Reworking sixel implementation based on veltza's implementation (#117)

* sixel: remove black bars from sixel images

When the images don't fully cover the text cells, black bars are added
to them. This fix removes those bars, but if you need the old behavior,
you can restore it by setting 'sixelremovebars' to zero in config.h

* sixel: fix a potential memory leak

* sixel: improve behavior with text reflow

* sixel: prevent animated gifs from choking the terminal

Animated gifs constantly spawn new images that eventually choke the
terminal because the old animation frames are kept in the image buffer.
This fix removes overlapping images from the image buffer and prevents
them from piling up.

* sixel: add zooming and clipping

* sixel: copying bulk of changes

* sixel: move sixel_parser_parse() and add missing sequences and blocks (#113)

- Move sixel_parser_parse() from tputc() to twrite()
- Add missing 8452, DECSDM, XTSMGRAPHICS and XTWINOPS sequences
- Add more conditional blocks for the scrollback and sync patches
- Remove unused reflow_y from ImageList. It is only used for the
  scrollback-reflow patch in st-sx.

* sixel: update vtiden to VT200 family

* sixel: fix scrolling issues inside tmux (#114)

tmux is using the scrolling region and sequence to clear the screen
below the shell prompt. This peculiar behavior caused the tscrollup()
function to be called, which always scrolled the images regardless of
whether they were inside the region or not. So the images moved out of
place whenever the bottom of the screen was cleared. This fix checks
that the images are inside the region before scrolling them.

* sixel: prevent images from being deleted when resizing (#115)

This fixes resizing issues outside of tmux not inside.

* Rewriting tresize logic based on veltza's proposed implementation in PR #115

* tresize: correction for tscrollup call when scrollback patch is used

---------

Co-authored-by: veltza <106755522+veltza@users.noreply.github.com>

config.def.h

@@ -54,7 +54,10 @@ char *stty_args = "stty raw pass8 nl -echo -iexten -cstopb 38400";
 
 /* identification sequence returned in DA and DECID */
 #if SIXEL_PATCH
-char *vtiden = "\033[?12;4c";
+char *vtiden = "\033[?62;4c"; /* VT200 family (62) with sixel (4) */
+
+/* sixel rgb byte order: LSBFirst or MSBFirst */
+int const sixelbyteorder = LSBFirst;
 #else
 char *vtiden = "\033[?6c";
 #endif

config.mk

@@ -13,10 +13,10 @@ X11LIB = /usr/X11R6/lib
 PKG_CONFIG = pkg-config
 
 # Uncomment this for the alpha patch / ALPHA_PATCH
-#XRENDER = -lXrender
+#XRENDER = `$(PKG_CONFIG) --libs xrender`
 
 # Uncomment this for the themed cursor patch / THEMED_CURSOR_PATCH
-#XCURSOR = -lXcursor
+#XCURSOR = `$(PKG_CONFIG) --libs xcursor`
 
 # Uncomment the lines below for the ligatures patch / LIGATURES_PATCH
 #LIGATURES_C = hb.c
@@ -26,13 +26,14 @@ PKG_CONFIG = pkg-config
 
 # Uncomment this for the SIXEL patch / SIXEL_PATCH
 #SIXEL_C = sixel.c sixel_hls.c
+#SIXEL_LIBS = `$(PKG_CONFIG) --libs imlib2`
 
 # includes and libs, uncomment harfbuzz for the ligatures patch
 INCS = -I$(X11INC) \
        `$(PKG_CONFIG) --cflags fontconfig` \
        `$(PKG_CONFIG) --cflags freetype2` \
        $(LIGATURES_INC)
-LIBS = -L$(X11LIB) -lm -lrt -lX11 -lutil -lXft ${XRENDER} ${XCURSOR}\
+LIBS = -L$(X11LIB) -lm -lrt -lX11 -lutil -lXft ${SIXEL_LIBS} ${XRENDER} ${XCURSOR}\
        `$(PKG_CONFIG) --libs fontconfig` \
        `$(PKG_CONFIG) --libs freetype2` \
        $(LIGATURES_LIBS)

patch/sixel_st.c

@@ -1,57 +0,0 @@
-sixel_state_t sixel_st;
-
-void
-dcshandle(void)
-{
-	int bgcolor;
-	unsigned char r, g, b, a = 255;
-
-	switch (csiescseq.mode[0]) {
-	default:
-		fprintf(stderr, "erresc: unknown csi ");
-		csidump();
-		/* die(""); */
-		break;
-	case 'q': /* DECSIXEL */
-		if (IS_TRUECOL(term.c.attr.bg)) {
-			r = term.c.attr.bg >> 16 & 255;
-			g = term.c.attr.bg >> 8 & 255;
-			b = term.c.attr.bg >> 0 & 255;
-		} else {
-			xgetcolor(term.c.attr.bg, &r, &g, &b);
-			#if ALPHA_PATCH
-			if (term.c.attr.bg == defaultbg)
-				a = dc.col[defaultbg].pixel >> 24 & 255;
-			#endif // ALPHA_PATCH
-		}
-		bgcolor = a << 24 | b << 16 | g << 8 | r;
-		if (sixel_parser_init(&sixel_st, 255 << 24, bgcolor, 1, win.cw, win.ch) != 0)
-			perror("sixel_parser_init() failed");
-		term.mode |= MODE_SIXEL;
-		break;
-	}
-}
-
-void
-scroll_images(int n) {
-	ImageList *im;
-	int tmp;
-
-	/* maximum sixel distance in lines from current view before
-	 * deallocation
-	 * TODO: should be in config.h */
-	int max_sixel_distance = 10000;
-
-	for (im = term.images; im; im = im->next) {
-		im->y += n;
-
-		/* check if the current sixel has exceeded the maximum
-		 * draw distance, and should therefore be deleted */
-		tmp = im->y;
-		if (tmp < 0) { tmp = tmp * -1; }
-		if (tmp > max_sixel_distance) {
-			fprintf(stderr, "im@0x%08x exceeded maximum distance\n");
-			im->should_delete = 1;
-		}
-	}
-}

patch/sixel_st.h

@@ -1,2 +0,0 @@
-static void dcshandle(void);
-static void scroll_images(int n);

patch/sixel_x.c

@@ -1,14 +0,0 @@
-void
-delete_image(ImageList *im)
-{
-	if (im->prev)
-		im->prev->next = im->next;
-	else
-		term.images = im->next;
-	if (im->next)
-		im->next->prev = im->prev;
-	if (im->pixmap)
-		XFreePixmap(xw.dpy, (Drawable)im->pixmap);
-	free(im->pixels);
-	free(im);
-}

patch/st_include.c

@@ -20,9 +20,6 @@
 #if SCROLLBACK_PATCH || SCROLLBACK_MOUSE_PATCH || SCROLLBACK_MOUSE_ALTSCREEN_PATCH
 #include "scrollback.c"
 #endif
-#if SIXEL_PATCH
-#include "sixel_st.c"
-#endif
 #if SYNC_PATCH
 #include "sync.c"
 #endif

patch/st_include.h

@@ -23,9 +23,6 @@
 #if SCROLLBACK_PATCH || SCROLLBACK_MOUSE_PATCH || SCROLLBACK_MOUSE_ALTSCREEN_PATCH
 #include "scrollback.h"
 #endif
-#if SIXEL_PATCH
-#include "sixel_st.h"
-#endif
 #if SYNC_PATCH
 #include "sync.h"
 #endif

patch/x_include.c

@@ -32,9 +32,6 @@
 #if RIGHTCLICKTOPLUMB_PATCH
 #include "rightclicktoplumb_x.c"
 #endif
-#if SIXEL_PATCH
-#include "sixel_x.c"
-#endif
 #if ST_EMBEDDER_PATCH
 #include "st_embedder_x.c"
 #endif

sixel.c

@@ -5,10 +5,12 @@
 #include <stdlib.h>
 #include <string.h>  /* memcpy */
 
+#include "st.h"
+#include "win.h"
 #include "sixel.h"
 #include "sixel_hls.h"
 
