thumbs_blend.c

Go to the documentation of this file.

/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version. 
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Contributor(s): Campbell Barton.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <string.h>

#include "zlib.h"

#include "BLI_utildefines.h"

#include "BKE_utildefines.h"
#include "BKE_global.h"

#include "IMB_imbuf_types.h"
#include "IMB_imbuf.h"
#include "IMB_thumbs.h"

#include "MEM_guardedalloc.h"

/* extracts the thumbnail from between the 'REND' and the 'GLOB'
 * chunks of the header, dont use typical blend loader because its too slow */

static ImBuf *loadblend_thumb(gzFile gzfile)
{
    char buf[12];
    int bhead[24/sizeof(int)]; /* max size on 64bit */
    char endian, pointer_size;
    char endian_switch;
    int sizeof_bhead ;

    /* read the blend file header */
    if(gzread(gzfile, buf, 12) != 12)
        return NULL;
    if(strncmp(buf, "BLENDER", 7))
        return NULL;

    if(buf[7]=='-')
        pointer_size= 8;
    else if(buf[7]=='_')
        pointer_size= 4;
    else
        return NULL;

    sizeof_bhead = 16 + pointer_size;

    if(buf[8]=='V')
        endian= B_ENDIAN; /* big: PPC */
    else if(buf[8]=='v')
        endian= L_ENDIAN; /* little: x86 */
    else
        return NULL;

    endian_switch = ((ENDIAN_ORDER != endian)) ? 1 : 0;

    while(gzread(gzfile, bhead, sizeof_bhead) == sizeof_bhead) {
        if(endian_switch)
            SWITCH_INT(bhead[1]); /* length */

        if (bhead[0]==REND) {
            gzseek(gzfile, bhead[1], SEEK_CUR); /* skip to the next */
        }
        else {
            break;
        }
    }

    /* using 'TEST' since new names segfault when loading in old blenders */
    if(bhead[0] == TEST) {
        ImBuf *img= NULL;
        int size[2];

        if(gzread(gzfile, size, sizeof(size)) != sizeof(size))
            return NULL;

        if(endian_switch) {
            SWITCH_INT(size[0]);
            SWITCH_INT(size[1]);
        }
        /* length */
        bhead[1] -= sizeof(int) * 2;

        /* inconsistent image size, quit early */
        if(bhead[1] != size[0] * size[1] * sizeof(int))
            return NULL;
    
        /* finally malloc and read the data */
        img= IMB_allocImBuf(size[0], size[1], 32, IB_rect | IB_metadata);
    
        if(gzread(gzfile, img->rect, bhead[1]) != bhead[1]) {
            IMB_freeImBuf(img);
            img= NULL;
        }
    
        return img;
    }
    
    return NULL;
}

ImBuf *IMB_loadblend_thumb(const char *path)
{
    gzFile gzfile;

    /* not necessarily a gzip */
    gzfile = gzopen(path, "rb");

    if (NULL == gzfile ) {
        return NULL;
    }
    else {
        ImBuf *img= loadblend_thumb(gzfile);

        /* read ok! */
        gzclose(gzfile);

        return img;
    }
}

/* add a fake passepartout overlay to a byte buffer, use for blend file thumbnails */
#define MARGIN 2

void IMB_overlayblend_thumb(unsigned int *thumb, int width, int height, float aspect)
{
    unsigned char *px= (unsigned char *)thumb;
    int margin_l = MARGIN;
    int margin_b = MARGIN;
    int margin_r = width - MARGIN;
    int margin_t = height - MARGIN;

    if(aspect < 1.0f) {
        margin_l= (int)((width - ((float)width * aspect)) / 2.0f);
        margin_l += MARGIN;
        CLAMP(margin_l, MARGIN, (width/2));
        margin_r = width - margin_l;
    }
    else if (aspect > 1.0f) {
        margin_b= (int)((height - ((float)height / aspect)) / 2.0f);
        margin_b += MARGIN;
        CLAMP(margin_b, MARGIN, (height/2));
        margin_t = height - margin_b;
    }

    {   
        int x, y;
        int stride_x= (margin_r - margin_l) - 2;
        
        for(y=0; y < height; y++) {
            for(x=0; x < width; x++, px+=4) {
                int hline= 0, vline= 0;
                if((x > margin_l && x < margin_r) && (y > margin_b && y < margin_t)) {
                    /* interior. skip */
                    x  += stride_x;
                    px += stride_x * 4;
                } else if(  (hline=(((x == margin_l || x == margin_r)) && y >= margin_b && y <= margin_t)) ||
                            (vline=(((y == margin_b || y == margin_t)) && x >= margin_l && x <= margin_r))
                ) {
                    /* dashed line */
                    if((hline && y % 2) || (vline && x % 2)) {
                        px[0]= px[1]= px[2]= 0;
                        px[3] = 255;
                    }
                }
                else {
                    /* outside, fill in alpha, like passepartout */
                    px[0] *= 0.5f;
                    px[1] *= 0.5f;
                    px[2] *= 0.5f;
                    px[3] = (px[3] * 0.5f) + 96;
                }
            }
        }
    }
}