How to set custom system icons(png files)


I have set of custom system icons(png files) and they’re in drawable-xhdpi,drawable-xxhdpi and drawable-xxxhdpi folders for android.

Now my question is when I use them how should I call them? For example, I want the system to pick the correct edit_pencil.png

This is what I have at the moment and I know this explicitly define the edit_pencil.png which I don’t want. Could anybody help?

<img class="addPictureIcon" src="assets/img/drawable-xhdpi/edit_pencil.png"