renderer/accessor: revise set() api for animation support

before:
unique_ptr<Picture> Accessor::set(unique_ptr<Picture> picture, function<bool(const Paint* paint)> func)

after:
Result Accessor::set(const Picture* picture, std::function<bool(const Paint* paint, void* data)> func, void* data)

examples/Accessor.cpp

@@ -42,7 +42,7 @@ struct UserExample : tvgexam::Example
 
         //The callback function from lambda expression.
         //This function will be called for every paint nodes of the picture tree.
-        auto f = [](const tvg::Paint* paint) -> bool
+        auto f = [](const tvg::Paint* paint, void* data) -> bool
         {
             if (paint->type() == tvg::Type::Shape) {
                 auto shape = (tvg::Shape*) paint;
@@ -58,7 +58,7 @@ struct UserExample : tvgexam::Example
             return true;
         };
 
-        picture = accessor->set(std::move(picture), f);
+        if (!tvgexam::verify(accessor->set(picture.get(), f, nullptr))) return false;
 
         canvas->push(std::move(picture));
 

inc/thorvg.h

@@ -2119,17 +2119,20 @@ class TVG_API Accessor final
 public:
     ~Accessor();
 
+    TVG_DEPRECATED std::unique_ptr<Picture> set(std::unique_ptr<Picture> picture, std::function<bool(const Paint* paint)> func) noexcept;
+
     /**
      * @brief Set the access function for traversing the Picture scene tree nodes.
      *
      * @param[in] picture The picture node to traverse the internal scene-tree.
      * @param[in] func The callback function calling for every paint nodes of the Picture.
-     *
+     * @param[in] data Data passed to the @p func as its argument.
-     * @return Return the given @p picture instance.
      *
      * @note The bitmap based picture might not have the scene-tree.
+     *
+     * @note Experimental API
      */
-    std::unique_ptr<Picture> set(std::unique_ptr<Picture> picture, std::function<bool(const Paint* paint)> func) noexcept;
+    Result set(const Picture* picture, std::function<bool(const Paint* paint, void* data)> func, void* data) noexcept;
 
     /**
      * @brief Creates a new Accessor object.

src/renderer/tvgAccessor.cpp

@@ -26,15 +26,15 @@
 /* Internal Class Implementation                                        */
 /************************************************************************/
 
-static bool accessChildren(Iterator* it, function<bool(const Paint* paint)> func)
+static bool accessChildren(Iterator* it, function<bool(const Paint* paint, void* data)> func, void* data)
 {
     while (auto child = it->next()) {
         //Access the child
-        if (!func(child)) return false;
+        if (!func(child, data)) return false;
 
         //Access the children of the child
         if (auto it2 = IteratorAccessor::iterator(child)) {
-            if (!accessChildren(it2, func)) {
+            if (!accessChildren(it2, func, data)) {
                 delete(it2);
                 return false;
             }
@@ -44,26 +44,40 @@ static bool accessChildren(Iterator* it, function<bool(const Paint* paint)> func
     return true;
 }
 
+
 /************************************************************************/
 /* External Class Implementation                                        */
 /************************************************************************/
 
-unique_ptr<Picture> Accessor::set(unique_ptr<Picture> picture, function<bool(const Paint* paint)> func) noexcept
+TVG_DEPRECATED unique_ptr<Picture> Accessor::set(unique_ptr<Picture> picture, function<bool(const Paint* paint)> func) noexcept
 {
-    auto p = picture.get();
+    auto backward = [](const tvg::Paint* paint, void* data) -> bool
-    if (!p || !func) return picture;
+    {
+        auto func = reinterpret_cast<function<bool(const Paint* paint)>*>(data);
+        if (!(*func)(paint)) return false;
+        return true;
+    };
+
+    set(picture.get(), backward, reinterpret_cast<void*>(&func));
+    return picture;
+}
+
+
+Result Accessor::set(const Picture* picture, function<bool(const Paint* paint, void* data)> func, void* data) noexcept
+{
+    if (!picture || !func) return Result::InvalidArguments;
 
     //Use the Preorder Tree-Search
 
     //Root
-    if (!func(p)) return picture;
+    if (!func(picture, data)) return Result::Success;
 
     //Children
-    if (auto it = IteratorAccessor::iterator(p)) {
+    if (auto it = IteratorAccessor::iterator(picture)) {
-        accessChildren(it, func);
+        accessChildren(it, func, data);
         delete(it);
     }
-    return picture;
+    return Result::Success;
 }
 
 

test/testAccessor.cpp

@@ -55,11 +55,10 @@ TEST_CASE("Set", "[tvgAccessor]")
     REQUIRE(accessor);
 
     //Case 1
-    picture = accessor->set(std::move(picture), nullptr);
+    REQUIRE(accessor->set(picture.get(), nullptr, nullptr) == Result::InvalidArguments);
-    REQUIRE(picture);
 
     //Case 2
-    auto f = [](const tvg::Paint* paint) -> bool
+    auto f = [](const tvg::Paint* paint, void* data) -> bool
     {
         if (paint->type() == Type::Shape) {
             auto shape = (tvg::Shape*) paint;
@@ -71,8 +70,7 @@ TEST_CASE("Set", "[tvgAccessor]")
         return true;
     };
 
-    picture = accessor->set(std::move(picture), f);
+    REQUIRE(accessor->set(picture.get(), f, nullptr) == Result::Success);
-    REQUIRE(picture);
 
     REQUIRE(Initializer::term(CanvasEngine::Sw) == Result::Success);
 }