lottie/slot: Introduce reusable Slot API

Introduce Slot APIs for efficient slot data reuse

New APIs:
- uint32_t LottieAnimation::genSlot(const char* slot)
- Result LottieAnimation::applySlot(uint32_t slotId)
- Result LottieAnimation::delSlot(uint32_t slotId)

Deprecated API:
- Result override(const char* slot)

src/loaders/lottie/thorvg_lottie.h

@@ -22,17 +22,6 @@ class TVG_API LottieAnimation final : public Animation
 public:
     ~LottieAnimation() override;
 
-    /**
-     * @brief Override Lottie properties using slot data.
-     *
-     * @param[in] slot The Lottie slot data in JSON format to override, or @c nullptr to reset.
-     *
-     * @retval Result::InsufficientCondition In case the animation is not loaded.
-     *
-     * @since 1.0
-     */
-    Result override(const char* slot) noexcept;
-
     /**
     * @brief Specifies a segment by marker. 
     * 
@@ -110,6 +99,39 @@ public:
      */
     Result assign(const char* layer, uint32_t ix, const char* var, float val);
 
+    /**
+     * @brief Generates a new slot from the given slot data.
+     *
+     * @param[in] slot The Lottie slot data in JSON format.
+     *
+     * @retval The generated slot ID when successful, 0 otherwise.
+     *
+     * @since 1.0
+     */
+    uint32_t genSlot(const char* slot) noexcept;
+
+    /**
+     * @brief Applies a previously generated slot to the animation.
+     *
+     * @param[in] slotId The ID of the slot to apply, or 0 to reset all slots.
+     *
+     * @retval Result::InsufficientCondition In case the animation is not loaded or the slot ID is invalid.
+     *
+     * @since 1.0
+     */
+    Result applySlot(uint32_t slotId) noexcept;
+
+    /**
+     * @brief Deletes a previously generated slot.
+     *
+     * @param[in] slotId The ID of the slot to delete, or 0 to delete all slots.
+     *
+     * @retval Result::InsufficientCondition In case the animation is not loaded or the slot ID is invalid.
+     *
+     * @since 1.0
+     */
+    Result delSlot(uint32_t slotId) noexcept;
+
     /**
      * @brief Creates a new LottieAnimation object.
      *

src/loaders/lottie/tvgLottieAnimation.cpp

@@ -30,12 +30,32 @@ LottieAnimation::LottieAnimation() = default;
 LottieAnimation::~LottieAnimation() = default;
 
 
-Result LottieAnimation::override(const char* slot) noexcept
+uint32_t LottieAnimation::genSlot(const char* slot) noexcept
+{
+    auto loader = PICTURE(pImpl->picture)->loader;
+    if (!loader) return 0;
+
+    return static_cast<LottieLoader*>(loader)->genSlot(slot);
+}
+
+
+Result LottieAnimation::applySlot(uint32_t slotId) noexcept
 {
     auto loader = PICTURE(pImpl->picture)->loader;
     if (!loader) return Result::InsufficientCondition;
 
-    if (static_cast<LottieLoader*>(loader)->override(slot)) return Result::Success;
+    if (static_cast<LottieLoader*>(loader)->applySlot(slotId)) return Result::Success;
+
+    return Result::InvalidArguments;
+}
+
+
+Result LottieAnimation::delSlot(uint32_t slotId) noexcept
+{
+    auto loader = PICTURE(pImpl->picture)->loader;
+    if (!loader) return Result::InsufficientCondition;
+
+    if (static_cast<LottieLoader*>(loader)->delSlot(slotId)) return Result::Success;
 
     return Result::InvalidArguments;
 }

src/loaders/lottie/tvgLottieLoader.cpp

@@ -25,6 +25,7 @@
 #include "tvgLottieModel.h"
 #include "tvgLottieParser.h"
 #include "tvgLottieBuilder.h"
+#include "tvgCompressor.h"
 
 /************************************************************************/
 /* Internal Class Implementation                                        */
@@ -44,7 +45,9 @@ void LottieLoader::run(unsigned tid)
             comp = parser.comp;
         }
         if (parser.slots) {
-            override(parser.slots, true);
+            auto slotId = genSlot(parser.slots);
+            applySlot(slotId, true);
+            delSlot(slotId, true);
             parser.slots = nullptr;
         }
         builder->build(comp);
@@ -288,45 +291,133 @@ Paint* LottieLoader::paint()
 }
 
