support relative image src for GraphvizCmdLineEngine (see #101)

Author: nidi3

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

@@ -31,7 +31,12 @@ public String execute(String src, Options options) {
     protected abstract String jsExecute(String jsCall);
 
     protected String jsVizExec(String src, Options options) {
-        return src.startsWith("render") ? src : ("render('" + jsEscape(src) + "'," + options.toJson(false) + ");");
+        return src.startsWith("render") ? src : ("render('" + preprocessCode(src) + "'," + options.toJson(false) + ");");
+    }
+
+    protected String preprocessCode(String src) {
+        if (src.contains("<img")) throw new IllegalArgumentException("Found <img> tag. This is not supported by JS engines. Either use the GraphvizCmdLineEngine or a node with image attribute.");
+        return jsEscape(src);
     }
 
     protected String jsEscape(String js) {

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

@@ -153,8 +153,8 @@ public Graphviz yInvert(@Nullable Boolean yInvert) {
         return new Graphviz(src, rasterizer, width, height, scale, fontAdjust, options.yInvert(yInvert));
     }
 
-    public Graphviz fontAdjust(double fontAdjust) {
-        return new Graphviz(src, rasterizer, width, height, scale, fontAdjust, options);
+    public Graphviz basedir(File basedir) {
+        return new Graphviz(src, rasterizer, width, height, scale, fontAdjust, options.basedir(basedir));
     }
 
     public Graphviz width(int width) {
@@ -169,6 +169,10 @@ public Graphviz scale(double scale) {
         return new Graphviz(src, rasterizer, width, height, scale, fontAdjust, options);
     }
 
+    public Graphviz fontAdjust(double fontAdjust) {
+        return new Graphviz(src, rasterizer, width, height, scale, fontAdjust, options);
+    }
+
     public Renderer rasterize(@Nullable Rasterizer rasterizer) {
         if (rasterizer == null) {
             throw new IllegalArgumentException("The provided rasterizer implementation was not found. "

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

@@ -26,6 +26,8 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import static java.util.Locale.ENGLISH;
 
@@ -36,6 +38,7 @@
  */
 public class GraphvizCmdLineEngine extends AbstractGraphvizEngine {
     private static final Logger LOG = LoggerFactory.getLogger(AbstractGraphvizEngine.class);
+    private static final Pattern IMG_SRC = Pattern.compile("<img .*?src\\s*=\\s*['\"]([^'\"]*)");
 
     private final String envPath;
     private final CommandRunner cmdRunner;
@@ -74,7 +77,7 @@ public String execute(String src, Options options) {
             final File dotfile = getDotFile(tempDirPath.toString());
             try (final BufferedWriter bw = new BufferedWriter(
                     new OutputStreamWriter(new FileOutputStream(dotfile), StandardCharsets.UTF_8))) {
-                bw.write(src);
+                bw.write(preprocessCode(src, options));
             }
             final String command = engine
                     + (options.yInvert != null && options.yInvert ? " -y" : "")
@@ -93,6 +96,21 @@ public String execute(String src, Options options) {
         }
     }
 
+    protected String preprocessCode(String src, Options options) {
+        final Matcher matcher = IMG_SRC.matcher(src);
+        final StringBuilder s = new StringBuilder();
+        int last = 0;
+        while (matcher.find()) {
+            final String attr = matcher.group(1);
+            s.append(src, last, matcher.start(1));
+            s.append((attr.startsWith("http://") || attr.startsWith("https://") || new File(attr).isAbsolute())
+                    ? attr
+                    : new File(options.basedir, attr).getAbsolutePath());
+            last = matcher.end(1);
+        }
+        return s.append(src.substring(last)).toString();
+    }
+
     private String getEngineExecutable(@Nullable Engine engine) {
         final String exe = SystemUtils.executableName(engine == null ? "dot" : engine.toString().toLowerCase(ENGLISH));
         if (!CommandRunner.isExecutableFound(exe, envPath)) {

