Make JNI converter traits easier to create

Not entirely happy with the syntax yet, but it reduces declaring converters
to a single line. Added one for QUrl to demonstrate this.

autotests/jnipropertytest.cpp

@@ -7,6 +7,8 @@
 #include <kandroidextras/jniproperty.h>
 #include <kandroidextras/jnitypes.h>
 #include <kandroidextras/manifestpermission.h>
+#include <kandroidextras/intent.h>
+#include <kandroidextras/uri.h>
 
 #include <QtTest/qtest.h>
 
@@ -23,6 +25,8 @@ class TestClass : android::content::Intent
     JNI_PROPERTY(java::lang::String, myStringField)
     JNI_PROPERTY(int, myIntField)
     JNI_PROPERTY(android::net::Uri, myUriField)
+    JNI_PROPERTY(android::content::Intent, myIntentField)
+
 
     inline QAndroidJniObject handle() const { return m_handle; }
 private:
@@ -58,17 +62,22 @@ private Q_SLOTS:
         const QString foo = obj.myStringField;
         obj.myStringField = foo;
         const int bar = obj.myIntField;
+        Q_UNUSED(bar);
         obj.myIntField = 42;
-        const QAndroidJniObject bla = obj.myUriField;
-        obj.myUriField = bla;
+        const QUrl url = obj.myUriField;
+        obj.myUriField = url;
+        const QAndroidJniObject bla = obj.myIntentField;
+        obj.myIntentField = bla;
 
-        QCOMPARE(obj.handle().protocol().size(), 6);
+        QCOMPARE(obj.handle().protocol().size(), 8);
         QCOMPARE(obj.handle().protocol().at(0), QLatin1String("getObjectField: myStringField Ljava/lang/String;"));
         QCOMPARE(obj.handle().protocol().at(1), QLatin1String("setField: myStringField Ljava/lang/String;"));
         QCOMPARE(obj.handle().protocol().at(2), QLatin1String("getField: myIntField I"));
         QCOMPARE(obj.handle().protocol().at(3), QLatin1String("setField: myIntField I"));
         QCOMPARE(obj.handle().protocol().at(4), QLatin1String("getObjectField: myUriField Landroid/net/Uri;"));
         QCOMPARE(obj.handle().protocol().at(5), QLatin1String("setField: myUriField Landroid/net/Uri;"));
+        QCOMPARE(obj.handle().protocol().at(6), QLatin1String("getObjectField: myIntentField Landroid/content/Intent;"));
+        QCOMPARE(obj.handle().protocol().at(7), QLatin1String("setField: myIntentField Landroid/content/Intent;"));
 #endif
     }
 };

src/kandroidextras/android/uri.cpp

@@ -6,12 +6,10 @@
 
 #include "uri.h"
 
-#include <KAndroidExtras/AndroidTypes>
 #include <KAndroidExtras/JniSignature>
 #include <KAndroidExtras/JavaTypes>
 
 #include <QAndroidJniObject>
-#include <QUrl>
 
 using namespace KAndroidExtras;
 

src/kandroidextras/android/uri.h

@@ -9,8 +9,12 @@
 
 #include "kandroidextras_export.h"
 
+#include <KAndroidExtras/AndroidTypes>
+#include <KAndroidExtras/JniTypeTraits>
+
+#include <QUrl>
+
 class QAndroidJniObject;
-class QUrl;
 
 namespace KAndroidExtras {
 
@@ -24,6 +28,8 @@ namespace Uri
     KANDROIDEXTRAS_EXPORT QUrl toUrl(const QAndroidJniObject &uri);
 }
 
+JNI_DECLARE_CONVERTER(android::net::Uri, QUrl, (Uri::toUrl(value)), (Uri::fromUrl(value)))
+
 }
 
 #endif // KANDROIDEXTRAS_URI_H

src/kandroidextras/java/javatypes.h

@@ -16,16 +16,7 @@ JNI_TYPE(java, io, File)
 JNI_TYPE(java, lang, String)
 JNI_TYPE(java, util, Locale)
 
-namespace Jni {
-template <> struct converter<QString> {
-    typedef java::lang::String type;
-    static inline QAndroidJniObject convert(const QString &value) { return QAndroidJniObject::fromString(value); }
-};
-template <> struct converter<java::lang::String> {
-    typedef QString type;
-    static inline QString convert(const QAndroidJniObject &value) { return value.toString(); }
-};
-}
+JNI_DECLARE_CONVERTER(java::lang::String, QString, (value.toString()), (QAndroidJniObject::fromString(value)))
 
 }
 

src/kandroidextras/jni/jnitypetraits.h

@@ -30,7 +30,7 @@ template <> struct is_basic_type<jlong> : std::true_type {};
 template <> struct is_basic_type<jfloat> : std::true_type {};
 template <> struct is_basic_type<jdouble> : std::true_type {};
 
-
+/** Type conversion trait, see @c JNI_DECLARE_CONVERTER. */
 template <typename T> struct converter {
     typedef void type;
 };
@@ -41,6 +41,25 @@ template <typename T> struct reverse_converter {
 
 }
 
+/**
+ * Declare a JNI type to be convertible to a native type.
+ * @param JniType A type declared with @p JNI_TYPE.
+ * @param NativeType A C++ type @p JniType can be converted to/from.
+ * @param FromJniFn Code converting a @c QAndroidJniObject @c value to @p NativeType.
+ * @param ToJniCode converting a @p NativeType @c value to a QAndroidJniObject.
+ */
+#define JNI_DECLARE_CONVERTER(JniType, NativeType, FromJniFn, ToJniFn) \
+namespace Jni { \
+template <> struct converter<NativeType> { \
+    typedef JniType type; \
+    static inline QAndroidJniObject convert(const NativeType &value) { return (ToJniFn); } \
+}; \
+template <> struct converter<JniType> { \
+    typedef NativeType type; \
+    static inline NativeType convert(const QAndroidJniObject &value) { return (FromJniFn); } \
+}; \
+}
+
 }
 
 #endif