📄 gifimage.pas
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unit GIFImage;
////////////////////////////////////////////////////////////////////////////////
// //
// Project: GIF Graphics Object //
// Module: gifimage //
// Description: TGraphic implementation of the GIF89a graphics format //
// Version: 2.1 //
// Release: 4 //
// Date: 15-OCT-1998 //
// Target: Win32, Delphi 2, 3 & 4, C++ Builder 3 //
// Author(s): anme: Anders Melander, anders@melander.dk //
// fila: Filip Larsen //
// rps: Reinier Sterkenburg //
// Copyright (c) 1997,98 Anders Melander. //
// All rights reserved. //
// Formatting: 2 space indent, 8 space tabs, 80 columns. //
// //
////////////////////////////////////////////////////////////////////////////////
// //
// This software is copyrighted as noted above. It may be freely copied, //
// modified, and redistributed, provided that the copyright notice(s) is //
// preserved on all copies. //
// //
// TGIFImage is freeware and I would like it to remain so. This means that it //
// may not be bundled with commercial libraries or sold as shareware. You are //
// welcome to use it in commercial and shareware applications providing you //
// do not charge for the functionality provided by TGIFImage. //
// If you are in doubt, please contact me and I will explain this. //
// //
// There is no warranty or other guarantee of fitness for this software, it //
// is provided solely "as is". Bug reports or fixes may be sent to the //
// author, who may or may not act on them as he desires. //
// //
// If you redistribute this code in binary form (i.e. as a library or linked //
// into an application), the accompanying documentation should state that //
// "this software is based, in part, on the work of Anders Melander" or words //
// to that effect. //
// //
// If you modify this software, you should include a notice in the revision //
// history in the history.txt file giving the date and the name of the person //
// performing the modification and a brief description of the modification. //
// //
// Please see the file copyright.txt for additional copyrights. //
// //
////////////////////////////////////////////////////////////////////////////////
// Known problems:
//
// * The combination of buffered, tiled and transparent draw will display the
// background incorrectly (scaled).
//
// * The combination of non-buffered and stretched draw is some times distorted
// with a pattern effect.
//
// * Buffered display flickers when TGIFImage is used by a transparent TImage
// component.
// This is a problem with TImage caused by the fact that TImage was designed
// with static images in mind. Not much I can do about it.
//
////////////////////////////////////////////////////////////////////////////////
// To do (in rough order of priority):
//
// * TImage hook for destroy notification.
//
// * TBitmap pool to limit resource consumption on Win95/98.
//
// * TImage.AssignTransparent method.
//
// * Modify GetDitherBitmap to use generic dithering engine.
//
// * Make BitsPerPixel property writable.
//
// * Optimized single global palette from multiple *external* palettes.
//
// * Import of bitmap(s) with color mapping to *external* palette.
//
// * Visual GIF component.
//
// * Easier method to determine DrawPainter status.
//
// * Import to 256+ color GIF.
//
// * Make some of TGIFImage's properties persistent (DrawOptions etc).
// Add TGIFImage.Persistent property. Should save published properties
// in application extension when this options is set.
//
// * Solution for background buffering in scollbox.
//
// * Implement TGIFPainter support for:
// Morphing
// goValidateCanvas option
// Source/Target canvas palette normalization
//
// * Optimize TGIFSubImage.Decompress
//
// * Implement TGIFPainter support for:
// Interlaced display
// Progressive display (piped load/decompress/display)
//
// * Implement TGIFPainter support for:
// UserInput
// Text extension
//
////////////////////////////////////////////////////////////////////////////////
interface
////////////////////////////////////////////////////////////////////////////////
//
// Conditional Compiler Symbols
//
////////////////////////////////////////////////////////////////////////////////
(*
DEBUG Must be defined if any of the DEBUG_xxx
symbols are defined.
If the symbol is defined the source will not be
optimized and overflow- and range checks will be
enabled.
DEBUG_HASHPERFORMANCE Calculates hash table performance data.
DEBUG_HASHFILLFACTOR Calculates fill factor of hash table -
Interferes with DEBUG_HASHPERFORMANCE.
DEBUG_COMPRESSPERFORMANCE Calculates LZW compressor performance data.
DEBUG_DECOMPRESSPERFORMANCE Calculates LZW decompressor performance data.
DEBUG_DITHERPERFORMANCE Calculates color reduction performance data.
DEBUG_DRAWPERFORMANCE Calculates low level drawing performance data.
The performance data for DEBUG_DRAWPERFORMANCE
will be displayed when you press the Ctrl key.
GIF_NOSAFETY Define this symbol to disable overflow- and
range checks.
Ignore if the DEBUG symbol is defined.
STRICT_MOZILLA Define to mimic Mozilla as closely as possible.
If not defined, a slightly more "optimal"
implementation is used (IMHO).
FAST_AS_HELL Define this symbol to use strictly GIF compliant
(but too fast) animation timing.
Since our paint routines are much faster and
more precise timed than Mozilla's, the standard
GIF and Mozilla values causes animations to loop
faster than they would in Mozilla.
If the symbol is _not_ defined, an alternative
set of tweaked timing values will be used.
The tweaked values are not optimal but are based
on tests performed on my reference system:
- Windows 95
- 133 MHz Pentium
- 64Mb RAM
- Diamond Stealth64/V3000
- 1600*1200 in 256 colors
The alternate values can be modified if you are
not satisfied with my defaults (they can be
found a few pages down).
REGISTER_TGIFIMAGE Define this symbol to register TGIFImage with
the TPicture class and integrate with TImage.
