Add explicitUpcast

src/main/java/org/bytedeco/javacpp/annotation/Virtual.java

@@ -21,4 +21,5 @@
     /** Pure (abstract) or not. */
     boolean value() default false;
     boolean subclasses() default true;
-}
+    String javaName() default "";
+}

src/main/java/org/bytedeco/javacpp/tools/Context.java

@@ -53,6 +53,7 @@ class Context {
         templateMap = c.templateMap;
         usingList = c.usingList;
         namespaceMap = c.namespaceMap;
+        upcast = c.upcast;
     }
 
     String namespace = null;
@@ -71,6 +72,7 @@ class Context {
     TemplateMap templateMap = null;
     List<String> usingList = null;
     Map<String,String> namespaceMap = null;
+    boolean upcast = false;
 
     /** Return all likely combinations of namespaces and template arguments for this C++ type */
     String[] qualify(String cppName) {

src/main/java/org/bytedeco/javacpp/tools/Generator.java

@@ -3406,8 +3406,10 @@ void callback(Class<?> cls, Method callbackMethod, String callbackName, int allo
         }
 
         if (methodInfo != null) {
+            Virtual virtualAnnotation = callbackMethod.getAnnotation(Virtual.class);
+            String javaName = (virtualAnnotation != null && virtualAnnotation.javaName().length() > 0) ? virtualAnnotation.javaName() : methodInfo.method.getName();
             out.println("    if (" + fieldName + " == NULL) {");
-            out.println("        " + fieldName + " = JavaCPP_getMethodID(env, " + jclasses.index(cls) + ", \"" + methodInfo.method.getName() + "\", \"(" +
+            out.println("        " + fieldName + " = JavaCPP_getMethodID(env, " + jclasses.index(cls) + ", \"" + javaName + "\", \"(" +
                     signature(methodInfo.method.getParameterTypes()) + ")" + signature(methodInfo.method.getReturnType()) + "\");");
             out.println("    }");
             out.println("    jmethodID mid = " + fieldName + ";");

src/main/java/org/bytedeco/javacpp/tools/Info.java

@@ -96,7 +96,7 @@ public Info(Info i) {
      * To use as keys in maps, etc, intern() must be called on instances returned from native code. */
     boolean enumerate = false;
     /** Outputs declarations for this class into their subclasses as well.
-     * Also adds methods for explicit casting, as done for multiple inheritance by default. */
+     * Also adds methods for upcasting, as done for multiple inheritance by default. */
     boolean flatten = false;
     /** Maps friend functions. Only functions having in their argument list an instance of the class they are friend
      * of are currently supported. They are mapped as instance methods of the class. */
@@ -124,6 +124,11 @@ public Info(Info i) {
     String cppText = null;
     /** Outputs the given code, instead of the result parsed from the declaration of C++ identifiers. */
     String javaText = null;
+    /** Whether a static_cast is needed to upcast a pointer to this cppName.
+     *  This is necessary for polymorphic classes that are virtually inherited from. */
+    boolean upcast = false;
+
+
 
     public Info cppNames(String... cppNames) { this.cppNames = cppNames; return this; }
     public Info javaNames(String... javaNames) { this.javaNames = javaNames; return this; }
@@ -161,4 +166,6 @@ public Info(Info i) {
     public Info base(String base) { this.base = base; return this; }
     public Info cppText(String cppText) { this.cppText = cppText; return this; }
     public Info javaText(String javaText) { this.javaText = javaText; return this; }
+    public Info upcast() { this.upcast = true; return this; }
+    public Info upcast(boolean eu) { this.upcast = eu; return this; }
 }