-#define SIXEL_RGB(r, g, b) ((r) + ((g) << 8) + ((b) << 16) + (255 << 24))
+#define SIXEL_RGB(r, g, b) ((255 << 24) + ((r) << 16) + ((g) << 8) +  (b))
 #define SIXEL_PALVAL(n,a,m) (((n) * (a) + ((m) / 2)) / (m))
 #define SIXEL_XRGB(r,g,b) SIXEL_RGB(SIXEL_PALVAL(r, 255, 100), SIXEL_PALVAL(g, 255, 100), SIXEL_PALVAL(b, 255, 100))
 
@@ -31,6 +33,43 @@ static sixel_color_t const sixel_default_color_table[] = {
 	SIXEL_XRGB(80, 80, 80),  /* 15 Gray 75% */
 };
 
+void
+scroll_images(int n) {
+	ImageList *im, *next;
+	#if SCROLLBACK_PATCH
+	int top = tisaltscr() ? 0 : term.scr - HISTSIZE;
+	#else
+	int top = 0;
+	#endif // SCROLLBACK_PATCH
+
+	for (im = term.images; im; im = next) {
+		next = im->next;
+		im->y += n;
+
+		/* check if the current sixel has exceeded the maximum
+		 * draw distance, and should therefore be deleted */
+		if (im->y < top) {
+			//fprintf(stderr, "im@0x%08x exceeded maximum distance\n");
+			delete_image(im);
+		}
+	}
+}
+
+void
+delete_image(ImageList *im)
+{
+	if (im->prev)
+		im->prev->next = im->next;
+	else
+		term.images = im->next;
+	if (im->next)
+		im->next->prev = im->prev;
+	if (im->pixmap)
+		XFreePixmap(xw.dpy, (Drawable)im->pixmap);
+	free(im->pixels);
+	free(im);
+}
+
 static int
 set_default_color(sixel_image_t *image)
 {
@@ -171,7 +210,8 @@ end:
 static void
 sixel_image_deinit(sixel_image_t *image)
 {
-	free(image->data);
+	if (image->data)
+		free(image->data);
 	image->data = NULL;
 }
 
@@ -212,15 +252,19 @@ sixel_parser_set_default_color(sixel_state_t *st)
 }
 
 int
-sixel_parser_finalize(sixel_state_t *st, unsigned char **pixels)
+sixel_parser_finalize(sixel_state_t *st, ImageList **newimages, int cx, int cy, int cw, int ch)
 {
-	int status = (-1);
 	sixel_image_t *image = &st->image;
 	int x, y;
 	sixel_color_no_t *src;
-	unsigned char *dst;
+	sixel_color_t *dst;
 	int color;
 	int w, h;
+	int i, j, cols, numimages;
+	ImageList *im, *next, *tail;
+
+	if (!image->data)
+		return -1;
 
 	if (++st->max_x < st->attributed_ph)
 		st->max_x = st->attributed_ph;
@@ -229,62 +273,83 @@ sixel_parser_finalize(sixel_state_t *st, unsigned char **pixels)
 		st->max_y = st->attributed_pv;
 
 	if (image->use_private_register && image->ncolors > 2 && !image->palette_modified) {
-		status = set_default_color(image);
+		if (set_default_color(image) < 0)
-		if (status < 0)
+			return -1;
-			goto end;
 	}
 
-	w = st->max_x < image->width ? st->max_x : image->width;
+	w = MIN(st->max_x, image->width);
-	h = st->max_y < image->height ? st->max_y : image->height;
+	h = MIN(st->max_y, image->height);
 
-	*pixels = malloc(w * h * 4);
+	if ((numimages = (h + ch-1) / ch) <= 0)
-	if (*pixels == NULL)
+		return -1;
-		goto end;
 
-	src = st->image.data;
+	cols = (w + cw-1) / cw;
-	dst = *pixels;
+
-	for (y = 0; y < h; y++) {
+	*newimages = NULL, tail = NULL;
-		src = st->image.data + image->width * y;
+	for (y = 0, i = 0; i < numimages; i++) {
-		for (x = 0; x < w; ++x) {
+		if ((im = malloc(sizeof(ImageList)))) {
-			color = st->image.palette[*src++];
+			if (!tail) {
-			*dst++ = color >> 16 & 0xff;   /* b */
+				*newimages = tail = im;
-			*dst++ = color >> 8 & 0xff;    /* g */
+				im->prev = im->next = NULL;
-			*dst++ = color >> 0 & 0xff;    /* r */
+			} else {
-			*dst++ = color >> 24 & 0xff;   /* a */
+				tail->next = im;
+				im->prev = tail;
+				im->next = NULL;
+				tail = im;
+			}
+			im->x = cx;
+			im->y = cy + i;
+			im->cols = cols;
+			im->width = w;
+			im->height = MIN(h - ch * i, ch);
+			im->pixels = malloc(im->width * im->height * 4);
+			im->pixmap = NULL;
+			im->cw = cw;
+			im->ch = ch;
+		}
+		if (!im || !im->pixels) {
+			for (im = *newimages; im; im = next) {
+				next = im->next;
+				if (im->pixels)
+					free(im->pixels);
+				free(im);
+			}
+			*newimages = NULL;
+			return -1;
+		}
+		dst = (sixel_color_t *)im->pixels;
+		for (j = 0; j < im->height && y < h; j++, y++) {
+			src = st->image.data + image->width * y;
+			for (x = 0; x < w; x++)
+				*dst++ = st->image.palette[*src++];
 		}
 	}
 
-	image->width = w;
+	return numimages;
-	image->height = h;
-
-	status = (0);
-
-end:
-	return status;
 }
 
 /* convert sixel data into indexed pixel bytes and palette data */
 int
-sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
+sixel_parser_parse(sixel_state_t *st, const unsigned char *p, size_t len)
 {
-	int status = (-1);
+	int n = 0;
-	int n;
 	int i;
 	int x;
 	int y;
 	int bits;
-	int sixel_vertical_mask;
 	int sx;
 	int sy;
 	int c;
 	int pos;
-	unsigned char *p0 = p;
+	int width;
+	const unsigned char *p0 = p, *p2 = p + len;
 	sixel_image_t *image = &st->image;
+	sixel_color_no_t *data, color_index;
 
-	if (! image->data)
+	if (!image->data)
-		goto end;
+		st->state = PS_ERROR;
 
-	while (p < p0 + len) {
+	while (p < p2) {
 		switch (st->state) {
 		case PS_ESC:
 			goto end;
@@ -293,7 +358,6 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			switch (*p) {
 			case '\x1b':
 				st->state = PS_ESC;
-				p++;
 				break;
 			case '"':
 				st->param = 0;
@@ -338,14 +402,15 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 							sy *= 2;
 						}
 
-						if (sx > DECSIXEL_WIDTH_MAX)
+						sx = MIN(sx, DECSIXEL_WIDTH_MAX);
-							sx = DECSIXEL_WIDTH_MAX;
+						sy = MIN(sy, DECSIXEL_HEIGHT_MAX);
-						if (sy > DECSIXEL_HEIGHT_MAX)
-							sy = DECSIXEL_HEIGHT_MAX;
 
