WM: Application Templates

This adds the ability to switch between different application-configurations
without interfering with Blender's normal operation.

This commit doesn't include any templates,
so its mostly to allow collaboration for the Blender 101 project
and other custom configurations.

Application templates can be installed & selected from the file menu.

Other details:

- The `bl_app_template_utils` module handles template activation
  (similar to `addon_utils`).
- The `bl_app_override` module is a general module
  to assist scripts overriding parts of Blender in reversible way.

See docs:
https://docs.blender.org/manual/en/dev/advanced/app_templates.html

See patch: D2565

4 files changed, 85 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_appdir.h b/source/blender/blenkernel/BKE_appdir.h
index c6587b94666..ac8f861fa56 100644
--- a/source/blender/blenkernel/BKE_appdir.h
+++ b/source/blender/blenkernel/BKE_appdir.h
@@ -33,6 +33,9 @@ const char *BKE_appdir_folder_id_create(const int folder_id, const char *subfold
 const char *BKE_appdir_folder_id_user_notest(const int folder_id, const char *subfolder);
 const char *BKE_appdir_folder_id_version(const int folder_id, const int ver, const bool do_check);
 
+bool BKE_appdir_app_template_any(void);
+bool BKE_appdir_app_template_id_search(const char *app_template, char *path, size_t path_len);
+
 /* Initialize path to program executable */
 void        BKE_appdir_program_path_init(const char *argv0);
 
diff --git a/source/blender/blenkernel/BKE_blender.h b/source/blender/blenkernel/BKE_blender.h
index 62a15bae153..d55926ffb1e 100644
--- a/source/blender/blenkernel/BKE_blender.h
+++ b/source/blender/blenkernel/BKE_blender.h
@@ -52,6 +52,8 @@ void BKE_blender_userdef_set_data(struct UserDef *userdef);
 void BKE_blender_userdef_free_data(struct UserDef *userdef);
 void BKE_blender_userdef_refresh(void);
 
+void BKE_blender_userdef_set_app_template(struct UserDef *userdef);
+
 /* set this callback when a UI is running */
 void BKE_blender_callback_test_break_set(void (*func)(void));
 int  BKE_blender_test_break(void);
diff --git a/source/blender/blenkernel/intern/appdir.c b/source/blender/blenkernel/intern/appdir.c
index 3fb8a147960..43fd47981b1 100644
--- a/source/blender/blenkernel/intern/appdir.c
+++ b/source/blender/blenkernel/intern/appdir.c
@@ -683,6 +683,48 @@ bool BKE_appdir_program_python_search(
 	return is_found;
 }
 
+static const char *app_template_directory_search[2] = {
+	"startup" SEP_STR "bl_app_templates_user",
+	"startup" SEP_STR "bl_app_templates_system",
+};
+
+static const int app_template_directory_id[2] = {
+	BLENDER_USER_SCRIPTS,
+	BLENDER_SYSTEM_SCRIPTS,
+};
+
+/**
+ * Return true if templates exist
+ */
+bool BKE_appdir_app_template_any(void)
+{
+	char temp_dir[FILE_MAX];
+	for (int i = 0; i < 2; i++) {
+		if (BKE_appdir_folder_id_ex(
+		        app_template_directory_id[i], app_template_directory_search[i],
+		        temp_dir, sizeof(temp_dir)))
+		{
+			return true;
+		}
+	}
+	return false;
+}
+
+bool BKE_appdir_app_template_id_search(const char *app_template, char *path, size_t path_len)
+{
+	for (int i = 0; i < 2; i++) {
+		char subdir[FILE_MAX];
+		BLI_join_dirfile(subdir, sizeof(subdir), app_template_directory_search[i], app_template);
+		if (BKE_appdir_folder_id_ex(
+		        app_template_directory_id[i], subdir,
+		        path, path_len))
+		{
+			return true;
+		}
+	}
+	return false;
+}
+
 /**
  * Gets the temp directory when blender first runs.
  * If the default path is not found, use try $TEMP
diff --git a/source/blender/blenkernel/intern/blender.c b/source/blender/blenkernel/intern/blender.c
index f661f18fbc0..ceb641073e0 100644
--- a/source/blender/blenkernel/intern/blender.c
+++ b/source/blender/blenkernel/intern/blender.c
@@ -238,6 +238,44 @@ void BKE_blender_userdef_refresh(void)
 
 }
 
+/**
+ * Write U from userdef.
+ * This function defines which settings a template will override for the user preferences.
+ */
+void BKE_blender_userdef_set_app_template(UserDef *userdef)
+{
+	/* TODO:
+	 * - keymaps
+	 * - various minor settings (add as needed).
+	 */
+
+#define LIST_OVERRIDE(id) { \
+	BLI_freelistN(&U.id); \
+	BLI_movelisttolist(&U.id, &userdef->id); \
+} ((void)0)
+
+#define MEMCPY_OVERRIDE(id) \
+	memcpy(U.id, userdef->id, sizeof(U.id));
+
+	/* for some types we need custom free functions */
+	userdef_free_addons(&U);
+	userdef_free_keymaps(&U);
+
+	LIST_OVERRIDE(uistyles);
+	LIST_OVERRIDE(uifonts);
+	LIST_OVERRIDE(themes);
+	LIST_OVERRIDE(addons);
+	LIST_OVERRIDE(user_keymaps);
+
+	MEMCPY_OVERRIDE(light);
+
+	MEMCPY_OVERRIDE(font_path_ui);
+	MEMCPY_OVERRIDE(font_path_ui_mono);
+
+#undef LIST_OVERRIDE
+#undef MEMCPY_OVERRIDE
+}
+
 /* *****************  testing for break ************* */
 
 static void (*blender_test_break_cb)(void) = NULL;