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author | Aki <please@ignore.pl> | 2021-10-01 23:46:47 +0200 |
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committer | Aki <please@ignore.pl> | 2021-10-01 23:46:47 +0200 |
commit | ddd76aa4e1571c8d5965709db5c3cd47a89c9a38 (patch) | |
tree | 4e07bfaebede6531a70984fdebc855bca52f394a /zlib/contrib/delphi/readme.txt | |
parent | 3a507e08b1d4e5970b27401a7e6517570d529400 (diff) | |
parent | c2d2c3551501110fddd78674d5435bfaa70382a3 (diff) | |
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Diffstat (limited to 'zlib/contrib/delphi/readme.txt')
-rw-r--r-- | zlib/contrib/delphi/readme.txt | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/zlib/contrib/delphi/readme.txt b/zlib/contrib/delphi/readme.txt new file mode 100644 index 0000000..2dc9a8b --- /dev/null +++ b/zlib/contrib/delphi/readme.txt @@ -0,0 +1,76 @@ + +Overview +======== + +This directory contains an update to the ZLib interface unit, +distributed by Borland as a Delphi supplemental component. + +The original ZLib unit is Copyright (c) 1997,99 Borland Corp., +and is based on zlib version 1.0.4. There are a series of bugs +and security problems associated with that old zlib version, and +we recommend the users to update their ZLib unit. + + +Summary of modifications +======================== + +- Improved makefile, adapted to zlib version 1.2.1. + +- Some field types from TZStreamRec are changed from Integer to + Longint, for consistency with the zlib.h header, and for 64-bit + readiness. + +- The zlib_version constant is updated. + +- The new Z_RLE strategy has its corresponding symbolic constant. + +- The allocation and deallocation functions and function types + (TAlloc, TFree, zlibAllocMem and zlibFreeMem) are now cdecl, + and _malloc and _free are added as C RTL stubs. As a result, + the original C sources of zlib can be compiled out of the box, + and linked to the ZLib unit. + + +Suggestions for improvements +============================ + +Currently, the ZLib unit provides only a limited wrapper around +the zlib library, and much of the original zlib functionality is +missing. Handling compressed file formats like ZIP/GZIP or PNG +cannot be implemented without having this functionality. +Applications that handle these formats are either using their own, +duplicated code, or not using the ZLib unit at all. + +Here are a few suggestions: + +- Checksum class wrappers around adler32() and crc32(), similar + to the Java classes that implement the java.util.zip.Checksum + interface. + +- The ability to read and write raw deflate streams, without the + zlib stream header and trailer. Raw deflate streams are used + in the ZIP file format. + +- The ability to read and write gzip streams, used in the GZIP + file format, and normally produced by the gzip program. + +- The ability to select a different compression strategy, useful + to PNG and MNG image compression, and to multimedia compression + in general. Besides the compression level + + TCompressionLevel = (clNone, clFastest, clDefault, clMax); + + which, in fact, could have used the 'z' prefix and avoided + TColor-like symbols + + TCompressionLevel = (zcNone, zcFastest, zcDefault, zcMax); + + there could be a compression strategy + + TCompressionStrategy = (zsDefault, zsFiltered, zsHuffmanOnly, zsRle); + +- ZIP and GZIP stream handling via TStreams. + + +-- +Cosmin Truta <cosmint@cs.ubbcluj.ro> |