Weird behaviour of elevation and translucent color

Question

Here's my view:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/bg_rounded"
    android:backgroundTint="@color/view_primary_color"
    android:elevation="4dp"
    android:foregroundTint="@android:color/white">

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/tvTitle"
        style="@style/Header4.Semibold16.White"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="Add to cart"
        android:textAllCaps="false"
        app:tint="@android:color/white"
        tools:ignore="ContentDescription" />

    <ProgressBar
        android:id="@+id/pbLoading"
        style="?android:attr/progressBarStyleSmall"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_centerInParent="true"
        android:layout_gravity="center"
        android:visibility="gone" />

</FrameLayout>

And here's @color/view_primary_color

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/colorPrimary" android:state_enabled="true" />
    <item android:color="@color/colorPrimaryDisabled" android:state_enabled="false" />
</selector>

When view's state is enabled it's color is colorPrimary.

When state is disabled view's color is colorPrimaryDisabled which is almost the same as colorPrimary but only with 20% of alpha.

Here's how my view looks like is idle (enabled) state.

But when I click on the view it became like this.

View supposed to just change it's color to slightly translucent, but for some reason there's some shadow inside it.

If I use non-translucent color everything is ok. Or if I remove elevation from the view everything is ok as well.

Feels like this is some kind of bug. Do you have any idea what is this?

Thanks!

Answer 1

using MaterialButton instead of textView like this

<com.google.android.material.button.MaterialButton
            android:id="@+id/btn_add_to_card"
            android:layout_width="120dp"
            android:layout_height="40dp"
            android:layout_gravity="center"
            android:layout_marginTop="24dp"
            android:layout_marginBottom="16dp"
            android:elevation="0dp"
            android:enabled="false"
            android:fontFamily="@font/sans_normal"
            android:gravity="center"
            android:insetLeft="0dp"
            android:insetTop="0dp"
            android:insetRight="0dp"
            android:insetBottom="0dp"
            android:minWidth="0dp"
            android:paddingLeft="16dp"
            android:paddingRight="16dp"
            android:stateListAnimator="@null"
            android:text="@string/addToCard"
            android:textColor="@color/white"
            android:textSize="16sp"
            android:translationZ="0dp"
            app:backgroundTint="@color/btn_primary_state"
            app:cornerRadius="24dp"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/scrollview_edittext" />

background tint:

<?xml version="1.0" encoding="utf-8"?>
<selector
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:state_enabled="true"
        android:color="@color/green_button" />
    <item
        android:state_enabled="false"
        android:color="@color/gray_button"
        />
</selector>