Pileus Git - ~andy/gtk/blob - gdk-pixbuf/gdk-pixbuf-util.c

   1 /* GdkPixbuf library - Utilities and miscellaneous convenience functions
   2  *
   3  * Copyright (C) 1999 The Free Software Foundation
   4  *
   5  * Authors: Federico Mena-Quintero <federico@gimp.org>
   6  *          Cody Russell  <bratsche@gnome.org>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the
  20  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21  * Boston, MA 02111-1307, USA.
  22  */
  23
  24 #include <config.h>
  25 #include "gdk-pixbuf-private.h"
  26 #include <string.h>
  27
  28 \f
  29
  30 /**
  31  * gdk_pixbuf_add_alpha:
  32  * @pixbuf: A pixbuf.
  33  * @substitute_color: Whether to set a color to zero opacity.  If this
  34  * is #FALSE, then the (@r, @g, @b) arguments will be ignored.
  35  * @r: Red value to substitute.
  36  * @g: Green value to substitute.
  37  * @b: Blue value to substitute.
  38  *
  39  * Takes an existing pixbuf and adds an alpha channel to it.
  40  * If the existing pixbuf already had an alpha channel, the channel
  41  * values are copied from the original; otherwise, the alpha channel
  42  * is initialized to 255 (full opacity).
  43  *
  44  * If @substitute_color is #TRUE, then the color specified by (@r, @g, @b) will be
  45  * assigned zero opacity. That is, if you pass (255, 255, 255) for the
  46  * substitute color, all white pixels will become fully transparent.
  47  *
  48  * Return value: A newly-created pixbuf with a reference count of 1.
  49  **/
  50 GdkPixbuf *
  51 gdk_pixbuf_add_alpha (const GdkPixbuf *pixbuf,
  52                       gboolean substitute_color, guchar r, guchar g, guchar b)
  53 {
  54         GdkPixbuf *new_pixbuf;
  55         int x, y;
  56
  57         g_return_val_if_fail (pixbuf != NULL, NULL);
  58         g_return_val_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB, NULL);
  59         g_return_val_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4, NULL);
  60         g_return_val_if_fail (pixbuf->bits_per_sample == 8, NULL);
  61
  62         if (pixbuf->has_alpha) {
  63                 new_pixbuf = gdk_pixbuf_copy (pixbuf);
  64                 if (!new_pixbuf)
  65                         return NULL;
  66
  67                 if (!substitute_color)
  68                         return new_pixbuf;
  69         } else {
  70                 new_pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8, pixbuf->width, pixbuf->height);
  71         }
  72
  73         if (!new_pixbuf)
  74                 return NULL;
  75
  76         for (y = 0; y < pixbuf->height; y++) {
  77                 guchar *src, *dest;
  78                 guchar tr, tg, tb;
  79
  80                 src = pixbuf->pixels + y * pixbuf->rowstride;
  81                 dest = new_pixbuf->pixels + y * new_pixbuf->rowstride;
  82
  83                 if (pixbuf->has_alpha) {
  84                         /* Just subst color, we already copied everything else */
  85                         for (x = 0; x < pixbuf->width; x++) {
  86                                 if (src[0] == r && src[1] == g && src[2] == b)
  87                                         dest[3] = 0;
  88                                 src += 4;
  89                                 dest += 4;
  90                         }
  91                 } else {
  92                         for (x = 0; x < pixbuf->width; x++) {
  93                                 tr = *dest++ = *src++;
  94                                 tg = *dest++ = *src++;
  95                                 tb = *dest++ = *src++;
  96
  97                                 if (substitute_color && tr == r && tg == g && tb == b)
  98                                         *dest++ = 0;
  99                                 else
 100                                         *dest++ = 255;
 101                         }
 102                 }
 103         }
 104
 105         return new_pixbuf;
 106 }
 107
 108 /**
 109  * gdk_pixbuf_copy_area:
 110  * @src_pixbuf: Source pixbuf.
 111  * @src_x: Source X coordinate within @src_pixbuf.
 112  * @src_y: Source Y coordinate within @src_pixbuf.
 113  * @width: Width of the area to copy.
 114  * @height: Height of the area to copy.
 115  * @dest_pixbuf: Destination pixbuf.
 116  * @dest_x: X coordinate within @dest_pixbuf.
 117  * @dest_y: Y coordinate within @dest_pixbuf.
 118  *
 119  * Copies a rectangular area from @src_pixbuf to @dest_pixbuf.  Conversion of
 120  * pixbuf formats is done automatically.
