V_D_M_X_.py 文件源码

def _getOffsets(self):
        """
        Calculate offsets to VDMX_Group records.
        For each ratRange return a list of offset values from the beginning of
        the VDMX table to a VDMX_Group.
        """
        lenHeader = sstruct.calcsize(VDMX_HeaderFmt)
        lenRatRange = sstruct.calcsize(VDMX_RatRangeFmt)
        lenOffset = struct.calcsize('>H')
        lenGroupHeader = sstruct.calcsize(VDMX_GroupFmt)
        lenVTable = sstruct.calcsize(VDMX_vTableFmt)
        # offset to the first group
        pos = lenHeader + self.numRatios*lenRatRange + self.numRatios*lenOffset
        groupOffsets = []
        for group in self.groups:
            groupOffsets.append(pos)
            lenGroup = lenGroupHeader + len(group) * lenVTable
            pos += lenGroup  # offset to next group
        offsets = []
        for ratio in self.ratRanges:
            groupIndex = ratio['groupIndex']
            offsets.append(groupOffsets[groupIndex])
        return offsets