lottie: support default slot overriding

issue: https://github.com/thorvg/thorvg/issues/2915

src/loaders/lottie/tvgLottieLoader.cpp

@@ -43,6 +43,10 @@ void LottieLoader::run(unsigned tid)
             ScopedLock lock(key);
             comp = parser.comp;
         }
+        if (parser.slots) {
+            override(parser.slots, false);
+            parser.slots = nullptr;
+        }
         builder->build(comp);
 
         release();
@@ -286,16 +290,16 @@ Paint* LottieLoader::paint()
 }
 
 
-bool LottieLoader::override(const char* slot)
+bool LottieLoader::override(const char* slots, bool copy)
 {
     if (!ready() || comp->slots.count == 0) return false;
 
     auto success = true;
 
     //override slots
-    if (slot) {
+    if (slots) {
         //Copy the input data because the JSON parser will encode the data immediately.
-        auto temp = strdup(slot);
+        auto temp = copy ? strdup(slots) : slots;
 
         //parsing slot json
         LottieParser parser(temp, dirName);
@@ -312,7 +316,7 @@ bool LottieLoader::override(const char* slot)
         }
 
         if (idx < 1) success = false;
-        free(temp);
+        free((char*)temp);
         rebuild = overridden = success;
     //reset slots
     } else if (overridden) {

src/loaders/lottie/tvgLottieLoader.h

@@ -57,7 +57,7 @@ public:
     bool resize(Paint* paint, float w, float h) override;
     bool read() override;
     Paint* paint() override;
-    bool override(const char* slot);
+    bool override(const char* slot, bool copy = true);
 
     //Frame Controls
     bool frame(float no) override;

src/loaders/lottie/tvgLottieModel.h

@@ -584,7 +584,6 @@ struct LottieGradient : LottieObject
         return nullptr;
     }
 
-
     uint32_t populate(ColorStop& color, size_t count);
     Fill* fill(float frameNo, LottieExpressions* exps);
 

src/loaders/lottie/tvgLottieParser.cpp

@@ -1478,6 +1478,47 @@ bool LottieParser::apply(LottieSlot* slot)
 }
 
 
+void LottieParser::captureSlots(const char* key)
+{
+    free(slots);
+
+    // TODO: Replace with immediate parsing, once the slot spec is confirmed by the LAC
+
+    auto begin = getPos();
+    auto end = getPos();
+    auto depth = 1;
+    auto invalid = true;
+
+    //get slots string
+    while (++end) {
+        if (*end == '}') {
+            --depth;
+            if (depth == 0) {
+                invalid = false;
+                break;
+            }
+        } else if (*end == '{') {
+            ++depth;
+        }
+    }
+
+    if (invalid) {
+        TVGERR("LOTTIE", "Invalid Slots!");
+        skip(key);
+        return;
+    }
+
+    //composite '{' + slots + '}'
+    auto len = (end - begin + 2);
+    slots = (char*)malloc(sizeof(char) * len + 1);
+    slots[0] = '{';
+    memcpy(slots + 1, begin, len);
+    slots[len] = '\0';
+
+    skip(key);
+}
+
+
 bool LottieParser::parse()
 {
     //verify json.
@@ -1506,6 +1547,7 @@ bool LottieParser::parse()
         else if (KEY_AS("fonts")) parseFonts();
         else if (KEY_AS("chars")) parseChars(glyphs);
         else if (KEY_AS("markers")) parseMarkers();
+        else if (KEY_AS("slots")) captureSlots(key);
         else skip(key);
     }
 

src/loaders/lottie/tvgLottieParser.h

@@ -38,10 +38,12 @@ public:
     bool parse();
     bool apply(LottieSlot* slot);
     const char* sid(bool first = false);
+    void captureSlots(const char* key);
     template<LottieProperty::Type type = LottieProperty::Type::Invalid> void registerSlot(LottieObject* obj);
 
     LottieComposition* comp = nullptr;
     const char* dirName = nullptr;       //base resource directory
+    char* slots = nullptr;
 
 private:
     RGB24 getColor(const char *str);

src/loaders/lottie/tvgLottieParserHandler.cpp

@@ -232,4 +232,10 @@ void LookaheadParserHandler::skip(const char* key)
     } else {
         skipOut(0);
     }
+}
+
+
+char* LookaheadParserHandler::getPos()
+{
+    return iss.src_;
 }

src/loaders/lottie/tvgLottieParserHandler.h

@@ -195,6 +195,7 @@ struct LookaheadParserHandler
     void skip(const char* key);
     void skipOut(int depth);
     int peekType();
+    char* getPos();
 };
 
