[TIMOB-20363] Fix Android: Buttons inside views appear on top of all other children

[maggieaxway]

JIRA: https://jira.appcelerator.org/browse/TIMOB-20363

Titanium.UI.setBackgroundColor('#000');

var window = Titanium.UI.createWindow({
backgroundColor:'#fff'
});
 
// create a main view which will contain the button and the view
var mainViewContainer = Ti.UI.createView({
top: 0,
left: 0,
right: 0,
bottom:0,
backgroundColor: 'red'
});
 
// create a view which will obscure the button
var shouldObscureButton = Ti.UI.createView({
top: 0,
left: 0,
width: 200,
bottom: 0,
backgroundColor: 'blue'
});
 
// create a button which is wider than the obscure view
var button = Ti.UI.createButton({
height: 350,
width: 350,
left: 0,
backgroundImage: 'buttonTest.png',
backgroundColor: 'yellow'
});
 
// add the button to the main view container before the obscure view
mainViewContainer.add(button);
 
// add a view that should obscure the button after the button has been added
mainViewContainer.add(shouldObscureButton);
 
// add the main view to the window and open it
window.add(mainViewContainer);
window.open();

[build]

	Fails
🚫	Tests have failed, see below for more information.
🚫	📝 Formatting reported as incorrect on the following files: android/modules/ui/src/java/ti/modules/titanium/ui/widget/TiUIButton.java You can fix the formatting by running: npx clang-format -style=file -i <filepath>

	Messages
📖	💾 Here's the generated SDK zipfile.

Tests:

Classname	Name	Time	Error
ios.Titanium.Network.HTTPClient	callbackTestForGETMethod	0.171	onreadystatechange@file:///Users/build/Library/De

Generated by 🚫 dangerJS

[jquick-axway]

I've tested this and noticed this removes the button's drop-shadow effect, which we don't want.

I'm pretty sure setting a Titanium view's elevation property to a value greater than zero will have the same z-ordering issue buttons have as well. So, this is a much bigger problem.
http://docs.appcelerator.com/platform/latest/#!/api/Titanium.UI.View-property-elevation

I'm not sure what the correct solution to this is. We need to use Android elevation feature to show the drop-shadow effect. So, I'm curious if we need to something like the below?

setTranslationZ(-getElevation());

This requires some experimentation.

[maggieaxway]

@jquick-axway Hi I couldn't reproduce the button's drop-shadow effect even before the code change. I did some experiments, it seems only affecting the Z so that the layers. I have been looking into the source code but couldn't figure out where went wrong. :(

[jquick-axway]

Closing since this change will remove the button's drop-shadow on Android 5.0 and higher. We need to find an alternative solution.