renderer: revise the internal logic.

dispose of the resources at the end of the paint deletion.
This will help retain the resources of the retained paints
and reuse them after reconstructing the next scene.

src/renderer/tvgCanvas.h

@@ -43,16 +43,16 @@ struct Canvas::Impl
         if (renderer) renderer->sync();
 
         clearPaints();
-        delete(renderer);
+
+        if (renderer) {
+            if ((--renderer->refCnt) == 0) delete(renderer);
+        }
     }
 
     void clearPaints()
     {
         for (auto paint : paints) {
-            P(paint)->unref();
-            if (paint->pImpl->dispose(renderer) && P(paint)->refCnt == 0) {
-                delete(paint);
-            }
+            if (P(paint)->unref() == 0) delete(paint);
         }
         paints.clear();
     }

src/renderer/tvgPaint.cpp

@@ -114,16 +114,6 @@ RenderRegion Paint::Impl::bounds(RenderMethod* renderer) const
 }
 
 
-bool Paint::Impl::dispose(RenderMethod* renderer)
-{
-    if (compData) compData->target->pImpl->dispose(renderer);
-
-    bool ret;
-    PAINT_METHOD(ret, dispose(renderer));
-    return ret;
-}
-
-
 Iterator* Paint::Impl::iterator()
 {
     Iterator* ret;
@@ -231,6 +221,12 @@ bool Paint::Impl::render(RenderMethod* renderer)
 
 RenderData Paint::Impl::update(RenderMethod* renderer, const RenderTransform* pTransform, Array<RenderData>& clips, uint8_t opacity, RenderUpdateFlag pFlag, bool clipper)
 {
+    if (this->renderer != renderer) {
+        if (this->renderer) TVGERR("RENDERER", "paint's renderer has been changed!");
+        ++renderer->refCnt;
+        this->renderer = renderer;
+    }
+
     if (renderFlag & RenderUpdateFlag::Transform) {
         if (!rTransform) return nullptr;
         rTransform->update();

src/renderer/tvgPaint.h

@@ -50,6 +50,7 @@ namespace tvg
         Paint* paint = nullptr;
         RenderTransform* rTransform = nullptr;
         Composite* compData = nullptr;
+        RenderMethod* renderer = nullptr;
         BlendMethod blendMethod = BlendMethod::Normal;              //uint8_t
         uint8_t renderFlag = RenderUpdateFlag::None;
         uint8_t ctxFlag = ContextFlag::Invalid;
@@ -57,9 +58,7 @@ namespace tvg
         uint8_t opacity = 255;
         uint8_t refCnt = 0;
 
-        Impl(Paint* pnt) : paint(pnt)
-        {
-        }
+        Impl(Paint* pnt) : paint(pnt) {}
 
         ~Impl()
         {
@@ -132,7 +131,6 @@ namespace tvg
         }
 
         RenderRegion bounds(RenderMethod* renderer) const;
-        bool dispose(RenderMethod* renderer);
         Iterator* iterator();
         bool rotate(float degree);
         bool scale(float factor);

src/renderer/tvgPicture.h

@@ -82,15 +82,12 @@ struct Picture::Impl
     ~Impl()
     {
         LoaderMgr::retrieve(loader);
-        delete(paint);
+        if (surface) {
+            if (auto renderer = PP(picture)->renderer) {
+                renderer->dispose(rd);
             }
-
-    bool dispose(RenderMethod* renderer)
-    {
-        if (paint) paint->pImpl->dispose(renderer);
-        else if (surface) renderer->dispose(rd);
-        rd = nullptr;
-        return true;
+        }
+        delete(paint);
     }
 
     RenderData update(RenderMethod* renderer, const RenderTransform* pTransform, Array<RenderData>& clips, uint8_t opacity, RenderUpdateFlag pFlag, bool clipper)

src/renderer/tvgScene.h

@@ -59,7 +59,6 @@ struct SceneIterator : Iterator
 struct Scene::Impl
 {
     list<Paint*> paints;
-    RenderMethod* renderer = nullptr;    //keep it for explicit clear
     RenderData rd = nullptr;
     Scene* scene = nullptr;
     uint8_t opacity;                     //for composition
@@ -74,19 +73,10 @@ struct Scene::Impl
         for (auto paint : paints) {
             if (P(paint)->unref() == 0) delete(paint);
         }
-    }
-
-    bool dispose(RenderMethod* renderer)
-    {
-        for (auto paint : paints) {
-            paint->pImpl->dispose(renderer);
-        }
 
+        if (auto renderer = PP(scene)->renderer) {
             renderer->dispose(rd);
-        this->renderer = nullptr;
-        this->rd = nullptr;
-
-        return true;
+        }
     }
 
     bool needComposition(uint8_t opacity)
@@ -120,8 +110,6 @@ struct Scene::Impl
             opacity = 255;
         }
 
-        this->renderer = renderer;
-
         if (clipper) {
             Array<RenderData> rds(paints.size());
             for (auto paint : paints) {
@@ -226,14 +214,10 @@ struct Scene::Impl
 
     void clear(bool free)
     {
-        auto dispose = renderer ? true : false;
-
         for (auto paint : paints) {
-            if (dispose) free &= P(paint)->dispose(renderer);
             if (P(paint)->unref() == 0 && free) delete(paint);
         }
         paints.clear();
-        renderer = nullptr;
     }
 
     Iterator* iterator()

src/renderer/tvgShape.h

@@ -41,11 +41,11 @@ struct Shape::Impl
     {
     }
 
-    bool dispose(RenderMethod* renderer)
+    ~Impl()
     {
+        if (auto renderer = PP(shape)->renderer) {
             renderer->dispose(rd);
-        rd = nullptr;
-        return true;
+        }
     }
 
     bool render(RenderMethod* renderer)

src/renderer/tvgText.h

@@ -35,7 +35,6 @@
 
 struct Text::Impl
 {
-    RenderData rd = nullptr;
     FontLoader* loader = nullptr;
     Shape* paint = nullptr;
     char* utf8 = nullptr;
@@ -94,7 +93,8 @@ struct Text::Impl
 
     RenderRegion bounds(RenderMethod* renderer)
     {
-        return renderer->region(rd);
+        if (paint) return P(paint)->bounds(renderer);
+        else return {0, 0, 0, 0};
     }
 
     bool render(RenderMethod* renderer)
@@ -142,8 +142,7 @@ struct Text::Impl
                 P(static_cast<RadialGradient*>(fill))->fr *= scale;
             }
         }
-        rd = PP(paint)->update(renderer, transform, clips, opacity, pFlag, clipper);
-        return rd;
+        return PP(paint)->update(renderer, transform, clips, opacity, pFlag, clipper);
     }
 
     bool bounds(float* x, float* y, float* w, float* h, TVG_UNUSED bool stroking)
@@ -153,13 +152,6 @@ struct Text::Impl
         return true;
     }
 
-    bool dispose(RenderMethod* renderer)
-    {
-        renderer->dispose(rd);
-        this->rd = nullptr;
-        return true;
-    }
-
     Paint* duplicate()
     {
         load();