[libshumate] vector: Hide behind a build flag

[Corentin Noël <corentinnoel src gnome org>]

commit ea8609d14eed7c33dc70adc8516e7ee3a1df519a
Author: James Westman <james jwestman net>
Date:   Mon Nov 8 12:17:35 2021 -0600

    vector: Hide behind a build flag
    
    Added a build option, -Dvector_renderer, to enable or disable the
    experimental vector tile renderer. It defaults to false.

 demos/org.gnome.Shumate.Demo.json |  3 ++-
 demos/shumate-demo-window.c       | 33 ++++++++++++++++--------------
 meson.build                       |  2 --
 meson_options.txt                 |  4 ++++
 shumate/meson.build               | 41 +++++++++++++++++++++++--------------
 shumate/shumate-vector-style.c    | 43 +++++++++++++++++++++++++++++++++++++++
 shumate/shumate-vector-style.h    |  4 ++++
 tests/meson.build                 | 11 +++++++---
 8 files changed, 105 insertions(+), 36 deletions(-)
---
diff --git a/demos/org.gnome.Shumate.Demo.json b/demos/org.gnome.Shumate.Demo.json
index 7e013fd..4077f51 100644
--- a/demos/org.gnome.Shumate.Demo.json
+++ b/demos/org.gnome.Shumate.Demo.json
@@ -55,7 +55,8 @@
             "buildsystem" : "meson",
             "config-opts" : [
                 "-Ddemos=true",
-                "-Dgtk_doc=false"
+                "-Dgtk_doc=false",
+                "-Dvector_renderer=true"
             ],
             "builddir" : true,
             "sources" : [
diff --git a/demos/shumate-demo-window.c b/demos/shumate-demo-window.c
index 794979d..5afd5d7 100644
--- a/demos/shumate-demo-window.c
+++ b/demos/shumate-demo-window.c
@@ -144,22 +144,25 @@ shumate_demo_window_init (ShumateDemoWindow *self)
   bytes = g_resources_lookup_data ("/org/gnome/Shumate/Demo/styles/map-style.json", 
G_RESOURCE_LOOKUP_FLAGS_NONE, NULL);
   style_json = g_bytes_get_data (bytes, NULL);
 
-  if (!(style = shumate_vector_style_create (style_json, &error)))
+  if (shumate_vector_style_is_supported ())
     {
-      g_warning ("Failed to create vector map style: %s", error->message);
-      g_clear_error (&error);
-    }
-  else
-    {
-      ShumateMapSource *map_source = SHUMATE_MAP_SOURCE (shumate_network_tile_source_new_vector_full (
-        "vector-tiles",
-        "Vector Tiles",
-        "© OpenStreetMap contributors", NULL, 0, 5, 512,
-        SHUMATE_MAP_PROJECTION_MERCATOR,
-        "https://jwestman.pages.gitlab.gnome.org/vector-tile-test-data/world_overview/#Z#/#X#/#Y#.pbf";,
-        style
-      ));
-      shumate_map_source_registry_add (self->registry, map_source);
+      if (!(style = shumate_vector_style_create (style_json, &error)))
+        {
+          g_warning ("Failed to create vector map style: %s", error->message);
+          g_clear_error (&error);
+        }
+      else
+        {
+          ShumateMapSource *map_source = SHUMATE_MAP_SOURCE (shumate_network_tile_source_new_vector_full (
+            "vector-tiles",
+            "Vector Tiles",
+            "© OpenStreetMap contributors", NULL, 0, 5, 512,
+            SHUMATE_MAP_PROJECTION_MERCATOR,
+            "https://jwestman.pages.gitlab.gnome.org/vector-tile-test-data/world_overview/#Z#/#X#/#Y#.pbf";,
+            style
+          ));
+          shumate_map_source_registry_add (self->registry, map_source);
+        }
     }
 
   viewport = shumate_map_get_viewport (self->map);
diff --git a/meson.build b/meson.build
index dd421d8..8cd9a08 100644
--- a/meson.build
+++ b/meson.build
@@ -69,8 +69,6 @@ cairo_dep = dependency('cairo', version: cairo_req)
 sqlite_dep = dependency('sqlite3', version: sqlite_req)
 libsoup_dep = dependency('libsoup-2.4', version: libsoup_req)
 gtk_dep = dependency('gtk4')
-json_glib_dep = dependency('json-glib-1.0', version: json_glib_req)
-protobuf_c_dep = dependency('libprotobuf-c')
 
