makeRasterN32Premul
Allocates raster Surface.
Canvas returned by Surface draws directly into pixels. Allocates and zeroes pixel memory. Pixel memory size is height times width times four. Pixel memory is deleted when Surface is deleted.
Internally, sets ImageInfo to width, height, native color type, and ColorAlphaType.PREMUL.
Surface is returned if width and height are greater than zero.
Use to create Surface that matches PMColor, the native pixel arrangement on the platform. Surface drawn to output device skips converting its pixel format.
Return
Surface if all parameters are valid; otherwise, null
Parameters
width
pixel column count; must be greater than zero
height
pixel row count; must be greater than zero