Opacity filter on Android (#44454)

Summary:
Pull Request resolved: #44454

tsia

Changelog: [Internal]

Reviewed By: NickGerleman

Differential Revision: D56847475

fbshipit-source-id: bbd51e8c744914f1d2caf392996d20ab03b3fb6f

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/FilterHelper.kt

@@ -35,9 +35,10 @@ internal object FilterHelper {
             "grayscale" -> createGrayscaleEffect(amount, chainedEffects)
             "sepia" -> createSepiaEffect(amount, chainedEffects)
             "saturate" -> createSaturateEffect(amount, chainedEffects)
-            "hue-rotate" -> createHueRotateEffect(amount, chainedEffects)
+            "hueRotate" -> createHueRotateEffect(amount, chainedEffects)
             "invert" -> createInvertEffect(amount, chainedEffects)
             "blur" -> createBlurEffect(amount, chainedEffects)
+            "opacity" -> createOpacityEffect(amount, chainedEffects)
             else -> throw IllegalArgumentException("Invalid filter name: $filterName")
           }
     }
@@ -63,6 +64,7 @@ internal object FilterHelper {
             "saturate" -> createSaturateColorMatrix(amount)
             "hueRotate" -> createHueRotateColorMatrix(amount)
             "invert" -> createInvertColorMatrix(amount)
+            "opacity" -> createOpacityColorMatrix(amount)
             else -> throw IllegalArgumentException("Invalid color matrix filter: $filterName")
           }
 
@@ -117,6 +119,20 @@ internal object FilterHelper {
     return matrix
   }
 
+  // https://www.w3.org/TR/filter-effects-1/#opacityEquivalent
+  public fun createOpacityEffect(
+      amount: Float,
+      chainedEffects: RenderEffect? = null
+  ): RenderEffect {
+    return createColorMatrixEffect(createOpacityColorMatrix(amount), chainedEffects)
+  }
+
+  public fun createOpacityColorMatrix(amount: Float): ColorMatrix {
+    val matrix = ColorMatrix()
+    matrix.setScale(1f, 1f, 1f, amount)
+    return matrix
+  }
+
   // https://www.w3.org/TR/filter-effects-1/#contrastEquivalent
   public fun createContrastEffect(
       amount: Float,