 
-bool LottieLoader::override(const char* slots, bool byDefault)
+bool LottieLoader::applySlot(uint32_t slotId, bool byDefault)
 {
-    if (!ready() || comp->slots.count == 0) return false;
+    if (!ready() || comp->slots.count == 0 || comp->slotDatas.empty()) return false;
 
-    //override slots
+    if (slotId == 0) {
-    if (slots) {
+        ARRAY_FOREACH(p, comp->slots) {
-        //Copy the input data because the JSON parser will encode the data immediately.
+            (*p)->reset();
-        auto temp = byDefault ? slots : duplicate(slots);
-
-        //parsing slot json
-        LottieParser parser(temp, dirName, builder->expressions());
-        parser.comp = comp;
-
-        auto idx = 0;
-        auto succeed = false;
-        while (auto sid = parser.sid(idx == 0)) {
-            auto applied = false;
-            ARRAY_FOREACH(p, comp->slots) {
-                if (strcmp((*p)->sid, sid)) continue;
-                if (parser.apply(*p, byDefault)) succeed = applied = true;
-                break;
-            }
-            if (!applied) parser.skip();
-            ++idx;
         }
-        tvg::free((char*)temp);
-        rebuild = succeed;
-        overridden |= succeed;
-        return rebuild;
-    //reset slots
-    } else if (overridden) {
-        ARRAY_FOREACH(p, comp->slots) (*p)->reset();
         overridden = false;
         rebuild = true;
+        return true;
     }
+
+    LottieSlotData* slotData = nullptr;
+
+    INLIST_FOREACH(comp->slotDatas, p) {
+        if (p->id == slotId) {
+            slotData = p;
+            break;
+        }
+    }
+
+    if (!slotData) return false;
+
+    ARRAY_FOREACH(p, slotData->datas) {
+        ARRAY_FOREACH(q, comp->slots) {
+            if (strcmp((*q)->sid, p->sid)) continue;
+            (*q)->apply(p->prop, byDefault);
+            break;
+        }
+    }
+
+    overridden = true;
+    rebuild = true;
     return true;
 }
 
 
+bool LottieLoader::delSlot(uint32_t slotId, bool byDefault)
+{
+    if (!ready() || comp->slots.count == 0 || comp->slotDatas.empty()) return false;
+
+    if (slotId == 0) {
+        if (!byDefault) {
+            ARRAY_FOREACH(p, comp->slots) {
+                (*p)->reset();
+            }
+            rebuild = true;
+        }
+
+        comp->slotDatas.free();
+        overridden = false;
+        return true;
+    }
+
+    LottieSlotData* slotData = nullptr;
+
+    INLIST_FOREACH(comp->slotDatas, p) {
+        if (p->id == slotId) {
+            slotData = p;
+            break;
+        }
+    }
+
+    if (!slotData) return false;
+
+    ARRAY_FOREACH(p, slotData->datas) {
+        ARRAY_FOREACH(q, comp->slots) {
+            if (strcmp((*q)->sid, p->sid)) continue;
+            if (!byDefault && (*q)->overridden) {
+                (*q)->reset();
+                rebuild = true;
+            }
+            break;
+        }
+    }
+
+    comp->slotDatas.remove(slotData);
+    delete(slotData);
+    return true;
+}
+
+
+uint32_t LottieLoader::genSlot(const char* slots)
+{
+    if (!slots || !ready() || comp->slots.count == 0) return 0;
+
+    auto slotId = djb2Encode(slots);
+    INLIST_FOREACH(comp->slotDatas, p) {
+        if (p->id == slotId) return slotId;
+    }
+
+    auto temp = duplicate(slots);
+
+    //parsing slot json
+    LottieParser parser(temp, dirName, builder->expressions());
+    parser.comp = comp;
+    
+    auto idx = 0;
+    bool generated = false;
+    LottieSlotData* slotData = new LottieSlotData(slotId);
+    while (auto sid = parser.sid(idx == 0)) {
+        ARRAY_FOREACH(p, comp->slots) {
+            if (strcmp((*p)->sid, sid)) continue;
+            auto prop = parser.slotData(*p);
+
+            if (prop) {
+                slotData->datas.push({duplicate(sid), prop});
+                generated = true;
+            }
+            break;
+        }
+        ++idx;
+    }
+
+    tvg::free((char*)temp);
+
+    if (generated) comp->slotDatas.back(slotData);
+    else {
+        delete(slotData);
+        return 0;
+    }
+
+    return slotData->id;
+}
+
+
 float LottieLoader::shorten(float frameNo)
 {
     //This ensures that the target frame number is reached.

