Adding sixel support ref. #7

Makefile

@@ -8,7 +8,10 @@ include config.mk
 #LIGATURES_C = hb.c
 #LIGATURES_H = hb.h
 
-SRC = st.c x.c $(LIGATURES_C)
+# Uncomment this for the SIXEL patch / SIXEL_PATCH
+#SIXEL_C = sixel.c sixel_hls.c
+
+SRC = st.c x.c $(LIGATURES_C) $(SIXEL_C)
 OBJ = $(SRC:.c=.o)
 
 all: options st

README.md

@@ -15,6 +15,8 @@ Refer to [https://st.suckless.org/](https://st.suckless.org/) for details on the
 
 ### Changelog:
 
+2021-03-10 - Added sixel support
+
 2021-02-26 - Added the dynamic cursor color patch
 
 2021-02-15 - Added the alpha gradient patch
@@ -145,6 +147,9 @@ Refer to [https://st.suckless.org/](https://st.suckless.org/) for details on the
    - [scrollback](https://st.suckless.org/patches/scrollback/)
       - allows you scroll back through terminal output using keyboard shortcuts or mousewheel
 
+   - sixel
+      - this patch adds SIXEL graphics support
+
    - st-embedder
       - this patch allows clients to embed into the st window and can be useful if you tend to start X applications from the terminal
       - the behavior is similar to Plan 9 where applications can take over windows

config.mk

@@ -13,7 +13,7 @@ X11LIB = /usr/X11R6/lib
 PKG_CONFIG = pkg-config
 
 # Uncomment this for the alpha patch / ALPHA_PATCH
-XRENDER = -lXrender
+#XRENDER = -lXrender
 
 # Uncomment this for the themed cursor patch / THEMED_CURSOR_PATCH
 #XCURSOR = -lXcursor

patch/sixel_st.c

@@ -0,0 +1,18 @@
+sixel_state_t sixel_st;
+
+void
+dcshandle(void)
+{
+	switch (csiescseq.mode[0]) {
+	default:
+		fprintf(stderr, "erresc: unknown csi ");
+		csidump();
+		/* die(""); */
+		break;
+	case 'q': /* DECSIXEL */
+		if (sixel_parser_init(&sixel_st, 0, 0 << 16 | 0 << 8 | 0, 1, win.cw, win.ch) != 0)
+			perror("sixel_parser_init() failed");
+		term.mode |= MODE_SIXEL;
+		break;
+	}
+}

patch/sixel_st.h

@@ -0,0 +1 @@
+static void dcshandle(void);

patch/sixel_x.c

@@ -0,0 +1,14 @@
+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

@@ -19,4 +19,7 @@
 #endif
 #if SCROLLBACK_PATCH || SCROLLBACK_MOUSE_PATCH || SCROLLBACK_MOUSE_ALTSCREEN_PATCH
 #include "scrollback.c"
+#endif
+#if SIXEL_PATCH
+#include "sixel_st.c"
 #endif

patch/st_include.h

@@ -19,4 +19,7 @@
 #endif
 #if SCROLLBACK_PATCH || SCROLLBACK_MOUSE_PATCH || SCROLLBACK_MOUSE_ALTSCREEN_PATCH
 #include "scrollback.h"
+#endif
+#if SIXEL_PATCH
+#include "sixel_st.h"
 #endif

patch/x_include.c

@@ -20,6 +20,9 @@
 #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

patches.def.h

@@ -208,6 +208,26 @@
  */
 #define SINGLE_DRAWABLE_BUFFER_PATCH 0
 
+/* This patch adds SIXEL graphics support for st.
+ * Note that patch/sixel.c/sixel_hls.c come from mintty, licensed under GPL.
+ * Known issues:
+ *    - Entering clear causes all sixels to be deleted from scrollback.
+ *    - Rendering sixel graphics may cause unusual cursor placement, this is
+ *      not specific to this variant of st - the same issue is present in
+ *      the xterm implementation. This is likely an issue of sixel height
+ *      not being detected correctly.
+ *    - If combined with the alpha patch sixel graphics disappear (become white)
+ *      when transparent and rendered against a white background. This is believed
+ *      to be related to how the sixel graphics use RGB colors instead of RGBA.
+ *      A pull request or instructions for how to properly add alpha support for
+ *      sixel graphics would be very welcome.
+ *
+ * Note that you need to uncomment the corresponding lines in Makefile when including this patch.
+ *
+ * https://gist.github.com/saitoha/70e0fdf22e3e8f63ce937c7f7da71809
+ */
+#define SIXEL_PATCH 0
+
 /* This patch allows clients to embed into the st window and is useful if you tend to
  * start X applications from the terminal. For example:
  *