Pillow/src/libImaging/GetBBox.c

/*
 * The Python Imaging Library
 * $Id$
 *
 * helpers to bounding boxes, min/max values, number of colors, etc.
 *
 * history:
 * 1996-07-22 fl   Created
 * 1996-12-30 fl   Added projection stuff
 * 1998-07-12 fl   Added extrema stuff
 * 2004-09-17 fl   Added colors stuff
 *
 * Copyright (c) 1997-2004 by Secret Labs AB.
 * Copyright (c) 1996-2004 by Fredrik Lundh.
 *
 * See the README file for details on usage and redistribution.
 */


#include "Imaging.h"


int
ImagingGetBBox(Imaging im, int bbox[4])
{
    /* Get the bounding box for any non-zero data in the image.*/

    int x, y;
    int has_data;

    /* Initialize bounding box to max values */
    bbox[0] = im->xsize;
    bbox[1] = -1;
    bbox[2] = bbox[3] = 0;

#define GETBBOX(image, mask)\
    for (y = 0; y < im->ysize; y++) {\
        has_data = 0;\
        for (x = 0; x < im->xsize; x++)\
            if (im->image[y][x] & mask) {\
                has_data = 1;\
                if (x < bbox[0])\
                    bbox[0] = x;\
                if (x >= bbox[2])\
                    bbox[2] = x+1;\
            }\
        if (has_data) {\
            if (bbox[1] < 0)\
            bbox[1] = y;\
            bbox[3] = y+1;\
        }\
    }

    if (im->image8) {
        GETBBOX(image8, 0xff);
    } else {
        INT32 mask = 0xffffffff;
        if (im->bands == 3) {
            ((UINT8*) &mask)[3] = 0;
        } else if (strcmp(im->mode, "RGBa") == 0 ||
                   strcmp(im->mode, "RGBA") == 0 ||
                   strcmp(im->mode, "La") == 0 ||
                   strcmp(im->mode, "LA") == 0 ||
                   strcmp(im->mode, "PA") == 0) {
#ifdef WORDS_BIGENDIAN
        mask = 0x000000ff;
#else
        mask = 0xff000000;
#endif
        }
        GETBBOX(image32, mask);
    }

    /* Check that we got a box */
    if (bbox[1] < 0)
        return 0; /* no data */

    return 1; /* ok */
}


int
ImagingGetProjection(Imaging im, UINT8* xproj, UINT8* yproj)
{
    /* Get projection arrays for non-zero data in the image.*/

    int x, y;
    int has_data;

    /* Initialize projection arrays */
    memset(xproj, 0, im->xsize);
    memset(yproj, 0, im->ysize);

    #define GETPROJ(image, mask)\
        for (y = 0; y < im->ysize; y++) {\
            has_data = 0;\
            for (x = 0; x < im->xsize; x++)\
                if (im->image[y][x] & mask) {\
                    has_data = 1;\
                    xproj[x] = 1;\
                }\
                if (has_data)\
                    yproj[y] = 1;\
                }

    if (im->image8) {
        GETPROJ(image8, 0xff);
    } else {
        INT32 mask = 0xffffffff;
        if (im->bands == 3)
            ((UINT8*) &mask)[3] = 0;
        GETPROJ(image32, mask);
    }

    return 1; /* ok */
}


int
ImagingGetExtrema(Imaging im, void *extrema)
{
    int x, y;
    INT32 imin, imax;
    FLOAT32 fmin, fmax;

    if (im->bands != 1) {
        (void) ImagingError_ModeError();
        return -1; /* mismatch */
    }

    if (!im->xsize || !im->ysize)
        return 0; /* zero size */

    switch (im->type) {
    case IMAGING_TYPE_UINT8:
        imin = imax = im->image8[0][0];
        for (y = 0; y < im->ysize; y++) {
            UINT8* in = im->image8[y];
            for (x = 0; x < im->xsize; x++) {
                if (imin > in[x])
                    imin = in[x];
                else if (imax < in[x])
                    imax = in[x];
            }
        }
        ((UINT8*) extrema)[0] = (UINT8) imin;
        ((UINT8*) extrema)[1] = (UINT8) imax;
        break;
    case IMAGING_TYPE_INT32:
        imin = imax = im->image32[0][0];
        for (y = 0; y < im->ysize; y++) {
            INT32* in = im->image32[y];
            for (x = 0; x < im->xsize; x++) {
                if (imin > in[x])
                    imin = in[x];
                else if (imax < in[x])
                    imax = in[x];
            }
        }
        memcpy(extrema, &imin, sizeof(imin));
        memcpy(((char*)extrema) + sizeof(imin), &imax, sizeof(imax));
        break;
    case IMAGING_TYPE_FLOAT32:
        fmin = fmax = ((FLOAT32*) im->image32[0])[0];
        for (y = 0; y < im->ysize; y++) {
            FLOAT32* in = (FLOAT32*) im->image32[y];
            for (x = 0; x < im->xsize; x++) {
                if (fmin > in[x])
                    fmin = in[x];
                else if (fmax < in[x])
                    fmax = in[x];
            }
        }
        memcpy(extrema, &fmin, sizeof(fmin));
        memcpy(((char*)extrema) + sizeof(fmin), &fmax, sizeof(fmax));
        break;
    case IMAGING_TYPE_SPECIAL:
      if (strcmp(im->mode, "I;16") == 0) {
          UINT16 v;
          UINT8* pixel = *im->image8;
#ifdef WORDS_BIGENDIAN
          v = pixel[0] + (pixel[1] << 8);
#else
          memcpy(&v, pixel, sizeof(v));
#endif
          imin = imax = v;
          for (y = 0; y < im->ysize; y++) {
              for (x = 0; x < im->xsize; x++) {
                  pixel = im->image[y] + x * sizeof(v);
#ifdef WORDS_BIGENDIAN
                  v = pixel[0] + (pixel[1] << 8);
#else
                  memcpy(&v, pixel, sizeof(v));
#endif
                  if (imin > v)
                      imin = v;
                  else if (imax < v)
                      imax = v;
              }
          }
          v = (UINT16) imin;
          memcpy(extrema, &v, sizeof(v));
          v = (UINT16) imax;
          memcpy(((char*)extrema) + sizeof(v), &v, sizeof(v));
          break;
      }
      /* FALL THROUGH */
    default:
        (void) ImagingError_ModeError();
        return -1;
    }
    return 1; /* ok */
}


