16 files changed, 224 insertions, 123 deletions

diff --git a/build.gradle b/build.gradle
index f6a0a4f..c7a64f4 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,13 +1,13 @@
 group 'org.pacien.pandoc.filter.plantuml'
 version '1.0-SNAPSHOT'
 
-apply plugin: 'java'
+apply plugin: 'kotlin'
 
 sourceCompatibility = 1.8
 
 jar {
   manifest {
-    attributes 'Main-Class': 'org.pacien.pandoc.filter.plantuml.Filter'
+    attributes 'Main-Class': 'org.pacien.pandoc.filter.plantuml.MainKt'
   }
 
   from {
@@ -23,4 +23,27 @@ dependencies {
   testCompile group: 'junit', name: 'junit', version: '4.12'
   compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.6'
   compile group: 'net.sourceforge.plantuml', name: 'plantuml', version: '8059'
+  compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+}
+
+buildscript {
+  ext.kotlin_version = '1.2.51'
+  repositories {
+    mavenCentral()
+  }
+  dependencies {
+    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+  }
+}
+
+compileKotlin {
+  kotlinOptions {
+    jvmTarget = "1.8"
+  }
+}
+
+compileTestKotlin {
+  kotlinOptions {
+    jvmTarget = "1.8"
+  }
 }
diff --git a/readme.md b/readme.md
index 015e375..c139337 100644
--- a/readme.md
+++ b/readme.md
@@ -3,34 +3,38 @@ pandoc-filter-plantuml
 
 A Pandoc AST filter rendering PlantUML code blocks into vector diagrams.
 
-This filter produces TikZ code that must then be rendered using another filter such as
-[tikz.py][tikz].
+This filter produces TikZ code that can be rendered as vector diagrams in PDF documents,
+or as raster graphics by using another filter such as [tikz.py][tikz].
 
 
-Usage
------
+Example
+-------
 
 A PlantUML diagram in an example Pandoc Markdown file `example.md`:
 
-    ```puml
+    ---
+    header-includes: \usepackage{tikz}
+    ---
+    
+    ```{.puml .centered caption="Courtesy protocol" width=\columnwidth}
     @startuml
     Bob->Alice : hello
+    Alice->Bob : hi
     @enduml
     ```
 
-Using the helper scripts [tikz.py][tikz] and `pandoc-filter-plantuml.sh`:
+Using the helper scripts `pandoc-filter-plantuml.sh`:
 
     #/bin/sh
     java -jar pandoc-filter-plantuml.jar <&0
 
-Can be rendered and included as a vector resource in a PDF by running:
+Can be rendered as a vector resource in a PDF by running:
 
     % pandoc --filter=pandoc-filter-plantuml.sh \
-             --filter=tikz.py \
              --output=example.pdf \
              example.md
 
-Or as an image in an HTML document with the following command:
+Or as a raster image using [tikz.py][tikz] in an HTML document with the following command:
 
     % pandoc --filter=pandoc-filter-plantuml.sh \
              --filter=tikz.py \
@@ -38,6 +42,18 @@ Or as an image in an HTML document with the following command:
              example.md
 
 
+Options
+-------
+
+The following rendering options can be supplied as [fenced code attributes][fenced_code_attribute]:
+
+* `.centered`: centers the diagram horizontally on the page
+* `caption="Some caption"`: adds a figure caption below the diagram
+* `label="somelabel`: adds a label to the figure
+* `width=\columnwidth` and `height=100pt`: resize the diagram using the `\resizebox` command,
+  keeping the aspect ration of only one of the two is given
+
+
 Build
 -----
 
@@ -54,3 +70,4 @@ See /license.txt
 
 
 [tikz]: https://github.com/jgm/pandocfilters/blob/master/examples/tikz.py
+[fenced_code_attribute]: http://pandoc.org/MANUAL.html#fenced-code-blocks
diff --git a/src/main/java/org/pacien/pandoc/filter/plantuml/Filter.java b/src/main/java/org/pacien/pandoc/filter/plantuml/Filter.java
deleted file mode 100644
index 66abc2d..0000000
--- a/src/main/java/org/pacien/pandoc/filter/plantuml/Filter.java
+++ /dev/null
@@ -1,84 +0,0 @@
-package org.pacien.pandoc.filter.plantuml;
-
-import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.node.ArrayNode;
-import com.fasterxml.jackson.databind.node.ObjectNode;
-import com.fasterxml.jackson.databind.node.TextNode;
-import net.sourceforge.plantuml.FileFormat;
-import net.sourceforge.plantuml.FileFormatOption;
-import net.sourceforge.plantuml.SourceStringReader;
-
-import java.io.*;
-import java.util.Iterator;
-import java.util.stream.Collectors;
-
-final public class Filter {
-
-  private static final String BEGIN_TAG = "\\begin{tikzpicture}[yscale=-1]";
-  private static final String LINE_SEP = "\n";
-  private static final String TYPE_KEY = "t";
-  private static final String CONTENT_KEY = "c";
-  private static final String CODE_BLOCK_TYPE = "CodeBlock";
-  private static final String RAW_BLOCK_TYPE = "RawBlock";
-  private static final String PLANTUML_TYPE = "puml";
-  private static final String LATEX_TYPE = "latex";
-  private static final int META_INDEX = 0;
-  private static final int META_PROP_INDEX = 1;
-  private static final int META_PROP_TYPE_INDEX = 0;
-  private static final int CONTENT_INDEX = 1;
-
-  private static String plantumlToLatex(String puml) throws IOException {
-    try (ByteArrayOutputStream s = new ByteArrayOutputStream()) {
-      new SourceStringReader(puml).generateImage(s, new FileFormatOption(FileFormat.LATEX_NO_PREAMBLE));
-      try (BufferedReader r = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(s.toByteArray())))) {
-        return BEGIN_TAG + LINE_SEP + r.lines().filter(l -> !l.equals(BEGIN_TAG)).collect(Collectors.joining(LINE_SEP));
-      }
-    }
-  }
-
-  private static void renderPlantumlNode(ObjectNode n) throws IOException {
-    String puml = n.get(CONTENT_KEY).get(CONTENT_INDEX).asText();
-    String tikz = plantumlToLatex(puml);
-
-    n.set(TYPE_KEY, TextNode.valueOf(RAW_BLOCK_TYPE));
-    ((ArrayNode) n.get(CONTENT_KEY)).removeAll()
-    .add(TextNode.valueOf(LATEX_TYPE))
-    .add(TextNode.valueOf(tikz));
-  }
-
-  private static boolean isPlantumlNode(JsonNode n) {
-    return n.path(TYPE_KEY).asText().equals(CODE_BLOCK_TYPE) &&
-           n.path(CONTENT_KEY).path(META_INDEX).path(META_PROP_INDEX).path(META_PROP_TYPE_INDEX).asText().equals(PLANTUML_TYPE);
-  }
-
-  private static void walk(JsonNode n) throws IOException {
-    if (isPlantumlNode(n))
-      renderPlantumlNode((ObjectNode) n);
-    else if (n.isContainerNode())
-      for (Iterator<JsonNode> i = n.elements(); i.hasNext(); ) walk(i.next());
-  }
-
-  public static void filter(InputStream i, OutputStream o) throws IOException {
-    ObjectMapper m = new ObjectMapper();