Expose background shape drawable in MaterialButtonHelper

PiperOrigin-RevId: 231321351

Author: gsajith

lib/java/com/google/android/material/button/MaterialButton.java

@@ -41,6 +41,7 @@
 import com.google.android.material.internal.ThemeEnforcement;
 import com.google.android.material.internal.ViewUtils;
 import com.google.android.material.resources.MaterialResources;
+import com.google.android.material.shape.MaterialShapeDrawable;
 import com.google.android.material.shape.ShapeAppearanceModel;
 import androidx.core.graphics.drawable.DrawableCompat;
 import androidx.core.view.ViewCompat;
@@ -752,6 +753,16 @@ public void setIconGravity(@IconGravity int iconGravity) {
     this.iconGravity = iconGravity;
   }
 
+  @RestrictTo(LIBRARY_GROUP)
+  @Nullable
+  protected MaterialShapeDrawable getBackgroundShapeDrawable() {
+    if (materialButtonHelper == null) {
+      return null;
+    }
+
+    return materialButtonHelper.getMaterialShapeDrawable();
+  }
+
   private boolean isUsingOriginalBackground() {
     return materialButtonHelper != null && !materialButtonHelper.isBackgroundOverwritten();
   }

lib/java/com/google/android/material/button/MaterialButtonHelper.java

@@ -323,7 +323,7 @@ private void adjustShapeAppearanceModelCornerRadius(
   }
 
   @Nullable
-  private MaterialShapeDrawable getMaterialShapeDrawable() {
+  MaterialShapeDrawable getMaterialShapeDrawable() {
     Drawable result = null;
     if (rippleDrawable != null && rippleDrawable.getNumberOfLayers() > 0) {
       result = rippleDrawable.getDrawable(0);