 introspection_dep = dependency('gobject-introspection-1.0', version: introspection_req, required: false)
 vapigen_dep = dependency('vapigen', version: vala_req, required: false)
diff --git a/meson_options.txt b/meson_options.txt
index f7a6938..238aef7 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -12,3 +12,7 @@ option('gtk_doc',
 option('demos',
        type: 'boolean', value: false,
        description: 'Build demonstration programs')
+
+option('vector_renderer',
+       type: 'boolean', value: false,
+       description: 'Build the experimental vector tile renderer')
diff --git a/shumate/meson.build b/shumate/meson.build
index 08acdc7..c8816a0 100644
--- a/shumate/meson.build
+++ b/shumate/meson.build
@@ -62,19 +62,6 @@ libshumate_sources = [
   'shumate-tile.c',
   'shumate-vector-style.c',
   'shumate-viewport.c',
-
-  'vector/shumate-vector-background-layer.c',
-  'vector/shumate-vector-expression.c',
-  'vector/shumate-vector-expression-interpolate.c',
-  'vector/shumate-vector-expression-filter.c',
-  'vector/shumate-vector-expression-literal.c',
-  'vector/shumate-vector-fill-layer.c',
-  'vector/shumate-vector-layer.c',
-  'vector/shumate-vector-line-layer.c',
-  'vector/shumate-vector-render-scope.c',
-  'vector/shumate-vector-utils.c',
-  'vector/shumate-vector-value.c',
-  'vector/vector_tile.pb-c.c',
 ]
 
 libshumate_deps = [
@@ -86,8 +73,6 @@ libshumate_deps = [
   cairo_dep,
   sqlite_dep,
   libsoup_dep,
-  json_glib_dep,
-  protobuf_c_dep,
 ]
 
 libshumate_c_args = [
@@ -156,6 +141,32 @@ install_headers(
   )
 )
 
+if get_option('vector_renderer')
+  libshumate_sources += [
+    'vector/shumate-vector-background-layer.c',
+    'vector/shumate-vector-expression.c',
+    'vector/shumate-vector-expression-interpolate.c',
+    'vector/shumate-vector-expression-filter.c',
+    'vector/shumate-vector-expression-literal.c',
+    'vector/shumate-vector-fill-layer.c',
+    'vector/shumate-vector-layer.c',
+    'vector/shumate-vector-line-layer.c',
+    'vector/shumate-vector-render-scope.c',
+    'vector/shumate-vector-utils.c',
+    'vector/shumate-vector-value.c',
+    'vector/vector_tile.pb-c.c',
+  ]
+
+  libshumate_deps += [
+    dependency('json-glib-1.0', version: json_glib_req),
+    dependency('libprotobuf-c'),
+  ]
+
+  libshumate_c_args += [
+    '-DSHUMATE_VECTOR_RENDERER',
+  ]
+endif
+
 libshumate_lib = library(
   package_string,
   libshumate_sources,
diff --git a/shumate/shumate-vector-style.c b/shumate/shumate-vector-style.c
index 6726a5c..600f4a6 100644
--- a/shumate/shumate-vector-style.c
+++ b/shumate/shumate-vector-style.c
@@ -15,12 +15,17 @@
  * License along with this library; if not, see <https://www.gnu.org/licenses/>.
  */
 
+
+#ifdef SHUMATE_VECTOR_RENDERER
 #include <json-glib/json-glib.h>
 #include <cairo/cairo.h>
 
 #include "vector/shumate-vector-render-scope-private.h"
 #include "vector/shumate-vector-utils-private.h"
 #include "vector/shumate-vector-layer-private.h"
+#endif
+
+#include <glib-object.h>
 #include "shumate-vector-style.h"
 
 struct _ShumateVectorStyle
@@ -67,6 +72,26 @@ shumate_vector_style_create (const char *style_json, GError **error)
 }
 
 
+/**
+ * shumate_vector_style_is_supported:
+ *
+ * Checks whether libshumate was compiled with vector tile support. If it was
+ * not, vector styles cannot be created or used.
+ *
+ * Returns: %TRUE if libshumate was compiled with `-Dvector_renderer=true` or
+ * %FALSE if it was not
+ */
+gboolean
+shumate_vector_style_is_supported ()
+{
+#ifdef SHUMATE_VECTOR_RENDERER
+  return TRUE;
+#else
+  return FALSE;
+#endif
+}
+
+
 static void
 shumate_vector_style_finalize (GObject *object)
 {
@@ -141,6 +166,7 @@ shumate_vector_style_initable_init (GInitable     *initable,
                                     GCancellable  *cancellable,
                                     GError       **error)
 {
+#ifdef SHUMATE_VECTOR_RENDERER
   ShumateVectorStyle *self = (ShumateVectorStyle *)initable;
   g_autoptr(JsonNode) node = NULL;
   JsonNode *layers_node;
@@ -183,6 +209,17 @@ shumate_vector_style_initable_init (GInitable     *initable,
     }
 
