
 func (ui *ui) showSixels() {
 	var buf strings.Builder
 	buf.WriteString("\0337")
-	for _, sixel := range ui.sixels {
+	for _, sixel := range ui.sxScreen.sx {
 		buf.WriteString(fmt.Sprintf("\033[%d;%dH", sixel.y+1, sixel.x+1))
 		buf.WriteString(sixel.str)
 	}

From 5929846f22e3b4f521a79c9f011ac462ec11ec7e Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 12 Jul 2022 14:19:56 +0200
Subject: [PATCH 33/44] fix prevent nested sixel sequences

---
 nav.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nav.go b/nav.go
index 0ea4eb84..f8b3a99a 100644
--- a/nav.go
+++ b/nav.go
@@ -720,7 +720,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen sixelScreen,
 			}
 		}
 		if sxScreen.wpx > 0 && sxScreen.hpx > 0 {
-			if a := strings.Index(text, gSixelBegin); a >= 0 {
+			if a := strings.Index(text, gSixelBegin); !processingSixel && a >= 0 {
 				reg.lines = append(reg.lines, text[:a])
 				text = text[a:]
 				processingSixel = true

From 2e0199d10a9093f74056520cedc0304bf307157c Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 12 Jul 2022 14:21:09 +0200
Subject: [PATCH 34/44] fix bug where rejected sixels cause indexing error

---
 nav.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/nav.go b/nav.go
index f8b3a99a..93f4c350 100644
--- a/nav.go
+++ b/nav.go
@@ -765,7 +765,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen sixelScreen,
 				continue
 
 			discard_sixel:
-				emptyLines := win.h - len(reg.lines)
+				emptyLines := min(win.h-len(reg.lines), len(sixelBuffer)-1)
 				reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + sixelBuffer[0]
 				if emptyLines > 0 {
 					reg.lines = append(reg.lines, sixelBuffer[1:emptyLines+1]...)
@@ -779,7 +779,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen sixelScreen,
 	}
 
 	if processingSixel && len(sixelBuffer) > 0 {
-		emptyLines := win.h - len(reg.lines)
+		emptyLines := min(win.h-len(reg.lines), len(sixelBuffer)-1)
 		reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + sixelBuffer[0]
 		if emptyLines > 0 {
 			reg.lines = append(reg.lines, sixelBuffer[1:emptyLines+1]...)

From 22883aa561a75086084765360882bc431aa99e9d Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 12 Jul 2022 14:22:46 +0200
Subject: [PATCH 35/44] add "alternating filler" to trick tcell into redrawing
 when switching between different images

---
 nav.go |  6 +++---
 ui.go  | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/nav.go b/nav.go
index 93f4c350..45df668a 100644
--- a/nav.go
+++ b/nav.go
@@ -633,7 +633,7 @@ func (nav *nav) previewLoop(ui *ui) {
 		}
 		if len(path) != 0 {
 			win := ui.wins[len(ui.wins)-1]
-			nav.preview(path, ui.screen, ui.sxScreen, win)
+			nav.preview(path, ui.screen, &ui.sxScreen, win)
 			prev = path
 		}
 	}
@@ -654,7 +654,7 @@ func matchPattern(pattern, name, path string) bool {
 	return matched
 }
 
-func (nav *nav) preview(path string, screen tcell.Screen, sxScreen sixelScreen, win *win) {
+func (nav *nav) preview(path string, screen tcell.Screen, sxScreen *sixelScreen, win *win) {
 	reg := &reg{loadTime: time.Now(), path: path}
 	defer func() { nav.regChan <- reg }()
 
@@ -747,7 +747,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen sixelScreen,
 						wc, hc := pxToCells(w, h, Wc, Hc, sxScreen.wpx, sxScreen.hpx)
 
 						reg.sixels = append(reg.sixels, sixel{xoff, yoff, w, h, sx})
-						fill := strings.Repeat("\u2800", wc)
+						fill := sxScreen.filler(path, wc)
 						paddedfill := strings.Repeat(" ", xoff) + fill
 						reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + fill
 						for j := 1; j < hc; j++ {
diff --git a/ui.go b/ui.go
index ece8643a..516b7a1d 100644
--- a/ui.go
+++ b/ui.go
@@ -1329,6 +1329,23 @@ func (sxs *sixelScreen) clear() {
 	sxs.sx = nil
 }
 
+func (sxs *sixelScreen) filler(path string, l int) (fill string) {
+	if path != sxs.lastFile {
+		sxs.altFill = !sxs.altFill
+		sxs.lastFile = path
+	}
+
+	if sxs.altFill {
+		fill = "\033[1m"
+		defer func() {
+			fill += "\033[0m"
+		}()
+	}
+
+	fill += strings.Repeat(string(gSixelFiller), l)
+	return
+}
+
 func (ui *ui) showSixels() {
 	var buf strings.Builder
 	buf.WriteString("\0337")

