Add support for springDamping in SpringInterpolator

Reviewed By: mdvacca

Differential Revision: D7201334

fbshipit-source-id: 50929b4294188cd5a2a8ffa2080c38c0a9983535

Author: axe-fb

ReactAndroid/src/main/java/com/facebook/react/uimanager/layoutanimation/AbstractLayoutAnimation.java

@@ -2,21 +2,20 @@
 
 package com.facebook.react.uimanager.layoutanimation;
 
-import javax.annotation.Nullable;
-
-import java.util.Map;
-
+import android.os.Build;
 import android.view.View;
 import android.view.animation.AccelerateDecelerateInterpolator;
 import android.view.animation.AccelerateInterpolator;
 import android.view.animation.Animation;
+import android.view.animation.BaseInterpolator;
 import android.view.animation.DecelerateInterpolator;
 import android.view.animation.Interpolator;
 import android.view.animation.LinearInterpolator;
-
 import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.common.MapBuilder;
 import com.facebook.react.uimanager.IllegalViewOperationException;
+import java.util.Map;
+import javax.annotation.Nullable;
 
 /**
  * Class responsible for parsing and converting layout animation data into native {@link Animation}
@@ -36,12 +35,11 @@
    */
   abstract @Nullable Animation createAnimationImpl(View view, int x, int y, int width, int height);
 
-  private static final Map<InterpolatorType, Interpolator> INTERPOLATOR = MapBuilder.of(
+  private static final Map<InterpolatorType, BaseInterpolator> INTERPOLATOR = MapBuilder.of(
       InterpolatorType.LINEAR, new LinearInterpolator(),
       InterpolatorType.EASE_IN, new AccelerateInterpolator(),
       InterpolatorType.EASE_OUT, new DecelerateInterpolator(),
-      InterpolatorType.EASE_IN_EASE_OUT, new AccelerateDecelerateInterpolator(),
-      InterpolatorType.SPRING, new SimpleSpringInterpolator());
+      InterpolatorType.EASE_IN_EASE_OUT, new AccelerateDecelerateInterpolator());
 
   private @Nullable Interpolator mInterpolator;
   private int mDelayMs;
@@ -64,7 +62,7 @@ public void initializeFromConfig(ReadableMap data, int globalDuration) {
     if (!data.hasKey("type")) {
       throw new IllegalArgumentException("Missing interpolation type.");
     }
-    mInterpolator = getInterpolator(InterpolatorType.fromString(data.getString("type")));
+    mInterpolator = getInterpolator(InterpolatorType.fromString(data.getString("type")), data);
 
     if (!isValid()) {
       throw new IllegalViewOperationException("Invalid layout animation : " + data);
@@ -100,8 +98,16 @@ public void initializeFromConfig(ReadableMap data, int globalDuration) {
     return animation;
   }
 
-  private static Interpolator getInterpolator(InterpolatorType type) {
-    Interpolator interpolator = INTERPOLATOR.get(type);
+  private static Interpolator getInterpolator(InterpolatorType type, ReadableMap params) {
+     Interpolator interpolator = null;
+     if (type.equals(InterpolatorType.SPRING)) {
+       interpolator = new SimpleSpringInterpolator(SimpleSpringInterpolator.getSpringDamping(params));
+     } else {
+       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
+         // Conversion from BaseInterpolator to Interpolator is only possible on this Android versions
+         interpolator = INTERPOLATOR.get(type);
+       }
+     }
     if (interpolator == null) {
       throw new IllegalArgumentException("Missing interpolator for type : " + type);
     }

ReactAndroid/src/main/java/com/facebook/react/uimanager/layoutanimation/SimpleSpringInterpolator.java

@@ -3,6 +3,8 @@
 package com.facebook.react.uimanager.layoutanimation;
 
 import android.view.animation.Interpolator;
+import com.facebook.react.bridge.ReadableMap;
+import com.facebook.react.bridge.ReadableType;
 
 /**
  * Simple spring interpolator
@@ -11,10 +13,30 @@
 /* package */  class SimpleSpringInterpolator implements Interpolator {
 
   private static final float FACTOR = 0.5f;
+  public static final String PARAM_SPRING_DAMPING = "springDamping";
+  private final float mSpringDamping;
+
+  public static float getSpringDamping(ReadableMap params){
+    if (params.getType(PARAM_SPRING_DAMPING).equals(ReadableType.Number)){
+      return (float) params.getDouble(PARAM_SPRING_DAMPING);
+    } else {
+      return FACTOR;
+    }
+  }
+
+  public SimpleSpringInterpolator() {
+    mSpringDamping = FACTOR;
+  }
+
+  public SimpleSpringInterpolator(float springDamping){
+    mSpringDamping = springDamping;
+  }
 
   @Override
   public float getInterpolation(float input) {
+    // Using mSpringDamping in this equation is not really the exact mathematical springDamping, but a good approximation
+    // We need to replace this equation with the right Factor that accounts for damping and friction
     return (float)
-        (1 + Math.pow(2, -10 * input) * Math.sin((input - FACTOR / 4) * Math.PI * 2 / FACTOR));
+        (1 + Math.pow(2, -10 * input) * Math.sin((input - mSpringDamping / 4) * Math.PI * 2 / mSpringDamping));
   }
 }