set headless mode per default

Signed-off-by: Stefan Niederhauser <[email protected]>

Author: nidi3

graphviz-java/src/main/java/guru/nidi/graphviz/engine/AbstractJsGraphvizEngine.java

@@ -31,7 +31,6 @@ public abstract class AbstractJsGraphvizEngine extends AbstractGraphvizEngine {
     private static final Pattern FONT_NAME_PATTERN = Pattern.compile("\"?fontname\"?\\s*=\\s*\"?(.*?)[\",;\\]]");
     private static final Map<Class<?>, ThreadLocal<EngineState>> ENGINES = new HashMap<>();
     private final Supplier<JavascriptEngine> engineSupplier;
-    private final FontMeasurer fontMeasurer = new FontMeasurer();
 
     protected AbstractJsGraphvizEngine(boolean sync, Supplier<JavascriptEngine> engineSupplier) {
         super(sync);
@@ -113,7 +112,7 @@ private void measureFonts(String src) {
         final Matcher matcher = FONT_NAME_PATTERN.matcher(src);
         while (matcher.find()) {
             final String font = matcher.group(1).trim();
-            final double[] widths = fontMeasurer.measureFont(font);
+            final double[] widths = FontMeasurer.measureFont(font);
             if (widths.length > 0) {
                 final String widthsString = Arrays.stream(widths).mapToObj(Double::toString).collect(joining(","));
                 engine().executeJavascript("initViz().setFontWidth('" + font + "',[" + widthsString + "])");

graphviz-java/src/main/java/guru/nidi/graphviz/engine/FontMeasurer.java

@@ -21,15 +21,18 @@
 import java.util.HashSet;
 import java.util.Set;
 
-class FontMeasurer {
+final class FontMeasurer {
     private static final FontRenderContext FONT_RENDER_CONTEXT =
             new BufferedImage(1, 1, BufferedImage.TYPE_3BYTE_BGR).createGraphics().getFontRenderContext();
     private static final double COURIER_WIDTH = .5999;
     private static final Font COURIER = new Font("Courier", Font.PLAIN, 10);
     private static final double COURIER_SPACE_WIDTH = charWidth(COURIER, ' ');
     private static final double COURIER_BORDER_WIDTH = borderWidth(COURIER);
     private static final double[] COURIER_WIDTHS = courierWidths();
-    private final Set<String> fonts = new HashSet<>();
+    private static final Set<String> FONTS = new HashSet<>();
+
+    private FontMeasurer() {
+    }
 
     private static double[] courierWidths() {
         double[] w = new double[256];
@@ -47,11 +50,11 @@ private static double borderWidth(Font font) {
         return font.createGlyphVector(FONT_RENDER_CONTEXT, new char[]{56, 56}).getVisualBounds().getWidth();
     }
 
-    double[] measureFont(String name) {
-        if (fonts.contains(name)) {
+    static double[] measureFont(String name) {
+        if (FONTS.contains(name)) {
             return new double[0];
         }
-        fonts.add(name);
+        FONTS.add(name);
         final Font font = new Font(name, Font.PLAIN, 10);
         final double spaceWidth = charWidth(font, ' ');
         final double borderWidth = borderWidth(font);

graphviz-java/src/main/java/guru/nidi/graphviz/engine/Graphviz.java

@@ -37,6 +37,12 @@
 import static java.util.regex.Pattern.CASE_INSENSITIVE;
 
 public final class Graphviz {
+    static {
+        if (System.getProperty("java.awt.headless") == null) {
+            System.setProperty("java.awt.headless", "true");
+        }
+    }
+
     private static final Logger LOG = LoggerFactory.getLogger(Graphviz.class);
 
     private static final Pattern DPI_PATTERN = Pattern.compile("\"?dpi\"?\\s*=\\s*\"?([0-9.]+)\"?", CASE_INSENSITIVE);
@@ -184,6 +190,10 @@ private static void doReleaseEngine(GraphvizEngine engine) {
         }
     }
 
+    public static void noHeadless() {
+        System.setProperty("java.awt.headless", "false");
+    }
+
     public static Graphviz fromFile(File src) throws IOException {
         try (final InputStream in = new FileInputStream(src)) {
             return fromString(readAsString(in)).basedir(src.getAbsoluteFile().getParentFile());