Add explicitUpcast

CHANGELOG.md

@@ -1,4 +1,5 @@
 
+ * Add `Info.upcast` to support class hierarchies with virtual inheritance ([pull #671](https://github.com/bytedeco/javacpp/pull/671))
  * Pick up `@Adapter`, `@SharedPtr`, etc annotations on `allocate()` as well ([pull #668](https://github.com/bytedeco/javacpp/pull/668))
  * Provide `@Virtual(subclasses=false)` to prevent `Generator` from subclassing subclasses ([pull #660](https://github.com/bytedeco/javacpp/pull/660))
  * Fix `Loader.getPlatform()` detection for `linux-armhf` with Temurin JDK ([issue bytedeco/javacv#2001](https://github.com/bytedeco/javacv/issues/2001))

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 method() default "";
+}

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

@@ -47,6 +47,7 @@ class Context {
         inaccessible = c.inaccessible;
         beanify = c.beanify;
         objectify = c.objectify;
+        upcast = c.upcast;
         virtualize = c.virtualize;
         variable = c.variable;
         infoMap = c.infoMap;
@@ -65,6 +66,7 @@ class Context {
     boolean inaccessible = false;
     boolean beanify = false;
     boolean objectify = false;
+    boolean upcast = false;
     boolean virtualize = false;
     Declarator variable = null;
     InfoMap infoMap = null;

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 virtual = callbackMethod.getAnnotation(Virtual.class);
+            String methodName = (virtual != null && virtual.method().length() > 0) ? virtual.method() : 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) + ", \"" + methodName + "\", \"(" +
                     signature(methodInfo.method.getParameterTypes()) + ")" + signature(methodInfo.method.getReturnType()) + "\");");
             out.println("    }");
             out.println("    jmethodID mid = " + fieldName + ";");

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

@@ -61,6 +61,7 @@ public Info(Info i) {
         skip = i.skip;
         skipDefaults = i.skipDefaults;
         purify = i.purify;
+        upcast = i.upcast;
         virtualize = i.virtualize;
         base = i.base;
         cppText = i.cppText;
@@ -96,7 +97,7 @@ 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. */
@@ -116,6 +117,9 @@ public Info(Info i) {
     boolean skipDefaults = false;
     /** Forces a class to be treated as if it were abstract. */
     boolean purify = false;
+    /** 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;
     /** Annotates virtual functions with @{@link Virtual} and adds appropriate constructors. */
     boolean virtualize = false;
     /** Allows to override the base class of {@link #pointerTypes}. Defaults to {@link Pointer}. */
@@ -156,6 +160,8 @@ public Info(Info i) {
     public Info skipDefaults(boolean skipDefaults) { this.skipDefaults = skipDefaults; return this; }
     public Info purify() { this.purify = true; return this; }
     public Info purify(boolean purify) { this.purify = purify; return this; }
+    public Info upcast() { this.upcast = true; return this; }
+    public Info upcast(boolean upcast) { this.upcast = upcast; return this; }
     public Info virtualize() { this.virtualize = true; return this; }
     public Info virtualize(boolean virtualize) { this.virtualize = virtualize; return this; }
     public Info base(String base) { this.base = base; return this; }