   return TRUE;
+#else
+  g_set_error (error,
+               SHUMATE_STYLE_ERROR,
+               SHUMATE_STYLE_ERROR_SUPPORT_OMITTED,
+               "Libshumate was compiled without support for vector tiles, so a "
+               "ShumateVectorStyle may not be constructed. You can fix this "
+               "by compiling libshumate with `-Dvector_renderer=true` or by "
+               "checking `shumate_vector_style_is_supported ()` before trying "
+               "to construct a ShumateVectorStyle.");
+  return FALSE;
+#endif
 }
 
 
@@ -216,6 +253,7 @@ shumate_vector_style_get_style_json (ShumateVectorStyle *self)
 }
 
 
+#ifdef SHUMATE_VECTOR_RENDERER
 static GdkTexture *
 texture_new_for_surface (cairo_surface_t *surface)
 {
@@ -240,6 +278,7 @@ texture_new_for_surface (cairo_surface_t *surface)
 
   return texture;
 }
+#endif
 
 
 /**
@@ -253,6 +292,7 @@ texture_new_for_surface (cairo_surface_t *surface)
 GdkTexture *
 shumate_vector_style_render (ShumateVectorStyle *self, int texture_size, GBytes *tile_data, double 
zoom_level)
 {
+#ifdef SHUMATE_VECTOR_RENDERER
   ShumateVectorRenderScope scope;
   GdkTexture *texture;
   cairo_surface_t *surface;
@@ -281,6 +321,9 @@ shumate_vector_style_render (ShumateVectorStyle *self, int texture_size, GBytes
   vector_tile__tile__free_unpacked (scope.tile, NULL);
 
   return texture;
+#else
+  g_return_val_if_reached (NULL);
+#endif
 }
 
 /**
diff --git a/shumate/shumate-vector-style.h b/shumate/shumate-vector-style.h
index 908f0ac..a2e0885 100644
--- a/shumate/shumate-vector-style.h
+++ b/shumate/shumate-vector-style.h
@@ -37,6 +37,7 @@ GQuark shumate_style_error_quark (void);
  * @SHUMATE_STYLE_ERROR_MALFORMED_STYLE: A JSON node in the style has the wrong type (e.g. an object where 
there should be an array).
  * @SHUMATE_STYLE_ERROR_UNSUPPORTED_LAYER: An unsupported layer type was encountered.
  * @SHUMATE_STYLE_ERROR_INVALID_EXPRESSION: An invalid or unrecognized expression was encountered.
+ * @SHUMATE_STYLE_ERROR_SUPPORT_OMITTED: Libshumate was compiled without vector tile support.
  *
  * Error codes in the [error@StyleError] domain.
  */
@@ -45,6 +46,7 @@ typedef enum {
   SHUMATE_STYLE_ERROR_MALFORMED_STYLE,
   SHUMATE_STYLE_ERROR_UNSUPPORTED_LAYER,
   SHUMATE_STYLE_ERROR_INVALID_EXPRESSION,
+  SHUMATE_STYLE_ERROR_SUPPORT_OMITTED,
 } ShumateStyleError;
 
 
@@ -52,10 +54,12 @@ typedef enum {
 
 G_DECLARE_FINAL_TYPE (ShumateVectorStyle, shumate_vector_style, SHUMATE, VECTOR_STYLE, GObject)
 
+gboolean shumate_vector_style_is_supported ();
 ShumateVectorStyle *shumate_vector_style_create (const char *style_json, GError **error);
 
 const char *shumate_vector_style_get_style_json (ShumateVectorStyle *self);
 
 GdkTexture *shumate_vector_style_render (ShumateVectorStyle *self, int texture_size, GBytes *tile_data, 
double zoom_level);
 
+
 G_END_DECLS
diff --git a/tests/meson.build b/tests/meson.build
index 9cbb99d..1ed5838 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -15,12 +15,17 @@ tests = [
   'marker-layer',
   'memory-cache',
   'network-tile-source',
-  'vector-expression',
-  'vector-style',
-  'vector-value',
   'viewport',
 ]
 
+if get_option('vector_renderer')
+  tests += [
+    'vector-expression',
+    'vector-style',
+    'vector-value',
+  ]
+endif
+
 subdir('data')
 
 test_utils_sources = [