Java example source code file (gifalloc.c)

This example Java source code file (gifalloc.c) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

colorcount, colormapobject, copyfrom\-, extensionblock, freeextension, freelastsavedimage, giffile-, image\-, len, new\-, null, object, object\-, savedimage

The gifalloc.c Java example source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*****************************************************************************
 *   "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
 *****************************************************************************/

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

    register int i;

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

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

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

    ColorMapObject *Object;

    /*** FIXME: Our ColorCount has to be a power of two.  Is it necessary to
     * make the user know that or should we automatically round up instead? */
    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) {
        free(Object);
        return ((ColorMapObject *) NULL);
    }

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

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

    return (Object);
}

/*
 * Free a color map object
 */
void
FreeMapObject(ColorMapObject * Object) {

    if (Object != NULL) {
        free(Object->Colors);
        free(Object);
        Object = NULL;
    }
}

#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 */

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

void
MakeExtension(SavedImage * New,
              int Function) {

    New->Function = Function;
    /*** FIXME:
     * Someday we might have to deal with multiple extensions.
     * ??? Was this a note from Gershon or from me?  Does the multiple
     * extension blocks solve this or do we need multiple Functions?  Or is
     * this an obsolete function?  (People should use AddExtensionBlock
     * instead?)
     * Looks like AddExtensionBlock needs to take the int Function argument
     * then it can take the place of this function.  Right now people have to
     * use both.  Fix AddExtensionBlock and add this to the deprecation list.
     */
}

int
AddExtensionBlock(SavedImage * New,
                  int Len,
                  unsigned 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++];

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

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

    return (GIF_OK);
}

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

    if ((Image == NULL) || (Image->ExtensionBlocks == NULL)) {
        return;
    }
    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
******************************************************************************/

/* Private Function:
 * Frees the last image in the GifFile->SavedImages array
 */
void
FreeLastSavedImage(GifFileType *GifFile) {

    SavedImage *sp;

    if ((GifFile == NULL) || (GifFile->SavedImages == NULL))
        return;

    /* Remove one SavedImage from the GifFile */
    GifFile->ImageCount--;
    sp = &GifFile->SavedImages[GifFile->ImageCount];

    /* Deallocate its Colormap */
    if (sp->ImageDesc.ColorMap)
        FreeMapObject(sp->ImageDesc.ColorMap);

    /* Deallocate the image data */
    if (sp->RasterBits)
        free((char *)sp->RasterBits);

    /* Deallocate any extensions */
    if (sp->ExtensionBlocks)
        FreeExtension(sp);

    /*** FIXME: We could realloc the GifFile->SavedImages structure but is
     * there a point to it? Saves some memory but we'd have to do it every
     * time.  If this is used in FreeSavedImages then it would be inefficient
     * (The whole array is going to be deallocated.)  If we just use it when
     * we want to free the last Image it's convenient to do it here.
     */
}

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

    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);
                if (sp->ImageDesc.ColorMap == NULL) {
                    FreeLastSavedImage(GifFile);
                    return (SavedImage *)(NULL);
                }
            }

            /* next, the raster */
            sp->RasterBits = (unsigned char *)malloc(sizeof(GifPixelType) *
                                                   CopyFrom->ImageDesc.Height *
                                                   CopyFrom->ImageDesc.Width);
            if (sp->RasterBits == NULL) {
                FreeLastSavedImage(GifFile);
                return (SavedImage *)(NULL);
            }
            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);
                if (sp->ExtensionBlocks == NULL) {
                    FreeLastSavedImage(GifFile);
                    return (SavedImage *)(NULL);
                }
                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.
                 *** FIXME: [Better check this out... Toshio]
                 * 2004 May 27: Looks like this was an ESR note.
                 * It means the blocks are shallow copied from InFile to
                 * OutFile.  However, I don't see that in this code....
                 * Did ESR fix it but never remove this note (And other notes
                 * in gifspnge?)
                 */
            }
        }

        return (sp);
    }
}

void
FreeSavedImages(GifFileType * GifFile) {

    SavedImage *sp;

    if ((GifFile == NULL) || (GifFile->SavedImages == NULL)) {
        return;
    }
    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);
    GifFile->SavedImages=NULL;
}