[gnome-builder/wip/gtk4-port] libide/gtk: add font-description for helper

[Christian Hergert <chergert src gnome org>]

commit 43812dda6aac1e51f4fd3469d00cfa58a558d32f
Author: Christian Hergert <chergert redhat com>
Date:   Tue Apr 5 18:48:15 2022 -0700

    libide/gtk: add font-description for helper

 src/libide/gtk/ide-font-description.c | 233 ++++++++++++++++++++++++++++++++++
 src/libide/gtk/ide-font-description.h |  33 +++++
 src/libide/gtk/libide-gtk.h           |   1 +
 src/libide/gtk/meson.build            |   2 +
 4 files changed, 269 insertions(+)
---
diff --git a/src/libide/gtk/ide-font-description.c b/src/libide/gtk/ide-font-description.c
new file mode 100644
index 000000000..40f5b5094
--- /dev/null
+++ b/src/libide/gtk/ide-font-description.c
@@ -0,0 +1,233 @@
+/* ide-font-description.c
+ *
+ * Copyright 2022 Christian Hergert <chergert redhat com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#define G_LOG_DOMAIN "ide-font-description"
+
+#include "config.h"
+
+#include <math.h>
+
+#include "ide-font-description.h"
+
+#define FONT_FAMILY  "font-family"
+#define FONT_VARIANT "font-variant"
+#define FONT_STRETCH "font-stretch"
+#define FONT_WEIGHT  "font-weight"
+#define FONT_STYLE   "font-style"
+#define FONT_SIZE    "font-size"
+
+char *
+ide_font_description_to_css (const PangoFontDescription *font_desc)
+{
+       PangoFontMask mask;
+       GString *str;
+
+#define ADD_KEYVAL(key,fmt) \
+       g_string_append(str,key":"fmt";")
+#define ADD_KEYVAL_PRINTF(key,fmt,...) \
+       g_string_append_printf(str,key":"fmt";", __VA_ARGS__)
+
+       g_return_val_if_fail (font_desc, NULL);
+
+       str = g_string_new (NULL);
+
+       mask = pango_font_description_get_set_fields (font_desc);
+
+       if ((mask & PANGO_FONT_MASK_FAMILY) != 0)
+       {
+               const gchar *family;
+
+               family = pango_font_description_get_family (font_desc);
+               ADD_KEYVAL_PRINTF (FONT_FAMILY, "\"%s\"", family);
+       }
+
+       if ((mask & PANGO_FONT_MASK_STYLE) != 0)
+       {
+               PangoStyle style;
+
+               style = pango_font_description_get_style (font_desc);
+
+               switch (style)
+               {
+                       case PANGO_STYLE_NORMAL:
+                               ADD_KEYVAL (FONT_STYLE, "normal");
+                               break;
+
+                       case PANGO_STYLE_OBLIQUE:
+                               ADD_KEYVAL (FONT_STYLE, "oblique");
+                               break;
+
+                       case PANGO_STYLE_ITALIC:
+                               ADD_KEYVAL (FONT_STYLE, "italic");
+                               break;
+
+                       default:
+                               break;
+               }
+       }
+
+       if ((mask & PANGO_FONT_MASK_VARIANT) != 0)
+       {
+               PangoVariant variant;
+
+               variant = pango_font_description_get_variant (font_desc);
+
+               switch (variant)
+               {
+                       case PANGO_VARIANT_NORMAL:
+                               ADD_KEYVAL (FONT_VARIANT, "normal");
+                               break;
+
+                       case PANGO_VARIANT_SMALL_CAPS:
+                               ADD_KEYVAL (FONT_VARIANT, "small-caps");
+                               break;
+
+#if PANGO_VERSION_CHECK(1, 49, 3)
+                       case PANGO_VARIANT_ALL_SMALL_CAPS:
+                               ADD_KEYVAL (FONT_VARIANT, "all-small-caps");
+                               break;
+
+                       case PANGO_VARIANT_PETITE_CAPS:
+                               ADD_KEYVAL (FONT_VARIANT, "petite-caps");
+                               break;
+
+                       case PANGO_VARIANT_ALL_PETITE_CAPS:
+                               ADD_KEYVAL (FONT_VARIANT, "all-petite-caps");
+                               break;
+
+                       case PANGO_VARIANT_UNICASE:
+                               ADD_KEYVAL (FONT_VARIANT, "unicase");
+                               break;
+
+                       case PANGO_VARIANT_TITLE_CAPS:
+                               ADD_KEYVAL (FONT_VARIANT, "titling-caps");
+                               break;
+#endif
+
+                       default:
+                               break;
+               }
+       }
+
+       if ((mask & PANGO_FONT_MASK_WEIGHT))
+       {
+               gint weight;
+
+               weight = pango_font_description_get_weight (font_desc);
+
+               /*
+                * WORKAROUND:
+                *
+                * font-weight with numbers does not appear to be working as expected
+                * right now. So for the common (bold/normal), let's just use the string
+                * and let gtk warn for the other values, which shouldn't really be
+                * used for this.
+                */
+
+               switch (weight)
+               {
+                       case PANGO_WEIGHT_SEMILIGHT:
+                       /*
