gifalloc.c

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/*****************************************************************************
*   "Gif-Lib" - Yet another gif library.                                     *
*                                                                            *
* Written by:  Gershon Elber                            Ver 0.1, Jun. 1989   *
* Extensively hacked by: Eric S. Raymond                Ver 1.?, Sep 1992    *
******************************************************************************
* GIF construction tools                                                      *
******************************************************************************
* History:                                                                   *
* 15 Sep 92 - Version 1.0 by Eric Raymond.                                   *
*****************************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "gif_lib.h"

#define MAX(x, y)       (((x) > (y)) ? (x) : (y))

/******************************************************************************
* Miscellaneous utility functions                                             *
******************************************************************************/

int BitSize(int n)
/* return smallest bitfield size n will fit in */
{
    register  int i;

    for (i = 1; i <= 8; i++)
        if ((1 << i) >= n)
            break;
    return(i);
}


/******************************************************************************
* Color map object functions                                                  *
******************************************************************************/

ColorMapObject *MakeMapObject(int ColorCount, const GifColorType *ColorMap)
/*
 * Allocate a color map of given size; initialize with contents of
 * ColorMap if that pointer is non-NULL.
 */
{
    ColorMapObject *Object;

    if (ColorCount != (1 << BitSize(ColorCount)))
        return((ColorMapObject *)NULL);

    Object = (ColorMapObject *)malloc(sizeof(ColorMapObject));
    if (Object == (ColorMapObject *)NULL)
        return((ColorMapObject *)NULL);

    Object->Colors = (GifColorType *)calloc(ColorCount, sizeof(GifColorType));
    if (Object->Colors == (GifColorType *)NULL)
        return((ColorMapObject *)NULL);

    Object->ColorCount = ColorCount;
    Object->BitsPerPixel = BitSize(ColorCount);

    if (ColorMap)
        memcpy((char *)Object->Colors,
               (char *)ColorMap, ColorCount * sizeof(GifColorType));

    return(Object);
}

void FreeMapObject(ColorMapObject *Object)
/*
 * Free a color map object
 */
{
    free(Object->Colors);
    free(Object);
}

#ifdef DEBUG
void DumpColorMap(ColorMapObject *Object, FILE *fp)
{
    if (Object)
    {
        int i, j, Len = Object->ColorCount;

        for (i = 0; i < Len; i+=4) {
            for (j = 0; j < 4 && j < Len; j++) {
                fprintf(fp,
                        "%3d: %02x %02x %02x   ", i + j,
                       Object->Colors[i + j].Red,
                       Object->Colors[i + j].Green,
                       Object->Colors[i + j].Blue);
            }
            fprintf(fp, "\n");
        }
    }
}
#endif /* DEBUG */

ColorMapObject *UnionColorMap(
                         const ColorMapObject *ColorIn1,
                         const ColorMapObject *ColorIn2,
                         GifPixelType ColorTransIn2[])
/*
 * Compute the union of two given color maps and return it.  If result can't 
 * fit into 256 colors, NULL is returned, the allocated union otherwise.
 * ColorIn1 is copied as is to ColorUnion, while colors from ColorIn2 are
 * copied iff they didn't exist before.  ColorTransIn2 maps the old
 * ColorIn2 into ColorUnion color map table.
 */
{
    int i, j, CrntSlot, RoundUpTo, NewBitSize;
    ColorMapObject *ColorUnion;

    /*
     * Allocate table which will hold the result for sure.
     */
    ColorUnion
        = MakeMapObject(MAX(ColorIn1->ColorCount,ColorIn2->ColorCount)*2,NULL);

    if (ColorUnion == NULL)
        return(NULL);

    /* Copy ColorIn1 to ColorUnionSize; */
    for (i = 0; i < ColorIn1->ColorCount; i++)
        ColorUnion->Colors[i] = ColorIn1->Colors[i];
    CrntSlot = ColorIn1->ColorCount;

    /*
     * Potentially obnoxious hack:
     *
     * Back CrntSlot down past all contiguous {0, 0, 0} slots at the end
     * of table 1.  This is very useful if your display is limited to
     * 16 colors.
     */
    while (ColorIn1->Colors[CrntSlot-1].Red == 0
           && ColorIn1->Colors[CrntSlot-1].Green == 0
           && ColorIn1->Colors[CrntSlot-1].Red == 0)
        CrntSlot--;

    /* Copy ColorIn2 to ColorUnionSize (use old colors if they exist): */
    for (i = 0; i < ColorIn2->ColorCount && CrntSlot<=256; i++)
    {
        /* Let's see if this color already exists: */
        for (j = 0; j < ColorIn1->ColorCount; j++)
            if (memcmp(&ColorIn1->Colors[j], &ColorIn2->Colors[i], sizeof(GifColorType)) == 0)
                break;

        if (j < ColorIn1->ColorCount)
            ColorTransIn2[i] = j;       /* color exists in Color1 */
        else
        {
            /* Color is new - copy it to a new slot: */
            ColorUnion->Colors[CrntSlot] = ColorIn2->Colors[i];
            ColorTransIn2[i] = CrntSlot++;
        }
    }

    if (CrntSlot > 256)
    {
        FreeMapObject(ColorUnion);
        return((ColorMapObject *)NULL);
    }

    NewBitSize = BitSize(CrntSlot);
    RoundUpTo = (1 << NewBitSize);

    if (RoundUpTo != ColorUnion->ColorCount)
    {
        register GifColorType   *Map = ColorUnion->Colors;

