BitmapDrawable cannot be cast to RoundRectDrawable

问题:

I am trying to extend a cardview to set the background image. I know that this can not be done with normal cardview. I have searched net and found plenty of solutions for setting a background color to the card view but none for image.

My code to do so:

public class CCView extends CardView {

    public  CCView (Context context) {
        super(context);
        init();
    }

    public CCView (Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public CCView (Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }


    private void init() {

       setBackground(getResources().getDrawable(R.drawable.cc_background));

    }
}

I get this exception when I populate the code from XML

android.graphics.drawable.BitmapDrawable cannot be cast to android.support.v7.widget.RoundRectDrawableWithShadow

Any solution?

回答1:

As CardView extends FrameLayout you can layer layouts on top of it. To get around the problem you're having, I'd try adding a blank view "underneath" all the other elements in your view, and then set that view to inherit the state of its parent. Something like this:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_height="match_parent"
android:layout_width="match_parent"
card_view:cardBackgroundColor="#DDFFFFFF"
card_view:cardElevation="@dimen/card_elevation">

    <View
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:duplicateParentState="true"
        android:background="@drawable/card_background"/>

    <LinearLayout
    ....
    ....
    ....
    /LinearLayout>

</android.support.v7.widget.CardView>