Allow inlining only SVG for now

mkdocs_drawio_exporter/exporter.py

@@ -232,6 +232,17 @@ def prepare_drawio_executable(self, executable, executable_names, platform_execu
         raise ConfigurationError.drawio_executable(
                 None, 'Unable to find Draw.io executable; ensure it\'s on PATH or set drawio_executable option')
 
+    def validate_config(self, config: Configuration):
+        """Validate the configuration.
+
+        :param dict config: Configuration.
+        :return bool: True if configuration is valid.
+        """
+        if '{content}' in config['embed_format'] and config['format'] != 'svg':
+            raise ConfigurationError(
+                    'embed_format', config['embed_format'],
+                    'cannot inline content of non-SVG format')
+
     def rewrite_image_embeds(self, page_dest_path, output_content, config: Configuration):
         """Rewrite image embeds.
 

mkdocs_drawio_exporter/plugin.py

@@ -43,6 +43,7 @@ def on_config(self, config):
                     self.config['drawio_executable'],
                     DrawIoExporter.DRAWIO_EXECUTABLE_NAMES,
                     self.exporter.drawio_executable_paths(sys.platform))
+            self.exporter.validate_config(self.config)
         except ConfigurationError as e:
             raise mkdocs.exceptions.ConfigurationError(str(e))