Merge pull request #18 from edusperoni/android-r-fix

fix: reduce lag when overriding animator

Author: JoshDSommer

lib/src/nativescript-ngx-shadow/common/shadow.ts

@@ -21,6 +21,22 @@ if (isAndroid) {
   PlainShadow = android.graphics.drawable.GradientDrawable.extend({});
 }
 
+const classCache: { [id: string]: { class: any, fieldCache: { [id: string]: number } } } = {};
+// https://github.com/NativeScript/android-runtime/issues/1330
+function getAndroidR(rtype: string, field: string): number {
+  const className = "android.R$" + rtype;
+  if (!classCache.hasOwnProperty(className)) {
+    classCache[className] = {
+      class: java.lang.Class.forName(className),
+      fieldCache: {}
+    };
+  }
+  if(!classCache[className].fieldCache.hasOwnProperty(field)) {
+    classCache[className].fieldCache[field] = +classCache[className].class.getField(field).get(null);
+  }
+  return classCache[className].fieldCache[field];
+}
+
 export class Shadow {
   static DEFAULT_SHAPE = ShapeEnum.RECTANGLE;
   static DEFAULT_BGCOLOR = '#FFFFFF';
@@ -138,7 +154,7 @@ export class Shadow {
 
     const ObjectAnimator = android.animation.ObjectAnimator;
     const AnimatorSet = android.animation.AnimatorSet;
-    const shortAnimTime = android.R.integer.config_shortAnimTime;
+    const shortAnimTime = getAndroidR("integer", "config_shortAnimTime");
 
     const buttonDuration =
       nativeView.getContext().getResources().getInteger(shortAnimTime) / 2;
@@ -169,10 +185,10 @@ export class Shadow {
     ]));
 
     sla.addState(
-      [android.R.attr.state_pressed, android.R.attr.state_enabled],
+      [getAndroidR("attr", "state_pressed"), getAndroidR("attr", "state_enabled")],
       pressedSet,
     );
-    sla.addState([android.R.attr.state_enabled], notPressedSet);
+    sla.addState([getAndroidR("attr", "state_enabled")], notPressedSet);
     sla.addState([], defaultSet);
     nativeView.setStateListAnimator(sla);
   }
@@ -197,7 +213,7 @@ export class Shadow {
     nativeView.layer.shouldRasterize = data.rasterize;
     nativeView.layer.rasterizationScale = screen.mainScreen.scale;
     let shadowPath = null;
-    if(data.useShadowPath) {
+    if (data.useShadowPath) {
       shadowPath = UIBezierPath.bezierPathWithRoundedRectCornerRadius(nativeView.bounds, nativeView.layer.shadowRadius).cgPath;
     }
     nativeView.layer.shadowPath = shadowPath;