[MaterialButton] Added methods to apply horizontal insets

[gabrielemariotti]

It closes #1770

This PR adds methods to support setting horizontal insets programatically.

[hunterstich]

Hey @gabrielemariotti,

Thanks for the PR! Added a few comments. Let me know what you think.

[hunterstich]

What do you think about merging this method with setVerticalInsets into something like setInsets(int, int, int, int) or updateInsets(int, int, int, int)? They're almost exactly the same, it might be nice to consolidate logic.

[gabrielemariotti]

Ok I will merge the 2 methods.

[hunterstich]

If we're using setPaddingRelative here, don't we want to expose setInsetStart and setInsetEnd since internally setPaddingRelative will swap the left/right values depending on the layout direction?

If we want to support setting left and right values, we'd need to change this to ViewCompat.setPadding(), if I understand correctly.

[gabrielemariotti]

@hunterstich In the current code in the loadFromAttributes you are using setPaddingRelative adding paddingStart + insetLeft. Let me know what you prefer. Maybe the best solution is to use insetLeft, paddingLeft and ViewCompat.setPadding() everywhere.

material-components-android/lib/java/com/google/android/material/button/MaterialButtonHelper.java

Lines 128 to 133 in 5e3ccdc

	ViewCompat.setPaddingRelative(
	materialButton,
	paddingStart + insetLeft,
	paddingTop + insetTop,
	paddingEnd + insetRight,
	paddingBottom + insetBottom);

[hunterstich]

Oh good catch

I agree, it would be nice to correct/avoid the mix of paddingStart|End and left|right. Using paddingLeft|Right + insetLeft|Right and ViewCompat.setPadding everywhere sounds like a good solution to me. Off the top of my head, I can't think of any behavior that this might break, but once you update MaterialButtonHelper and I pull it in and run all our test, we can double check.

In the future (or now if you want...), we can add in support for insetStart|End and ViewCompat.setPaddingRelative.