Q79342: Windows Paintbrush File Format
Article: Q79342
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s):
Keyword(s): kb16bitonly
Last Modified: 06-NOV-1999
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The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1
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SUMMARY
=======
This article provides the format of Windows Paintbrush files.
MORE INFORMATION
================
Paintbrush files are preceded by 32 bytes of header information. Following the
header is an index table into run-length encoded data.
Header
------
The header structure is defined in the C programming language, as follows:
typedef struct
{
WORD key1;
WORD key2;
WORD dxFile;
WORD dyFile;
/* NOTE: PBRUSH.EXE version 3.0 and 3.1 ignore the remaining values */
/* in this structure. Future versions may or may not. */
WORD ScrAspectX;
WORD ScrAspectY;
WORD PrnAspectX;
WORD PrnAspectY;
WORD dxPrinter;
WORD dyPrinter;
WORD AspCorX;
WORD AspCorY;
WORD wCheck;
WORD res1;
WORD res2;
WORD res3;
WORD res4;
} FILEHDR;
The first 32 bytes contain the header information described by the above
structure:
Bytes Name Win 1.0 Win 2.0 Win 3.0
----- ---- ------- ------- -------
0 - 1 Key1 0x6144 0x694C |0x6144| or |0x694C|
2 - 3 Key2 0x4D6E 0x536E |0x4D6E| |0x536E|
4 - 5 dxFile X-dimension size of bitmap, in pixels
6 - 7 dyFile Y-dimension size of bitmap, in pixels
8 - 9 SrcAspectX Aspect ratio of the screen for which file was
created. Obtained from GetDeviceCaps(hScreenDC,
ASPECTX);
10 - 11 SrcAspectY Aspect ratio of the screen for which file was
created. Obtained from GetDeviceCaps(hScreenDC,
ASPECTY);
12 - 13 PrnAspectX Aspect ratio of the printer for which file was
created. Obtained from GetDeviceCaps(hPrinterDC,
ASPECTX);
14 - 15 PrnAspectY Aspect ratio of the printer for which file was
created. Obtained from GetDeviceCaps(hPrinterDC,
ASPECTY);
16 - 17 dxPrinter Resolution of the printer for which file was
created. Contains the number of pixels in the x
direction on the printer. The selected paper and
printer orientation affect this value.
18 - 19 dyPrinter Resolution of the printer for which file was
created. Contains the number of pixels in the y
direction on the printer. The selected paper and
printer orientation affect this value.
20 - 21 AspCorX Not used. Set to zero.
22 - 23 AspCorY Not used. Set to zero.
24 - 25 wCheck Checksum field. Makes sure that this file is Paint
format.
26 - 31 Reserved
Index
-----
The Paintbrush bitmap is run-length encoded. Each scan line is encoded
separately. The length of the resulting encoded string depends on the pattern of
the bitmap. There is an index table following the header. Each entry of this
index corresponds to a scan line. It is an unsigned integer and shows the length
of the encoded data. Following this table is the encoded data.
32 - xxx xxx = 32 + sizeof(unsigned int) * dyPrinter
ALGORITHM FOR ENCODING
----------------------
Paint encoding is read in BYTES. There are two types of encoded data: one starts
with 0 (zero), the other starts with a nonzero value.
If the data starts with 0, it is a repeated byte pattern. The byte following the
0 tells how many times to repeat the pattern and the subsequent byte is the
pattern itself. For example, 0, 0x80, 0xff, should be expanded to eighty (hex)
bytes of 0xff.
If the data starts with a nonzero value, X, the following X number of bytes
contain unmodified bitmap data, without recognizable pattern. Each scan line can
be composed of several of the above mentioned groups of data. Of course, the
groups should alternate, meaning that a scan line can start with a repeated
pattern followed by some random pattern, which is followed by another repeated
pattern.
To reach the data for the nth scan line, add up the values in the index table
from entry 0 to entry n - 1.
Additional query words: 3.00 no32bit 3.10
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Keywords : kb16bitonly
Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version : WINDOWS:3.0,3.1
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