diff options
Diffstat (limited to 'libmate-desktop/mate-thumbnail-pixbuf-utils.c')
| -rw-r--r-- | libmate-desktop/mate-thumbnail-pixbuf-utils.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/libmate-desktop/mate-thumbnail-pixbuf-utils.c b/libmate-desktop/mate-thumbnail-pixbuf-utils.c new file mode 100644 index 0000000..4c50e3e --- /dev/null +++ b/libmate-desktop/mate-thumbnail-pixbuf-utils.c @@ -0,0 +1,172 @@ +/* + * mate-thumbnail-pixbuf-utils.c: Utilities for handling pixbufs when thumbnailing + * + * Copyright (C) 2002 Red Hat, Inc. + * + * This file is part of the Mate Library. + * + * The Mate Library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * The Mate Library 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 + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with the Mate Library; see the file COPYING.LIB. If not, + * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + * + * Author: Alexander Larsson <[email protected]> + */ + +#include <config.h> + +#include <stdlib.h> +#include <string.h> +#include <glib.h> + +#define MATE_DESKTOP_USE_UNSTABLE_API +#include "libmateui/mate-desktop-thumbnail.h" + +#define LOAD_BUFFER_SIZE 65536 + +/** + * mate_thumbnail_scale_down_pixbuf: + * @pixbuf: a #GdkPixbuf + * @dest_width: the desired new width + * @dest_height: the desired new height + * + * Scales the pixbuf to the desired size. This function + * is a lot faster than gdk-pixbuf when scaling down by + * large amounts. + * + * Return value: a scaled pixbuf + * + * Since: 2.2 + **/ +GdkPixbuf * +mate_desktop_thumbnail_scale_down_pixbuf (GdkPixbuf *pixbuf, + int dest_width, + int dest_height) +{ + int source_width, source_height; + int s_x1, s_y1, s_x2, s_y2; + int s_xfrac, s_yfrac; + int dx, dx_frac, dy, dy_frac; + div_t ddx, ddy; + int x, y; + int r, g, b, a; + int n_pixels; + gboolean has_alpha; + guchar *dest, *src, *xsrc, *src_pixels; + GdkPixbuf *dest_pixbuf; + int pixel_stride; + int source_rowstride, dest_rowstride; + + if (dest_width == 0 || dest_height == 0) { + return NULL; + } + + source_width = gdk_pixbuf_get_width (pixbuf); + source_height = gdk_pixbuf_get_height (pixbuf); + + g_assert (source_width >= dest_width); + g_assert (source_height >= dest_height); + + ddx = div (source_width, dest_width); + dx = ddx.quot; + dx_frac = ddx.rem; + + ddy = div (source_height, dest_height); + dy = ddy.quot; + dy_frac = ddy.rem; + + has_alpha = gdk_pixbuf_get_has_alpha (pixbuf); + source_rowstride = gdk_pixbuf_get_rowstride (pixbuf); + src_pixels = gdk_pixbuf_get_pixels (pixbuf); + + dest_pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, has_alpha, 8, + dest_width, dest_height); + dest = gdk_pixbuf_get_pixels (dest_pixbuf); + dest_rowstride = gdk_pixbuf_get_rowstride (dest_pixbuf); + + pixel_stride = (has_alpha)?4:3; + + s_y1 = 0; + s_yfrac = -dest_height/2; + while (s_y1 < source_height) { + s_y2 = s_y1 + dy; + s_yfrac += dy_frac; + if (s_yfrac > 0) { + s_y2++; + s_yfrac -= dest_height; + } + + s_x1 = 0; + s_xfrac = -dest_width/2; + while (s_x1 < source_width) { + s_x2 = s_x1 + dx; + s_xfrac += dx_frac; + if (s_xfrac > 0) { + s_x2++; + s_xfrac -= dest_width; + } + + /* Average block of [x1,x2[ x [y1,y2[ and store in dest */ + r = g = b = a = 0; + n_pixels = 0; + + src = src_pixels + s_y1 * source_rowstride + s_x1 * pixel_stride; + for (y = s_y1; y < s_y2; y++) { + xsrc = src; + if (has_alpha) { + for (x = 0; x < s_x2-s_x1; x++) { + n_pixels++; + + r += xsrc[3] * xsrc[0]; + g += xsrc[3] * xsrc[1]; + b += xsrc[3] * xsrc[2]; + a += xsrc[3]; + xsrc += 4; + } + } else { + for (x = 0; x < s_x2-s_x1; x++) { + n_pixels++; + r += *xsrc++; + g += *xsrc++; + b += *xsrc++; + } + } + src += source_rowstride; + } + + if (has_alpha) { + if (a != 0) { + *dest++ = r / a; + *dest++ = g / a; + *dest++ = b / a; + *dest++ = a / n_pixels; + } else { + *dest++ = 0; + *dest++ = 0; + *dest++ = 0; + *dest++ = 0; + } + } else { + *dest++ = r / n_pixels; + *dest++ = g / n_pixels; + *dest++ = b / n_pixels; + } + + s_x1 = s_x2; + } + s_y1 = s_y2; + dest += dest_rowstride - dest_width * pixel_stride; + } + + return dest_pixbuf; +} |