Packages.md

+
 ## Package Overview for printerbackend:
 ![PrinterBackend.svg](uploads/0359a1b084241740a97e5afde116a21e/PrinterBackend.svg)
 
+## **Extension**
+To add a new printer without any special modes to the system, just use the Printercapability NORMALPRINTER in the config.
+
+If a new printermode is discovered, please inherit from the **AbstractDocumentBuilder** to ensure that your new class has the same *contract* for the **PrintDirector** as all the other builder classes.  
+If would be beneficial to make a abstract class representing the printer itself, so let it inherit from **AbstractDocumentBuilder**, name it accordingly (e.g. PRINTERNAME_BUILDER), then create an class representing the protocol for the desired printermode, and inherit from the logical abstract class representing the printer.  
+You can add all the special byte sequences for the printer in the logical class, so that you do not need to use specific byte, but human readable abbreviations. 
+You can also set defaults if the documentation of the printer is verbose enough.
+
+For example like in the **AbstractIndexV4Builder**:
+
+```java
+abstract class AbstractIndexV4Builder<T extends PrintableData> extends AbstractDocumentBuilder<T> {
+
+    /**
+     * Standard byte Sequence to announce StartTemporary document ([ESC]D).
+     * Must be always at the beginning.
+     */
+
+    final byte[] mStartTemporaryDoc = new byte[] {0x1B, 0x44};
+
+    final byte[] mStartFloatingMode = new byte[] {0x1B, 0x46};
+
+    final byte[] mNewLine = new byte[] {0x0A};
+
+```
+
+To make it visible for the **Printdirector**, please add it in the class:
+
+```java
+    public PrintDirector(final PrinterCapability printerCap, final Printer printerConfig) {
+        Objects.requireNonNull(printerCap);
+        Objects.requireNonNull(printerConfig);
+        this.mPrinter = printerCap;
+        mPrinterName = printerConfig.getProperty("name").toString();
+        mLogger.trace("Using following printercapability {}", printerCap.toString(), " loaded");
+        mLogger.info("Using the following printer: {}", mPrinterName);
+        switch (mPrinter) {
+            case NORMALPRINTER:
+                mBuilder = new NormalBuilder();
+                mLogger.trace("Using NormalBuilder as protocol");
+                break;
+            case INDEX_EVEREST_D_V4_GRAPHIC_PRINTER:
+                mBuilder = new GraphicPrintBuilder();
+                mLogger.trace("Using Index Everest-D V4 graphic print as protocol");
+                break;
+            case INDEX_EVEREST_D_V4_FLOATINGDOT_PRINTER:
+                mBuilder = new FloatingDotAreaBuilder();
+                mLogger.trace("Using Index Everest-D V4 floatingdot as protocol");
+                break;
+            // Here goes the new Builder
+            // case PRINTERNAME_PROTOCOL:
+            // mBuilder = new BUILDERCLASS()
+            default: throw new IllegalArgumentException();
+        }
+    }
+```
+... and also in the enumeration:
+
+```java
+public enum PrinterCapability {
+    NORMALPRINTER, INDEX_EVEREST_D_V4_FLOATINGDOT_PRINTER, INDEX_EVEREST_D_V4_GRAPHIC_PRINTER
+    // PRINTERNAME_PROTOCOL
+}
+```
+
 ## Package Overview for brailleparser:
 ![brailleparser.svg](uploads/66abd2031fbd218077c664ad1fd99129/brailleparser.svg)
 
+## **Extension**
+If you want to extend the architecture, for example to add support for new fileformats, inherit from **AbstractBrailleTableParser**, adhere to the *contract* and register it in the **AbstractBrailleTableParser**:
+
+```java
+    public static AbstractBrailleTableParser getParser(final Printer printer, final String property) throws NotSupportedFileExtensionException {
+        //read braille table path
+        String brailleTablePath = printer.getProperty(property).toString();
+
+        //read which kind of parser is needed (properties, json, xml,...)
+        String[] parts = brailleTablePath.split("\\.");
+        String fileEnding = parts[parts.length - 1]; // made safe for relative paths containing "./" or "../"
+        switch (fileEnding) {
+            case "properties":
+                return new PropertiesParser(brailleTablePath);
+            case "json":
+                return new JsonParser(brailleTablePath);
+            case "xml":
+                return new XmlParser(brailleTablePath);
+            // Add here a new case with the class
+            default:
+                throw new NotSupportedFileExtensionException("The Fileextension " + fileEnding + " is currently not supported.");
+        }
+    }
+```
+
 ## Package Overview for rendering:
 ![rendering_detail.svg](uploads/a5c9fa84a7de13a68d7c2d4d65dd0941/rendering_detail.svg)
 ![rendering_basic.svg](uploads/c37a67538cdfa24942301508418c02f3/rendering_basic.svg)