Fix getOpacity() for drawables (#47103)

Summary:
Pull Request resolved: #47103

`getOpacity()` is supposed to return a PixelFormat enum instead of a value between 0..255.
https://developer.android.com/reference/android/graphics/drawable/Drawable#getOpacity()

Also, I'm taking the value from the paint instead of the color's alpha since the paint might've been modified by setAlpha by this point and otherwise the paint will hold the alpha set by the color anyway since setAlpha() on Paints is just a helper for setColor() (https://developer.android.com/reference/android/graphics/Paint#setAlpha(int))

Changelog: [Internal]

Reviewed By: NickGerleman

Differential Revision: D64273014

fbshipit-source-id: e2c524f1d816ee3705c5118232be759898e666ea

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/drawable/CSSBackgroundDrawable.java

@@ -18,6 +18,7 @@
 import android.graphics.Paint;
 import android.graphics.Path;
 import android.graphics.PathEffect;
+import android.graphics.PixelFormat;
 import android.graphics.PointF;
 import android.graphics.PorterDuff;
 import android.graphics.Rect;
@@ -189,7 +190,15 @@ public int getLayoutDirection() {
 
   @Override
   public int getOpacity() {
-    return (Color.alpha(mColor) * mAlpha) >> 8;
+    int alpha = (Color.alpha(mColor) * mAlpha) >> 8;
+    switch (alpha) {
+      case 255:
+        return PixelFormat.OPAQUE;
+      case 0:
+        return PixelFormat.TRANSPARENT;
+      default:
+        return PixelFormat.TRANSLUCENT;
+    }
   }
 
   /* Android's elevation implementation requires this to be implemented to know where to draw the shadow. */
@@ -385,7 +394,7 @@ private void drawRoundedBackgroundWithBorders(Canvas canvas) {
     canvas.clipPath(Preconditions.checkNotNull(mOuterClipPathForBorderRadius), Region.Op.INTERSECT);
 
     // Draws the View without its border first (with background color fill)
-    int useColor = ColorUtils.setAlphaComponent(mColor, getOpacity());
+    int useColor = ColorUtils.setAlphaComponent(mColor, (Color.alpha(mColor) * mAlpha) >> 8);
     if (Color.alpha(useColor) != 0) {
       mPaint.setColor(useColor);
       mPaint.setStyle(Paint.Style.FILL);

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

@@ -75,9 +75,12 @@ internal class InsetBoxShadowDrawable(
 
   @Deprecated("Deprecated in Java")
   override fun getOpacity(): Int {
-    val alpha = Color.alpha(shadowColor)
-    return if (alpha == 0) PixelFormat.TRANSPARENT
-    else ((shadowPaint.alpha / 255f) / (alpha / 255f) * 255f).roundToInt()
+    val alpha = shadowPaint.alpha
+    return when (alpha) {
+      255 -> PixelFormat.OPAQUE
+      in 1..254 -> PixelFormat.TRANSLUCENT
+      else -> PixelFormat.TRANSPARENT
+    }
   }
 
   override fun draw(canvas: Canvas) {

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

@@ -15,6 +15,7 @@ import android.graphics.DashPathEffect
 import android.graphics.Paint
 import android.graphics.Path
 import android.graphics.PathEffect
+import android.graphics.PixelFormat
 import android.graphics.RectF
 import android.graphics.drawable.Drawable
 import com.facebook.react.uimanager.PixelUtil.dpToPx
@@ -104,8 +105,14 @@ internal class OutlineDrawable(
   }
 
   @Deprecated("Deprecated in Java")
-  override fun getOpacity(): Int =
-      ((outlinePaint.alpha / 255f) / (Color.alpha(outlineColor) / 255f) * 255f).roundToInt()
+  override fun getOpacity(): Int {
+    val alpha = outlinePaint.alpha
+    return when (alpha) {
+      255 -> PixelFormat.OPAQUE
+      in 1..254 -> PixelFormat.TRANSLUCENT
+      else -> PixelFormat.TRANSPARENT
+    }
+  }
 
   override fun draw(canvas: Canvas) {
     if (outlineWidth == 0f) {

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

@@ -71,9 +71,12 @@ internal class OutsetBoxShadowDrawable(
 
   @Deprecated("Deprecated in Java")
   override fun getOpacity(): Int {
-    val alpha = Color.alpha(shadowColor)
-    return if (alpha == 0) PixelFormat.TRANSPARENT
-    else ((shadowPaint.alpha / 255f) / (alpha / 255f) * 255f).roundToInt()
+    val alpha = shadowPaint.alpha
+    return when (alpha) {
+      255 -> PixelFormat.OPAQUE
+      in 1..254 -> PixelFormat.TRANSLUCENT
+      else -> PixelFormat.TRANSPARENT
+    }
   }
 
   override fun draw(canvas: Canvas) {