From 412176e15f37f9a41ecc7f9771fee5a0c921d362 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 12 Jul 2022 14:37:47 +0200
Subject: [PATCH 36/44] fix filler string wrongly indented

---
 nav.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nav.go b/nav.go
index 45df668a..9a691dc6 100644
--- a/nav.go
+++ b/nav.go
@@ -748,7 +748,7 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen *sixelScreen,
 
 						reg.sixels = append(reg.sixels, sixel{xoff, yoff, w, h, sx})
 						fill := sxScreen.filler(path, wc)
-						paddedfill := strings.Repeat(" ", xoff) + fill
+						paddedfill := strings.Repeat(" ", xoff-2) + fill
 						reg.lines[len(reg.lines)-1] = reg.lines[len(reg.lines)-1] + fill
 						for j := 1; j < hc; j++ {
 							reg.lines = append(reg.lines, paddedfill)

From 1150515f54a283a43c5f6adef9b5215649a0fc13 Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Tue, 12 Jul 2022 14:38:01 +0200
Subject: [PATCH 37/44] add comment

---
 ui.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ui.go b/ui.go
index 516b7a1d..f6e28d75 100644
--- a/ui.go
+++ b/ui.go
@@ -1329,6 +1329,8 @@ func (sxs *sixelScreen) clear() {
 	sxs.sx = nil
 }
 
+// fillers are used to control when tcell redraws the region where a sixel image is drawn.
+// alternating between bold("ESC [1m") and regular is to clear the image before drawing a new one.
 func (sxs *sixelScreen) filler(path string, l int) (fill string) {
 	if path != sxs.lastFile {
 		sxs.altFill = !sxs.altFill

From 91efd8d5b3358dbdc441a3ab5fea21e0eea8a9cc Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 14:30:55 +0200
Subject: [PATCH 38/44] replace pxToCells() with sixelScreen.pxToCells()

---
 eval.go |  7 +------
 nav.go  |  3 +--
 ui.go   | 33 ++++++++++++++++++++++-----------
 3 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/eval.go b/eval.go
index 876b1b7d..5bcb2521 100644
--- a/eval.go
+++ b/eval.go
@@ -1196,12 +1196,7 @@ func (e *callExpr) eval(app *app, args []string) {
 		if !app.nav.init {
 			return
 		}
-		var err error
-		app.ui.sxScreen.wpx, app.ui.sxScreen.hpx, err = getTermPixels()
-		if err != nil {
-			app.ui.sxScreen.wpx, app.ui.sxScreen.hpx = -1, -1
-			log.Printf("getting terminal pixel size: %s", err)
-		}
+		app.ui.sxScreen.updateSizes(app.ui.screen.Size())
 		app.ui.renew()
 		app.ui.screen.Sync()
 		if app.nav.height != app.ui.wins[0].h {
diff --git a/nav.go b/nav.go
index 9a691dc6..22af4b94 100644
--- a/nav.go
+++ b/nav.go
@@ -739,12 +739,11 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen *sixelScreen,
 
 						xoff := runeSliceWidth([]rune(reg.lines[len(reg.lines)-1])) + 2
 						yoff := len(reg.lines) - 1
-						Wc, Hc := screen.Size()
 						w, h := sixelDimPx(sx)
 						if w < 0 || h < 0 {
 							goto discard_sixel
 						}
-						wc, hc := pxToCells(w, h, Wc, Hc, sxScreen.wpx, sxScreen.hpx)
+						wc, hc := sxScreen.pxToCells(w, h)
 
 						reg.sixels = append(reg.sixels, sixel{xoff, yoff, w, h, sx})
 						fill := sxScreen.filler(path, wc)
diff --git a/ui.go b/ui.go
index f6e28d75..43c33d29 100644
--- a/ui.go
+++ b/ui.go
@@ -474,10 +474,11 @@ type sixel struct {
 }
 
 type sixelScreen struct {
-	wpx, hpx int
-	sx       []sixel
-	lastFile string
-	altFill  bool
+	wpx, hpx     int
+	fontw, fonth int
+	sx           []sixel
+	lastFile     string
+	altFill      bool
 }
 
 type ui struct {
@@ -553,7 +554,6 @@ func getWins(screen tcell.Screen) []*win {
 }
 
 func newUI(screen tcell.Screen) *ui {
-	var err error
 	wtot, htot := screen.Size()
 
 	ui := &ui{
@@ -572,12 +572,7 @@ func newUI(screen tcell.Screen) *ui {
 		menuSelected: -2,
 	}
 