-						status = image_buffer_resize(image, sx, sy);
+						if (image_buffer_resize(image, sx, sy) < 0) {
-						if (status < 0)
+							perror("sixel_parser_parse() failed");
-							goto end;
+							st->state = PS_ERROR;
+							p++;
+							break;
+						}
 					}
 
 					if (st->color_index > image->ncolors)
@@ -357,43 +422,44 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 					if (st->repeat_count > 0 && st->pos_y + 5 < image->height) {
 						bits = *p - '?';
 						if (bits != 0) {
-							sixel_vertical_mask = 0x01;
+							data = image->data + image->width * st->pos_y + st->pos_x;
+							width = image->width;
+							color_index = st->color_index;
 							if (st->repeat_count <= 1) {
-								for (i = 0; i < 6; i++) {
+								if (bits & 0x01)
-									if ((bits & sixel_vertical_mask) != 0) {
+									*data = color_index, n = 0;
-										pos = image->width * (st->pos_y + i) + st->pos_x;
+								data += width;
-										image->data[pos] = st->color_index;
+								if (bits & 0x02)
-										if (st->max_x < st->pos_x)
+									*data = color_index, n = 1;
-											st->max_x = st->pos_x;
+								data += width;
-										if (st->max_y < (st->pos_y + i))
+								if (bits & 0x04)
-											st->max_y = st->pos_y + i;
+									*data = color_index, n = 2;
-									}
+								data += width;
-									sixel_vertical_mask <<= 1;
+								if (bits & 0x08)
-								}
+									*data = color_index, n = 3;
+								data += width;
+								if (bits & 0x10)
+									*data = color_index, n = 4;
+								if (bits & 0x20)
+									data[width] = color_index, n = 5;
+								if (st->max_x < st->pos_x)
+									st->max_x = st->pos_x;
 							} else {
 								/* st->repeat_count > 1 */
-								for (i = 0; i < 6; i++) {
+								for (i = 0; bits; bits >>= 1, i++, data += width) {
-									if ((bits & sixel_vertical_mask) != 0) {
+									if (bits & 1) {
-										c = sixel_vertical_mask << 1;
+										data[0] = color_index;
-										for (n = 1; (i + n) < 6; n++) {
+										data[1] = color_index;
-											if ((bits & c) == 0)
+										for (x = 2; x < st->repeat_count; x++)
-												break;
+											data[x] = color_index;
-											c <<= 1;
+										n = i;
-										}
-										for (y = st->pos_y + i; y < st->pos_y + i + n; ++y) {
-											for (x = st->pos_x; x < st->pos_x + st->repeat_count; ++x)
-												image->data[image->width * y + x] = st->color_index;
-										}
-										if (st->max_x < (st->pos_x + st->repeat_count - 1))
-											st->max_x = st->pos_x + st->repeat_count - 1;
-										if (st->max_y < (st->pos_y + i + n - 1))
-											st->max_y = st->pos_y + i + n - 1;
-										i += (n - 1);
-										sixel_vertical_mask <<= (n - 1);
 									}
-									sixel_vertical_mask <<= 1;
 								}
+								if (st->max_x < (st->pos_x + st->repeat_count - 1))
+									st->max_x = st->pos_x + st->repeat_count - 1;
 							}
+							if (st->max_y < (st->pos_y + n))
+								st->max_y = st->pos_y + n;
 						}
 					}
 					if (st->repeat_count > 0)
@@ -410,7 +476,6 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			switch (*p) {
 			case '\x1b':
 				st->state = PS_ESC;
-				p++;
 				break;
 			case '0':
 			case '1':
@@ -423,8 +488,7 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			case '8':
 			case '9':
 				st->param = st->param * 10 + *p - '0';
-				if (st->param > DECSIXEL_PARAMVALUE_MAX)
+				st->param = MIN(st->param, DECSIXEL_PARAMVALUE_MAX);
-					st->param = DECSIXEL_PARAMVALUE_MAX;
 				p++;
 				break;
 			case ';':
@@ -452,27 +516,22 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 
 				if (image->width < st->attributed_ph ||
 				        image->height < st->attributed_pv) {
-					sx = st->attributed_ph;
+					sx = MAX(image->width, st->attributed_ph);
-					if (image->width > st->attributed_ph)
+					sy = MAX(image->height, st->attributed_pv);
-						sx = image->width;
-
-					sy = st->attributed_pv;
-					if (image->height > st->attributed_pv)
-						sy = image->height;
 
 					/* the height of the image buffer must be divisible by 6
-					 * to avoid unnecessary resizing of the image buffer in
+					 * to avoid unnecessary resizing of the image buffer when
-					 * sixel_parser_parse() */
+					 * parsing the last sixel line */
 					sy = (sy + 5) / 6 * 6;
 
-					if (sx > DECSIXEL_WIDTH_MAX)
+					sx = MIN(sx, DECSIXEL_WIDTH_MAX);
-						sx = DECSIXEL_WIDTH_MAX;
+					sy = MIN(sy, DECSIXEL_HEIGHT_MAX);
-					if (sy > DECSIXEL_HEIGHT_MAX)
-						sy = DECSIXEL_HEIGHT_MAX;
 
-					status = image_buffer_resize(image, sx, sy);
+					if (image_buffer_resize(image, sx, sy) < 0) {
-					if (status < 0)
+						perror("sixel_parser_parse() failed");
-						goto end;
+						st->state = PS_ERROR;
+						break;
+					}
 				}
 				st->state = PS_DECSIXEL;
 				st->param = 0;
@@ -485,7 +544,6 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			switch (*p) {
 			case '\x1b':
 				st->state = PS_ESC;
-				p++;
 				break;
 			case '0':
 			case '1':
@@ -498,14 +556,11 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			case '8':
 			case '9':
 				st->param = st->param * 10 + *p - '0';
-				if (st->param > DECSIXEL_PARAMVALUE_MAX)
+				st->param = MIN(st->param, DECSIXEL_PARAMVALUE_MAX);
-					st->param = DECSIXEL_PARAMVALUE_MAX;
 				p++;
 				break;
 			default:
-				st->repeat_count = st->param;
+				st->repeat_count = MAX(st->param, 1);
-				if (st->repeat_count == 0)
-					st->repeat_count = 1;
 				st->state = PS_DECSIXEL;
 				st->param = 0;
 				st->nparams = 0;
@@ -518,7 +573,6 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			switch (*p) {
 			case '\x1b':
 				st->state = PS_ESC;
-				p++;
 				break;
 			case '0':
 			case '1':
@@ -531,8 +585,7 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 			case '8':
 			case '9':
 				st->param = st->param * 10 + *p - '0';
-				if (st->param > DECSIXEL_PARAMVALUE_MAX)
+				st->param = MIN(st->param, DECSIXEL_PARAMVALUE_MAX);
-					st->param = DECSIXEL_PARAMVALUE_MAX;
 				p++;
 				break;
 			case ';':
@@ -559,22 +612,16 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 					st->image.palette_modified = 1;
 					if (st->params[1] == 1) {
 						/* HLS */
-						if (st->params[2] > 360)
+						st->params[2] = MIN(st->params[2], 360);
-							st->params[2] = 360;
+						st->params[3] = MIN(st->params[3], 100);
-						if (st->params[3] > 100)
+						st->params[4] = MIN(st->params[4], 100);
-							st->params[3] = 100;
-						if (st->params[4] > 100)
-							st->params[4] = 100;
 						image->palette[st->color_index]
 						    = hls_to_rgb(st->params[2], st->params[3], st->params[4]);
 					} else if (st->params[1] == 2) {
 						/* RGB */
-						if (st->params[2] > 100)
+						st->params[2] = MIN(st->params[2], 100);
-							st->params[2] = 100;
+						st->params[3] = MIN(st->params[3], 100);
-						if (st->params[3] > 100)
+						st->params[4] = MIN(st->params[4], 100);
-							st->params[3] = 100;
-						if (st->params[4] > 100)
-							st->params[4] = 100;
 						image->palette[st->color_index]
 						    = SIXEL_XRGB(st->params[2], st->params[3], st->params[4]);
 					}
@@ -582,15 +629,21 @@ sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len)
 				break;
 			}
 			break;
+
+		case PS_ERROR:
+			if (*p == '\x1b') {
+				st->state = PS_ESC;
+				goto end;
+			}
+			p++;
+			break;
 		default:
 			break;
 		}
 	}
 
-	status = (0);
-
 end:
-	return status;
+	return p - p0;
 }
 
 void

sixel.h

@@ -26,6 +26,7 @@ typedef enum parse_state {
 	PS_DECGRA     = 3,  /* DECGRA Set Raster Attributes " Pan; Pad; Ph; Pv */
 	PS_DECGRI     = 4,  /* DECGRI Graphics Repeat Introducer ! Pn Ch */
 	PS_DECGCI     = 5,  /* DECGCI Graphics Color Introducer # Pc; Pu; Px; Py; Pz */
+	PS_ERROR      = 6,
 } parse_state_t;
 
 typedef struct parser_context {
@@ -49,10 +50,12 @@ typedef struct parser_context {
 	sixel_image_t image;
 } sixel_state_t;
 
