Introduced AnimatedDivision

Summary:
Combining 2 animated values via addition, multiplication, and modulo are already supported, and this adds another one: division.
There are some cases where an animated value needs to invert (1 / x) another animated value for calculation. An example is inverting a scale (2x --> 0.5x), e.g.:

```
const a = Animated.Value(1);
const b = Animated.divide(1, a);

Animated.spring(a, {
  toValue: 2,
}).start();
```

`b` will then follow `a`'s spring animation and produce the value of `1 / a`.

The basic usage is like this:

```
<Animated.View style={{transform: [{scale: a}]}}>
  <Animated.Image style={{transform: [{scale: b}]}} />
<Animated.View>
```

In this example, the inner image won't get stretched at all because the parent's scaling gets cancelled out.

Also added this to native animated implementation.

Reviewed By: foghina, mmmulani

Differential Revision: D3922891

fbshipit-source-id: 32508956c4b65b2deb7574d50a10c85b4809b961

Libraries/Animated/src/AnimatedImplementation.js

@@ -1136,6 +1136,54 @@ class AnimatedAddition extends AnimatedWithChildren {
   }
 }
 
+class AnimatedDivision extends AnimatedWithChildren {
+  _a: Animated;
+  _b: Animated;
+
+  constructor(a: Animated | number, b: Animated | number) {
+    super();
+    this._a = typeof a === 'number' ? new AnimatedValue(a) : a;
+    this._b = typeof b === 'number' ? new AnimatedValue(b) : b;
+  }
+
+  __makeNative() {
+    super.__makeNative();
+    this._a.__makeNative();
+    this._b.__makeNative();
+  }
+
+  __getValue(): number {
+    const a = this._a.__getValue();
+    const b = this._b.__getValue();
+    if (b === 0) {
+      console.error('Detected division by zero in AnimatedDivision');
+    }
+    return a / b;
+  }
+
+  interpolate(config: InterpolationConfigType): AnimatedInterpolation {
+    return new AnimatedInterpolation(this, config);
+  }
+
+  __attach(): void {
+    this._a.__addChild(this);
+    this._b.__addChild(this);
+  }
+
+  __detach(): void {
+    this._a.__removeChild(this);
+    this._b.__removeChild(this);
+    super.__detach();
+  }
+
+  __getNativeConfig(): any {
+    return {
+      type: 'division',
+      input: [this._a.__getNativeTag(), this._b.__getNativeTag()],
+    };
+  }
+}
+
 class AnimatedMultiplication extends AnimatedWithChildren {
   _a: Animated;
   _b: Animated;
@@ -1795,15 +1843,22 @@ type CompositeAnimation = {
 };
 
 var add = function(
-  a: Animated,
-  b: Animated
+  a: Animated | number,
+  b: Animated | number,
 ): AnimatedAddition {
   return new AnimatedAddition(a, b);
 };
 
+var divide = function(
+  a: Animated | number,
+  b: Animated | number,
+): AnimatedDivision {
+  return new AnimatedDivision(a, b);
+};
+
 var multiply = function(
-  a: Animated,
-  b: Animated
+  a: Animated | number,
+  b: Animated | number,
 ): AnimatedMultiplication {
   return new AnimatedMultiplication(a, b);
 };
@@ -2295,6 +2350,13 @@ module.exports = {
    * together.
    */
   add,
+
+  /**
+   * Creates a new Animated value composed by dividing the first Animated value
+   * by the second Animated value.
+   */
+  divide,
+
   /**
    * Creates a new Animated value composed from two Animated values multiplied
    * together.

Libraries/NativeAnimation/Nodes/RCTDivisionAnimatedNode.h

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "RCTValueAnimatedNode.h"
+
+@interface RCTDivisionAnimatedNode : RCTValueAnimatedNode
+
+@end

