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Improve QR binary encoding compression

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This commit is contained in:
Gary Sharp
2016-09-21 19:55:00 +10:00
parent 4b866c9486
commit 85425d2a1f
4 changed files with 442 additions and 107 deletions
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Disco.Services/Documents/DocumentUniqueIdentifier.cs
+122 -97
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@@ -37,6 +37,7 @@ namespace Disco.Services.Documents
if (documentTemplate != null)
{
attachmentType = documentTemplate.AttachmentType;
DocumentTemplateId = documentTemplate.Id;
}
}
@@ -108,6 +109,10 @@ namespace Disco.Services.Documents
default:
throw new ArgumentException("Unexpected Attachment Type", nameof(AttachmentType));
}
if (target != null)
{
TargetId = target.AttachmentReferenceId;
}
}
return target;
@@ -121,6 +126,10 @@ namespace Disco.Services.Documents
if (creator == null)
{
creator = database.Users.Find(ActiveDirectory.ParseDomainAccountId(CreatorId));
if (creator != null)
{
CreatorId = creator.UserId;
}
}
return creator;
}
@@ -176,85 +185,95 @@ namespace Disco.Services.Documents
public byte[] ToQRCodeBytes()
{
// Byte | Meaning
// 0 | magic number = 0x0D
// 1 | bits 0-3 = version; 4-7 = flags (1 = has document template id, 2 = device attachment,
// | 4 = job attachment, 8 = user attachment)
// 0 | magic number = 0xC4
// 1 | bits 0-3 = version;
// | 4 = flag: has document template id
// | 5-6 = (01 = device attachment, 10 = job attachment, 11 = user attachment)
// | 7 = not used
// 2-3 | deployment checksum (int16)
// 4-7 | timestamp (uint32 unix epoch)
// 8-9 | page index (uint16)
// 10 | creator id length
// 11-? | creator id (UTF8)
// ? | target id length
// ?-? | target id
// ? | document template id length (optional based on flag)
// ?-? | document template id (UTF8, optional based on flag)
// 10 | creator id encoded
// ? | target id encoded
// ? | document template id encoded (optional based on flag)
const int version = 2;
var encoding = Encoding.UTF8;
byte flags = 0;
// encode variable-length parameters first
// encode creator id (strip default domain)
var creatorIdBytes = this.BinaryEncode(ActiveDirectory.FriendlyAccountId(CreatorId));
// encode target id
byte[] targetIdBytes;
if (AttachmentType.HasValue && AttachmentType.Value == AttachmentTypes.User)
{
// strip default domain from user targetted attachments
targetIdBytes = this.BinaryEncode(ActiveDirectory.FriendlyAccountId(TargetId));
}
else
{
targetIdBytes = this.BinaryEncode(TargetId);
}
byte[] documentTemplateIdBytes = null;
if (DocumentTemplateId != null)
{
documentTemplateIdBytes = this.BinaryEncode(DocumentTemplateId);
}
var result = new byte[10 + creatorIdBytes.Length + targetIdBytes.Length + (documentTemplateIdBytes?.Length ?? 0)];
// write magic number
result[0] = MagicNumber;
// write version
result[1] = (version << 4);
// write 'has document template id' flag
if (documentTemplateIdBytes != null)
{
result[1] |= 0x8; // 0000 1000
}
// write attachment type
switch (AttachmentType)
{
case AttachmentTypes.Device:
flags = 2;
result[1] |= 0x2; // 0000 0010 - 01
break;
case AttachmentTypes.Job:
flags = 4;
result[1] |= 0x4; // 0000 0100 - 10
break;
case AttachmentTypes.User:
flags = 8;
result[1] |= 0x6; // 0000 0110 - 11
break;
}
var deploymentChecksumBytes = BitConverter.GetBytes(DeploymentChecksum);
var timeStampEpochBytes = BitConverter.GetBytes((uint)(TimeStamp.ToUniversalTime().Subtract(DateTime.FromFileTimeUtc(116444736000000000L)).Ticks / TimeSpan.TicksPerSecond));
var pageIndexBytes = BitConverter.GetBytes((ushort)PageIndex);
// write deployment checksum
result[2] = (byte)(DeploymentChecksum >> 8);
result[3] = (byte)DeploymentChecksum;
// write timestamp
var timestamp = (uint)(TimeStamp.ToUniversalTime().Subtract(DateTime.FromFileTimeUtc(116444736000000000L)).Ticks / TimeSpan.TicksPerSecond);
result[4] = (byte)(timestamp >> 24);
result[5] = (byte)(timestamp >> 16);
result[6] = (byte)(timestamp >> 8);
result[7] = (byte)timestamp;
// magic number (1) + version/flags (1) + deployment checksum (2) + timestamp (4) +
// page index (2) + creator id length (1) + target id length (1)
var creatorIdLength = encoding.GetByteCount(CreatorId);
var targetIdLength = encoding.GetByteCount(TargetId);
var requiredBytes = 12 + creatorIdLength + targetIdLength;
var documentTemplateIdLength = 0;
// write page index
result[8] = (byte)(PageIndex >> 8);
result[9] = (byte)PageIndex;
if (DocumentTemplateId != null)
// write creator id
creatorIdBytes.CopyTo(result, 10);
// write target id
targetIdBytes.CopyTo(result, 10 + creatorIdBytes.Length);
// write document template id
if (documentTemplateIdBytes != null)
{
flags |= 1;
requiredBytes++;