-	ui.sxScreen.wpx, ui.sxScreen.hpx, err = getTermPixels()
-	// TODO getting pixel size does not gurantee sixel support
-	if err != nil {
-		ui.sxScreen.wpx, ui.sxScreen.hpx = -1, -1
-		log.Printf("getting terminal pixel size: %s", err)
-	}
+	ui.sxScreen.updateSizes(screen.Size())
 
 	go ui.pollEvents()
 
@@ -1348,6 +1343,22 @@ func (sxs *sixelScreen) filler(path string, l int) (fill string) {
 	return
 }
 
+func (sxs *sixelScreen) updateSizes(wc, hc int) {
+	var err error
+	sxs.wpx, sxs.hpx, err = getTermPixels()
+	if err != nil {
+		sxs.wpx, sxs.hpx = -1, -1
+		log.Printf("getting terminal pixel size: %s", err)
+	}
+
+	sxs.fontw = sxs.wpx / wc
+	sxs.fonth = sxs.hpx / hc
+}
+
+func (xsx *sixelScreen) pxToCells(x, y int) (int, int) {
+	return x/xsx.fontw + 1, y/xsx.fonth + 1
+}
+
 func (ui *ui) showSixels() {
 	var buf strings.Builder
 	buf.WriteString("\0337")

From af92f4c71cf6203097f0122bb6c276df39d7ed6c Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 14:37:16 +0200
Subject: [PATCH 39/44] add trim sixel height during preview

---
 misc.go | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++----
 nav.go  |  2 ++
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/misc.go b/misc.go
index 87af887e..05c9d25b 100644
--- a/misc.go
+++ b/misc.go
@@ -384,10 +384,57 @@ main_body:
 	return w, h * 6
 }
 
-func pxToCells(x, y, wc, hc, wpx, hpx int) (int, int) {
-	var fw int = wpx / wc
-	var fh int = hpx / hc
-	return x/fw + 1, y/fh + 1 // TODO should probably use ceiling instead of +1
+// maybe merge with sixelDimPx()
+func trimSixelHeight(s string, maxh int) (string, int) {
+	var h int
+	maxh = maxh - (maxh % 6)
+
+	i := strings.Index(s, "q") + 1
+	if i == 0 {
+		// syntax error
+		return "", -1
+	}
+
+	if s[i] == '"' {
+		i++
+		for j := 0; j < 3; j++ {
+			b := strings.Index(s[i:], ";")
+			i += b + 1
+		}
+		b := strings.Index(s[i:], "#")
+		pv, err := strconv.Atoi(s[i : i+b])
+
+		if err == nil && pv > maxh {
+			mh := strconv.Itoa(maxh)
+			s = s[:i] + mh + s[i+b:]
+			i += len(mh)
+		} else {
+			i += b
+		}
+	}
+
+	for h < maxh {
+		k := strings.IndexRune(s[i+1:], '-')
+		if k == -1 {
+			if s[len(s)-3] != '-' {
+				h += 6
+				i = len(s) - 3
+			}
+			break
+		}
+		i += k + 1
+		h += 6
+	}
+
+	if i == 0 {
+		return s, 6
+	}
+
+	if len(s) > i+3 {
+		return s[:i+1] + "\x1b\\", h
+	}
+
+	return s, h
 }
 
 // We don't need no generic code
diff --git a/nav.go b/nav.go
index 22af4b94..2a04f0ce 100644
--- a/nav.go
+++ b/nav.go
@@ -739,10 +739,12 @@ func (nav *nav) preview(path string, screen tcell.Screen, sxScreen *sixelScreen,
 
 						xoff := runeSliceWidth([]rune(reg.lines[len(reg.lines)-1])) + 2
 						yoff := len(reg.lines) - 1
+						maxh := (win.h - yoff) * sxScreen.fonth
 						w, h := sixelDimPx(sx)
 						if w < 0 || h < 0 {
 							goto discard_sixel
 						}
+						sx, h = trimSixelHeight(sx, maxh)
 						wc, hc := sxScreen.pxToCells(w, h)
 
 						reg.sixels = append(reg.sixels, sixel{xoff, yoff, w, h, sx})

From cef82a039b178e2c7973fb41929f9962aada4b8f Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 14:37:35 +0200
Subject: [PATCH 40/44] add tests for trimSixelHeight

