Change Button icon during runtime - xamarin

Question

I have activity with button inside GridLayout that is defined like this:
<Button
android:id="#+id/btnOpion4"
android:layout_columnWeight="1"
android:layout_rowWeight="1"
android:layout_width="0dp"
android:layout_height="0dp"
android:drawableStart="#drawable/btnSend"/>
To be able to show icon on that button i had to create drawable xml:
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#drawable/ic_send"
android:state_pressed="true" />
<item android:drawable="#drawable/ic_send"
android:state_focused="true" />
<item android:drawable="#drawable/ic_send" />
</selector>
And all of this is working just fine...
Problem is, how can i change image from code behind?
For example if user click on some option, then change icon on this button?
EDIT:
Can I find that drawable by it's ID, and change icon?
Something like var btnsendDraw = FindViewById(Resource.Drawable.btnSend);

Answer 1

You can accomplish that by using the SetCompoundDrawablesWithIntrinsicBounds method found in the Button class.
In your case, I would create another drawable file with my other background:
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#drawable/ic_sent"
android:state_pressed="true" />
<item android:drawable="#drawable/ic_sent"
android:state_focused="true" />
<item android:drawable="#drawable/ic_sent" />
</selector>
and let's call it: btnSent.
Now in your code, when you want to change the image just do:
var drawable = GetDrawable(Resource.Drawable.btnSent);
btn1.SetCompoundDrawablesWithIntrinsicBounds(drawable, null, null, null);
This method gets the 4 different Drawables: left, top, end & bottom in this specific order. Since you only want to replace the start you will set the first parameter.
Note: left and start are "the same".
More about this method here
At the end you should have something like this:
Hope this helps.-