gistfile1.gradle

apply plugin: 'com.android.application'

def createTheme(colorPrimary, colorPrimaryDark, colorAccent, colorDisabled) {
    def returnTheme = new Expando()
    returnTheme.colorPrimary = colorPrimary
    returnTheme.colorPrimaryDark = colorPrimaryDark
    returnTheme.colorAccent = colorAccent
    returnTheme.colorDisabled = colorDisabled
    return returnTheme
}

def colorDisabled = "ADADAD"

//define theme
def themeOrangeBlueGrey = createTheme("F57C00", "E65100", "78909C", colorDisabled)
def themeIndigoPink = createTheme("3F51B5", "1A237E", "F50057", colorDisabled)
def themeOSA1 = createTheme("284E3D", "293326", "8CC63F", colorDisabled)
def themeOSA1a = createTheme("284E3D", "1A3327", "8CC63F", colorDisabled)
def themeOSA2 = createTheme("404F3C", "1F261D", "A6C03B", colorDisabled)
def themeTealLime = createTheme("009688", "00796B", "C6FF00", colorDisabled)

//select theme
def theme = themeOSA1a


.
.
.
.
.
.

android.applicationVariants.all { variant ->

    variant.resValue "color", "colorPrimary", "#" + theme.colorPrimary
    variant.resValue "color", "colorPrimaryDark", "#" + theme.colorPrimaryDark
    variant.resValue "color", "colorAccent", "#" + theme.colorAccent
    variant.resValue "color", "colorDisabled", "#" + theme.colorDisabled
    for ( i in 1..9 ) {
        def hex =  Integer.toHexString(((int)i * 25.5))
        variant.resValue "color", "colorPrimary" + "A" + i + "0", "#" + hex + theme.colorPrimary
        variant.resValue "color", "colorPrimaryDark" + "A" + i + "0", "#" + hex + theme.colorPrimaryDark
        variant.resValue "color", "colorAccent" + "A" + i + "0", "#" + hex + theme.colorAccent
        variant.resValue "color", "colorDisabled" + "A" + i + "0", "#" + hex + theme.colorDisabled
    }
    variant.outputs.each { output ->
        def apk = output.outputFile
        def newName = "TheApp"
        newName = newName + "-${android.defaultConfig.versionName}.apk"
        output.outputFile = new File(new File(apk.parentFile, variant.name), newName)
    }
}