---
 misc_test.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/misc_test.go b/misc_test.go
index 3568fa2f..062d34bc 100644
--- a/misc_test.go
+++ b/misc_test.go
@@ -243,3 +243,48 @@ func TestNaturalLess(t *testing.T) {
 		}
 	}
 }
+
+func TestTrimSixelHeight(t *testing.T) {
+	tests := []struct {
+		si string
+		hi int
+		so string
+		ho int
+	}{
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{\x1b\\", 12,
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{\x1b\\", 6,
+		},
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N\x1b\\", 30,
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N\x1b\\", 12,
+		},
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N\x1b\\", 12,
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N\x1b\\", 12,
+		},
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N\x1b\\", 11,
+			"\x1bPq\"1;1;1;6#0;2;97;97;97#1;2;75;75;75#0B$#1{-\x1b\\", 6,
+		},
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N-\x1b\\", 30,
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N-\x1b\\", 12,
+		},
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N-\x1b\\", 12,
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N-\x1b\\", 12,
+		},
+		{
+			"\x1bPq\"1;1;1;12#0;2;97;97;97#1;2;75;75;75#0B$#1{-#0o$#1N-\x1b\\", 11,
+			"\x1bPq\"1;1;1;6#0;2;97;97;97#1;2;75;75;75#0B$#1{-\x1b\\", 6,
+		},
+	}
+
+	for i, test := range tests {
+		if got1, got2 := trimSixelHeight(test.si, test.hi); got1 != test.so || got2 != test.ho {
+			t.Errorf("test #%d expected height %d, got %d and string %s", i, test.ho, got2, got1[1:])
+		}
+	}
+
+}

From 18d4d42c3856cbdc709d61b8df19b66ee4a2d0ca Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 14:56:56 +0200
Subject: [PATCH 41/44] prevent sixel redrawing during input prompts

---
 ui.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ui.go b/ui.go
index 43c33d29..12147226 100644
--- a/ui.go
+++ b/ui.go
@@ -939,7 +939,7 @@ func (ui *ui) draw(nav *nav) {
 	}
 
 	ui.screen.Show()
-	if ui.menuBuf == nil && len(ui.sxScreen.sx) > 0 {
+	if ui.menuBuf == nil && ui.cmdPrefix == "" && len(ui.sxScreen.sx) > 0 {
 		ui.showSixels()
 	}
 

From 0e7f5ee1b9c0e85887f915f72ef16a66d019753d Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 15:08:52 +0200
Subject: [PATCH 42/44] change sixel filler to braille space

---
 nav.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nav.go b/nav.go
index 2a04f0ce..2a6cabb9 100644
--- a/nav.go
+++ b/nav.go
@@ -25,7 +25,7 @@ const (
 )
 
 var (
-	gSixelFiller = '.'
+	gSixelFiller = '\u2800'
 )
 
 type linkState byte

From 4925d87c4e7b71ee390bf37b90b79b99210cdd8f Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 15:14:50 +0200
Subject: [PATCH 43/44] clean up

---
 nav.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/nav.go b/nav.go
index 2a6cabb9..d84bccf3 100644
--- a/nav.go
+++ b/nav.go
@@ -15,7 +15,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/gdamore/tcell/v2"
 	times "gopkg.in/djherbis/times.v1"
 )
 
@@ -633,7 +632,7 @@ func (nav *nav) previewLoop(ui *ui) {
 		}
 		if len(path) != 0 {
 			win := ui.wins[len(ui.wins)-1]
-			nav.preview(path, ui.screen, &ui.sxScreen, win)
+			nav.preview(path, &ui.sxScreen, win)
 			prev = path
 		}
 	}
@@ -654,7 +653,7 @@ func matchPattern(pattern, name, path string) bool {
 	return matched
 }
 
-func (nav *nav) preview(path string, screen tcell.Screen, sxScreen *sixelScreen, win *win) {
+func (nav *nav) preview(path string, sxScreen *sixelScreen, win *win) {
 	reg := &reg{loadTime: time.Now(), path: path}
 	defer func() { nav.regChan <- reg }()
 

From 6dfd6561fd3da51f08a2107d587704bd27e58efc Mon Sep 17 00:00:00 2001
From: Ching Pei Yang <badnam3o.0@gmail.com>
Date: Wed, 13 Jul 2022 15:18:53 +0200
Subject: [PATCH 44/44] use strings.Index instead of regex for simple search

---
 misc.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/misc.go b/misc.go
index 05c9d25b..17cffc2f 100644
--- a/misc.go
+++ b/misc.go
@@ -334,9 +334,9 @@ func sixelDimPx(s string) (w int, h int) {
 		ph, err1 := strconv.Atoi(s[i : i+b])
 
 		i += b + 1
-		n := reNumber.FindString(s[i:]) // use stirngs.Index(s[i:], "#") instead?
-		pv, err2 := strconv.Atoi(n)
-		i += len(n)
+		b = strings.Index(s[i:], "#")
+		pv, err2 := strconv.Atoi(s[i : i+b])
+		i += b
 
 		if err1 != nil || err2 != nil {
 			goto main_body // keep trying