From 9f3ce9236f9818263437cb6a4f26b20c5506a218 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Fri, 3 Mar 2023 17:21:11 +0100
Subject: [PATCH] =?UTF-8?q?config:=20apply=20fontconfig=20rules=20if=20use?=
 =?UTF-8?q?r=20didn=E2=80=99t=20set=20an=20explicit=20font=20size?=
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If the user didn’t explicitly set the font size (e.g. font=monospace,
instead of font=monospace:size=12), our initial attempt to read the
FC_SIZE and FC_PIXEL_SIZE attributes will fail, and we used to
fallback to setting the size to 8pt.

Change this slightly, so that when we fail to read the FC_*_SIZE
attributes, apply the fontconfig rules, but *without expanding*
them (i.e. without calling FcDefaultSubstitute()).

Then try reading FC_*_SIZE again.

If that too fails, _then_ set size to 8pt. This allows us to pick up
rules that set a default {pixel}size:

    <fontconfig>
      <match>
        <edit name="pixelsize" mode="append"><double>14</double></edit>
    </fontconfig>

Closes #1287
---
 CHANGELOG.md |  4 ++++
 config.c     | 40 ++++++++++++++++++++++++++++++++++------
 2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 40072182..08d7d69f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -81,10 +81,14 @@
 * DPI is now forced to 96 when found to be unreasonably high.
 * Set default log level to warning ([#1215][1215]).
 * Default `grapheme-width-method` from `wcswidth` to `double-width`.
+* When determining initial font size, do FontConfig config
+  substitution if the user-provided font pattern has no {pixel}size
+  option ([#1287][1287]).
 
 [1166]: https://codeberg.org/dnkl/foot/issues/1166
 [1179]: https://codeberg.org/dnkl/foot/issues/1179
 [1215]: https://codeberg.org/dnkl/foot/pulls/1215
+[1287]: https://codeberg.org/dnkl/foot/issues/1287
 
 
 ### Deprecated
diff --git a/config.c b/config.c
index d77b50b8..2ede1aa5 100644
--- a/config.c
+++ b/config.c
@@ -3390,20 +3390,48 @@ config_font_parse(const char *pattern, struct config_font *font)
     if (pat == NULL)
         return false;
 
+    /*
+     * First look for user specified {pixel}size option
+     * e.g. “font-name:size=12”
+     */
+
     double pt_size = -1.0;
-    FcPatternGetDouble(pat, FC_SIZE, 0, &pt_size);
-    FcPatternRemove(pat, FC_SIZE, 0);
+    FcResult have_pt_size = FcPatternGetDouble(pat, FC_SIZE, 0, &pt_size);
 
     int px_size = -1;
-    FcPatternGetInteger(pat, FC_PIXEL_SIZE, 0, &px_size);
-    FcPatternRemove(pat, FC_PIXEL_SIZE, 0);
+    FcResult have_px_size = FcPatternGetInteger(pat, FC_PIXEL_SIZE, 0, &px_size);
 
-    if (pt_size == -1. && px_size == -1)
-        pt_size = 8.0;
+    if (have_pt_size != FcResultMatch && have_px_size != FcResultMatch) {
+        /*
+         * Apply fontconfig config. Can’t do that until we’ve first
+         * checked for a user provided size, since we may end up with
+         * both “size” and “pixelsize” being set, and we don’t know
+         * which one takes priority.
+         */
+        FcPattern *pat_copy = FcPatternDuplicate(pat);
+        if (pat_copy == NULL ||
+            !FcConfigSubstitute(NULL, pat_copy, FcMatchPattern))
+        {
+            LOG_WARN("%s: failed to do config substitution", pattern);
+        } else {
+            have_pt_size = FcPatternGetDouble(pat_copy, FC_SIZE, 0, &pt_size);
+            have_px_size = FcPatternGetInteger(pat_copy, FC_PIXEL_SIZE, 0, &px_size);
+        }
+
+        FcPatternDestroy(pat_copy);
+
+        if (have_pt_size != FcResultMatch && have_px_size != FcResultMatch)
+            pt_size = 8.0;
+    }
+
+    FcPatternRemove(pat, FC_SIZE, 0);
+    FcPatternRemove(pat, FC_PIXEL_SIZE, 0);
 
     char *stripped_pattern = (char *)FcNameUnparse(pat);
     FcPatternDestroy(pat);
 
+    LOG_DBG("%s: pt-size=%.2f, px-size=%d", stripped_pattern, pt_size, px_size);
+
     *font = (struct config_font){
         .pattern = stripped_pattern,
         .pt_size = pt_size,