LazPaint LZP directory structure: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		The [[LazPaint LZP directory structure\|directory structure]] contains additional information about the [[LazPaint LZP Format\|layered image]], in particular originals used to render the layers. It can be discarded by raster editors as it contains essentially information necessary to render the layers from vector originals.
2	2
3	3		### Global header
4	4
5		-	~~`Offset Size Content`\~~
6		-	~~`------ ---- -------------------------------------------------------`\~~
7		-	~~`0 16 Contains the string 'TMemDirectory' followed by the bytes 1A 00 00`\~~
8		-	~~`16 8 Root 64-bit offset R0`\~~
9		-	~~`24 8 Root 64-bit size S0`\~~
10		-	~~`R0 S0 Root entry`~~
	5	+	```text
	6	+	Offset Size Content
	7	+	------ ---- -------------------------------------------------------
	8	+	0 16 Contains the string 'TMemDirectory' followed by the bytes 1A 00 00
	9	+	16 8 Root 64-bit offset R0
	10	+	24 8 Root 64-bit size S0
	11	+	R0 S0 Root entry
	12	+	```
11	13
12	14		The headers thus locates the root of the directory structure.
13	15
14	16		### Directory
15	17
16	18		The root directory and the subdirectory have the same format.
17	19
18		-	~~`Offset Size Content`\~~
19		-	~~`------ ---- -------------------------------------------------------`\~~
20		-	~~`0 4 Number of entries in the directory`\~~
21		-	~~`4 First entry if any`~~
	20	+	```text
	21	+	Offset Size Content
	22	+	------ ---- -------------------------------------------------------
	23	+	0 4 Number of entries in the directory
	24	+	4 First entry if any
	25	+	```
22	26
23	27		All entries are one after another.
24	28
25	29		#### Entry
26	30
27	31		An entry has a variable length depending on its content.
28	32
29		-	~~`Offset Size Content`\~~
30		-	~~`------ ---- -------------------------------------------------------`\~~
31		-	~~`0 2 Flags of the entry`\~~
32		-	~~`2 2 Filename size in bytes FS`\~~
33		-	~~`4 8 Offset to the content (relative to the global header)`\~~
34		-	~~`12 8 Compressed size CS (optional)`\~~
35		-	~~`20 8 Uncompressed size UC (optional)`\~~
36		-	~~`? Filename (not null terminated)`~~
	33	+	```text
	34	+	Offset Size Content
	35	+	------ ---- -------------------------------------------------------
	36	+	0 2 Flags of the entry
	37	+	2 2 Filename size in bytes FS
	38	+	4 8 Offset to the content (relative to the global header)
	39	+	12 8 Compressed size CS (optional)
	40	+	20 8 Uncompressed size UC (optional)
	41	+	? Filename (not null terminated)
	42	+	```
37	43
38	44		Possible flags:
39	45
40	46		- 1: the entry is a directory
41	47		- 2: the entry is compressed
42	48		- \$8000: the entry is small (content and name each 255 bytes or less)
43	49
44	50		##### Small entry
45	51
46	52		When the entry is small, the size fields are not supplied, so the entry header size without filename is 12 bytes. The content size is extracted from the filename size field. The content cannot be compressed.
47	53
48		-	~~`CS = UC = FS shr 8`\~~
49		-	~~`FS = FS and 255`~~
	54	+	```text
	55	+	CS = UC = FS shr 8
	56	+	FS = FS and 255
	57	+	```
50	58
51	59		The entry header can also be summarized as:
52	60
53		-	~~`Offset Size Content`\~~
54		-	~~`------ ---- -------------------------------------------------------`\~~
55		-	~~`0 2 Flags of the entry`\~~
56		-	~~`2 1 Filename size in bytes FS`\~~
57		-	~~`3 1 Content size`\~~
58		-	~~`4 8 Offset to the content (relative to the global header)`\~~
59		-	~~`12 FS Filename (not null terminated)`~~
	61	+	```text
	62	+	Offset Size Content
	63	+	------ ---- -------------------------------------------------------
	64	+	0 2 Flags of the entry
	65	+	2 1 Filename size in bytes FS
	66	+	3 1 Content size
	67	+	4 8 Offset to the content (relative to the global header)
	68	+	12 FS Filename (not null terminated)
	69	+	```
60	70
61	71		##### Non small entry
62	72
63	73		When the entry is not small, the entry header size without filename is 28 bytes. The content can be compressed using the adequate flag.
64	74
65	75		The filename is not null terminated and encoded as UTF8. Its size is supplied in bytes and not in characters.
66	76
67	77		#### Entry content
68	78
69	79		The entry content offset is relative to the start of the global header of the directory structure. If the flag directory flag is set, then it is to be interpreted as a directory like the root directory. Otherwise, it is to be interpreted as a file.
70	80
71	81		The root is the path '/'. An entry in the root and called 'hello' has the path '/hello'.
72	82
73	83		When directories are nested, the resulting path is concatenated with a '/' character as in Unix paths. For example, if there is a subdirectory called 'container' in the root directory and that it contains a file called 'readme.txt', then its path is '/container/readme.txt'.
74	84
75	85		A file that does not contain '.' has thus no extension and is considered to be an attribute. An attribute is a value associated to the object that the directory represents, like a number or a list of numbers.
76	86
77	87		If a file is not an attribute, it is similar to file that would be saved on a disk, like an image in PNG format.
