What is alternative of android:background in MaterialComponents?

问题

Question: android:background is not giving effect in MaterialComponents.

In my project, I was using AppCompat

( <style name="DayTheme" parent="Theme.AppCompat.Light.NoActionBar">) and everything was working fine. but, because of some requirement in my project, now, I've to use MaterialComponents

( <style name="DayTheme" parent="Theme.MaterialComponents.Light.NoActionBar"> )

And because of that some UI looks bad.

Problem: In AppComapt, I was using android:background="@drawable/bg_circle_btn" which was working fine, but in MaterialComponents, this background is not giving effect.

I tried to change color, shape n all but it's not giving effect.

 <Button
                                android:id="@+id/custom_category_image"
                                android:layout_width="match_parent"
                                android:layout_height="25dp"
                                android:layout_alignParentTop="true"
                                android:layout_centerHorizontal="true"
                                android:background="@drawable/bg_circle_btn"
                                android:text="A"
                                android:textColor="@color/colorWhite"
                                android:textSize="12dp"
                                android:visibility="gone"
                                app:srcCompat="@drawable/ic_navigate_next_black_24dp" />

(I'm using button, because, instead of any fixed image, I'm setting the first letter of title in this button and this button is actually inside carview, so it'll be cirlce also.)

bg_circle_btn:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">

    <solid android:color="?attr/toolbarcolor" />

    <size
        android:width="120dp"
        android:height="120dp" />
</shape>

Please note that, in whole project, I need to use this background, so please do not give any other alternative ways.

回答1:

You could use androidx.appcompat.widget.AppCompatButton instead of Button. This will solve your problem.

Besides this you can use android:backgroundTint to change the color only.

To change both (Shape&Color) for com.google.android.material.button.MaterialButton, you have to do this from you code:

setBackgroundResource(R.drawable.bg_circle_btn) setBackgroundTintList(ColorStateList.valueOf(Color.RED))

回答2:

Since you are using the Material Components theme, <Button> is replaced by the <com.google.android.material.button.MaterialButton> at runtime. There is an auto-inflation (check this post).

To change the background color just use the app:backgroundTint attribute. It works with a color, not a drawable.
Something like:

<com.google.android.material.button.MaterialButton
   app:backgroundTint="@color/...."
   ../>

回答3:

You cannot use background attribute, when using MaterialComponents theme.

You can only change its color using backgroundTint attribute.

Possible way of achieving your task is to use View/Layout, then providing a shape background on it. For example using CardView, you can do this as follow.

You cannot use background on CardView, but using some of the CardView useful attributes you can achieve your task:

<androidx.cardview.widget.CardView
    android:layout_width="120dp"
    android:layout_height="120dp"
    app:cardBackgroundColor="@color/colorPrimary"
    app:cardCornerRadius="65dp">
    <Widget_You_Want />
</androidx.cardview.widget.CardView>

回答4:

For a round circle you could use shape theming with Material Components. You would probably want to define a ShapeAppearance like

<style name="ShapeAppearance.Round" parent="">
  <item name="cornerFamily">rounded</item>
  <item name="cornerSize">50%</item>
</style>

Then apply that to your button (or button style) with app:shapeAppearance="@style/ShapeAppearance.Round"

来源：https://stackoverflow.com/questions/58301863/what-is-alternative-of-androidbackground-in-materialcomponents