 #endif //_TVG_LOTTIE_PARSER_HANDLER_H_

test/resources/lottieslot.json

@@ -1 +1 @@
-{"v":"4.8.0","meta":{"g":"LottieFiles AE 3.0.2","a":"","k":"","d":"","tc":""},"fr":60,"ip":0,"op":121,"w":550,"h":550,"nm":"C","assets":[],"layers":[{"ind":1,"ty":4,"nm":"S","sr":1,"ks":{"o":{"a":0,"k":100},"r":{"a":1,"k":[{"i":{"x":[0.833],"y":[0.833]},"o":{"x":[0.167],"y":[0.167]},"t":0,"s":[0]},{"t":120,"s":[360]}]},"p":{"a":0,"k":[275,275,0]},"a":{"a":0,"k":[-7.886,88.719,0]},"s":{"a":0,"k":[100,100,100]}},"ao":0,"shapes":[{"ty":"gr","it":[{"ty":"rc","d":1,"s":{"a":0,"k":[282.019,134.888]},"p":{"a":0,"k":[0,0]},"r":{"a":0,"k":0},"nm":"R"},{"ty":"st","c":{"a":0,"k":[0.991,0,1,1]},"o":{"a":0,"k":100},"w":{"a":0,"k":3},"lc":1,"lj":1,"ml":4,"nm":"S"},{"ty":"gf","o":{"a":0,"k":100},"r":1,"g":{"p":9,"k":{"a":0,"k":[0,0.514,0.373,0.984,0.141,0.478,0.412,0.984,0.283,0.443,0.451,0.984,0.379,0.408,0.49,0.984,0.475,0.373,0.529,0.984,0.606,0.278,0.647,0.925,0.737,0.184,0.765,0.867,0.868,0.092,0.882,0.808,1,0,1,0.749]},"sid":"gradient_fill"},"s":{"a":0,"k":[-159.51,23.531]},"e":{"a":0,"k":[183.084,8.059]},"t":1,"nm":"G"},{"ty":"tr","p":{"a":0,"k":[-7.886,88.719]},"a":{"a":0,"k":[0,0]},"s":{"a":0,"k":[100,100]},"r":{"a":0,"k":0},"o":{"a":0,"k":100},"sk":{"a":0,"k":0},"sa":{"a":0,"k":0},"nm":"T"}],"nm":"R"}],"ip":0,"op":300,"st":0}],"slots":{"gradient_fill":{"p":{"a":0,"k":[0,0.1,0.1,0.2,1,1,0.1,0.2,0.1,1]}}},"markers":[]}
+{"v":"4.8.0","meta":{"g":"LottieFiles AE 3.0.2","a":"","k":"","d":"","tc":""},"fr":60,"ip":0,"op":121,"w":550,"h":550,"nm":"C","assets":[],"layers":[{"ind":1,"ty":4,"nm":"S","sr":1,"ks":{"o":{"a":0,"k":100},"r":{"a":1,"k":[{"i":{"x":[0.833],"y":[0.833]},"o":{"x":[0.167],"y":[0.167]},"t":0,"s":[0]},{"t":120,"s":[360]}]},"p":{"a":0,"k":[275,275,0]},"a":{"a":0,"k":[-7.886,88.719,0]},"s":{"a":0,"k":[100,100,100]}},"ao":0,"shapes":[{"ty":"gr","it":[{"ty":"rc","d":1,"s":{"a":0,"k":[282.019,134.888]},"p":{"a":0,"k":[0,0]},"r":{"a":0,"k":0},"nm":"R"},{"ty":"st","c":{"a":0,"k":[0.991,0,1,1]},"o":{"a":0,"k":100},"w":{"a":0,"k":3},"lc":1,"lj":1,"ml":4,"nm":"S"},{"ty":"gf","o":{"a":0,"k":100},"r":1,"g":{"p":9,"k":{"a":0,"k":[0,0.514,0.373,0.984,0.141,0.478,0.412,0.984,0.283,0.443,0.451,0.984,0.379,0.408,0.49,0.984,0.475,0.373,0.529,0.984,0.606,0.278,0.647,0.925,0.737,0.184,0.765,0.867,0.868,0.092,0.882,0.808,1,0,1,0.749]},"sid":"gradient_fill"},"s":{"a":0,"k":[-159.51,23.531]},"e":{"a":0,"k":[183.084,8.059]},"t":1,"nm":"G"},{"ty":"tr","p":{"a":0,"k":[-7.886,88.719]},"a":{"a":0,"k":[0,0]},"s":{"a":0,"k":[100,100]},"r":{"a":0,"k":0},"o":{"a":0,"k":100},"sk":{"a":0,"k":0},"sa":{"a":0,"k":0},"nm":"T"}],"nm":"R"}],"ip":0,"op":300,"st":0}],"markers":[]}