Issue #19:

Create a base class GdsOutputRenderer with a virtual function render_output,
which can be derived by the different output renderers.

output-renderers/gds-output-renderer.c

@@ -0,0 +1,98 @@
+/*
+ * GDSII-Converter
+ * Copyright (C) 2019  Mario Hüttel <mario.huettel@gmx.net>
+ *
+ * This file is part of GDSII-Converter.
+ *
+ * GDSII-Converter is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * GDSII-Converter 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 GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+  * @file gds-output-renderer.c
+  * @brief Base GObject class for output renderers
+  *
+  * All output renderers are derived from this class
+  *
+  * @author Mario Hüttel <mario.huettel@gmx.net>
+  */
+
+/** @addtogroup GdsOutputRenderer
+ *  @{
+ */
+
+#include <gds-render/output-renderers/gds-output-renderer.h>
+
+typedef struct {
+	gpointer padding[12];
+} GdsOutputRendererPrivate;
+
+G_DEFINE_TYPE_WITH_PRIVATE(GdsOutputRenderer, gds_output_renderer, G_TYPE_OBJECT)
+
+static int gds_output_renderer_render_dummy(GdsOutputRenderer *renderer,
+						struct gds_cell *cell,
+						GList *layer_infos,
+						const char *output_file,
+						double scale)
+{
+	(void)renderer;
+	(void)cell;
+	(void)layer_infos;
+	(void)output_file;
+	(void)scale;
+
+	g_warning("Output renderer does not define a render_output function!");
+	return 0;
+}
+
+static void gds_output_renderer_class_init(GdsOutputRendererClass *klass)
+{
+	klass->render_output = gds_output_renderer_render_dummy;
+}
+
+void gds_output_renderer_init(GdsOutputRenderer *self)
+{
+	(void)self;
+
+	return;
+}
+
+GdsOutputRenderer *gds_output_renderer_new()
+{
+	return GDS_RENDER_OUTPUT_RENDERER(g_object_new(GDS_RENDER_TYPE_OUTPUT_RENDERER, NULL));
+}
+
+int gds_output_renderer_render_output(GdsOutputRenderer *renderer, struct gds_cell *cell, GList *layer_infos, const char *output_file, double scale)
+{
+	GdsOutputRendererClass *klass;
+
+	if (GDS_RENDER_IS_OUTPUT_RENDERER(renderer) == FALSE) {
+		g_error("Output Renderer not valid.");
+		return GDS_OUTPUT_RENDERER_GEN_ERR;
+	}
+
+	if (!cell || !layer_infos || !output_file) {
+		g_error("Output renderer called with insufficient parameters.");
+		return GDS_OUTPUT_RENDERER_PARAM_ERR;
+	}
+
+	klass = GDS_RENDER_OUTPUT_RENDERER_GET_CLASS(renderer);
+	if (klass->render_output == NULL) {
+		g_critical("Output Renderer: Rendering function broken. This is a bug.");
+		return GDS_OUTPUT_RENDERER_GEN_ERR;
+	}
+
+	return klass->render_output(renderer, cell, layer_infos, output_file, scale);
+}
+
+
+/** @} */