This is required to be able to display GIFs in
the TImage component.
The symbol is defined by default.
Undefine if you use another GIF library to
provide GIF support for TImage.
PIXELFORMAT_TOO_SLOW When this symbol is defined, the internal
PixelFormat routines are used in some places
instead of TBitmap.PixelFormat
The current implementation (Delphi4, Builder 3)
of TBitmap.PixelFormat can in some situation
degrade performance.
The symbol is defined by default.
*)
{$DEFINE REGISTER_TGIFIMAGE}
{$DEFINE PIXELFORMAT_TOO_SLOW}
////////////////////////////////////////////////////////////////////////////////
//
// Determine Delphi and C++ Builder version
//
////////////////////////////////////////////////////////////////////////////////
// Delphi 1.x
{$IFDEF VER80}
'Error: TGIFImage does not support Delphi 1.x'
{$ENDIF}
// Delphi 2.x
{$IFDEF VER90}
{$DEFINE VER9x}
{$ENDIF}
// C++ Builder 1.x
{$IFDEF VER93}
// Good luck...
{$DEFINE VER9x}
{$ENDIF}
// Delphi 3.x
{$IFDEF VER100}
{$DEFINE VER10x}
{$ENDIF}
// C++ Builder 3.x
{$IFDEF VER110}
{$DEFINE VER10x}
{$DEFINE VER11_PLUS}
{$DEFINE D4_BCB3}
{$ENDIF}
// Delphi 4.x
{$IFDEF VER120}
{$DEFINE VER10x}
{$DEFINE VER11_PLUS}
{$DEFINE VER12_PLUS}
{$DEFINE D4_BCB3}
{$ENDIF}
// Unknown compiler version - assume D3 compatible
{$IFNDEF VER9x}
{$IFNDEF VER10x}
{$DEFINE VER10x}
{$ENDIF}
{$ENDIF}
////////////////////////////////////////////////////////////////////////////////
//
// Compiler Options required to compile this library
//
////////////////////////////////////////////////////////////////////////////////
{$A+,B-,H+,J+,K-,M-,T-,X+}
// Debug control - You can safely change these settings
{$IFDEF DEBUG}
{$C+} // ASSERTIONS
{$O-} // OPTIMIZATION
{$Q+} // OVERFLOWCHECKS
{$R+} // RANGECHECKS
{$ELSE}
{$C-} // ASSERTIONS
{$IFDEF GIF_NOSAFETY}
{$Q-}// OVERFLOWCHECKS
{$R-}// RANGECHECKS
{$ENDIF}
{$ENDIF}
////////////////////////////////////////////////////////////////////////////////
//
// External dependecies
//
////////////////////////////////////////////////////////////////////////////////
uses
sysutils,
Windows,
Graphics,
Classes;
////////////////////////////////////////////////////////////////////////////////
//
// TGIFImage library version
//
////////////////////////////////////////////////////////////////////////////////
const
GIFVersion = $0201;
GIFVersionMajor = 2;
GIFVersionMinor = 1;
GIFVersionRelease = 4;
////////////////////////////////////////////////////////////////////////////////
//
// Misc constants and support types
//
////////////////////////////////////////////////////////////////////////////////
const
GIFMaxColors = 256; // Max number of colors supported by GIF
// Don't bother changing this value!
BitmapAllocationThreshold = 500000; // Bitmap pixel count limit at which
// a newly allocated bitmap will be
// converted to 1 bit format before
// being resized and converted to 8 bit.
var
{$IFDEF FAST_AS_HELL}
GIFDelayExp: integer = 10; // Delay multiplier in mS.
{$ELSE}
GIFDelayExp: integer = 12; // Delay multiplier in mS. Tweaked.
{$ENDIF}
// * GIFDelayExp:
// The following delay values should all
// be multiplied by this value to
// calculate the effective time (in mS).
// According to the GIF specs, this
// value should be 10.
// Since our paint routines are much
// faster than Mozilla's, you might need
// to increase this value if your
// animations loops too fast. The
// optimal value is impossible to
// determine since it depends on the
// speed of the CPU, the viceo card,
// memory and many other factors.
GIFDefaultDelay: integer = 10; // * GIFDefaultDelay:
// Default animation delay.
// This value is used if no GCE is
// defined.
// (10 = 100 mS)
{$IFDEF FAST_AS_HELL}
GIFMinimumDelay: integer = 1; // Minimum delay (from Mozilla source).
// (1 = 10 mS)
{$ELSE}
GIFMinimumDelay: integer = 3; // Minimum delay - Tweaked.
{$ENDIF}
// * GIFMinimumDelay:
// The minumum delay used in the Mozilla
// source is 10mS. This corresponds to a
// value of 1. However, since our paint
// routines are much faster than
// Mozilla's, a value of 3 or 4 gives
// better results.
GIFMaximumDelay: integer = 1000; // * GIFMaximumDelay:
// Maximum delay when painter is running
// in main thread (goAsync is not set).
// This value guarantees that a very
// long and slow GIF does not hang the
// system.
// (1000 = 10000 mS = 10 Seconds)
MaxRenderThreads: integer = 4; // Max # of concurrent rendering worker
// threads.
// This number should probably be
// dependant on the CPU speed...
// If Win95/98 is detected, the value
// is decreased in the initialization
// section.
// MaxRenderBatch: integer = 1; // Max number of rendering jobs to
// submit at once for each GIF.
// Not implemented!
// MinRenderThreshold: integer = 2; // Lower threshold at which to submit a
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