font: use font-config to load font

This allows us to a) move away from cairo's "toy" API, and b) let the
user specify font options in a single font "name" string:

  Serif:size=10:weight=bold:slant=italic

This also allows us to simplify the font code significantly (except
for the fontconfig parts...); the font no longer sets itself in a
cairo surface - font users do that; the font simply returns a
cairo_scaled_font_t.

Furthermore, font_clone() has now been simplified to basically just
refcount the scaled font. I.e. there's no need to run the full
constructor and lookup and instantiate the cairo scaled font again.

particles/string.c

@@ -4,33 +4,46 @@
 #include <string.h>
 #include <assert.h>
 
+#define LOG_MODULE "string"
+#define LOG_ENABLE_DBG 1
+#include "../log.h"
+
 struct private {
     char *text;
+    size_t max_len;
 
     struct font *font;
     struct rgba foreground;
 };
 
+struct eprivate {
+    char *text;
+
+    const struct font *font;
+    struct rgba foreground;
+
+    cairo_text_extents_t extents;
+};
+
 static void
 exposable_destroy(struct exposable *exposable)
 {
-    struct private *e = exposable->private;
+    struct eprivate *e = exposable->private;
     free(e->text);
     free(e);
     exposable_default_destroy(exposable);
 }
 
 static int
-begin_expose(struct exposable *exposable, cairo_t *cr)
+begin_expose(struct exposable *exposable)
 {
-    const struct private *e = exposable->private;
+    struct eprivate *e = exposable->private;
 
-    cairo_scaled_font_t *scaled = font_use_in_cairo(e->font, cr);
-    cairo_text_extents_t extents;
-    cairo_scaled_font_text_extents(scaled, e->text, &extents);
+    cairo_scaled_font_t *scaled = font_scaled_font(e->font);
+    cairo_scaled_font_text_extents(scaled, e->text, &e->extents);
 
     exposable->width = (exposable->particle->left_margin +
-                        extents.x_advance +
+                        e->extents.x_advance +
                         exposable->particle->right_margin);
 
     return exposable->width;
@@ -39,12 +52,12 @@ begin_expose(struct exposable *exposable, cairo_t *cr)
 static void
 expose(const struct exposable *exposable, cairo_t *cr, int x, int y, int height)
 {
-    const struct private *e = exposable->private;
+    exposable_render_deco(exposable, cr, x, y, height);
 
-    cairo_scaled_font_t *scaled = font_use_in_cairo(e->font, cr);
+    const struct eprivate *e = exposable->private;
+    const size_t text_len = strlen(e->text);
 
-    cairo_text_extents_t extents;
-    cairo_scaled_font_text_extents(scaled, e->text, &extents);
+    cairo_scaled_font_t *scaled = font_scaled_font(e->font);
 
     cairo_glyph_t *glyphs = NULL;
     cairo_text_cluster_t *clusters = NULL;
@@ -53,37 +66,47 @@ expose(const struct exposable *exposable, cairo_t *cr, int x, int y, int height)
     cairo_scaled_font_text_to_glyphs(
         scaled,
         x + exposable->particle->left_margin,
-        (double)y + ((double)height - extents.y_bearing) / 2 + font_y_offset(e->font),
-        e->text, strlen(e->text), &glyphs, &num_glyphs,
+        (double)y + ((double)height - e->extents.height) / 2 - e->extents.y_bearing,
+        e->text, text_len, &glyphs, &num_glyphs,
         &clusters, &num_clusters, &cluster_flags);
 
-    exposable_render_deco(exposable, cr, x, y, height);
-
+    cairo_set_scaled_font(cr, scaled);
     cairo_set_source_rgba(cr,
                           e->foreground.red,
                           e->foreground.green,
                           e->foreground.blue,
                           e->foreground.alpha);
-
     cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
-    cairo_show_text_glyphs(cr, e->text, strlen(e->text),
-                           glyphs, num_glyphs,
-                           clusters, num_clusters, cluster_flags);
+
+    cairo_show_text_glyphs(
+        cr, e->text, text_len, glyphs, num_glyphs,
+        clusters, num_clusters, cluster_flags);
+
     cairo_glyph_free(glyphs);
     cairo_text_cluster_free(clusters);
-    /*cairo_scaled_font_destroy(scaled);*/
-
 }
 
 static struct exposable *
 instantiate(const struct particle *particle, const struct tag_set *tags)
 {
     const struct private *p = particle->private;
-    struct private *e = malloc(sizeof(*e));
+    struct eprivate *e = malloc(sizeof(*e));
 
     e->text = tags_expand_template(p->text, tags);
     e->font = p->font;
     e->foreground = p->foreground;
+    memset(&e->extents, 0, sizeof(e->extents));
+
+    if (p->max_len > 0) {
+        size_t len = strlen(e->text);
+        if (len > p->max_len) {
+            if (p->max_len >= 3) {
+                for (size_t i = 0; i < 3; i++)
+                    e->text[p->max_len - 3 + i] = '.';
+            }
+            e->text[p->max_len] = '\0';
+        }
+    }
 
     char *on_click = tags_expand_template(particle->on_click_template, tags);
 
@@ -108,12 +131,13 @@ particle_destroy(struct particle *particle)
 }
 
 struct particle *
-particle_string_new(const char *text, struct font *font,
+particle_string_new(const char *text, size_t max_len, struct font *font,
                     struct rgba foreground, int left_margin, int right_margin,
                     const char *on_click_template)
 {
     struct private *p = malloc(sizeof(*p));
     p->text = strdup(text);
+    p->max_len = max_len;
     p->font = font;
     p->foreground = foreground;
 

particles/string.h

@@ -2,5 +2,5 @@
 #include "../particle.h"
 
 struct particle *particle_string_new(
-    const char *text, struct font *font, struct rgba foreground,
+    const char *text, size_t max_len, struct font *font, struct rgba foreground,
     int left_margin, int right_margin, const char *on_click_template);