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Diffstat (limited to 'test/buffer_diff.c')
| -rw-r--r-- | test/buffer_diff.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/test/buffer_diff.c b/test/buffer_diff.c new file mode 100644 index 000000000..07abd62a3 --- /dev/null +++ b/test/buffer_diff.c @@ -0,0 +1,73 @@ +/* imagediff - Compare two images + * + * Copyright © 2004 Richard D. Worth + * + * Permission to use, copy, modify, distribute, and sell this software + * and its documentation for any purpose is hereby granted without + * fee, provided that the above copyright notice appear in all copies + * and that both that copyright notice and this permission notice + * appear in supporting documentation, and that the name of Richard Worth + * not be used in advertising or publicity pertaining to distribution + * of the software without specific, written prior permission. + * Richard Worth makes no representations about the suitability of this + * software for any purpose. It is provided "as is" without express + * or implied warranty. + * + * RICHARD WORTH DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, + * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN + * NO EVENT SHALL RICHARD WORTH BE LIABLE FOR ANY SPECIAL, INDIRECT OR + * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS + * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, + * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * + * Author: Richard D. Worth <richard@theworths.org> */ + +#include "buffer_diff.h" + +/* Image comparison code courttesy of Richard Worth. + * Returns number of pixels changed. + * Also fills out a "diff" image intended to visually show where the + * images differ. + */ +int +buffer_diff (char *buf_a, char *buf_b, char *buf_diff, + int width, int height, int stride) +{ + int x, y; + int total_pixels_changed = 0; + unsigned char *row_a, *row_b, *row; + + for (y = 0; y < height; y++) + { + row_a = buf_a + y * stride; + row_b = buf_b + y * stride; + row = buf_diff + y * stride; + for (x = 0; x < width; x++) + { + int channel; + unsigned char value_a, value_b; + int pixel_changed = 0; + for (channel = 0; channel < 4; channel++) + { + double diff; + value_a = row_a[x * 4 + channel]; + value_b = row_b[x * 4 + channel]; + if (value_a != value_b) + pixel_changed = 1; + diff = value_a - value_b; + row[x * 4 + channel] = 128 + diff / 3.0; + } + if (pixel_changed) { + total_pixels_changed++; + } else { + row[x*4+0] = 0; + row[x*4+1] = 0; + row[x*4+2] = 0; + } + row[x * 4 + 3] = 0xff; /* Set ALPHA to 100% (opaque) */ + } + } + + return total_pixels_changed; +} |