Libraries/NativeAnimation/Nodes/RCTDivisionAnimatedNode.m

@@ -0,0 +1,34 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "RCTDivisionAnimatedNode.h"
+#import "RCTLog.h"
+
+@implementation RCTDivisionAnimatedNode
+
+- (void)performUpdate
+{
+  [super performUpdate];
+
+  NSArray<NSNumber *> *inputNodes = self.config[@"input"];
+  if (inputNodes.count > 1) {
+    RCTValueAnimatedNode *parent1 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[0]];
+    RCTValueAnimatedNode *parent2 = (RCTValueAnimatedNode *)self.parentNodes[inputNodes[1]];
+    if ([parent1 isKindOfClass:[RCTValueAnimatedNode class]] &&
+        [parent2 isKindOfClass:[RCTValueAnimatedNode class]]) {
+      if (parent2.value == 0) {
+        RCTLogError(@"Detected a division by zero in Animated.divide node");
+        return;
+      }
+      self.value = parent1.value / parent2.value;
+    }
+  }
+}
+
+@end

Libraries/NativeAnimation/RCTAnimation.xcodeproj/project.pbxproj

@@ -19,8 +19,9 @@
 		13E501EE1D07A6C9005F35D8 /* RCTStyleAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 13E501E31D07A6C9005F35D8 /* RCTStyleAnimatedNode.m */; };
 		13E501EF1D07A6C9005F35D8 /* RCTTransformAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 13E501E51D07A6C9005F35D8 /* RCTTransformAnimatedNode.m */; };
 		13E501F01D07A6C9005F35D8 /* RCTValueAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 13E501E71D07A6C9005F35D8 /* RCTValueAnimatedNode.m */; };
-		94DAE3F91D7334A70059942F /* RCTModuloAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 94DAE3F81D7334A70059942F /* RCTModuloAnimatedNode.m */; };
 		193F64F41D776EC6004D1CAA /* RCTDiffClampAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 193F64F31D776EC6004D1CAA /* RCTDiffClampAnimatedNode.m */; };
+		5C9894951D999639008027DB /* RCTDivisionAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 5C9894941D999639008027DB /* RCTDivisionAnimatedNode.m */; };
+		94DAE3F91D7334A70059942F /* RCTModuloAnimatedNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 94DAE3F81D7334A70059942F /* RCTModuloAnimatedNode.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -61,10 +62,12 @@
 		13E501E51D07A6C9005F35D8 /* RCTTransformAnimatedNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTTransformAnimatedNode.m; sourceTree = "<group>"; };
 		13E501E61D07A6C9005F35D8 /* RCTValueAnimatedNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTValueAnimatedNode.h; sourceTree = "<group>"; };
 		13E501E71D07A6C9005F35D8 /* RCTValueAnimatedNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTValueAnimatedNode.m; sourceTree = "<group>"; };
-		94DAE3F71D7334A70059942F /* RCTModuloAnimatedNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTModuloAnimatedNode.h; sourceTree = "<group>"; };
-		94DAE3F81D7334A70059942F /* RCTModuloAnimatedNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTModuloAnimatedNode.m; sourceTree = "<group>"; };
 		193F64F21D776EC6004D1CAA /* RCTDiffClampAnimatedNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTDiffClampAnimatedNode.h; sourceTree = "<group>"; };
 		193F64F31D776EC6004D1CAA /* RCTDiffClampAnimatedNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTDiffClampAnimatedNode.m; sourceTree = "<group>"; };
+		5C9894931D999639008027DB /* RCTDivisionAnimatedNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTDivisionAnimatedNode.h; sourceTree = "<group>"; };
+		5C9894941D999639008027DB /* RCTDivisionAnimatedNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTDivisionAnimatedNode.m; sourceTree = "<group>"; };
+		94DAE3F71D7334A70059942F /* RCTModuloAnimatedNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTModuloAnimatedNode.h; sourceTree = "<group>"; };
+		94DAE3F81D7334A70059942F /* RCTModuloAnimatedNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTModuloAnimatedNode.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -89,6 +92,8 @@
 		13E501D51D07A6C9005F35D8 /* Nodes */ = {
 			isa = PBXGroup;
 			children = (
+				5C9894931D999639008027DB /* RCTDivisionAnimatedNode.h */,
+				5C9894941D999639008027DB /* RCTDivisionAnimatedNode.m */,
 				193F64F21D776EC6004D1CAA /* RCTDiffClampAnimatedNode.h */,
 				193F64F31D776EC6004D1CAA /* RCTDiffClampAnimatedNode.m */,
 				13E501D61D07A6C9005F35D8 /* RCTAdditionAnimatedNode.h */,
@@ -196,6 +201,7 @@
 				13E501E91D07A6C9005F35D8 /* RCTAnimatedNode.m in Sources */,
 				13E501EB1D07A6C9005F35D8 /* RCTInterpolationAnimatedNode.m in Sources */,
 				13E501E81D07A6C9005F35D8 /* RCTAdditionAnimatedNode.m in Sources */,
+				5C9894951D999639008027DB /* RCTDivisionAnimatedNode.m in Sources */,
 				13E501EA1D07A6C9005F35D8 /* RCTAnimationDriverNode.m in Sources */,
 				13E501EF1D07A6C9005F35D8 /* RCTTransformAnimatedNode.m in Sources */,
 				13E501D41D07A644005F35D8 /* RCTViewPropertyMapper.m in Sources */,

