Add c api for skin type recoloring

inc/rlottie_capi.h

@@ -72,6 +72,22 @@ LOT_EXPORT Lottie_Animation *lottie_animation_from_file(const char *path);
  */
 LOT_EXPORT Lottie_Animation *lottie_animation_from_data(const char *data, const char *key, const char *resource_path);
 
+/**
+ *  @brief Constructs an animation object from JSON string data and recolors it to correct skin color.
+ *
+ *  @param[in] data The JSON string data.
+ *  @param[in] key the string that will be used to cache the JSON string data.
+ *  @param[in] resource_path the path that will be used to load external resource needed by the JSON data.
+ *  @param[in] fitzpatrick_type emoji modifier fitzpatrick type; 0-6; 0 if none
+ *
+ *  @return Animation object that can build the contents of the
+ *          Lottie resource represented by JSON string data.
+ *
+ *  @ingroup Lottie_Animation
+ *  @internal
+ */
+LOT_EXPORT Lottie_Animation *lottie_animation_from_data_recolored(const char *data, const char *key, const char *resource_path, const int32_t fitzpatrick_type);
+
 /**
  *  @brief Free given Animation object resource.
  *

src/binding/c/lottieanimation_capi.cpp

@@ -55,6 +55,16 @@ LOT_EXPORT Lottie_Animation_S *lottie_animation_from_data(const char *data, cons
     }
 }
 
+LOT_EXPORT Lottie_Animation* lottie_animation_from_data_recolored(const char* data, const char* key, const char* resourcePath, const int32_t fitzpatrickType) {
+    if (auto animation = Animation::loadFromData(data, key, resourcePath, true, {}, rlottie::FitzModifier(fitzpatrickType))) {
+        Lottie_Animation_S* handle = new Lottie_Animation_S();
+        handle->mAnimation = std::move(animation);
+        return handle;
+    } else {
+        return nullptr;
+    }
+}
+
 LOT_EXPORT void lottie_animation_destroy(Lottie_Animation_S *animation)
 {
     if (animation) {

src/lottie/lottiemodel.cpp

@@ -188,11 +188,11 @@ void LOTGradient::populate(VGradientStops &stops, int frameNo)
         return;
     }
     int            colorPoints = mColorPoints;
-    if (colorPoints < 0 || colorPoints > size / 4) {  // for legacy bodymovin (ref: lottie-android)
+    if (colorPoints < 0 || size_t(colorPoints) > size / 4) {  // for legacy bodymovin (ref: lottie-android)
         colorPoints = int(size / 4);
     }
     auto    opacityArraySize = size - colorPoints * 4;
-    if ((opacityArraySize % 2 != 0) || (colorPoints > opacityArraySize / 2 && opacityArraySize < 4)) {
+    if ((opacityArraySize % 2 != 0) || (size_t(colorPoints) > opacityArraySize / 2 && opacityArraySize < 4)) {
         opacityArraySize = 0;
     }
     float *opacityPtr = ptr + (colorPoints * 4);