config: add tweak.grapheme-width-method=max

‘max’ is a new value for ‘tweak.grapheme-width-method’. When enabled,
the width of a grapheme cluster is that of the cluster’s widest
codepoint.

CHANGELOG.md

@@ -35,7 +35,12 @@
 
 
 ## Unreleased
+
 ### Added
+
+* New value, `max`, for `[tweak].grapheme-width-method`.
+
+
 ### Changed
 ### Deprecated
 ### Removed

config.c

@@ -2248,7 +2248,7 @@ parse_section_tweak(struct context *ctx)
 
         return value_to_enum(
             ctx,
-            (const char *[]){"wcswidth", "double-width", NULL},
+            (const char *[]){"wcswidth", "double-width", "max", NULL},
             (int *)&conf->tweak.grapheme_width_method);
     }
 

config.h

@@ -256,7 +256,11 @@ struct config {
         enum fcft_scaling_filter fcft_filter;
         bool overflowing_glyphs;
         bool grapheme_shaping;
-        enum {GRAPHEME_WIDTH_WCSWIDTH, GRAPHEME_WIDTH_DOUBLE} grapheme_width_method;
+        enum {
+            GRAPHEME_WIDTH_WCSWIDTH,
+            GRAPHEME_WIDTH_DOUBLE,
+            GRAPHEME_WIDTH_MAX,
+        } grapheme_width_method;
         bool render_timer_osd;
         bool render_timer_log;
         bool damage_whole_window;

doc/foot.ini.5.scd

@@ -1093,7 +1093,7 @@ any of these options.
 *grapheme-width-method*
 	Selects which method to use when calculating the width
 	(i.e. number of columns) of a grapheme cluster. One of
-	*double-width* and *wcswidth*.
+	*wcswidth*, *double-width* and *max*.
 	
 	*wcswidth* simply adds together the individual width of all
 	codepoints making up the cluster.
@@ -1104,6 +1104,8 @@ any of these options.
 	internally to calculate the width. This results in cursor
 	de-synchronization issues.
 	
+	*max* uses the width of the largest codepoint in the cluster.
+	
 	Default: _wcswidth_
 
 *font-monospace-warn*

vt.c

@@ -792,6 +792,10 @@ action_utf8_print(struct terminal *term, wchar_t wc)
                 composed != NULL ? composed->width : base_width;
 
             switch (term->conf->tweak.grapheme_width_method) {
+            case GRAPHEME_WIDTH_MAX:
+                new_cc->width = max(grapheme_width, width);
+                break;
+
             case GRAPHEME_WIDTH_DOUBLE:
                 if (unlikely(wc == 0xfe0f))
                     width = 2;