documentTemplateIdLength = encoding.GetByteCount(DocumentTemplateId);
requiredBytes += documentTemplateIdLength;
}
int position = 0;
var result = new byte[requiredBytes];
// magic number
result[position++] = MagicNumber;
// version & flags
result[position++] = (byte)(flags | (2 << 4));
// deployment checksum
deploymentChecksumBytes.CopyTo(result, position);
position += 2;
// timestamp
timeStampEpochBytes.CopyTo(result, position);
position += 4;
// page index
pageIndexBytes.CopyTo(result, position);
position += 2;
// creator id length
result[position++] = (byte)creatorIdLength;
// creator id
position += encoding.GetBytes(CreatorId, 0, CreatorId.Length, result, position);
// target id length
result[position++] = (byte)targetIdLength;
// target id
position += encoding.GetBytes(TargetId, 0, TargetId.Length, result, position);
if (documentTemplateIdLength > 0)
{
// document template id length
result[position++] = (byte)documentTemplateIdLength;
// document template id
position += encoding.GetBytes(DocumentTemplateId, 0, DocumentTemplateId.Length, result, position);
documentTemplateIdBytes.CopyTo(result, 10 + creatorIdBytes.Length + targetIdBytes.Length);
}
return result;
@@ -339,68 +358,74 @@ namespace Disco.Services.Documents
return false;
}
public static bool TryParse(DiscoDataContext Database, byte[] UniqueIdentifier, out DocumentUniqueIdentifier Identifier)
public static bool TryParse(DiscoDataContext Database, byte[] Data, out DocumentUniqueIdentifier Identifier)
{
if (IsDocumentUniqueIdentifier(UniqueIdentifier))
if (IsDocumentUniqueIdentifier(Data))
{
// first 4 bit indicate version
var version = UniqueIdentifier[1] >> 4;
var version = Data[1] >> 4;
// Version 2
if (version == 2)
{
// Byte | Meaning
// 0 | magic number = 0x0D
// 1 | bits 0-3 = version; 4-7 = flags (1 = has document template id, 2 = device attachment,
// | 4 = job attachment, 8 = user attachment)
// 0 | magic number = 0xC4
// 1 | bits 0-3 = version;
// | 4 = flag: has document template id
// | 5-6 = (01 = device attachment, 10 = job attachment, 11 = user attachment)
// | 7 = not used
// 2-3 | deployment checksum (int16)
// 4-7 | timestamp (uint32 unix epoch)
// 8-9 | page index (uint16)
// 10 | creator id length
// 11-? | creator id (UTF8)
// ? | target id length
// ?-? | target id
// ? | document template id length (optional based on flag)
// ?-? | document template id (UTF8, optional based on flag)
var encoding = Encoding.UTF8;
var position = 1;
// 10 | creator id encoded
// ? | target id encoded
// ? | document template id encoded (optional based on flag)
// next 4 bits are flags
var flags = UniqueIdentifier[position++] & 0x0F;
// read flags
var flags = Data[1] & 0x0F;
var deploymentChecksum = BitConverter.ToInt16(UniqueIdentifier, position);
position += 2;
// read deployment checksum
short deploymentChecksum = (short)((Data[2] << 8) | Data[3]);
var timeStampEpoch = BitConverter.ToUInt32(UniqueIdentifier, position);
position += 4;
// read timestamp
var timeStampEpoch = ((long)Data[4] << 24) |
((long)Data[5] << 16) |
((long)Data[6] << 8) |
Data[7];
var pageIndex = BitConverter.ToUInt16(UniqueIdentifier, position);
position += 2;
// write page index
var pageIndex = (Data[8] << 8) | Data[9];
var creatorIdLength = UniqueIdentifier[position++];
var creatorId = encoding.GetString(UniqueIdentifier, position, creatorIdLength);
position += creatorIdLength;
var position = 10;
var targetIdLength = UniqueIdentifier[position++];
var targetId = encoding.GetString(UniqueIdentifier, position, targetIdLength);
position += targetIdLength;
// write creator id
var creatorId = DocumentUniqueIdentifierExtensions.BinaryDecode(Data, position, out position);
// write target id
var targetId = DocumentUniqueIdentifierExtensions.BinaryDecode(Data, position, out position);
// write document template id
string documentTemplateId = null;
// Has document template id flag
if ((flags & 1) == 1)
if ((flags & 0x8) == 0x8)
{
var documentTemplateIdLength = UniqueIdentifier[position++];
documentTemplateId = encoding.GetString(UniqueIdentifier, position, documentTemplateIdLength);
documentTemplateId = DocumentUniqueIdentifierExtensions.BinaryDecode(Data, position, out position);
}
AttachmentTypes? attachmentType = null;
if ((flags & 2) == 2)
attachmentType = AttachmentTypes.Device;
else if ((flags & 4) == 4)
attachmentType = AttachmentTypes.Job;
else if ((flags & 8) == 8)
attachmentType = AttachmentTypes.User;
switch (flags & 0x6)
{
case 0x2:
attachmentType = AttachmentTypes.Device;
break;
case 0x4:
attachmentType = AttachmentTypes.Job;
break;
case 0x6:
attachmentType = AttachmentTypes.User;
break;
}
var timeStamp = DateTime.FromFileTimeUtc(116444736000000000L).AddTicks(TimeSpan.TicksPerSecond * timeStampEpoch).ToLocalTime();