Aspect ratio mode

typedef enum _PRL_SCALE_VIEW_MODE {
  PSVM_OFF = 0,
  PSVM_AUTO = 1,
  PSVM_KEEP_ASPECT_RATIO = 2,
  PSVM_KEEP_ASPECT_RATIO_BY_EXPANDING = 3,
  PSVM_IGNORE_ASPECT_RATIO = 4
} PRL_SCALE_VIEW_MODE;