libsysprof-gtk: start on new XY series

This will extract the values using the expressions instead of manually
building series as we previously would need to do.

src/libsysprof-gtk/sysprof-xy-series.h

@@ -0,0 +1,50 @@
+/* sysprof-xy-series.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 <gtk/gtk.h>
+
+#include "sysprof-series.h"
+
+G_BEGIN_DECLS
+
+#define SYSPROF_TYPE_XY_SERIES (sysprof_xy_series_get_type())
+
+SYSPROF_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (SysprofXYSeries, sysprof_xy_series, SYSPROF, XY_SERIES, SysprofSeries)
+
+SYSPROF_AVAILABLE_IN_ALL
+SysprofSeries *sysprof_xy_series_new              (const char      *title,
+                                                   GListModel      *model,
+                                                   GtkExpression   *x_expression,
+                                                   GtkExpression   *y_expression);
+SYSPROF_AVAILABLE_IN_ALL
+GtkExpression *sysprof_xy_series_get_x_expression (SysprofXYSeries *self);
+SYSPROF_AVAILABLE_IN_ALL
+void           sysprof_xy_series_set_x_expression (SysprofXYSeries *self,
+                                                   GtkExpression   *x_expression);
+SYSPROF_AVAILABLE_IN_ALL
+GtkExpression *sysprof_xy_series_get_y_expression (SysprofXYSeries *self);
+SYSPROF_AVAILABLE_IN_ALL
+void           sysprof_xy_series_set_y_expression (SysprofXYSeries *self,
+                                                   GtkExpression   *y_expression);
+
+G_END_DECLS