lottie: revise the masking logic

- Allow the masking data even though they were mask None mode.
  Those will be used by the layer stroke effect.
- Fixed masking Offset to apply to all masking chains.
- Optimized fast track masking with resolving the opaicty condition.
- Clean up the overall code.

src/loaders/lottie/tvgLottieBuilder.cpp

@@ -1224,32 +1224,58 @@ void LottieBuilder::updateMaskings(LottieLayer* layer, float frameNo)
 {
     if (layer->masks.count == 0) return;
 
-    //Apply the base mask
+    Shape* pShape = nullptr;
-    auto pMask = static_cast<LottieMask*>(layer->masks[0]);
+    MaskMethod pMethod;
-    auto pMethod = pMask->method;
+    uint8_t pOpacity;
-    auto opacity = pMask->opacity(frameNo);
-    auto expand = pMask->expand(frameNo);
 
-    auto pShape = layer->pooling();
+    for (auto m = layer->masks.begin(); m < layer->masks.end(); ++m) {
-    pShape->reset();
+        auto mask = *m;
-    pShape->fill(255, 255, 255, opacity);
+        if (mask->method == MaskMethod::None) continue;
-    pShape->transform(layer->cache.matrix);
 
-    //Apply Masking Expansion (Offset)
+        auto method = mask->method;
-    if (expand == 0.0f) {
+        auto opacity = mask->opacity(frameNo);
-        pMask->pathset(frameNo, SHAPE(pShape)->rs.path.cmds, SHAPE(pShape)->rs.path.pts, nullptr, nullptr, nullptr, exps);
+        auto expand = mask->expand(frameNo);
-    } else {
+        auto fastTrack = false;  //single clipping
-        //TODO: Once path direction support is implemented, ensure that the direction is ignored here
-        auto offset = LottieOffsetModifier(pMask->expand(frameNo));
-        pMask->pathset(frameNo, SHAPE(pShape)->rs.path.cmds, SHAPE(pShape)->rs.path.pts, nullptr, nullptr, &offset, exps);
-    }
 
-    auto compMethod = (pMethod == MaskMethod::Subtract || pMethod == MaskMethod::InvAlpha) ? MaskMethod::InvAlpha : MaskMethod::Alpha;
+        //the first mask
+        if (!pShape) {
+            pShape = layer->pooling();
+            pShape->reset();
+            pShape->fill(255, 255, 255, opacity);
+            pShape->transform(layer->cache.matrix);
+            auto compMethod = (method == MaskMethod::Subtract || method == MaskMethod::InvAlpha) ? MaskMethod::InvAlpha : MaskMethod::Alpha;
+            //Cheaper. Replace the masking with a clipper
+            if (layer->masks.count == 1 && compMethod == MaskMethod::Alpha) {
+                layer->scene->opacity(MULTIPLY(layer->scene->opacity(), opacity));
+                layer->scene->clip(pShape);
+                fastTrack = true;
+            } else {
+                layer->scene->mask(pShape, compMethod);
+            }
+        //Chain mask composition
+        } else if (pMethod != method || pOpacity != opacity || (method != MaskMethod::Subtract && method != MaskMethod::Difference)) {
+            auto shape = layer->pooling();
+            shape->reset();
+            shape->fill(255, 255, 255, opacity);
+            shape->transform(layer->cache.matrix);
+            pShape->mask(shape, method);
+            pShape = shape;
+        }
 
-    //Cheaper. Replace the masking with a clipper
+        //Default Masking
-    if (layer->masks.count == 1 && compMethod == MaskMethod::Alpha && opacity == 255) {
+        if (expand == 0.0f) {
-        layer->scene->clip(pShape);
+            mask->pathset(frameNo, SHAPE(pShape)->rs.path.cmds, SHAPE(pShape)->rs.path.pts, nullptr, nullptr, nullptr, exps);
-        return;
+        //Masking with Expansion (Offset)
+        } else {
+            //TODO: Once path direction support is implemented, ensure that the direction is ignored here
+            auto offset = LottieOffsetModifier(expand);
+            mask->pathset(frameNo, SHAPE(pShape)->rs.path.cmds, SHAPE(pShape)->rs.path.pts, nullptr, nullptr, &offset, exps);
+        }
+
+        if (fastTrack) return;
+
+        pOpacity = opacity;
+        pMethod = method;
     }
 
     //Introduce an intermediate scene for embracing the matte + masking
@@ -1258,30 +1284,6 @@ void LottieBuilder::updateMaskings(LottieLayer* layer, float frameNo)
         scene->push(layer->scene);
         layer->scene = scene;
     }
-
-    layer->scene->mask(pShape, compMethod);
-
-    //Apply the subsquent masks
-    for (auto m = layer->masks.begin() + 1; m < layer->masks.end(); ++m) {
-        auto mask = static_cast<LottieMask*>(*m);
-        auto method = mask->method;
-        if (method == MaskMethod::None) continue;
-
-        //Append the mask shape
-        if (pMethod == method && (method == MaskMethod::Subtract || method == MaskMethod::Difference)) {
-            mask->pathset(frameNo, SHAPE(pShape)->rs.path.cmds, SHAPE(pShape)->rs.path.pts, nullptr, nullptr, nullptr, exps);
-        //Chain composition
-        } else {
-            auto shape = layer->pooling();
-            shape->reset();
-            shape->fill(255, 255, 255, mask->opacity(frameNo));
-            shape->transform(layer->cache.matrix);
-            mask->pathset(frameNo, SHAPE(shape)->rs.path.cmds, SHAPE(shape)->rs.path.pts, nullptr, nullptr, nullptr, exps);
-            pShape->mask(shape, method);
-            pShape = shape;
-            pMethod = method;
-        }
-    }
 }
 
 

src/loaders/lottie/tvgLottieParser.cpp

@@ -1235,27 +1235,15 @@ void LottieParser::getLayerSize(float& val)
 LottieMask* LottieParser::parseMask()
 {
     auto mask = new LottieMask;
-    auto valid = true;  //skip if the mask mode is none.
-
     enterObject();
     while (auto key = nextObjectKey()) {
         if (KEY_AS("inv")) mask->inverse = getBool();
-        else if (KEY_AS("mode"))
+        else if (KEY_AS("mode")) mask->method = getMaskMethod(mask->inverse);
-        {
+        else if (KEY_AS("pt")) getPathSet(mask->pathset);
-            mask->method = getMaskMethod(mask->inverse);
+        else if (KEY_AS("o")) parseProperty<LottieProperty::Type::Opacity>(mask->opacity);
-            if (mask->method == MaskMethod::None) valid = false;
+        else if (KEY_AS("x")) parseProperty<LottieProperty::Type::Float>(mask->expand);
-        }
-        else if (valid && KEY_AS("pt")) getPathSet(mask->pathset);
-        else if (valid && KEY_AS("o")) parseProperty<LottieProperty::Type::Opacity>(mask->opacity);
-        else if (valid && KEY_AS("x")) parseProperty<LottieProperty::Type::Float>(mask->expand);
         else skip();
     }
-
-    if (!valid) {
-        delete(mask);
-        return nullptr;
-    }
-
     return mask;
 }