config: add inheritable option “font-shaping”

This patch adds an inheritable option, “font-shaping”, that controls
whether a particle that renders text should enable font-shaping or
not.

The option works similar to the ‘font’ option: one can set it at the
top-level, and it gets inherited down through all modules and to their
particles.

Or, you can set it on a module and it gets inherited to all its
particles, but not to other modules’ particles.

Finally, you can set it on individual particles, in which case it only
applies to them (or “child” particles).

When font-shaping is enabled (the default), the string particle shapes
full text runs using the fcft_rasterize_text_run_utf32() API. In fcft,
this results in HarfBuzz being used to shape the string.

When disabled, the string particle instead uses the simpler
fcft_rasterize_char_utf32() API, which rasterizes individual
characters.

This gives user greater control over the font rendering. One example
is bitmap fonts, which HarfBuzz often doesn’t get right.

Closes #159

config.c

@@ -101,6 +101,44 @@ conf_to_font(const struct yml_node *node)
     return ret;
 }
 
+enum font_shaping
+conf_to_font_shaping(const struct yml_node *node)
+{
+    const char *v = yml_value_as_string(node);
+
+    if (strcmp(v, "none") == 0)
+        return FONT_SHAPE_NONE;
+
+    else if (strcmp(v, "graphemes") == 0) {
+        static bool have_warned = false;
+
+        if (!have_warned &&
+            !(fcft_capabilities() & FCFT_CAPABILITY_GRAPHEME_SHAPING))
+        {
+            have_warned = true;
+            LOG_WARN("cannot enable grapheme shaping; no support in fcft");
+        }
+        return FONT_SHAPE_GRAPHEMES;
+    }
+
+    else if (strcmp(v, "full") == 0) {
+        static bool have_warned = false;
+
+        if (!have_warned &&
+            !(fcft_capabilities() & FCFT_CAPABILITY_TEXT_RUN_SHAPING))
+        {
+            have_warned = true;
+            LOG_WARN("cannot enable full text shaping; no support in fcft");
+        }
+        return FONT_SHAPE_FULL;
+    }
+
+    else {
+        assert(false);
+        return FONT_SHAPE_NONE;
+    }
+}
+
 struct deco *
 conf_to_deco(const struct yml_node *node)
 {
@@ -144,7 +182,8 @@ particle_simple_list_from_config(const struct yml_node *node,
     }
 
     struct particle *common = particle_common_new(
-        0, 0, NULL, fcft_clone(inherited.font), inherited.foreground, NULL);
+        0, 0, NULL, fcft_clone(inherited.font), inherited.font_shaping,
+        inherited.foreground, NULL);
 
     return particle_list_new(common, parts, count, 0, 2);
 }
@@ -163,6 +202,7 @@ conf_to_particle(const struct yml_node *node, struct conf_inherit inherited)
     const struct yml_node *right_margin = yml_get_value(pair.value, "right-margin");
     const struct yml_node *on_click = yml_get_value(pair.value, "on-click");
     const struct yml_node *font_node = yml_get_value(pair.value, "font");
+    const struct yml_node *font_shaping_node = yml_get_value(pair.value, "font-shaping");
     const struct yml_node *foreground_node = yml_get_value(pair.value, "foreground");
     const struct yml_node *deco_node = yml_get_value(pair.value, "deco");
 
@@ -215,12 +255,14 @@ conf_to_particle(const struct yml_node *node, struct conf_inherit inherited)
      */
     struct fcft_font *font = font_node != NULL
         ? conf_to_font(font_node) : fcft_clone(inherited.font);
+    enum font_shaping font_shaping = font_shaping_node != NULL
+        ? conf_to_font_shaping(font_shaping_node) : inherited.font_shaping;
     pixman_color_t foreground = foreground_node != NULL
         ? conf_to_color(foreground_node) : inherited.foreground;
 
     /* Instantiate base/common particle */
     struct particle *common = particle_common_new(
-        left, right, on_click_templates, font, foreground, deco);
+        left, right, on_click_templates, font, font_shaping, foreground, deco);
 
     const struct particle_iface *iface = plugin_load_particle(type);
 
@@ -237,6 +279,7 @@ conf_to_bar(const struct yml_node *bar, enum bar_backend backend)
     struct bar_config conf = {
         .backend = backend,
         .layer = BAR_LAYER_BOTTOM,
+        .font_shaping = FONT_SHAPE_FULL,
     };
 
     /*
@@ -359,6 +402,7 @@ conf_to_bar(const struct yml_node *bar, enum bar_backend backend)
      * foreground color at top-level.
      */
     struct fcft_font *font = fcft_from_name(1, &(const char *){"sans"}, NULL);
+    enum font_shaping font_shaping = FONT_SHAPE_FULL;
     pixman_color_t foreground = {0xffff, 0xffff, 0xffff, 0xffff}; /* White */
 
     const struct yml_node *font_node = yml_get_value(bar, "font");
@@ -367,12 +411,17 @@ conf_to_bar(const struct yml_node *bar, enum bar_backend backend)
         font = conf_to_font(font_node);
     }
 
+    const struct yml_node *font_shaping_node = yml_get_value(bar, "font-shaping");
+    if (font_shaping_node != NULL)
+        font_shaping = conf_to_font_shaping(font_shaping_node);
+
     const struct yml_node *foreground_node = yml_get_value(bar, "foreground");
     if (foreground_node != NULL)
         foreground = conf_to_color(foreground_node);
 
     struct conf_inherit inherited = {
         .font = font,
+        .font_shaping = font_shaping,
         .foreground = foreground,
     };
 
@@ -402,12 +451,15 @@ conf_to_bar(const struct yml_node *bar, enum bar_backend backend)
                  * applied to all its particles.
                  */
                 const struct yml_node *mod_font = yml_get_value(m.value, "font");
+                const struct yml_node *mod_font_shaping = yml_get_value(m.value, "font-shaping");
                 const struct yml_node *mod_foreground = yml_get_value(
                     m.value, "foreground");
 
                 struct conf_inherit mod_inherit = {
                     .font = mod_font != NULL
                         ? conf_to_font(mod_font) : inherited.font,
+                    .font_shaping = mod_font_shaping != NULL
+                        ? conf_to_font_shaping(mod_font_shaping) : inherited.font_shaping,
                     .foreground = mod_foreground != NULL
                         ? conf_to_color(mod_foreground) : inherited.foreground,
                 };