Add Base64 support

src/main/java/net/sourceforge/plantuml/servlet/DiagramResponse.java

@@ -25,6 +25,7 @@ package net.sourceforge.plantuml.servlet;
 
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.io.ByteArrayOutputStream;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
@@ -38,6 +39,7 @@ import net.sourceforge.plantuml.FileFormatOption;
 import net.sourceforge.plantuml.NullOutputStream;
 import net.sourceforge.plantuml.SourceStringReader;
 import net.sourceforge.plantuml.StringUtils;
+import net.sourceforge.plantuml.code.Base64Coder;
 import net.sourceforge.plantuml.core.DiagramDescription;
 import net.sourceforge.plantuml.core.Diagram;
 import net.sourceforge.plantuml.core.ImageData;
@@ -64,6 +66,7 @@ class DiagramResponse {
         map.put(FileFormat.SVG, "image/svg+xml");
         map.put(FileFormat.EPS, "application/postscript");
         map.put(FileFormat.UTXT, "text/plain;charset=UTF-8");
+        map.put(FileFormat.BASE64, "text/plain; charset=x-user-defined");
         CONTENT_TYPE = Collections.unmodifiableMap(map);
     }
 
@@ -76,6 +79,15 @@ class DiagramResponse {
     void sendDiagram(String uml, int idx) throws IOException {
         response.setContentType(getContentType());
         SourceStringReader reader = new SourceStringReader(uml);
+        if (format == FileFormat.BASE64) {
+            final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            final DiagramDescription result = reader.outputImage(baos, idx, new FileFormatOption(FileFormat.PNG));
+            baos.close();
+            final String encodedBytes = "data:image/png;base64,"
+                + Base64Coder.encodeLines(baos.toByteArray()).replaceAll("\\s", "");
+            response.getOutputStream().write(encodedBytes.getBytes());
+            return;
+        }
         final BlockUml blockUml = reader.getBlocks().get(0);
         if (notModified(blockUml)) {
             addHeaderForCache(blockUml);