Libraries/NativeAnimation/RCTNativeAnimatedModule.m

@@ -16,6 +16,7 @@
 #import "RCTInterpolationAnimatedNode.h"
 #import "RCTLog.h"
 #import "RCTDiffClampAnimatedNode.h"
+#import "RCTDivisionAnimatedNode.h"
 #import "RCTModuloAnimatedNode.h"
 #import "RCTMultiplicationAnimatedNode.h"
 #import "RCTPropsAnimatedNode.h"
@@ -71,6 +72,7 @@ RCT_EXPORT_METHOD(createAnimatedNode:(nonnull NSNumber *)tag
             @"interpolation" : [RCTInterpolationAnimatedNode class],
             @"addition" : [RCTAdditionAnimatedNode class],
             @"diffclamp": [RCTDiffClampAnimatedNode class],
+            @"division" : [RCTDivisionAnimatedNode class],
             @"multiplication" : [RCTMultiplicationAnimatedNode class],
             @"modulus" : [RCTModuloAnimatedNode class],
             @"transform" : [RCTTransformAnimatedNode class]};

ReactAndroid/src/main/java/com/facebook/react/animated/DivisionAnimatedNode.java

@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.animated;
+
+import com.facebook.react.bridge.JSApplicationCausedNativeException;
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
+
+/**
+ * Animated node which takes two or more value node as an input and outputs an in-order
+ * division of their values.
+ */
+/*package*/ class DivisionAnimatedNode extends ValueAnimatedNode {
+
+  private final NativeAnimatedNodesManager mNativeAnimatedNodesManager;
+  private final int[] mInputNodes;
+
+  public DivisionAnimatedNode(
+      ReadableMap config,
+      NativeAnimatedNodesManager nativeAnimatedNodesManager) {
+    mNativeAnimatedNodesManager = nativeAnimatedNodesManager;
+    ReadableArray inputNodes = config.getArray("input");
+    mInputNodes = new int[inputNodes.size()];
+    for (int i = 0; i < mInputNodes.length; i++) {
+      mInputNodes[i] = inputNodes.getInt(i);
+    }
+  }
+
+  @Override
+  public void update() {
+    for (int i = 0; i < mInputNodes.length; i++) {
+      AnimatedNode animatedNode = mNativeAnimatedNodesManager.getNodeById(mInputNodes[i]);
+      if (animatedNode != null && animatedNode instanceof ValueAnimatedNode) {
+        double value = ((ValueAnimatedNode) animatedNode).mValue;
+        if (i == 0) {
+          mValue = value;
+          continue;
+        }
+        if (value == 0) {
+          throw new JSApplicationCausedNativeException("Detected a division by zero in " +
+            "Animated.divide node");
+        }
+        mValue /= value;
+      } else {
+        throw new JSApplicationCausedNativeException("Illegal node ID set as an input for " +
+          "Animated.divide node");
+      }
+    }
+  }
+}

ReactAndroid/src/main/java/com/facebook/react/animated/NativeAnimatedNodesManager.java

@@ -89,6 +89,8 @@ import javax.annotation.Nullable;
       node = new InterpolationAnimatedNode(config);
     } else if ("addition".equals(type)) {
       node = new AdditionAnimatedNode(config, this);
+    } else if ("division".equals(type)) {
+      node = new DivisionAnimatedNode(config, this);
     } else if ("multiplication".equals(type)) {
       node = new MultiplicationAnimatedNode(config, this);
     } else if ("diffclamp".equals(type)) {