common loader: code refactoring.

replace from Scene to Paint at the internal interface.

Picture doesn't need to know the returned Node type.
base class, Paint is enough to in the data passing.

src/lib/tvgLoadModule.h

@@ -40,13 +40,13 @@ public:
 
     virtual ~LoadModule() {}
 
-    virtual bool open(const string& path) { /* Not supported */ return false; };
-    virtual bool open(const char* data, uint32_t size, bool copy) { /* Not supported */ return false; };
-    virtual bool open(const uint32_t* data, uint32_t w, uint32_t h, bool copy) { /* Not supported */ return false; };
+    virtual bool open(const string& path) { return false; };
+    virtual bool open(const char* data, uint32_t size, bool copy) { return false; };
+    virtual bool open(const uint32_t* data, uint32_t w, uint32_t h, bool copy) { return false; };
     virtual bool read() = 0;
     virtual bool close() = 0;
     virtual const uint32_t* pixels() { return nullptr; };
-    virtual unique_ptr<Scene> scene() { return nullptr; };
+    virtual unique_ptr<Paint> paint() { return nullptr; };
 };
 
 }

src/lib/tvgPictureImpl.h

@@ -112,9 +112,8 @@ struct Picture::Impl
     {
         if (loader) {
             if (!paint) {
-                auto scene = loader->scene();
-                if (scene) {
-                    paint = scene.release();
+                if (auto p = loader->paint()) {
+                    paint = p.release();
                     loader->close();
                     if (w != loader->w && h != loader->h) resize();
                     if (paint) return RenderUpdateFlag::None;

src/loaders/svg/tvgSvgLoader.cpp

@@ -2885,7 +2885,7 @@ bool SvgLoader::close()
 }
 
 
-unique_ptr<Scene> SvgLoader::scene()
+unique_ptr<Paint> SvgLoader::paint()
 {
     this->done();
     if (root) return move(root);

src/loaders/svg/tvgSvgLoader.h

@@ -49,7 +49,7 @@ public:
     bool close() override;
     void run(unsigned tid) override;
 
-    unique_ptr<Scene> scene() override;
+    unique_ptr<Paint> paint() override;
 
 private:
     void clear();

src/loaders/tvg/tvgTvgLoader.cpp

@@ -125,7 +125,7 @@ void TvgLoader::run(unsigned tid)
     if (!root) clear();
 }
 
-unique_ptr<Scene> TvgLoader::scene()
+unique_ptr<Paint> TvgLoader::paint()
 {
     this->done();
     if (root) return move(root);

src/loaders/tvg/tvgTvgLoader.h

@@ -45,7 +45,7 @@ public:
     bool close() override;
 
     void run(unsigned tid) override;
-    unique_ptr<Scene> scene() override;
+    unique_ptr<Paint> paint() override;
 
 private:
     void clear();