78	88
79	89		##### Attributes
80	90
81	91		An attribute can have various types, but those are not saved explicitly. The reader needs to know what kind of value it expects from an attribute. Attributes are stored in ASCII unless specified.
82	92
83	93		Here is the list of possible types:
84	94
85	95		- integer: an optional sign and a sequence of digits forming a signed 32-bit integer.
86	96		- float: a single precision floating point number written using '.' decimal separator and that can have an exponent E.
87	97		- boolean: either 'true' or 'false'
88	98		- string: any sequence of characters (quotes are not added)
89	99		- color: can be a VGA or CSS color name, an RGB value with or without hashtag using one or two digit per channel with or without the alpha channel (example: red = \#f00 = ff0000ff), an RGB value expressed in CSS format (exemple: rgb(255,0,0) = rgba(100%,0,0,1))
90	100		- list of float: float values (or 'none' to specify undefined) separated by ','
91	101		- list of colors: color values separated by ','
92	102		- affine matrix: an affine matrix stored as binary so a sequence of 6 single precision floats (each 4 bytes in little endian) representing ux, uy, vx, vy, tx and tx
93	103
94	104		Note:
95	105
96	106		- a 2D coordinate is a list of 2 values (x and y), a 2D rectangle is a list of 4 values (left, top, right and bottom).
97	107		- the affine matrix is stored as binary to ensure exact equality when comparing matrices
98	108
99	109		### Tree
100	110
101	111		Here as an example of tree structure of a LazPaint file, with 3 layers and 2 originals.
102	112
103	113		The first two layers has some registry entries, for example if layer1 is an effect generated for layer2.
104	114
105	115		The second layer contains render backup, for example because it contains text that might not be rendered the same way on a different computer.
106	116
107	117		There are two originals for example because layer2 is a vector layer and layer3 is a rotated image.
108	118
109		-	~~`root`\~~
110		-	~~` ├─ layers`\~~
111		-	~~` │ ├─ layer1`\~~
112		-	~~` │ │ └─ registry`\~~
113		-	~~` │ ├─ layer2`\~~
114		-	~~` │ │ ├─ registry`\~~
115		-	~~` │ │ └─ render`\~~
116		-	~~` │ └─ layer3`\~~
117		-	~~` ├─ originals`\~~
118		-	~~` │ ├─ {7F5D5954-8EAC-D992-6D0A-9CD24929EBEB}`\~~
119		-	~~` │ │ ├─ shape1`\~~
120		-	~~` │ │ ├─ shape2`\~~
121		-	~~` │ │ └─ shape3`\~~
122		-	~~` │ └─ {61BD152C-9F86-1325-B256-B50D877389E8}`\~~
123		-	~~` └─ registry`~~
	119	+	```text
	120	+	root
	121	+	├─ layers
	122	+	│ ├─ layer1
	123	+	│ │ └─ registry
	124	+	│ ├─ layer2
	125	+	│ │ ├─ registry
	126	+	│ │ └─ render
	127	+	│ └─ layer3
	128	+	├─ originals
	129	+	│ ├─ {7F5D5954-8EAC-D992-6D0A-9CD24929EBEB}
	130	+	│ │ ├─ shape1
	131	+	│ │ ├─ shape2
	132	+	│ │ └─ shape3
	133	+	│ └─ {61BD152C-9F86-1325-B256-B50D877389E8}
	134	+	└─ registry
	135	+	```
124	136
125	137		#### Registry
126	138
127	139		A registry is a series of attributes containing any kind of value. The identifier can only contain the following characters: 'A'..'Z','a'..'z','0'..'9','_','-'
128	140
129	141		The registry at the root does not have predefined attributes. It can be used by scripts to store values like the last parameters used.
130	142
131	143		#### Layers
132	144
133	145		The layers represent the layer stack. The first layer is at the bottom and the last is on top.
134	146
135	147		Each layer can have its own registry. The attribute 'guid' can define a Guid identifier for the layer, for example {5A8F1094-8386-E527-39E9-6F843771EDC6}. Script can also store values like the parameters of an effect.
136	148
137	149		Each layer can have its own render directory. This directory contains at least a 'last-matrix' attribute containing the last affine matrix used to render the layer. If it is equal to the current affine matrix of the layer, then the render backup can be used to draw the layer. A part from that, each original is free to use the render directory as it wants.
138	150
139	151		#### Originals
140	152
141	153		The originals are graphical elements that can be transformed according to an affine matrix.
142	154
143	155		Each original has a Guid and a directory named after its Guid.
144	156
145	157		In each original directory, there is a 'class' attribute that identifies the type of original. The reader can know from this classname whether it can understand its structure. Apart from that, the content of the original directory is completely up to the class.
146	158
147	159		The following classnames are defined in LazPaint:
148	160
149	161		- image: a bitmap (PNG or JPEG)
150	162		- gradient: a gradient that fills the whole layer
151	163		- vector: a vectorial layer (containing vector objects of LazPaint)
152	164		- svg: an SVG file
153	165
154	166		Using an image original is useful when an image is transformed as it allows to keep the original bitmap and thus avoid loss of information after multiple transformations.
155	167
156	168		---
157	169		From the Free Pascal wiki, page "LazPaint LZP directory structure", as it stood on 2020-12-04 after a change by Circular, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).

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