+void scroll_images(int n);
+void delete_image(ImageList *im);
 int sixel_parser_init(sixel_state_t *st, sixel_color_t fgcolor, sixel_color_t bgcolor, unsigned char use_private_register, int cell_width, int cell_height);
-int sixel_parser_parse(sixel_state_t *st, unsigned char *p, size_t len);
+int sixel_parser_parse(sixel_state_t *st, const unsigned char *p, size_t len);
 int sixel_parser_set_default_color(sixel_state_t *st);
-int sixel_parser_finalize(sixel_state_t *st, unsigned char **pixels);
+int sixel_parser_finalize(sixel_state_t *st, ImageList **newimages, int cx, int cy, int cw, int ch);
 void sixel_parser_deinit(sixel_state_t *st);
 
 #endif

st.c

@@ -14,6 +14,7 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <termios.h>
+#include <time.h>
 #include <unistd.h>
 #include <wchar.h>
 
@@ -64,15 +65,17 @@ static inline int min(int a, int b) { return a < b ? a : b; }
 #endif // VIM_BROWSE_PATCH
 
 enum term_mode {
-	MODE_WRAP        = 1 << 0,
+	MODE_WRAP         = 1 << 0,
-	MODE_INSERT      = 1 << 1,
+	MODE_INSERT       = 1 << 1,
-	MODE_ALTSCREEN   = 1 << 2,
+	MODE_ALTSCREEN    = 1 << 2,
-	MODE_CRLF        = 1 << 3,
+	MODE_CRLF         = 1 << 3,
-	MODE_ECHO        = 1 << 4,
+	MODE_ECHO         = 1 << 4,
-	MODE_PRINT       = 1 << 5,
+	MODE_PRINT        = 1 << 5,
-	MODE_UTF8        = 1 << 6,
+	MODE_UTF8         = 1 << 6,
 	#if SIXEL_PATCH
-	MODE_SIXEL       = 1 << 7,
+	MODE_SIXEL        = 1 << 7,
+	MODE_SIXEL_CUR_RT = 1 << 8,
+	MODE_SIXEL_SDM    = 1 << 9
 	#endif // SIXEL_PATCH
 };
 
@@ -163,6 +166,9 @@ static void ttywriteraw(const char *, size_t);
 
 static void csidump(void);
 static void csihandle(void);
+#if SIXEL_PATCH
+static void dcshandle(void);
+#endif // SIXEL_PATCH
 #if UNDERCURL_PATCH
 static void readcolonargs(char **, int, int[][CAR_PER_ARG]);
 #endif // UNDERCURL_PATCH
@@ -183,6 +189,9 @@ static void tdump(void);
 static void tclearregion(int, int, int, int);
 static void tcursor(int);
 static void tdeletechar(int);
+#if SIXEL_PATCH
+static void tdeleteimages(void);
+#endif // SIXEL_PATCH
 static void tdeleteline(int);
 static void tinsertblank(int);
 static void tinsertblankline(int);
@@ -1358,12 +1367,11 @@ treset(void)
 		#else
 		tclearregion(0, 0, term.col-1, term.row-1);
 		#endif // COLUMNS_PATCH
+		#if SIXEL_PATCH
+		tdeleteimages();
+		#endif // SIXEL_PATCH
 		tswapscreen();
 	}
-	#if SIXEL_PATCH
-	for (im = term.images; im; im = im->next)
-		im->should_delete = 1;
-	#endif // SIXEL_PATCH
 }
 
 void
@@ -1405,6 +1413,16 @@ tscrolldown(int orig, int n)
 	#endif // VIM_BROWSE_PATCH
 	int i;
 	Line temp;
+	#if SIXEL_PATCH
+	int bot = term.bot;
+	#if SCROLLBACK_PATCH
+	int scr = IS_SET(MODE_ALTSCREEN) ? 0 : term.scr;
+	#else
+	int scr = 0;
+	#endif // SCROLLBACK_PATCH
+	int itop = orig + scr, ibot = bot + scr;
+	ImageList *im, *next;
+	#endif // SIXEL_PATCH
 
 	LIMIT(n, 0, term.bot-orig+1);
 
@@ -1423,11 +1441,12 @@ tscrolldown(int orig, int n)
 
 	#if SIXEL_PATCH
 	/* move images, if they are inside the scrolling region */
-	ImageList *im;
+	for (im = term.images; im; im = next) {
-	for (im = term.images; im; im = im->next) {
+		next = im->next;
-		if (im->y * win.ch + im->height > orig * win.ch && im->y <= term.bot) {
+		if (im->y >= itop && im->y <= ibot) {
 			im->y += n;
-			im->should_delete |= (im->y >= term.row);
+			if (im->y > ibot)
+				delete_image(im);
 		}
 	}
 	#endif // SIXEL_PATCH
@@ -1457,6 +1476,16 @@ tscrollup(int orig, int n)
 	#endif // VIM_BROWSE_PATCH
 	int i;
 	Line temp;
+	#if SIXEL_PATCH
+	int bot = term.bot;
+	#if SCROLLBACK_PATCH
+	int scr = IS_SET(MODE_ALTSCREEN) ? 0 : term.scr;
+	#else
+	int scr = 0;
+	#endif // SCROLLBACK_PATCH
+	int itop = orig + scr, ibot = bot + scr;
+	ImageList *im, *next;
+	#endif // SIXEL_PATCH
 
 	LIMIT(n, 0, term.bot-orig+1);
 
@@ -1490,11 +1519,45 @@ tscrollup(int orig, int n)
 
 	#if SIXEL_PATCH
 	#if SCROLLBACK_PATCH
-	if (term.scr == 0)
+	if (IS_SET(MODE_ALTSCREEN) || !copyhist || orig != 0) {
-		scroll_images(-1 * n);
+		/* move images, if they are inside the scrolling region */
+		for (im = term.images; im; im = next) {
+			next = im->next;
+			if (im->y >= itop && im->y <= ibot) {
+				im->y -= n;
+				if (im->y < itop)
+					delete_image(im);
+			}
+		}
+	} else {
+		/* move images, if they are inside the scrolling region or scrollback */
+		for (im = term.images; im; im = next) {
+			next = im->next;
+			im->y -= scr;
+			if (im->y < 0) {
+				im->y -= n;
+			} else if (im->y >= orig && im->y <= bot) {
+				im->y -= n;
+				if (im->y < orig)
+					im->y -= orig; // move to scrollback
+			}
+			if (im->y < -HISTSIZE)
+				delete_image(im);
+			else
+				im->y += term.scr;
+		}
+	}
 	#else
-	scroll_images(-1 * n);
+	/* move images, if they are inside the scrolling region */
-	#endif
+	for (im = term.images; im; im = next) {
+		next = im->next;
+		if (im->y >= itop && im->y <= ibot) {
+			im->y -= n;
+			if (im->y < itop)
+				delete_image(im);
+		}
+	}
+	#endif // SCROLLBACK_PATCH
 	#endif // SIXEL_PATCH
 
 	#if SCROLLBACK_PATCH
@@ -1743,6 +1806,19 @@ tinsertblankline(int n)
 		tscrolldown(term.c.y, n);
 }
 
