From 4c954be7a6d86b21da512fc533eb3362ac737221 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Mon, 31 May 2021 17:10:05 +0200
Subject: [PATCH] config: add boolean option tweak.pua-double-width

When enabled, PUA (Private Usage Area) codepoints are always treated
as double-width glyphs, regardless of the actual glyph width.

Requires allow-overflowing-double-width-glyphs=yes
---
 CHANGELOG.md       |  3 +++
 config.c           |  7 +++++++
 config.h           |  1 +
 doc/foot.ini.5.scd | 14 +++++++++++++-
 render.c           | 18 +++++++++++-------
 5 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d8e604a..5fe9b236 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,6 +57,9 @@
   (https://codeberg.org/dnkl/foot/issues/555).
 * `ENVIRONMENT` section in **foot**(1) and **footclient**(1) man pages
   (https://codeberg.org/dnkl/foot/issues/556).
+* `tweak.pua-double-width` option to `foot.ini`, letting you force
+  _Private Usage Area_ codepoints to be treated as double-width
+  characters.
 
 
 ### Changed
diff --git a/config.c b/config.c
index 92ef0c99..17d6ce5f 100644
--- a/config.c
+++ b/config.c
@@ -2005,6 +2005,12 @@ parse_section_tweak(
             LOG_WARN("tweak: disabled overflowing double-width glyphs");
     }
 
+    else if (strcmp(key, "pua-double-width") == 0) {
+        conf->tweak.pua_double_width = str_to_bool(value);
+        if (conf->tweak.pua_double_width)
+            LOG_WARN("tweak: PUA double width glyphs enabled");
+    }
+
     else if (strcmp(key, "damage-whole-window") == 0) {
         conf->tweak.damage_whole_window = str_to_bool(value);
         if (conf->tweak.damage_whole_window)
@@ -2573,6 +2579,7 @@ config_load(struct config *conf, const char *conf_path,
             .damage_whole_window = false,
             .box_drawing_base_thickness = 0.04,
             .box_drawing_solid_shades = true,
+            .pua_double_width = false,
         },
 
         .notifications = tll_init(),
diff --git a/config.h b/config.h
index 95083e6c..f5e20879 100644
--- a/config.h
+++ b/config.h
@@ -237,6 +237,7 @@ struct config {
         off_t max_shm_pool_size;
         float box_drawing_base_thickness;
         bool box_drawing_solid_shades;
+        bool pua_double_width;
     } tweak;
 
     user_notifications_t notifications;
diff --git a/doc/foot.ini.5.scd b/doc/foot.ini.5.scd
index d9b61c39..e434c84b 100644
--- a/doc/foot.ini.5.scd
+++ b/doc/foot.ini.5.scd
@@ -826,7 +826,7 @@ any of these options.
 	Default: _lanczos3_.
 
 *allow-overflowing-double-width-glyphs*
-	Boolean. when enabled, double width glyphs with a character width
+	Boolean. When enabled, double width glyphs with a character width
 	of 1 are allowed to overflow into the neighbouring cell.
 	
 	One use case for this is fonts "icon" characters in the Unicode
@@ -839,8 +839,20 @@ any of these options.
 	Note: this feature uses _heuristics_ to determine *which* glyphs
 	should be allowed to overflow.
 	
+	See also: *pua-double-width*
+	
 	Default: _yes_.
 
+*pua-double-width*
+	Boolean. When enabled, Unicode code points from the private usage
+	area (PUA) are always considered to be double width, regardless of
+	the actual glyph width.
+	
+	Ignored if *allow-overflowing-double-width-glyphs* has been
+	disabled.
+	
+	Default: _no_.
+
 *render-timer*
 	Enables a frame rendering timer, that prints the time it takes to
 	render each frame, in microseconds, either on-screen, to stderr,
diff --git a/render.c b/render.c
index 5ca64738..d66058c8 100644
--- a/render.c
+++ b/render.c
@@ -499,9 +499,9 @@ render_cell(struct terminal *term, pixman_image_t *pix,
     const struct fcft_glyph *glyph = NULL;
     const struct composed *composed = NULL;
 
-    if (cell->wc != 0) {
-        wchar_t base = cell->wc;
+    wchar_t base = cell->wc;
 
+    if (base != 0) {
         if (base >= CELL_COMB_CHARS_LO &&
             base < (CELL_COMB_CHARS_LO + term->composed_count))
         {
@@ -576,11 +576,15 @@ render_cell(struct terminal *term, pixman_image_t *pix,
      *  - *this* cells is followed by an empty cell, or a space
      */
     if (term->conf->tweak.allow_overflowing_double_width_glyphs &&
-        glyph != NULL &&
-        glyph->cols == 1 &&
-        glyph->width >= term->cell_width * 15 / 10 &&
-        glyph->width < 3 * term->cell_width &&
-        col < term->cols - 1 &&
+        ((glyph != NULL &&
+          glyph->cols == 1 &&
+          glyph->width >= term->cell_width * 15 / 10 &&
+          glyph->width < 3 * term->cell_width &&
+          col < term->cols - 1) ||
+         (term->conf->tweak.pua_double_width &&
+          ((base >= 0x00e000 && base <= 0x00f8ff) ||
+           (base >= 0x0f0000 && base <= 0x0ffffd) ||
+           (base >= 0x100000 && base <= 0x10fffd)))) &&
         (row->cells[col + 1].wc == 0 || row->cells[col + 1].wc == L' '))
     {
         cell_cols = 2;