cairodriver/draw_bitmap.c

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/*!
   \file lib/cairodriver/draw_bitmap.c
 
   \brief GRASS cairo display driver - draw bitmap
 
   (C) 2007-2008 by Lars Ahlzen and the GRASS Development Team
 
   This program is free software under the GNU General Public License
   (>=v2). Read the file COPYING that comes with GRASS for details.
 
   \author Lars Ahlzen <lars ahlzen.com> (original contributor)
   \author Glynn Clements
 */
 
#include <grass/glocale.h>
 
#include "cairodriver.h"
 
/*!
   \brief Draw bitmap
 
   \param ncols,nrows number of columns and rows
   \param threshold threshold value
   \param buf data buffer
 */
void Cairo_Bitmap(int ncols, int nrows, int threshold, const unsigned char *buf)
{
    cairo_surface_t *surf;
    int stride;
    unsigned char *data;
    int i;
 
    G_debug(1, "Cairo_Bitmap: %d %d %d", ncols, nrows, threshold);
 
#if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 5, 8)
    stride = cairo_format_stride_for_width(CAIRO_FORMAT_A8, ncols);
#else
#define MULTIPLE 4
    stride = (ncols + (MULTIPLE - 1)) / MULTIPLE * MULTIPLE;
#endif
    data = malloc(stride * nrows);
    surf = cairo_image_surface_create_for_data(data, CAIRO_FORMAT_A8, ncols,
                                               nrows, stride);
 
    if (cairo_surface_status(surf) != CAIRO_STATUS_SUCCESS)
        G_fatal_error(_("Cairo_Bitmap: Failed to create source"));
 
    for (i = 0; i < nrows; i++)
        memcpy(&data[i * stride], &buf[i * ncols], ncols);
 
    cairo_surface_mark_dirty(surf);
    cairo_mask_surface(cairo, surf, cur_x, cur_y);
 
    cairo_surface_destroy(surf);
    ca.modified = 1;
}