+#if SIXEL_PATCH
+void
+tdeleteimages(void)
+{
+	ImageList *im, *next;
+
+	for (im = term.images; im; im = next) {
+		next = im->next;
+		delete_image(im);
+	}
+}
+#endif // SIXEL_PATCH
+
 void
 tdeleteline(int n)
 {
@@ -2079,6 +2155,14 @@ tsetmode(int priv, int set, const int *args, int narg)
 				      and can be mistaken for other control
 				      codes. */
 				break;
+			#if SIXEL_PATCH
+			case 80: /* DECSDM -- Sixel Display Mode */
+				MODBIT(term.mode, set, MODE_SIXEL_SDM);
+				break;
+			case 8452: /* sixel scrolling leaves cursor to right of graphic */
+				MODBIT(term.mode, set, MODE_SIXEL_CUR_RT);
+				break;
+			#endif // SIXEL_PATCH
 			default:
 				fprintf(stderr,
 					"erresc: unknown private set/reset mode %d\n",
@@ -2117,7 +2201,8 @@ csihandle(void)
 	char buffer[40];
 	int len;
 	#if SIXEL_PATCH
-	ImageList *im;
+	ImageList *im, *next;
+	int n, pi, pa;
 	#endif // SIXEL_PATCH
 	#if COLUMNS_PATCH && !VIM_BROWSE_PATCH
 	int maxcol = term.maxcol;
@@ -2259,10 +2344,8 @@ csihandle(void)
 			#endif // SCROLLBACK_PATCH
 
 			tclearregion(0, 0, maxcol-1, term.row-1);
-
 			#if SIXEL_PATCH
-			for (im = term.images; im; im = im->next)
+			tdeleteimages();
-				im->should_delete = 1;
 			#endif // SIXEL_PATCH
 			break;
 		case 3: /* scrollback */
@@ -2291,16 +2374,17 @@ csihandle(void)
 			}
 			#endif // SCROLLBACK_PATCH
 			#if SIXEL_PATCH
-			if (!IS_SET(MODE_ALTSCREEN)) {
+			for (im = term.images; im; im = next) {
-				for (im = term.images; im; im = im->next)
+				next = im->next;
-					im->should_delete |= (im->y * win.ch + im->height <= 0);
+				if (im->y < 0)
+					delete_image(im);
 			}
 			#endif // SIXEL_PATCH
 			break;
 		#if SIXEL_PATCH
 		case 6: /* sixels */
-			for (im = term.images; im; im = im->next)
+			tdeleteimages();
-				im->should_delete = 1;
+			tfulldirt();
 			break;
 		#endif // SIXEL_PATCH
 		default:
@@ -2321,9 +2405,35 @@ csihandle(void)
 			break;
 		}
 		break;
-	case 'S': /* SU -- Scroll <n> line up */
+	case 'S': /* SU -- Scroll <n> line up ; XTSMGRAPHICS */
-		if (csiescseq.priv)
+		if (csiescseq.priv) {
-			break;
+			#if SIXEL_PATCH
+			if (csiescseq.narg > 1) {
+				/* XTSMGRAPHICS */
+				pi = csiescseq.arg[0];
+				pa = csiescseq.arg[1];
+				if (pi == 1 && (pa == 1 || pa == 2 || pa == 4)) {
+					/* number of sixel color registers */
+					/* (read, reset and read the maximum value give the same response) */
+					n = snprintf(buffer, sizeof buffer, "\033[?1;0;%dS", DECSIXEL_PALETTE_MAX);
+					ttywrite(buffer, n, 1);
+					break;
+				} else if (pi == 2 && (pa == 1 || pa == 2 || pa == 4)) {
+					/* sixel graphics geometry (in pixels) */
+					/* (read, reset and read the maximum value give the same response) */
+					n = snprintf(buffer, sizeof buffer, "\033[?2;0;%d;%dS",
+					             MIN(term.col * win.cw, DECSIXEL_WIDTH_MAX),
+					             MIN(term.row * win.ch, DECSIXEL_HEIGHT_MAX));
+					ttywrite(buffer, n, 1);
+					break;
+				}
+				/* the number of color registers and sixel geometry can't be changed */
+				n = snprintf(buffer, sizeof buffer, "\033[?%d;3;0S", pi); /* failure */
+				ttywrite(buffer, n, 1);
+			}
+			#endif // SIXEL_PATCH
+			goto unknown;
+		}
 		DEFAULT(csiescseq.arg[0], 1);
 		#if SIXEL_PATCH && SCROLLBACK_PATCH
 		tscrollup(term.top, csiescseq.arg[0], 1);
@@ -2343,12 +2453,6 @@ csihandle(void)
 		break;
 	case 'l': /* RM -- Reset Mode */
 		tsetmode(csiescseq.priv, 0, csiescseq.arg, csiescseq.narg);
-		#if SIXEL_PATCH
-		if (IS_SET(MODE_ALTSCREEN)) {
-			for (im = term.images; im; im = im->next)
-				im->should_delete = 1;
-		}
-		#endif // SIXEL_PATCH
 		break;
 	case 'M': /* DL -- Delete <n> lines */
 		DEFAULT(csiescseq.arg[0], 1);
@@ -2404,9 +2508,27 @@ csihandle(void)
 	case 's': /* DECSC -- Save cursor position (ANSI.SYS) */
 		tcursor(CURSOR_SAVE);
 		break;
-	#if CSI_22_23_PATCH
+	#if CSI_22_23_PATCH | SIXEL_PATCH
-	case 't': /* title stack operations */
+	case 't': /* title stack operations ; XTWINOPS */
 		switch (csiescseq.arg[0]) {
+		#if SIXEL_PATCH
+		case 14: /* text area size in pixels */
+			if (csiescseq.narg > 1)
+				goto unknown;
+			n = snprintf(buffer, sizeof buffer, "\033[4;%d;%dt",
+			             term.row * win.ch, term.col * win.cw);
+			ttywrite(buffer, n, 1);
+			break;
+		case 16: /* character cell size in pixels */
+			n = snprintf(buffer, sizeof buffer, "\033[6;%d;%dt", win.ch, win.cw);
+			ttywrite(buffer, n, 1);
+			break;
+		case 18: /* size of the text area in characters */
+			n = snprintf(buffer, sizeof buffer, "\033[8;%d;%dt", term.row, term.col);
+			ttywrite(buffer, n, 1);
+			break;
+		#endif // SIXEL_PATCH
+		#if CSI_22_23_PATCH
 		case 22: /* pust current title on stack */
 			switch (csiescseq.arg[1]) {
 			case 0:
@@ -2429,11 +2551,12 @@ csihandle(void)
 				goto unknown;
 			}
 			break;
+		#endif // CSI_22_23_PATCH
 		default:
 			goto unknown;
 		}
 		break;
-	#endif // CSI_22_23_PATCH
+	#endif // CSI_22_23_PATCH | SIXEL_PATCH
 	case 'u': /* DECRC -- Restore cursor position (ANSI.SYS) */
 		tcursor(CURSOR_LOAD);
 		break;
@@ -2522,8 +2645,15 @@ strhandle(void)
 	char *p = NULL, *dec;
 	int j, narg, par;
 	#if SIXEL_PATCH
-	ImageList *new_image;
+	ImageList *im, *newimages, *next, *tail;
-	int i;
+	int i, x, y, x1, y1, x2, y2, numimages;
+	int cx, cy;
+	Line line;
+	#if SCROLLBACK_PATCH
+	int scr = IS_SET(MODE_ALTSCREEN) ? 0 : term.scr;
+	#else
+	int scr = 0;
+	#endif // SCROLLBACK_PATCH
 	#endif // SIXEL_PATCH
 
