fix: Ensure parameter values persist after updates and add getParameterValue API

Author: Eatgrapes

.gitignore

@@ -6,6 +6,7 @@ native/include/
 target/
 **/target/
 *.log
+*.class
 
 # SDK
 /sdk/

binding/src/main/java/dev/eatgrapes/live2d/CubismUserModel.java

@@ -61,6 +61,9 @@ private void onMotionFinished(String name) {
     public void setParameterValue(String id, float value) { setParameterValueNative(_ptr, id, value); }
     private static native void setParameterValueNative(long ptr, String id, float value);
 
+    public float getParameterValue(String id) { return getParameterValueNative(_ptr, id); }
+    private static native float getParameterValueNative(long ptr, String id);
+
     public float getCanvasWidth() { return getCanvasWidthNative(_ptr); }
     private static native float getCanvasWidthNative(long ptr);
 

native/src/CubismUserModel_JNI.cpp

@@ -247,8 +247,17 @@ JNIEXPORT void JNICALL Java_dev_eatgrapes_live2d_CubismUserModel_updateNative(JN
 
 JNIEXPORT void JNICALL Java_dev_eatgrapes_live2d_CubismUserModel_setParameterValueNative(JNIEnv* env, jclass, jlong ptr, jstring id, jfloat value) {
     const char* s = env->GetStringUTFChars(id, nullptr);
-    ((JniUserModel*)ptr)->GetModel()->SetParameterValue(CubismFramework::GetIdManager()->GetId(s), value);
+    auto* model = ((JniUserModel*)ptr)->GetModel();
+    model->SetParameterValue(CubismFramework::GetIdManager()->GetId(s), value);
+    model->SaveParameters();
+    env->ReleaseStringUTFChars(id, s);
+}
+
+JNIEXPORT jfloat JNICALL Java_dev_eatgrapes_live2d_CubismUserModel_getParameterValueNative(JNIEnv* env, jclass, jlong ptr, jstring id) {
+    const char* s = env->GetStringUTFChars(id, nullptr);
+    float value = ((JniUserModel*)ptr)->GetModel()->GetParameterValue(CubismFramework::GetIdManager()->GetId(s));
     env->ReleaseStringUTFChars(id, s);
+    return value;
 }
 
 JNIEXPORT jfloat JNICALL Java_dev_eatgrapes_live2d_CubismUserModel_getCanvasWidthNative(JNIEnv*, jclass, jlong ptr) {