libsysprof-gtk: start on new axis/series design

This will mean we move series work from libsysprof-analyze into
libsysprof-gtk so we get access to things like GtkExpression.

src/libsysprof-gtk/sysprof-axis.h

@@ -0,0 +1,47 @@
+/* sysprof-axis.h
+ *
+ * Copyright 2023 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
+
+#include <glib-object.h>
+
+#include <sysprof-capture.h>
+
+G_BEGIN_DECLS
+
+#define SYSPROF_TYPE_AXIS         (sysprof_axis_get_type())
+#define SYSPROF_IS_AXIS(obj)      (G_TYPE_CHECK_INSTANCE_TYPE(obj, SYSPROF_TYPE_AXIS))
+#define SYSPROF_AXIS(obj)         (G_TYPE_CHECK_INSTANCE_CAST(obj, SYSPROF_TYPE_AXIS, SysprofAxis))
+#define SYSPROF_AXIS_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST(klass, SYSPROF_TYPE_AXIS, SysprofAxisClass))
+
+typedef struct _SysprofAxis SysprofAxis;
+typedef struct _SysprofAxisClass SysprofAxisClass;
+
+SYSPROF_AVAILABLE_IN_ALL
+GType       sysprof_axis_get_type  (void) G_GNUC_CONST;
+SYSPROF_AVAILABLE_IN_ALL
+const char *sysprof_axis_get_title (SysprofAxis *self);
+SYSPROF_AVAILABLE_IN_ALL
+void        sysprof_axis_set_title (SysprofAxis *self,
+                                    const char *title);
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (SysprofAxis, g_object_unref)
+
+G_END_DECLS