 	term.esc &= ~(ESC_STR_END|ESC_STR);
@@ -2650,35 +2780,69 @@ strhandle(void)
 		#if SIXEL_PATCH
 		if (IS_SET(MODE_SIXEL)) {
 			term.mode &= ~MODE_SIXEL;
-			new_image = malloc(sizeof(ImageList));
+			if (!sixel_st.image.data) {
-			memset(new_image, 0, sizeof(ImageList));
-			if (sixel_parser_finalize(&sixel_st, &new_image->pixels) != 0) {
-				perror("sixel_parser_finalize() failed");
 				sixel_parser_deinit(&sixel_st);
-				free(new_image);
 				return;
 			}
-			new_image->x = term.c.x;
+			cx = IS_SET(MODE_SIXEL_SDM) ? 0 : term.c.x;
-			new_image->y = term.c.y;
+			cy = IS_SET(MODE_SIXEL_SDM) ? 0 : term.c.y;
-			new_image->width = sixel_st.image.width;
+			if ((numimages = sixel_parser_finalize(&sixel_st, &newimages,
-			new_image->height = sixel_st.image.height;
+					cx, cy + scr, win.cw, win.ch)) <= 0) {
+				sixel_parser_deinit(&sixel_st);
+				perror("sixel_parser_finalize() failed");
+				return;
+			}
 			sixel_parser_deinit(&sixel_st);
-			if (term.images) {
+			x1 = newimages->x;
-				ImageList *im;
+			y1 = newimages->y;
-				for (im = term.images; im->next;)
+			x2 = x1 + newimages->cols;
-					im = im->next;
+			y2 = y1 + numimages;
-				im->next = new_image;
+			for (tail = NULL, im = term.images; im; im = next) {
-				new_image->prev = im;
+				next = im->next;
+				if (im->x >= x1 && im->x + im->cols <= x2 &&
+					im->y >= y1 && im->y <= y2) {
+					delete_image(im);
+					continue;
+				}
+				tail = im;
+			}
+			if (tail) {
+				tail->next = newimages;
+				newimages->prev = tail;
 			} else {
-				term.images = new_image;
+				term.images = newimages;
 			}
-			for (i = 0; i < (sixel_st.image.height + win.ch-1)/win.ch; ++i) {
+			x2 = MIN(x2, term.col);
-				int x;
+			for (i = 0, im = newimages; im; im = next, i++) {
-				tclearregion(term.c.x, term.c.y, term.c.x+(sixel_st.image.width+win.cw-1)/win.cw-1, term.c.y);
+				next = im->next;
-				for (x = term.c.x; x < MIN(term.col, term.c.x+(sixel_st.image.width+win.cw-1)/win.cw); x++)
+				#if SCROLLBACK_PATCH
-					term.line[term.c.y][x].mode |= ATTR_SIXEL;
+				scr = IS_SET(MODE_ALTSCREEN) ? 0 : term.scr;
-				tnewline(0);
+				#endif // SCROLLBACK_PATCH
+				if (IS_SET(MODE_SIXEL_SDM)) {
+					if (i >= term.row) {
+						delete_image(im);
+						continue;
+					}
+					im->y = i + scr;
+					line = term.line[i];
+				} else {
+					im->y = term.c.y + scr;
+					line = term.line[term.c.y];
+				}
+				for (x = im->x; x < x2; x++) {
+					line[x].u = ' ';
+					line[x].mode = ATTR_SIXEL;
+				}
+				term.dirty[MIN(im->y, term.row-1)] = 1;
+				if (!IS_SET(MODE_SIXEL_SDM) && i < numimages-1) {
+					im->next = NULL;
+					tnewline(0);
+					im->next = next;
+				}
 			}
+			/* if mode 8452 is set, sixel scrolling leaves cursor to right of graphic */
+			if (!IS_SET(MODE_SIXEL_SDM) && IS_SET(MODE_SIXEL_CUR_RT))
+				term.c.x = MIN(term.c.x + newimages->cols, term.col-1);
 		}
 		#endif // SIXEL_PATCH
 		#if SYNC_PATCH
@@ -3009,6 +3173,50 @@ tcontrolcode(uchar ascii)
 	term.esc &= ~(ESC_STR_END|ESC_STR);
 }
 
+#if SIXEL_PATCH
+void
+dcshandle(void)
+{
+	int bgcolor;
+	unsigned char r, g, b, a = 255;
+
+	switch (csiescseq.mode[0]) {
+	default:
+	unknown:
+		fprintf(stderr, "erresc: unknown csi ");
+		csidump();
+		/* die(""); */
+		break;
+	#if SYNC_PATCH
+	case '=':
+		/* https://gitlab.com/gnachman/iterm2/-/wikis/synchronized-updates-spec */
+		if (csiescseq.buf[2] == 's' && csiescseq.buf[1] == '1')
+			tsync_begin();  /* BSU */
+		else if (csiescseq.buf[2] == 's' && csiescseq.buf[1] == '2')
+			tsync_end();  /* ESU */
+		else
+			goto unknown;
+		break;
+	#endif // SYNC_PATCH
+	case 'q': /* DECSIXEL */
+		if (IS_TRUECOL(term.c.attr.bg)) {
+			r = term.c.attr.bg >> 16 & 255;
+			g = term.c.attr.bg >> 8 & 255;
+			b = term.c.attr.bg >> 0 & 255;
+		} else {
+			xgetcolor(term.c.attr.bg, &r, &g, &b);
+			if (term.c.attr.bg == defaultbg)
+				a = dc.col[defaultbg].pixel >> 24 & 255;
+		}
+		bgcolor = a << 24 | r << 16 | g << 8 | b;
+		if (sixel_parser_init(&sixel_st, (255 << 24), bgcolor, 1, win.cw, win.ch) != 0)
+			perror("sixel_parser_init() failed");
+		term.mode |= MODE_SIXEL;
+		break;
+	}
+}
+#endif // SIXEL_PATCH
+
 /*
  * returns 1 when the sequence is finished and it hasn't to read
  * more characters for this sequence, otherwise 0
@@ -3123,11 +3331,7 @@ tputc(Rune u)
 	Glyph *gp;
 
 	control = ISCONTROL(u);
-	#if SIXEL_PATCH
-	if (u < 127 || !IS_SET(MODE_UTF8 | MODE_SIXEL))
-	#else
 	if (u < 127 || !IS_SET(MODE_UTF8))
-	#endif // SIXEL_PATCH
 	{
 		c[0] = u;
 		width = len = 1;
@@ -3159,11 +3363,6 @@ tputc(Rune u)
 		}
 
 		#if SIXEL_PATCH
-		if (IS_SET(MODE_SIXEL)) {
-			if (sixel_parser_parse(&sixel_st, (unsigned char *)&u, 1) != 0)
-				perror("sixel_parser_parse() failed");
-			return;
-		}
 		if (term.esc & ESC_DCS)
 			goto check_control_code;
 		#endif // SIXEL_PATCH
@@ -3310,7 +3509,10 @@ twrite(const char *buf, int buflen, int show_ctrl)
 
 	for (n = 0; n < buflen; n += charsize) {
 		#if SIXEL_PATCH
-		if (IS_SET(MODE_UTF8) && !IS_SET(MODE_SIXEL))
+		if (IS_SET(MODE_SIXEL) && sixel_st.state != PS_ESC) {
+			charsize = sixel_parser_parse(&sixel_st, (const unsigned char*)buf + n, buflen - n);
+			continue;
+		} else if (IS_SET(MODE_UTF8))
 		#else
 		if (IS_SET(MODE_UTF8))
 		#endif // SIXEL_PATCH
@@ -3344,6 +3546,7 @@ twrite(const char *buf, int buflen, int show_ctrl)
 	return n;
 }
 
+#if VIM_BROWSE_PATCH
 void
 tresize(int col, int row)
 {
@@ -3371,6 +3574,11 @@ tresize(int col, int row)
 	#endif // VIM_BROWSE_PATCH
 	int *bp;
 	TCursor c;
+	#if SIXEL_PATCH
+	int x, x2;
+	Line line;
+	ImageList *im, *next;
+	#endif // SIXEL_PATCH
 
