Textured progress bar implementation. [ProgressBar] implementation that is easier to theme (by just passing a few textures). Returns true if textures are stretched as nine-patches or false otherwise. Return nine-patch texture offset for a given margin (MARGIN_LEFT, MARGIN_TOP, MARGIN_RIGHT, MARGIN_BOTTOM). Set if textures should be stretched as nine-patches. Set nine-patch texture offset for a given margin (MARGIN_LEFT, MARGIN_TOP, MARGIN_RIGHT, MARGIN_BOTTOM).