 121  **/
 122 void
 123 gdk_pixbuf_copy_area (const GdkPixbuf *src_pixbuf,
 124                       int src_x, int src_y,
 125                       int width, int height,
 126                       GdkPixbuf *dest_pixbuf,
 127                       int dest_x, int dest_y)
 128 {
 129         g_return_if_fail (src_pixbuf != NULL);
 130         g_return_if_fail (dest_pixbuf != NULL);
 131
 132         g_return_if_fail (src_x >= 0 && src_x + width <= src_pixbuf->width);
 133         g_return_if_fail (src_y >= 0 && src_y + height <= src_pixbuf->height);
 134
 135         g_return_if_fail (dest_x >= 0 && dest_x + width <= dest_pixbuf->width);
 136         g_return_if_fail (dest_y >= 0 && dest_y + height <= dest_pixbuf->height);
 137
 138         g_return_if_fail (!(gdk_pixbuf_get_has_alpha (src_pixbuf) && !gdk_pixbuf_get_has_alpha (dest_pixbuf)));
 139
 140         /* This will perform format conversions automatically */
 141
 142         gdk_pixbuf_scale (src_pixbuf,
 143                           dest_pixbuf,
 144                           dest_x, dest_y,
 145                           width, height,
 146                           (double) (dest_x - src_x),
 147                           (double) (dest_y - src_y),
 148                           1.0, 1.0,
 149                           GDK_INTERP_NEAREST);
 150 }
 151
 152
 153
 154 #define INTENSITY(r, g, b) ((r) * 0.30 + (g) * 0.59 + (b) * 0.11)
 155
 156 /**
 157  * gdk_pixbuf_saturate_and_pixelate:
 158  * @src: source image
 159  * @dest: place to write modified version of @src
 160  * @saturation: saturation factor
 161  * @pixelate: whether to pixelate
 162  *
 163  * Modifies saturation and optionally pixelates @src, placing the
 164  * result in @dest. @src and @dest may be the same pixbuf with no ill
 165  * effects.  If @saturation is 1.0 then saturation is not changed. If
 166  * it's less than 1.0, saturation is reduced (the image is darkened);
 167  * if greater than 1.0, saturation is increased (the image is
 168  * brightened). If @pixelate is TRUE, then pixels are faded in a
 169  * checkerboard pattern to create a pixelated image. @src and @dest
 170  * must have the same image format, size, and rowstride.
 171  *
 172  **/
 173 void
 174 gdk_pixbuf_saturate_and_pixelate(const GdkPixbuf *src,
 175                                  GdkPixbuf *dest,
 176                                  gfloat saturation,
 177                                  gboolean pixelate)
 178 {
 179         /* NOTE that src and dest MAY be the same pixbuf! */
 180
 181         g_return_if_fail (GDK_IS_PIXBUF (src));
 182         g_return_if_fail (GDK_IS_PIXBUF (dest));
 183         g_return_if_fail (gdk_pixbuf_get_height (src) == gdk_pixbuf_get_height (dest));
 184         g_return_if_fail (gdk_pixbuf_get_width (src) == gdk_pixbuf_get_width (dest));
 185         g_return_if_fail (gdk_pixbuf_get_rowstride (src) == gdk_pixbuf_get_rowstride (dest));
 186         g_return_if_fail (gdk_pixbuf_get_colorspace (src) == gdk_pixbuf_get_colorspace (dest));
 187
 188         if (saturation == 1.0 && !pixelate) {
 189                 if (dest != src)
 190                         memcpy (gdk_pixbuf_get_pixels (dest),
 191                                 gdk_pixbuf_get_pixels (src),
 192                                 gdk_pixbuf_get_height (src) * gdk_pixbuf_get_rowstride (src));
 193
 194                 return;
 195         } else {
 196                 gint i, j;
 197                 gint width, height, has_alpha, rowstride;
 198                 guchar *target_pixels;
 199                 guchar *original_pixels;
 200                 guchar *current_pixel;
 201                 guchar intensity;
 202
 203                 has_alpha = gdk_pixbuf_get_has_alpha (src);
 204                 width = gdk_pixbuf_get_width (src);
 205                 height = gdk_pixbuf_get_height (src);
 206                 rowstride = gdk_pixbuf_get_rowstride (src);
 207
 208                 target_pixels = gdk_pixbuf_get_pixels (dest);
 209                 original_pixels = gdk_pixbuf_get_pixels (src);
 210
 211                 for (i = 0; i < height; i++) {
 212                         for (j = 0; j < width; j++) {
 213                                 current_pixel = original_pixels + i*rowstride + j*(has_alpha?4:3);
 214                                 intensity = INTENSITY (*(current_pixel), *(current_pixel + 1), *(current_pixel + 2));
 215                                 if (pixelate && (i+j)%2 == 0) {
 216                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3)) = intensity/2 + 127;
 217                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 1) = intensity/2 + 127;
 218                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 2) = intensity/2 + 127;
 219                                 } else if (pixelate) {
 220 #define DARK_FACTOR 0.7
 221                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3)) =
 222                                                 (guchar) (((1.0 - saturation) * intensity
 223                                                            + saturation * (*(current_pixel)))) * DARK_FACTOR;
 224                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 1) =
 225                                                 (guchar) (((1.0 - saturation) * intensity
 226                                                            + saturation * (*(current_pixel + 1)))) * DARK_FACTOR;
 227                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 2) =
 228                                                 (guchar) (((1.0 - saturation) * intensity
 229                                                            + saturation * (*(current_pixel + 2)))) * DARK_FACTOR;
 230                                 } else {
 231                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3)) =
 232                                                 (guchar) ((1.0 - saturation) * intensity
 233                                                           + saturation * (*(current_pixel)));
 234                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 1) =
 235                                                 (guchar) ((1.0 - saturation) * intensity
 236                                                           + saturation * (*(current_pixel + 1)));
 237                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 2) =
 238                                                 (guchar) ((1.0 - saturation) * intensity
 239                                                           + saturation * (*(current_pixel + 2)));
 240                                 }
 241
 242                                 if (has_alpha)
 243                                         *(target_pixels + i*rowstride + j*(has_alpha?4:3) + 3) = *(current_pixel + 3);
 244                         }
 245                 }
 246
 247                 return;
 248         }
 249 }