+                        * 350 is not actually a valid css font-weight, so we will just round
+                        * up to 400.
+                        */
+                       case PANGO_WEIGHT_NORMAL:
+                               ADD_KEYVAL (FONT_WEIGHT, "normal");
+                               break;
+
+                       case PANGO_WEIGHT_BOLD:
+                               ADD_KEYVAL (FONT_WEIGHT, "bold");
+                               break;
+
+                       case PANGO_WEIGHT_THIN:
+                       case PANGO_WEIGHT_ULTRALIGHT:
+                       case PANGO_WEIGHT_LIGHT:
+                       case PANGO_WEIGHT_BOOK:
+                       case PANGO_WEIGHT_MEDIUM:
+                       case PANGO_WEIGHT_SEMIBOLD:
+                       case PANGO_WEIGHT_ULTRABOLD:
+                       case PANGO_WEIGHT_HEAVY:
+                       case PANGO_WEIGHT_ULTRAHEAVY:
+                       default:
+                               /* round to nearest hundred */
+                               weight = round (weight / 100.0) * 100;
+                               ADD_KEYVAL_PRINTF ("font-weight", "%d", weight);
+                               break;
+               }
+       }
+
+       if ((mask & PANGO_FONT_MASK_STRETCH))
+       {
+               switch (pango_font_description_get_stretch (font_desc))
+               {
+                       case PANGO_STRETCH_ULTRA_CONDENSED:
+                               ADD_KEYVAL (FONT_STRETCH, "ultra-condensed");
+                               break;
+
+                       case PANGO_STRETCH_EXTRA_CONDENSED:
+                               ADD_KEYVAL (FONT_STRETCH, "extra-condensed");
+                               break;
+
+                       case PANGO_STRETCH_CONDENSED:
+                               ADD_KEYVAL (FONT_STRETCH, "condensed");
+                               break;
+
+                       case PANGO_STRETCH_SEMI_CONDENSED:
+                               ADD_KEYVAL (FONT_STRETCH, "semi-condensed");
+                               break;
+
+                       case PANGO_STRETCH_NORMAL:
+                               ADD_KEYVAL (FONT_STRETCH, "normal");
+                               break;
+
+                       case PANGO_STRETCH_SEMI_EXPANDED:
+                               ADD_KEYVAL (FONT_STRETCH, "semi-expanded");
+                               break;
+
+                       case PANGO_STRETCH_EXPANDED:
+                               ADD_KEYVAL (FONT_STRETCH, "expanded");
+                               break;
+
+                       case PANGO_STRETCH_EXTRA_EXPANDED:
+                               ADD_KEYVAL (FONT_STRETCH, "extra-expanded");
+                               break;
+
+                       case PANGO_STRETCH_ULTRA_EXPANDED:
+                               ADD_KEYVAL (FONT_STRETCH, "ultra-expanded");
+                               break;
+
+                       default:
+                               break;
+               }
+       }
+
+       if ((mask & PANGO_FONT_MASK_SIZE))
+       {
+               gint font_size;
+
+               font_size = pango_font_description_get_size (font_desc) / PANGO_SCALE;
+               ADD_KEYVAL_PRINTF ("font-size", "%dpt", font_size);
+       }
+
+       return g_string_free (str, FALSE);
+
+#undef ADD_KEYVAL
+#undef ADD_KEYVAL_PRINTF
+}
diff --git a/src/libide/gtk/ide-font-description.h b/src/libide/gtk/ide-font-description.h
new file mode 100644
index 000000000..d095ce7c9
--- /dev/null
+++ b/src/libide/gtk/ide-font-description.h
@@ -0,0 +1,33 @@
+/* ide-font-description.h
+ *
+ * Copyright 2022 Christian Hergert <chergert redhat com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#if !defined (IDE_GTK_INSIDE) && !defined (IDE_GTK_COMPILATION)
+# error "Only <libide-gtk.h> can be included directly."
+#endif
+
+#include <pango/pango.h>
+
+G_BEGIN_DECLS
+
+char *ide_font_description_to_css (const PangoFontDescription *font_desc);
+
+G_END_DECLS
diff --git a/src/libide/gtk/libide-gtk.h b/src/libide/gtk/libide-gtk.h
index 3a4b7673d..09ca16481 100644
--- a/src/libide/gtk/libide-gtk.h
+++ b/src/libide/gtk/libide-gtk.h
@@ -26,6 +26,7 @@
 # include "ide-entry-popover.h"
 # include "ide-fancy-tree-view.h"
 # include "ide-file-manager.h"
+# include "ide-font-description.h"
 # include "ide-gtk.h"
 # include "ide-gtk-enums.h"
 # include "ide-menu-manager.h"
diff --git a/src/libide/gtk/meson.build b/src/libide/gtk/meson.build
index 2713241b3..36476a41f 100644
--- a/src/libide/gtk/meson.build
+++ b/src/libide/gtk/meson.build
@@ -12,6 +12,7 @@ libide_gtk_public_headers = [
   'ide-entry-popover.h',
   'ide-fancy-tree-view.h',
   'ide-file-manager.h',
+  'ide-font-description.h',
   'ide-gtk.h',
   'ide-menu-manager.h',
   'ide-progress-icon.h',
@@ -36,6 +37,7 @@ libide_gtk_public_sources = [
   'ide-entry-popover.c',
   'ide-fancy-tree-view.c',
   'ide-file-manager.c',
+  'ide-font-description.c',
   'ide-gtk.c',
   'ide-menu-manager.c',
   'ide-progress-icon.c',