lottie: support drop shadow effect

issue: https://github.com/thorvg/thorvg/issues/2153
issue: https://github.com/thorvg/thorvg/issues/2718

src/loaders/lottie/tvgLottieBuilder.cpp

@@ -1297,14 +1297,23 @@ bool LottieBuilder::updateMatte(LottieComposition* comp, float frameNo, Scene* s
 
 void LottieBuilder::updateEffect(LottieLayer* layer, float frameNo)
 {
+    constexpr int QUALITY = 25;
+    constexpr float BLUR_TO_SIGMA = 0.3f;
+
     if (layer->effects.count == 0) return;
 
     for (auto ef = layer->effects.begin(); ef < layer->effects.end(); ++ef) {
         if (!(*ef)->enable) continue;
         switch ((*ef)->type) {
+            case LottieEffect::DropShadow: {
+                auto effect = static_cast<LottieDropShadow*>(*ef);
+                auto color = effect->color(frameNo);
+                layer->scene->push(SceneEffect::DropShadow, color.rgb[0], color.rgb[1], color.rgb[2], effect->opacity(frameNo), effect->angle(frameNo), effect->distance(frameNo), effect->blurness(frameNo), QUALITY);
+                break;
+            }
             case LottieEffect::GaussianBlur: {
                 auto effect = static_cast<LottieGaussianBlur*>(*ef);
-                layer->scene->push(SceneEffect::GaussianBlur, sqrt(effect->blurness(frameNo)), effect->direction(frameNo) - 1, effect->wrap(frameNo), 25);
+                layer->scene->push(SceneEffect::GaussianBlur, effect->blurness(frameNo) * BLUR_TO_SIGMA, effect->direction(frameNo) - 1, effect->wrap(frameNo), QUALITY);
                 break;
             }
             default: break;

src/loaders/lottie/tvgLottieModel.h

@@ -81,7 +81,8 @@ struct LottieEffect
 {
     enum Type : uint8_t
     {
-        GaussianBlur = 0,
+        DropShadow = 0,
+        GaussianBlur = 1,
     };
 
     virtual ~LottieEffect() {}
@@ -91,6 +92,21 @@ struct LottieEffect
 };
 
 
+struct LottieDropShadow : LottieEffect
+{
+    LottieColor color;
+    LottieOpacity opacity = 0;
+    LottieAngle angle = 0.0f;
+    LottieSlider distance = 0.0f;
+    LottieSlider blurness = 0.0f;
+
+    LottieDropShadow()
+    {
+        type = DropShadow;
+    }
+};
+
+
 struct LottieGaussianBlur : LottieEffect
 {
     LottieSlider blurness = 0.0f;

src/loaders/lottie/tvgLottieParser.cpp

@@ -60,6 +60,7 @@ static unsigned long _int2str(int num)
 LottieEffect* LottieParser::getEffect(int type)
 {
     switch (type) {
+        case 25: return new LottieDropShadow;
         case 29: return new LottieGaussianBlur;
         default: return nullptr;
     }
@@ -1296,6 +1297,32 @@ void LottieParser::parseGaussianBlur(LottieGaussianBlur* effect)
 }
 
 
+void LottieParser::parseDropShadow(LottieDropShadow* effect)
+{
+    int idx = 0;  //color -> opacity -> angle -> distance -> blur
+    enterArray();
+    while (nextArrayValue()) {
+        enterObject();
+        while (auto key = nextObjectKey()) {
+            if (KEY_AS("v")) {
+                enterObject();
+                while (auto key = nextObjectKey()) {
+                    if (KEY_AS("k")) {
+                        if (idx == 0) parsePropertyInternal(effect->color);
+                        else if (idx == 1) parsePropertyInternal(effect->opacity);
+                        else if (idx == 2) parsePropertyInternal(effect->angle);
+                        else if (idx == 3) parsePropertyInternal(effect->distance);
+                        else if (idx == 4) parsePropertyInternal(effect->blurness);
+                        else skip(key);
+                        ++idx;
+                    } else skip(key);
+                }
+            } else skip(key);
+        }
+    }
+}
+
+
 void LottieParser::parseEffect(LottieEffect* effect)
 {
     switch (effect->type) {
@@ -1303,6 +1330,10 @@ void LottieParser::parseEffect(LottieEffect* effect)
             parseGaussianBlur(static_cast<LottieGaussianBlur*>(effect));
             break;
         }
+        case LottieEffect::DropShadow: {
+            parseDropShadow(static_cast<LottieDropShadow*>(effect));
+            break;
+        }
         default: break;
     }
 }

src/loaders/lottie/tvgLottieParser.h

@@ -99,6 +99,7 @@ private:
     LottieMarker* parseMarker();
 
     void parseGaussianBlur(LottieGaussianBlur* effect);
+    void parseDropShadow(LottieDropShadow* effect);
 
     bool parseDirection(LottieShape* shape, const char* key);
     bool parseCommon(LottieObject* obj, const char* key);

src/loaders/lottie/tvgLottieProperty.h

@@ -905,6 +905,7 @@ using LottieFloat = LottieGenericProperty<float>;
 using LottieOpacity = LottieGenericProperty<uint8_t>;
 using LottieColor = LottieGenericProperty<RGB24>;
 using LottieSlider = LottieFloat;
+using LottieAngle = LottieFloat;
 using LottieCheckbox = LottieGenericProperty<int8_t>;
 
 #endif //_TVG_LOTTIE_PROPERTY_H_