UVShrink

## how to use:
## select a poly face of each UV shell island you would like to scale and hit apply.
## command to run from Maya python window/shelf (copy + paste exactly the following inside the """ box while changing the path):
"""

filepath = "C:\Users\UserName\Documents\maya\scripts\MayaPythonTools"       ## << change this path to your folder.
paths = sys.path ; sys.path.append(filepath) ; exec 'import ' + 'UVShrink' in globals(); exec( 'reload( ' + 'UVShrink' + ' )' ) in globals();


"""

import maya.cmds as cmds
import maya.mel as mel

def variables(varType):
    toolID = 'UVShrink'
    returnData = eval(varType)
    return returnData

def ShrinkUV():
    _selected_Meshs = cmds.ls( selection = True , flatten = True )
    cmds.select(clear = True)
    for _item in _selected_Meshs:
        cmds.select(_item)
        mel.eval('polySelectBorderShell 0;')
        _tempBoundingBox = cmds.polyEvaluate( bc2 = True , ae = True)
        _tempPivot = [ 0,0]
        _tempPivot[0] = ((_tempBoundingBox[0][0] + _tempBoundingBox[0][1]) /2 )
        _tempPivot[1] = ((_tempBoundingBox[1][0] + _tempBoundingBox[1][1]) /2 )
        _scale = cmds.floatSlider( 'UVShrink_Float_UI' , query = True , value = True )
        cmds.polyEditUV( pu = _tempPivot[0] , pv = _tempPivot[1] , su = _scale, sv = _scale )
        cmds.select(clear = True)
    cmds.select(_selected_Meshs)

def UpdateWindowValue():
    fullLabel = str(cmds.floatSlider( 'UVShrink_Float_UI' , query = True , value = True ))
    cmds.text( 'UVShrink_Float_UI_Text' , edit = True , label = str(fullLabel[0:4])   )

def UVShrink_Window():
    UVShrink_Window = "UVShrink_Window"
    if cmds.window(UVShrink_Window, exists = True):
        cmds.deleteUI(UVShrink_Window, window = True)
    if cmds.windowPref(UVShrink_Window, exists = True):
        cmds.windowPref(UVShrink_Window, remove = True )
    cmds.window(UVShrink_Window ,  rtf = True , toolbox = True , wh = (200, 55) )
    cmds.columnLayout( adjustableColumn=True )
    cmds.floatSlider( 'UVShrink_Float_UI' , min= .01, max=2.0, value=.2, step=1 , cc = ( variables('toolID') + '.UpdateWindowValue()') )
    cmds.text( 'UVShrink_Float_UI_Text' ,label='0.2' )
    cmds.button( label='Apply', command= ( variables('toolID') + '.ShrinkUV()') )
    cmds.setParent( '..' )
    cmds.showWindow( UVShrink_Window )

def init():
    UVShrink_Window() ## run self

UVShrink_Window()