 	#if KEYBOARDSELECT_PATCH
 	if ( row < term.row  || col < term.col )
@@ -3514,7 +3722,213 @@ tresize(int col, int row)
 		tcursor(CURSOR_LOAD);
 	}
 	term.c = c;
+
+	#if SIXEL_PATCH
+	/* expand images into new text cells to prevent them from being deleted in
+	 * xfinishdraw() that draws the images */
+	for (i = 0; i < 2; i++) {
+		for (im = term.images; im; im = next) {
+			next = im->next;
+			#if SCROLLBACK_PATCH
+			if (IS_SET(MODE_ALTSCREEN)) {
+				if (im->y < 0 || im->y >= term.row) {
+					delete_image(im);
+					continue;
+				}
+				line = term.line[im->y];
+			} else {
+				if (im->y - term.scr < -HISTSIZE || im->y - term.scr >= term.row) {
+					delete_image(im);
+					continue;
+				}
+				line = TLINE(im->y);
+			}
+			#else
+			if (im->y < 0 || im->y >= term.row) {
+				delete_image(im);
+				continue;
+			}
+			line = term.line[im->y];
+			#endif // SCROLLBACK_PATCH
+			x2 = MIN(im->x + im->cols, term.col);
+			for (x = im->x; x < x2; x++) {
+				line[x].u = ' ';
+				line[x].mode = ATTR_SIXEL;
+			}
+		}
+		tswapscreen();
+	}
+	#endif // SIXEL_PATCH
 }
+#else // !VIM_BROWSE_PATCH
+void
+tresize(int col, int row)
+{
+	int i, j;
+	#if COLUMNS_PATCH
+	int tmp = col;
+	int minrow, mincol;
+
+	if (!term.maxcol)
+		term.maxcol = term.col;
+	col = MAX(col, term.maxcol);
+	minrow = MIN(row, term.row);
+	mincol = MIN(col, term.maxcol);
+	#else
+	int minrow = MIN(row, term.row);
+	int mincol = MIN(col, term.col);
+	#endif // COLUMNS_PATCH
+	int *bp;
+	#if SIXEL_PATCH
+	int x, x2;
+	Line line;
+	ImageList *im, *next;
+	#endif // SIXEL_PATCH
+
+	#if KEYBOARDSELECT_PATCH
+	if ( row < term.row  || col < term.col )
+		toggle_winmode(trt_kbdselect(XK_Escape, NULL, 0));
+	#endif // KEYBOARDSELECT_PATCH
+
+	if (col < 1 || row < 1) {
+		fprintf(stderr,
+		        "tresize: error resizing to %dx%d\n", col, row);
+		return;
+	}
+
+	#if VIM_BROWSE_PATCH
+	if (alt)
+		tswapscreen();
+	#endif // VIM_BROWSE_PATCH
+
+	/* scroll both screens independently */
+	if (row < term.row) {
+		tcursor(CURSOR_SAVE);
+		tsetscroll(0, term.row - 1);
+		for (i = 0; i < 2; i++) {
+			if (term.c.y >= row) {
+				#if SCROLLBACK_PATCH
+				tscrollup(0, term.c.y - row + 1, !IS_SET(MODE_ALTSCREEN));
+				#else
+				tscrollup(0, term.c.y - row + 1);
+				#endif // SCROLLBACK_PATCH
+			}
+			for (j = row; j < term.row; j++)
+				free(term.line[j]);
+			tswapscreen();
+			tcursor(CURSOR_LOAD);
+		}
+	}
+
+	/* resize to new height */
+	term.line = xrealloc(term.line, row * sizeof(Line));
+	term.alt  = xrealloc(term.alt,  row * sizeof(Line));
+	term.dirty = xrealloc(term.dirty, row * sizeof(*term.dirty));
+	term.tabs = xrealloc(term.tabs, col * sizeof(*term.tabs));
+
+	#if SCROLLBACK_PATCH
+	Glyph gc=(Glyph){.bg=term.c.attr.bg, .fg=term.c.attr.fg, .u=' ', .mode=0};
+	for (i = 0; i < HISTSIZE; i++) {
+		term.hist[i] = xrealloc(term.hist[i], col * sizeof(Glyph));
+		for (j = mincol; j < col; j++)
+			term.hist[i][j] = gc;
+	}
+	#endif // SCROLLBACK_PATCH
+
+	/* resize each row to new width, zero-pad if needed */
+	for (i = 0; i < minrow; i++) {
+		term.line[i] = xrealloc(term.line[i], col * sizeof(Glyph));
+		term.alt[i]  = xrealloc(term.alt[i],  col * sizeof(Glyph));
+	}
+
+	/* allocate any new rows */
+	for (/* i = minrow */; i < row; i++) {
+		term.line[i] = xmalloc(col * sizeof(Glyph));
+		term.alt[i] = xmalloc(col * sizeof(Glyph));
+	}
+	#if COLUMNS_PATCH
+	if (col > term.maxcol)
+	#else
+	if (col > term.col)
+	#endif // COLUMNS_PATCH
+	{
+		#if COLUMNS_PATCH
+		bp = term.tabs + term.maxcol;
+		memset(bp, 0, sizeof(*term.tabs) * (col - term.maxcol));
+		#else
+		bp = term.tabs + term.col;
+		memset(bp, 0, sizeof(*term.tabs) * (col - term.col));
+		#endif // COLUMNS_PATCH
+
+		while (--bp > term.tabs && !*bp)
+			/* nothing */ ;
+		for (bp += tabspaces; bp < term.tabs + col; bp += tabspaces)
+			*bp = 1;
+	}
+
+	/* update terminal size */
+	#if COLUMNS_PATCH
+	term.col = tmp;
+	term.maxcol = col;
+	#else
+	term.col = col;
+	#endif // COLUMNS_PATCH
+	term.row = row;
+
+	/* reset scrolling region */
+	tsetscroll(0, row-1);
+	/* Clearing both screens (it makes dirty all lines) */
+	for (i = 0; i < 2; i++) {
+		tmoveto(term.c.x, term.c.y);  /* make use of the LIMIT in tmoveto */
+		tcursor(CURSOR_SAVE);
+		if (mincol < col && 0 < minrow) {
+			tclearregion(mincol, 0, col - 1, minrow - 1);
+		}
+		if (0 < col && minrow < row) {
+			tclearregion(0, minrow, col - 1, row - 1);
+		}
+		tswapscreen();
+		tcursor(CURSOR_LOAD);
+	}
+
+	#if SIXEL_PATCH
+	/* expand images into new text cells to prevent them from being deleted in
+	 * xfinishdraw() that draws the images */
+	for (i = 0; i < 2; i++) {
+		for (im = term.images; im; im = next) {
+			next = im->next;
+			#if SCROLLBACK_PATCH
+			if (IS_SET(MODE_ALTSCREEN)) {
+				if (im->y < 0 || im->y >= term.row) {
+					delete_image(im);
+					continue;
+				}
+				line = term.line[im->y];
+			} else {
+				if (im->y - term.scr < -HISTSIZE || im->y - term.scr >= term.row) {
+					delete_image(im);
+					continue;
+				}
+				line = TLINE(im->y);
+			}
+			#else
+			if (im->y < 0 || im->y >= term.row) {
+				delete_image(im);
+				continue;
+			}
+			line = term.line[im->y];
+			#endif // SCROLLBACK_PATCH
+			x2 = MIN(im->x + im->cols, term.col);
+			for (x = im->x; x < x2; x++) {
+				line[x].u = ' ';
+				line[x].mode = ATTR_SIXEL;
+			}
+		}
+		tswapscreen();
+	}
+	#endif // SIXEL_PATCH
+}
+#endif // VIM_BROWSE_PATCH
 
 void
 resettitle(void)

st.h

@@ -1,6 +1,7 @@
 /* See LICENSE for license details. */
 
 #include <stdint.h>
+#include <time.h>
 #include <sys/types.h>
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
@@ -79,7 +80,9 @@ typedef struct _ImageList {
 	int height;
 	int x;
 	int y;
-	int should_delete;
+	int cols;
+	int cw;
+	int ch;
 } ImageList;
 #endif // SIXEL_PATCH
 

x.c

@@ -27,6 +27,11 @@ char *argv0;
 #include <X11/Xcursor/Xcursor.h>
 #endif // THEMED_CURSOR_PATCH
 
