如何仅在按钮的背景色上应用透明度

Question

I'm a beginner on Android Studio and I need your help to apply a specific transparency on my layout.

I applied a background and border color to my layout by using this drawable:

    <?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="@android:color/black" />
    <corners android:radius="3dp" />
    <stroke android:width="5px" android:color="#ffa500" />
</shape>

Now I want to apply dynamically a transparency to this button ( by using a seek bar ) but only on the background color I don't want to modify my border color. I tried to use setAlpha function but it also change my border color transparency.

How can I do this? Thanks.

Answer 1

You need to use the alpha portion of the color your specify in item.

For example - #aarrggbb -- aa part is the alpha.

If you want to change stroke / solid color separately, I recommend using GradientDrawable to setStroke() and `setColor()'.

For reference -

https://developer.android.com/reference/android/graphics/drawable/GradientDrawable#setColor(int)

https://developer.android.com/reference/android/graphics/drawable/GradientDrawable.html#setStroke(int,%20android.content.res.ColorStateList,%20float,%20float)

Answer 2

In your shape change the <solid android:color="@android:color/black" /> to <solid android:color="#00FFFFFF" /> This will make your shape transparent. And in your xml <Button .... android:background="@drawable/your_shape" />