csd: add support for a visible border

When we’re using CSDs, we’ve up until now rendered a 5px invisible
border. This border handles interactive resizing. I.e. hovering it
changes the mouse cursor, and mouse button events are used to start an
interactive resize.

This patch makes it possible to color part of (or the entire) border,
with a configurable color.

To facilitate this, two new options have been added:

* csd.border-width
* csd.border-color

border-width defaults to 0, resulting in the look we’re used to.

border-color defaults to the title bar color. If the title bar color
hasn’t been set, it defaults to the default foreground color (just
like the title bar color does).

This means that, setting border-width but not border-color, results in
a border that blends with the title bar.

CHANGELOG.md

@@ -44,6 +44,8 @@
   action will not be sent to the application
   (https://codeberg.org/dnkl/foot/issues/765).
 * Color schemes are now installed to `${datadir}/foot/themes`.
+* `[csd].border-width` and `[csd].border-color`, allowing you to
+  configure the width and color of the CSD border.
 
 
 ### Changed

config.c

@@ -1489,7 +1489,9 @@ parse_section_csd(const char *key, const char *value, struct config *conf,
     else if (strcmp(key, "size") == 0) {
         unsigned long pixels;
         if (!str_to_ulong(value, 10, &pixels)) {
-            LOG_AND_NOTIFY_ERR("%s:%d: expected an integer, got '%s'", path, lineno, value);
+            LOG_AND_NOTIFY_ERR(
+                "%s:%d: [csd]: size: expected an integer, got '%s'",
+                path, lineno, value);
             return false;
         }
 
@@ -1499,7 +1501,9 @@ parse_section_csd(const char *key, const char *value, struct config *conf,
     else if (strcmp(key, "button-width") == 0) {
         unsigned long pixels;
         if (!str_to_ulong(value, 10, &pixels)) {
-            LOG_AND_NOTIFY_ERR("%s:%d: expected an integer, got '%s'", path, lineno, value);
+            LOG_AND_NOTIFY_ERR(
+                "%s:%d: [csd]: button-width: expected an integer, got '%s'",
+                path, lineno, value);
             return false;
         }
 
@@ -1542,6 +1546,27 @@ parse_section_csd(const char *key, const char *value, struct config *conf,
         conf->csd.color.close = color;
     }
 
+    else if (strcmp(key, "border-color") == 0) {
+        uint32_t color;
+        if (!str_to_color(value, &color, true, conf, path, lineno, "csd", "border-color"))
+            return false;
+
+        conf->csd.color.border_set = true;
+        conf->csd.color.border = color;
+    }
+
+    else if (strcmp(key, "border-width") == 0) {
+        unsigned long width;
+        if (!str_to_ulong(value, 10, &width)) {
+            LOG_AND_NOTIFY_ERR(
+                "%s:%u: [csd]: border-width: expected an integer, got '%s'",
+                path, lineno, value);
+            return false;
+        }
+
+        conf->csd.border_width_visible = width;
+    }
+
     else {
         LOG_AND_NOTIFY_ERR("%s:%u: [csd]: %s: invalid action",
                            path, lineno, key);

config.h

@@ -214,6 +214,7 @@ struct config {
 
         int title_height;
         int border_width;
+        int border_width_visible;
         int button_width;
 
         struct {
@@ -222,11 +223,13 @@ struct config {
             bool minimize_set:1;
             bool maximize_set:1;
             bool close_set:1;
+            bool border_set:1;
             uint32_t title;
             uint32_t buttons;
             uint32_t minimize;
             uint32_t maximize;
             uint32_t close;
+            uint32_t border;
         } color;
 
         struct config_font_list font;

doc/foot.ini.5.scd

@@ -564,6 +564,17 @@ component.
 	title bar size. That is, all *:size* and *:pixelsize* attributes
 	will be ignored. Default: _primary font_.
 