+#if SIXEL_PATCH
+#include <Imlib2.h>
+#include "sixel.h"
+#endif // SIXEL_PATCH
+
 #if UNDERCURL_PATCH
 /* Undercurl slope types */
 enum undercurl_slope_type {
@@ -282,17 +287,36 @@ zoom(const Arg *arg)
 	Arg larg;
 
 	larg.f = usedfontsize + arg->f;
+	#if SIXEL_PATCH
+	if (larg.f >= 1.0)
+		zoomabs(&larg);
+	#else
 	zoomabs(&larg);
+	#endif // SIXEL_PATCH
 }
 
 void
 zoomabs(const Arg *arg)
 {
+	#if SIXEL_PATCH
+	ImageList *im;
+	#endif // SIXEL_PATCH
+
 	xunloadfonts();
 	xloadfonts(usedfont, arg->f);
 	#if FONT2_PATCH
 	xloadsparefonts();
 	#endif // FONT2_PATCH
+
+	#if SIXEL_PATCH
+	/* deleting old pixmaps forces the new scaled pixmaps to be created */
+	for (im = term.images; im; im = im->next) {
+		if (im->pixmap)
+			XFreePixmap(xw.dpy, (Drawable)im->pixmap);
+		im->pixmap = NULL;
+	}
+	#endif // SIXEL_PATCH
+
 	cresize(0, 0);
 	redraw();
 	xhints();
@@ -850,7 +874,7 @@ cresize(int width, int height)
 
 	col = (win.w - 2 * borderpx) / win.cw;
 	row = (win.h - 2 * borderpx) / win.ch;
-	col = MAX(1, col);
+	col = MAX(2, col);
 	row = MAX(1, row);
 
 	#if ANYSIZE_PATCH
@@ -2981,71 +3005,121 @@ xfinishdraw(void)
 {
 	#if SIXEL_PATCH
 	ImageList *im, *next;
+	Imlib_Image origin, scaled;
 	XGCValues gcvalues;
 	GC gc;
+	int width, height;
+	int x, x2, del;
+	Line line;
 	#endif // SIXEL_PATCH
 
 	#if SIXEL_PATCH
 	for (im = term.images; im; im = next) {
-		/* get the next image here, because delete_image() will delete the current image */
 		next = im->next;
 
-		if (im->should_delete) {
+		/* do not draw or process the image, if it is not visible */
-			delete_image(im);
+		if (im->x >= term.col || im->y >= term.row || im->y < 0)
 			continue;
-		}
 
+		/* scale the image */
+		width = im->width * win.cw / im->cw;
+		height = im->height * win.ch / im->ch;
 		if (!im->pixmap) {
-			im->pixmap = (void *)XCreatePixmap(xw.dpy, xw.win, im->width, im->height,
+			im->pixmap = (void *)XCreatePixmap(xw.dpy, xw.win, width, height,
 				#if ALPHA_PATCH
 				xw.depth
 				#else
 				DefaultDepth(xw.dpy, xw.scr)
 				#endif // ALPHA_PATCH
 			);
-			XImage ximage = {
+			if (win.cw == im->cw && win.ch == im->ch) {
-				.format = ZPixmap,
+				XImage ximage = {
-				.data = (char *)im->pixels,
+					.format = ZPixmap,
-				.width = im->width,
+					.data = (char *)im->pixels,
-				.height = im->height,
+					.width = im->width,
-				.xoffset = 0,
+					.height = im->height,
-				.byte_order = LSBFirst,
+					.xoffset = 0,
-				.bitmap_bit_order = MSBFirst,
+					.byte_order = sixelbyteorder,
-				.bits_per_pixel = 32,
+					.bitmap_bit_order = MSBFirst,
-				.bytes_per_line = im->width * 4,
+					.bits_per_pixel = 32,
-				.bitmap_unit = 32,
+					.bytes_per_line = im->width * 4,
-				.bitmap_pad = 32,
+					.bitmap_unit = 32,
-				#if ALPHA_PATCH
+					.bitmap_pad = 32,
-				.depth = xw.depth
+					#if ALPHA_PATCH
-				#else
+					.depth = xw.depth
-				.depth = 24
+					#else
-				#endif // ALPHA_PATCH
+					.depth = 24
-			};
+					#endif // ALPHA_PATCH
-			XPutImage(xw.dpy, (Drawable)im->pixmap, dc.gc, &ximage, 0, 0, 0, 0, im->width, im->height);
+				};
-			free(im->pixels);
+				XPutImage(xw.dpy, (Drawable)im->pixmap, dc.gc, &ximage, 0, 0, 0, 0, width, height);
-			im->pixels = NULL;
+			} else {
+				origin = imlib_create_image_using_data(im->width, im->height, (DATA32 *)im->pixels);
+				if (!origin)
+					continue;
+				imlib_context_set_image(origin);
+				imlib_image_set_has_alpha(1);
+				scaled = imlib_create_cropped_scaled_image(0, 0, im->width, im->height, width, height);
+				imlib_free_image_and_decache();
+				if (!scaled)
+					continue;
+				imlib_context_set_image(scaled);
+				imlib_image_set_has_alpha(1);
+				XImage ximage = {
+					.format = ZPixmap,
+					.data = (char *)imlib_image_get_data_for_reading_only(),
+					.width = width,
+					.height = height,
+					.xoffset = 0,
+					.byte_order = sixelbyteorder,
+					.bitmap_bit_order = MSBFirst,
+					.bits_per_pixel = 32,
+					.bytes_per_line = width * 4,
+					.bitmap_unit = 32,
+					.bitmap_pad = 32,
+					#if ALPHA_PATCH
+					.depth = xw.depth
+					#else
+					.depth = 24
+					#endif // ALPHA_PATCH
+				};
+				XPutImage(xw.dpy, (Drawable)im->pixmap, dc.gc, &ximage, 0, 0, 0, 0, width, height);
+				imlib_free_image_and_decache();
+			}
 		}
 
+		/* clip the image so it does not go over to borders */
+		x2 = MIN(im->x + im->cols, term.col);
+		width = MIN(width, (x2 - im->x) * win.cw);
+
+		/* delete the image if the text cells behind it have been changed */
+		#if SCROLLBACK_PATCH
+		line = TLINE(im->y);
+		#else
+		line = term.line[im->y];
+		#endif // SCROLLBACK_PATCH
+		for (del = 0, x = im->x; x < x2; x++) {
+			if ((del = !(line[x].mode & ATTR_SIXEL)))
+				break;
+		}
+		if (del) {
+			delete_image(im);
+			continue;
+		}
+
+		/* draw the image */
 		memset(&gcvalues, 0, sizeof(gcvalues));
 		gcvalues.graphics_exposures = False;
 		gc = XCreateGC(xw.dpy, xw.win, GCGraphicsExposures, &gcvalues);
-
+		XCopyArea(xw.dpy, (Drawable)im->pixmap, xw.buf, gc, 0, 0,
-		#if ANYSIZE_PATCH
+		    width, height, borderpx + im->x * win.cw, borderpx + im->y * win.ch);
-		XCopyArea(xw.dpy, (Drawable)im->pixmap, xw.buf, gc, 0, 0, im->width, im->height, win.hborderpx + im->x * win.cw, win.vborderpx + im->y * win.ch);
-		#else
-		XCopyArea(xw.dpy, (Drawable)im->pixmap, xw.buf, gc, 0, 0, im->width, im->height, borderpx + im->x * win.cw, borderpx + im->y * win.ch);
-		#endif // ANYSIZE_PATCH
 		XFreeGC(xw.dpy, gc);
-
 	}
 	#endif // SIXEL_PATCH
 
 	#if !SINGLE_DRAWABLE_BUFFER_PATCH
 	XCopyArea(xw.dpy, xw.buf, xw.win, dc.gc, 0, 0, win.w, win.h, 0, 0);
 	#endif // SINGLE_DRAWABLE_BUFFER_PATCH
-	XSetForeground(xw.dpy, dc.gc,
+	XSetForeground(xw.dpy, dc.gc, dc.col[IS_SET(MODE_REVERSE) ? defaultfg : defaultbg].pixel);
-			dc.col[IS_SET(MODE_REVERSE)?
-				defaultfg : defaultbg].pixel);
 }
 
 void