按下时如何使按钮颜色透明（或更改不透明度）？

Question

I have a button and I want to give it %20 opacity. After click it has to be in old color without an opacity or transparency.

This is my XML:

<com.example.android.custombutton.CustomButton
                android:id="@+id/custombutton_cardselection_turkish_id"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:backgroundTint="@color/blue_button"
                android:layout_marginStart="16dp"
                android:layout_marginEnd="16dp"
                android:layout_marginBottom="16dp"
                android:text="@string/nfc_new_turkish_id"
                android:textColor="@color/white"
                app:layout_constraintBottom_toTopOf="@+id/custombutton_cardselection_passport"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@id/guideline_cardselection_top" />

I want to change it in XML not in the kotlin part. How can I do that?

Answer 1

use this code

btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            btn.getBackground().setAlpha(0);
        }
    });

you can also set android:background="#10FF0000" in xml file

Answer 2

You can use OnTouchListener to achieve the hover effect as you were asking. However, you can't achieve this using XML instead you need to do this programmatically.

for java use this

yourBtn.onTouchEvent(new View.OnTouchListener(){
                   @Override
                public boolean onTouch(View v, MotionEvent event) {
                   yourBtn.getBackground().setAlpha(1);
                   yourBtn.setBackgroundColor("#ffffff");
    
          if (event.getAction() == MotionEvent.ACTION_UP) {
      yourBtn.getBackground().setAlpha((float) 0.2);
    }
                    return false;
                }
            });

for kotlin use this

yourBtn.onTouchEvent(object:View.OnTouchListener() {
  fun onTouch(v:View, event:MotionEvent):Boolean {
    yourBtn.getBackground().setAlpha(1)
    yourBtn.setBackgroundColor("#ffffff")
    if (event.getAction() === MotionEvent.ACTION_UP)
    {
      yourBtn.getBackground().setAlpha(0.2.toFloat())
    }
    return false
  }
})

if the user clicks your button (I mean touches your button) then it will become opaque and you can set the background color as you want and then if the user lifts up his finger then it will become 20% transparent.