        /*
         * Zero out slots up to next power of 2.
         * We know these slots exist because of the way ColorUnion's
         * start dimension was computed.
         */
        for (j = CrntSlot; j < RoundUpTo; j++)
            Map[j].Red = Map[j].Green = Map[j].Blue = 0;

        /* perhaps we can shrink the map? */
        if (RoundUpTo < ColorUnion->ColorCount)
            ColorUnion->Colors 
                = (GifColorType *)realloc(Map, sizeof(GifColorType)*RoundUpTo);
    }

    ColorUnion->ColorCount = RoundUpTo;
    ColorUnion->BitsPerPixel = NewBitSize;

    return(ColorUnion);
}

void ApplyTranslation(SavedImage *Image, GifPixelType Translation[])
/*
 * Apply a given color translation to the raster bits of an image
 */
{
    register int i;
    register int RasterSize = Image->ImageDesc.Height * Image->ImageDesc.Width;

    for (i = 0; i < RasterSize; i++)
        Image->RasterBits[i] = Translation[(int)(Image->RasterBits[i])];
}

/******************************************************************************
* Extension record functions                                                  *
******************************************************************************/

void MakeExtension(SavedImage *New, int Function)
{
    New->Function = Function;
    /*
     * Someday we might have to deal with multiple extensions.
     */
}

int AddExtensionBlock(SavedImage *New, int Len, char ExtData[])
{
    ExtensionBlock      *ep;

    if (New->ExtensionBlocks == NULL)
        New->ExtensionBlocks = (ExtensionBlock *)malloc(sizeof(ExtensionBlock));
    else
        New->ExtensionBlocks =
            (ExtensionBlock *)realloc(New->ExtensionBlocks,
                      sizeof(ExtensionBlock) * (New->ExtensionBlockCount + 1));

    if (New->ExtensionBlocks == NULL)
        return(GIF_ERROR);

    ep = &New->ExtensionBlocks[New->ExtensionBlockCount++];

    if ((ep->Bytes = (char *)malloc(ep->ByteCount = Len)) == NULL)
        return(GIF_ERROR);

    if (ExtData) {
            memcpy(ep->Bytes, ExtData, Len);
        ep->Function = New->Function;
    }

    return(GIF_OK);
}

void FreeExtension(SavedImage *Image)
{
    ExtensionBlock      *ep;

    for (ep = Image->ExtensionBlocks;
         ep < Image->ExtensionBlocks + Image->ExtensionBlockCount;
         ep++)
        (void) free((char *)ep->Bytes);
    free((char *)Image->ExtensionBlocks);
    Image->ExtensionBlocks = NULL;
}

/******************************************************************************
* Image block allocation functions                                            *
******************************************************************************/
SavedImage *MakeSavedImage(GifFileType *GifFile, const SavedImage *CopyFrom)
/*
 * Append an image block to the SavedImages array  
 */
{
    SavedImage  *sp;

    if (GifFile->SavedImages == NULL)
        GifFile->SavedImages = (SavedImage *)malloc(sizeof(SavedImage));
    else
        GifFile->SavedImages = (SavedImage *)realloc(GifFile->SavedImages,
                                sizeof(SavedImage) * (GifFile->ImageCount+1));

    if (GifFile->SavedImages == NULL)
        return((SavedImage *)NULL);
    else
    {
        sp = &GifFile->SavedImages[GifFile->ImageCount++];
        memset((char *)sp, '\0', sizeof(SavedImage));

        if (CopyFrom)
        {
            memcpy((char *)sp, CopyFrom, sizeof(SavedImage));

            /*
             * Make our own allocated copies of the heap fields in the
             * copied record.  This guards against potential aliasing
             * problems.
             */

            /* first, the local color map */
            if (sp->ImageDesc.ColorMap)
                sp->ImageDesc.ColorMap =
                    MakeMapObject(CopyFrom->ImageDesc.ColorMap->ColorCount,
                                  CopyFrom->ImageDesc.ColorMap->Colors);

            /* next, the raster */
            sp->RasterBits = (char *)malloc(sizeof(GifPixelType)
                                * CopyFrom->ImageDesc.Height
                                * CopyFrom->ImageDesc.Width);
            memcpy(sp->RasterBits,
                   CopyFrom->RasterBits,
                   sizeof(GifPixelType)
                        * CopyFrom->ImageDesc.Height
                        * CopyFrom->ImageDesc.Width);

            /* finally, the extension blocks */
            if (sp->ExtensionBlocks)
            {
                sp->ExtensionBlocks
                    = (ExtensionBlock*)malloc(sizeof(ExtensionBlock)
                                              * CopyFrom->ExtensionBlockCount);
                memcpy(sp->ExtensionBlocks,
                   CopyFrom->ExtensionBlocks,
                   sizeof(ExtensionBlock)
                        * CopyFrom->ExtensionBlockCount);

                /*
                 * For the moment, the actual blocks can take their
                 * chances with free().  We'll fix this later. 
                 */
            }
        }

        return(sp);
    }
}

void FreeSavedImages(GifFileType *GifFile)
{
    SavedImage  *sp;

    for (sp = GifFile->SavedImages;
         sp < GifFile->SavedImages + GifFile->ImageCount;
         sp++)
    {
        if (sp->ImageDesc.ColorMap)
            FreeMapObject(sp->ImageDesc.ColorMap);

        if (sp->RasterBits)
            free((char *)sp->RasterBits);

        if (sp->ExtensionBlocks)
            FreeExtension(sp);
    }
    free((char *) GifFile->SavedImages);
}

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