src/loaders/lottie/tvgLottieLoader.h

@@ -56,7 +56,11 @@ public:
     bool resize(Paint* paint, float w, float h) override;
     bool read() override;
     Paint* paint() override;
-    bool override(const char* slot, bool byDefault = false);
+
+    //Slot APIs
+    uint32_t genSlot(const char* slot);
+    bool applySlot(uint32_t slotId, bool byDefault = false);
+    bool delSlot(uint32_t slotId, bool byDefault = false);
 
     //Frame Controls
     bool frame(float no) override;

src/loaders/lottie/tvgLottieModel.cpp

@@ -174,7 +174,62 @@ void LottieSlot::reset()
 }
 
 
-void LottieSlot::assign(LottieObject* target, bool byDefault)
+LottieProperty* LottieSlot::data(LottieObject* target)
+{
+    LottieProperty* prop = nullptr;
+    //apply slot object to all targets
+    ARRAY_FOREACH(pair, pairs) {
+        //backup the original properties before overwriting
+        switch (type) {
+            case LottieProperty::Type::Vector: {
+                prop = new LottieVector;
+                static_cast<LottieVector*>(prop)->copy(static_cast<LottieTransform*>(target)->position, false);
+                break;
+            }
+            case LottieProperty::Type::Scalar: {
+                prop = new LottieScalar;
+                static_cast<LottieScalar*>(prop)->copy(static_cast<LottieTransform*>(target)->scale, false);
+                break;
+            }
+            case LottieProperty::Type::Float: {
+                prop = new LottieFloat;
+                static_cast<LottieFloat*>(prop)->copy(static_cast<LottieTransform*>(target)->rotation, false);
+                break;
+            }
+            case LottieProperty::Type::Opacity: {
+                prop = new LottieOpacity;
+                static_cast<LottieOpacity*>(prop)->copy(static_cast<LottieSolid*>(target)->opacity, false);
+                break;
+            }
+            case LottieProperty::Type::Color: {
+                prop = new LottieColor;
+                static_cast<LottieColor*>(prop)->copy(static_cast<LottieSolid*>(target)->color, false);
+                break;
+            }
+            case LottieProperty::Type::ColorStop: {
+                prop = new LottieColorStop;
+                static_cast<LottieColorStop*>(prop)->copy(static_cast<LottieGradient*>(target)->colorStops, false);
+                break;
+            }
+            case LottieProperty::Type::TextDoc: {
+                prop = new LottieTextDoc;
+                static_cast<LottieTextDoc*>(prop)->copy(static_cast<LottieText*>(target)->doc, false);
+                break;
+            }
+            case LottieProperty::Type::Image: {
+                prop = new LottieBitmap;
+                static_cast<LottieBitmap*>(prop)->copy(static_cast<LottieImage*>(target)->data, false);
+                break;
+            }
+            default: break;
+        }
+    }
+
+    return prop;
+}
+
+
+void LottieSlot::apply(LottieProperty* prop, bool byDefault)
 {
     auto copy = !overridden && !byDefault;
     auto shallow = pairs.count == 1 ? true : false;
@@ -185,22 +240,22 @@ void LottieSlot::assign(LottieObject* target, bool byDefault)
         switch (type) {
             case LottieProperty::Type::Float: {
                 if (copy) pair->prop = new LottieFloat(static_cast<LottieTransform*>(pair->obj)->rotation);
-                pair->obj->override(&static_cast<LottieTransform*>(target)->rotation, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::Scalar: {
                 if (copy) pair->prop = new LottieScalar(static_cast<LottieTransform*>(pair->obj)->scale);
-                pair->obj->override(&static_cast<LottieTransform*>(target)->scale, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::Vector: {
                 if (copy) pair->prop = new LottieVector(static_cast<LottieTransform*>(pair->obj)->position);
-                pair->obj->override(&static_cast<LottieTransform*>(target)->position, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::Color: {
                 if (copy) pair->prop = new LottieColor(static_cast<LottieSolid*>(pair->obj)->color);
-                pair->obj->override(&static_cast<LottieSolid*>(target)->color, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::Opacity: {
@@ -208,27 +263,28 @@ void LottieSlot::assign(LottieObject* target, bool byDefault)
                     if (pair->obj->type == LottieObject::Type::Transform) pair->prop = new LottieOpacity(static_cast<LottieTransform*>(pair->obj)->opacity);
                     else pair->prop = new LottieOpacity(static_cast<LottieSolid*>(pair->obj)->opacity);
                 }
-                pair->obj->override(&static_cast<LottieSolid*>(target)->opacity, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::ColorStop: {
                 if (copy) pair->prop = new LottieColorStop(static_cast<LottieGradient*>(pair->obj)->colorStops);
-                pair->obj->override(&static_cast<LottieGradient*>(target)->colorStops, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::TextDoc: {
                 if (copy) pair->prop = new LottieTextDoc(static_cast<LottieText*>(pair->obj)->doc);
-                pair->obj->override(&static_cast<LottieText*>(target)->doc, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             case LottieProperty::Type::Image: {
                 if (copy) pair->prop = new LottieBitmap(static_cast<LottieImage*>(pair->obj)->data);
-                pair->obj->override(&static_cast<LottieImage*>(target)->data, shallow, !copy);
+                pair->obj->override(prop, shallow, !copy);
                 break;
             }
             default: break;
         }
     }
+
     if (!byDefault) overridden = true;
 }
 