+*border-width*
+	Width of the border, in pixels (subject to output scaling). Note
+	that the border encompasses the entire window, including the title
+	bar. Default: _0_.
+
+*border-color*
+	Color of border, on the format AARRGGBB. By default, the title bar
+	color is used. If the title bar color has not been set, the
+	default foreground color (from the color scheme) is used. Default:
+	_titlebar color_.
+
 *button-width*
 	Width, in pixels (subject to output scaling), of the
 	minimize/maximize/close buttons. Default: _26_.

foot.ini

@@ -98,6 +98,8 @@
 # size=26
 # font=<primary font>
 # color=<foreground color>
+# border-width=0
+# border-color=<color>
 # button-width=26
 # button-color=<background color>
 # button-minimize-color=<regular4>

render.c

@@ -1508,7 +1508,8 @@ get_csd_data(const struct terminal *term, enum csd_surface surf_idx)
 
     /* Only title bar is rendered in maximized mode */
     const int border_width = !term->window->is_maximized
-        ? term->conf->csd.border_width * term->scale : 0;
+        ? max(term->conf->csd.border_width,
+              term->conf->csd.border_width_visible) * term->scale : 0;
 
     const int title_height = term->window->is_fullscreen
         ? 0
@@ -1565,12 +1566,12 @@ render_csd_part(struct terminal *term,
 {
     xassert(term->window->csd_mode == CSD_YES);
 
-    pixman_image_t *src = pixman_image_create_solid_fill(color);
+    //pixman_image_t *src = pixman_image_create_solid_fill(color);
 
     pixman_image_fill_rectangles(
         PIXMAN_OP_SRC, buf->pix[0], color, 1,
         &(pixman_rectangle16_t){0, 0, buf->width, buf->height});
-    pixman_image_unref(src);
+    //pixman_image_unref(src);
 }
 
 static void
@@ -1729,8 +1730,56 @@ render_csd_border(struct terminal *term, enum csd_surface surf_idx,
     xassert(info->width % term->scale == 0);
     xassert(info->height % term->scale == 0);
 
-    pixman_color_t color = color_hex_to_pixman_with_alpha(0, 0);
-    render_csd_part(term, surf, buf, info->width, info->height, &color);
+    {
+        pixman_color_t color = color_hex_to_pixman_with_alpha(0, 0);
+        render_csd_part(term, surf, buf, info->width, info->height, &color);
+    }
+
+    /*
+     * The “visible” border.
+     */
+
+    int bwidth = term->conf->csd.border_width;          /* Full border size */
+    int vwidth = term->conf->csd.border_width_visible;  /* Visibls size */
+
+    if (vwidth > 0) {
+
+        const struct config *conf = term->conf;
+        int x = 0, y = 0, w = 0, h = 0;
+
+        switch (surf_idx) {
+        case CSD_SURF_TOP:
+        case CSD_SURF_BOTTOM:
+            x = bwidth - vwidth;
+            y = surf_idx == CSD_SURF_TOP ? info->height - vwidth : 0;
+            w = info->width - 2 * x;
+            h = vwidth;
+            break;
+
+        case CSD_SURF_LEFT:
+        case CSD_SURF_RIGHT:
+            x = surf_idx == CSD_SURF_LEFT ? bwidth - vwidth : 0;
+            y = 0;
+            w = vwidth;
+            h = info->height;
+            break;
+
+        default:
+            break;
+        }
+
+        uint32_t _color =
+            conf->csd.color.border_set ? conf->csd.color.border :
+            conf->csd.color.title_set ? conf->csd.color.title :
+            0xffu << 24 | term->conf->colors.fg;
+        uint16_t alpha = _color >> 24 | (_color >> 24 << 8);
+        pixman_color_t color = color_hex_to_pixman_with_alpha(_color, alpha);
+
+        pixman_image_fill_rectangles(
+            PIXMAN_OP_SRC, buf->pix[0], &color, 1,
+            &(pixman_rectangle16_t){x, y, w, h});
+    }
+
     csd_commit(term, surf, buf);
 }