Axiom.Media.Image.CalculateSize C# (CSharp) Method

		public static int CalculateSize( int mipmaps, int faces, int width, int height, int depth, PixelFormat format )
		{
			int size = 0;
			for ( int mip = 0; mip <= mipmaps; ++mip )
			{
				size += PixelUtil.GetMemorySize( width, height, depth, format ) * faces;
				if ( width != 1 )
					width /= 2;
				if ( height != 1 )
					height /= 2;
				if ( depth != 1 )
					depth /= 2;
			}
			return size;

		}

        public override Codec.DecodeResult Decode(Stream input)
        {
            using (var br = new BinaryReader(input))
            {
                var numFaces = 1;                 // Assume one face until we know otherwise
                var imgData  = new ImageData();

                // Read the PVRTC header
                var header = PVRTCTexHeader.Read(br);

                // Get the file type identifier
                var pvrTag = header.pvrTag;

                if (this.PVR_MAGIC != pvrTag)
                {
                    throw new AxiomException("This is not a PVR file!");
                }

                // Get format flags
                var flags = header.flags;
                using (var wrap = BufferBase.Wrap(flags, 2))
                {
                    _flipEndian(wrap, sizeof(int));
                }
                var formatFlags = flags & PVR_TEXTURE_FLAG_TYPE_MASK;

                var bitmaskAlpha = header.bitmaskAlpha;
                using (var wrap = BufferBase.Wrap(bitmaskAlpha, 2))
                {
                    _flipEndian(wrap, sizeof(int));
                }

                if (formatFlags == kPVRTextureFlagTypePVRTC_4 || formatFlags == kPVRTextureFlagTypePVRTC_2)
                {
                    if (formatFlags == kPVRTextureFlagTypePVRTC_4)
                    {
                        imgData.format = bitmaskAlpha != 0 ? PixelFormat.PVRTC_RGBA4 : PixelFormat.PVRTC_RGB4;
                    }
                    else if (formatFlags == kPVRTextureFlagTypePVRTC_2)
                    {
                        imgData.format = bitmaskAlpha != 0 ? PixelFormat.PVRTC_RGBA2 : PixelFormat.PVRTC_RGB2;
                    }

                    imgData.depth      = 1;
                    imgData.width      = header.width;
                    imgData.height     = header.height;
                    imgData.numMipMaps = header.numMipmaps;

                    // PVRTC is a compressed format
                    imgData.flags |= ImageFlags.Compressed;
                }

                // Calculate total size from number of mipmaps, faces and size
                imgData.size = Image.CalculateSize(imgData.numMipMaps, numFaces, imgData.width, imgData.height, imgData.depth,
                                                   imgData.format);

                // Now deal with the data
                var dest = br.ReadBytes(imgData.size);
                return(new DecodeResult(new MemoryStream(dest), imgData));
            }
        }