@@ -704,4 +760,5 @@ LottieComposition::~LottieComposition()
     ARRAY_FOREACH(p, fonts) delete(*p);
     ARRAY_FOREACH(p, slots) delete(*p);
     ARRAY_FOREACH(p, markers) delete(*p);
+    slotDatas.free();
 }

src/loaders/lottie/tvgLottieModel.h

@@ -26,6 +26,7 @@
 #include "tvgCommon.h"
 #include "tvgStr.h"
 #include "tvgCompressor.h"
+#include "tvgInlist.h"
 #include "tvgRender.h"
 #include "tvgLottieProperty.h"
 #include "tvgLottieRenderPooler.h"
@@ -1044,6 +1045,30 @@ struct LottieLayer : LottieGroup
 };
 
 
+struct LottieSlotData
+{
+    INLIST_ITEM(LottieSlotData);
+
+    struct SlotData {
+        char* sid;
+        LottieProperty* prop;
+    };
+
+    LottieSlotData(uint32_t id) : id(id) {}
+
+    ~LottieSlotData()
+    {
+        ARRAY_FOREACH(p, datas) {
+            delete(p->prop);
+            tvg::free(p->sid);
+        }
+    }
+
+    uint32_t id;
+    Array<SlotData> datas;
+};
+
+
 struct LottieSlot
 {
     struct Pair {
@@ -1051,7 +1076,8 @@ struct LottieSlot
         LottieProperty* prop;
     };
 
-    void assign(LottieObject* target, bool byDefault);
+    LottieProperty* data(LottieObject* target);
+    void apply(LottieProperty* prop, bool byDefault = false);
     void reset();
 
     LottieSlot(LottieLayer* layer, LottieObject* parent, char* sid, LottieObject* obj, LottieProperty::Type type) : context{layer, parent}, sid(sid), type(type)
@@ -1131,6 +1157,7 @@ struct LottieComposition
     Array<LottieFont*> fonts;
     Array<LottieSlot*> slots;
     Array<LottieMarker*> markers;
+    Inlist<LottieSlotData> slotDatas;
     bool expressions = false;
     bool initiated = false;
 };

src/loaders/lottie/tvgLottieParser.cpp

@@ -1536,7 +1536,7 @@ const char* LottieParser::sid(bool first)
 }
 
 
-bool LottieParser::apply(LottieSlot* slot, bool byDefault)
+LottieProperty* LottieParser::slotData(LottieSlot* slot)
 {
     enterObject();
 
@@ -1595,14 +1595,13 @@ bool LottieParser::apply(LottieSlot* slot, bool byDefault)
 
     if (!obj || Invalid()) {
         delete(obj);
-        return false;
+        return nullptr;
     }
 
-    slot->assign(obj, byDefault);
+    auto prop = slot->data(obj);
-
     delete(obj);
 
-    return true;
+    return prop;
 }
 
 

src/loaders/lottie/tvgLottieParser.h

@@ -37,8 +37,8 @@ public:
     }
 
     bool parse();
-    bool apply(LottieSlot* slot, bool byDefault);
     const char* sid(bool first = false);
+    LottieProperty* slotData(LottieSlot* slot);
     void captureSlots(const char* key);
     void registerSlot(LottieObject* obj, const char* sid, LottieProperty::Type type);