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

@@ -16,6 +16,7 @@
 package guru.nidi.graphviz.engine;
 
 import javax.annotation.Nullable;
+import java.io.File;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -41,24 +42,27 @@ public final class Options {
             FORMAT = Pattern.compile("format:'(.*?)'"),
             ENGINE = Pattern.compile("engine:'(.*?)'"),
             MEMORY = Pattern.compile("totalMemory:'(.*?)'"),
-            Y_INVERT = Pattern.compile("yInvert:(.*?)");
+            Y_INVERT = Pattern.compile("yInvert:(.*?)"),
+            BASE_DIR = Pattern.compile("basedir:'(.*?)'");
 
     final Engine engine;
     final Format format;
     @Nullable
     final Integer totalMemory;
     @Nullable
     final Boolean yInvert;
+    final File basedir;
 
-    private Options(Engine engine, Format format, @Nullable Integer totalMemory, @Nullable Boolean yInvert) {
+    private Options(Engine engine, Format format, @Nullable Integer totalMemory, @Nullable Boolean yInvert, File basedir) {
         this.engine = engine;
         this.format = format;
         this.totalMemory = totalMemory;
         this.yInvert = yInvert;
+        this.basedir = basedir;
     }
 
     public static Options create() {
-        return new Options(Engine.DOT, Format.SVG, null, null);
+        return new Options(Engine.DOT, Format.SVG, null, null, new File("."));
     }
 
     public static Options fromJson(String json) {
@@ -70,38 +74,43 @@ public static Options fromJson(String json) {
         final boolean hasMemory = memory.find();
         final Matcher yInvert = Y_INVERT.matcher(json);
         final boolean hasYInvert = yInvert.find();
+        final Matcher basedir = BASE_DIR.matcher(json);
+        basedir.find();
+
         return new Options(
                 Engine.valueOf(engine.group(1)),
                 Format.valueOf(format.group(1)),
                 hasMemory ? Integer.parseInt(memory.group(1)) : null,
-                hasYInvert ? Boolean.parseBoolean(yInvert.group(1)) : null);
+                hasYInvert ? Boolean.parseBoolean(yInvert.group(1)) : null,
+                new File(basedir.group(1)));
     }
 
     public Options engine(Engine engine) {
-        return new Options(engine, format, totalMemory, yInvert);
+        return new Options(engine, format, totalMemory, yInvert, basedir);
     }
 
     public Options format(Format format) {
-        return new Options(engine, format, totalMemory, yInvert);
+        return new Options(engine, format, totalMemory, yInvert, basedir);
     }
 
     public Options totalMemory(@Nullable Integer totalMemory) {
-        return new Options(engine, format, totalMemory, yInvert);
+        return new Options(engine, format, totalMemory, yInvert, basedir);
     }
 
     public Options yInvert(@Nullable Boolean yInvert) {
-        return new Options(engine, format, totalMemory, yInvert);
+        return new Options(engine, format, totalMemory, yInvert, basedir);
     }
 
-    public Options fontAdjust(double fontAdjust) {
-        return new Options(engine, format, totalMemory, yInvert);
+    public Options basedir(File basedir) {
+        return new Options(engine, format, totalMemory, yInvert, basedir);
     }
 
     public String toJson(boolean raw) {
         final String form = "format:'" + (raw ? format : format.vizName) + "'";
         final String eng = ",engine:'" + (raw ? engine : engine.toString().toLowerCase(ENGLISH)) + "'";
         final String mem = totalMemory == null ? "" : (",totalMemory:'" + totalMemory + "'");
         final String yInv = yInvert == null ? "" : (",yInvert:" + yInvert);
-        return "{" + form + eng + mem + yInv + "}";
+        final String base = ",basedir:'" + basedir.getAbsolutePath() + "'";
+        return "{" + form + eng + mem + yInv + base + ",images: [ { path: '/Users/nidi/idea/graphviz-java-parent/out2.png', width: '400px', height: '300px' }]}";
     }
 }