common: improve thread safety for partial rendering

- clear resources on the main thread to safely remove resources associated with dirty regions.
- skip redundant condition checks for unsafe disabled add calls.

src/loaders/lottie/tvgLottieBuilder.cpp

@@ -1542,15 +1542,12 @@ bool LottieBuilder::update(LottieComposition* comp, float frameNo)
         if (equal(frameNo, tween.frameNo)) offTween();
     }
 
-    //update children layers
-    auto root = comp->root;
-    root->scene->remove();
-
     if (exps && comp->expressions) exps->update(comp->timeAtFrame(frameNo));
 
-    ARRAY_REVERSE_FOREACH(child, root->children) {
+    //update children layers
+    ARRAY_REVERSE_FOREACH(child, comp->root->children) {
         auto layer = static_cast<LottieLayer*>(*child);
-        if (!layer->matteSrc) updateLayer(comp, root->scene, layer, frameNo);
+        if (!layer->matteSrc) updateLayer(comp, comp->root->scene, layer, frameNo);
     }
 
     return true;

src/loaders/lottie/tvgLottieLoader.cpp

@@ -347,6 +347,8 @@ bool LottieLoader::frame(float no)
 
     builder->offTween();
 
+    if (comp) comp->clear();     //clear synchronously
+
     TaskScheduler::request(this);
 
     return true;
@@ -452,6 +454,8 @@ bool LottieLoader::tween(float from, float to, float progress)
 
     builder->onTween(shorten(to), progress);
 
+    if (comp) comp->clear();     //clear synchronously
+
     TaskScheduler::request(this);
 
     return true;

src/loaders/lottie/tvgLottieModel.h

@@ -1089,6 +1089,11 @@ struct LottieComposition
 {
     ~LottieComposition();
 
+    void clear()
+    {
+        if (root && root->scene) root->scene->remove();
+    }
+
     float duration() const
     {
         return frameCnt() / frameRate;  // in second

src/renderer/sw_engine/tvgSwRenderer.cpp

@@ -384,7 +384,7 @@ bool SwRenderer::postRender()
 void SwRenderer::damage(RenderData rd, const RenderRegion& region)
 {
     SwTask* task = static_cast<SwTask*>(rd);
-    if (task && task->opacity == 0) return;
+    if (dirtyRegion.deactivated() || (task && task->opacity == 0)) return;
     dirtyRegion.add(region);
 }
 

src/renderer/tvgRender.cpp

@@ -160,8 +160,6 @@ void RenderDirtyRegion::init(uint32_t w, uint32_t h)
 
 bool RenderDirtyRegion::add(const RenderRegion& bbox)
 {
-    if (disabled) return false;
-
     for (int idx = 0; idx < PARTITIONING; ++idx) {
         auto& partition = partitions[idx];
         if (bbox.max.y <= partition.region.min.y) break;
@@ -176,7 +174,6 @@ bool RenderDirtyRegion::add(const RenderRegion& bbox)
 
 bool RenderDirtyRegion::add(const RenderRegion& prv, const RenderRegion& cur)
 {
-    if (disabled) return false;
     if (prv == cur) return add(prv);
 
     for (int idx = 0; idx < PARTITIONING; ++idx) {