/* static ImagingColorItem* getcolors8(Imaging im, int maxcolors, int* size);*/
static ImagingColorItem* getcolors32(Imaging im, int maxcolors, int* size);

ImagingColorItem*
ImagingGetColors(Imaging im, int maxcolors, int* size)
{
    /* FIXME: add support for 8-bit images */
    return getcolors32(im, maxcolors, size);
}

static ImagingColorItem*
getcolors32(Imaging im, int maxcolors, int* size)
{
    unsigned int h;
    unsigned int i, incr;
    int colors;
    INT32 pixel_mask;
    int x, y;
    ImagingColorItem* table;
    ImagingColorItem* v;

    unsigned int code_size;
    unsigned int code_poly;
    unsigned int code_mask;

    /* note: the hash algorithm used here is based on the dictionary
       code in Python 2.1.3; the exact implementation is borrowed from
       Python's Unicode property database (written by yours truly) /F */

    static int SIZES[] = {
        4,3, 8,3, 16,3, 32,5, 64,3, 128,3, 256,29, 512,17, 1024,9, 2048,5,
        4096,83, 8192,27, 16384,43, 32768,3, 65536,45, 131072,9, 262144,39,
        524288,39, 1048576,9, 2097152,5, 4194304,3, 8388608,33, 16777216,27,
        33554432,9, 67108864,71, 134217728,39, 268435456,9, 536870912,5,
        1073741824,83, 0
    };

    code_size = code_poly = code_mask = 0;

    for (i = 0; SIZES[i]; i += 2) {
        if (SIZES[i] > maxcolors) {
            code_size = SIZES[i];
            code_poly = SIZES[i+1];
            code_mask = code_size - 1;
            break;
        }
    }

    /* printf("code_size=%d\n", code_size); */
    /* printf("code_poly=%d\n", code_poly); */

    if (!code_size)
        return ImagingError_MemoryError(); /* just give up */

    if (!im->image32)
        return ImagingError_ModeError();

    table = calloc(code_size + 1, sizeof(ImagingColorItem));
    if (!table)
        return ImagingError_MemoryError();

    pixel_mask = 0xffffffff;
    if (im->bands == 3)
        ((UINT8*) &pixel_mask)[3] = 0;

    colors = 0;

    for (y = 0; y < im->ysize; y++) {
        INT32* p = im->image32[y];
        for (x = 0; x < im->xsize; x++) {
            INT32 pixel = p[x] & pixel_mask;
            h = (pixel); /* null hashing */
            i = (~h) & code_mask;
            v = &table[i];
            if (!v->count) {
                /* add to table */
                if (colors++ == maxcolors)
                    goto overflow;
                v->x = x; v->y = y;
                v->pixel = pixel;
                v->count = 1;
                continue;
            } else if (v->pixel == pixel) {
                v->count++;
                continue;
            }
            incr = (h ^ (h >> 3)) & code_mask;
            if (!incr)
                incr = code_mask;
            for (;;) {
                i = (i + incr) & code_mask;
                v = &table[i];
                if (!v->count) {
                    /* add to table */
                    if (colors++ == maxcolors)
                        goto overflow;
                    v->x = x; v->y = y;
                    v->pixel = pixel;
                    v->count = 1;
                    break;
                } else if (v->pixel == pixel) {
                    v->count++;
                    break;
                }
                incr = incr << 1;
                if (incr > code_mask)
                    incr = incr ^ code_poly;
            }
        }
    }

overflow:

    /* pack the table */
    for (x = y = 0; x < (int) code_size; x++)
        if (table[x].count) {
            if (x != y)
                table[y] = table[x];
            y++;
        }
    table[y].count = 0; /* mark end of table */

    *size = colors;

    return table;
}