Fix alpha blending - sent - simple plaintext presentation tool
HTML git clone git://git.suckless.org/sent
DIR Log
DIR Files
DIR Refs
DIR README
DIR LICENSE
---
DIR commit 68ac6486b106751f79e2ff2f4d53e56843521ce5
DIR parent b0ad67036e35bc148ebda08184881375e716ec0b
HTML Author: FRIGN <dev@frign.de>
Date: Sun, 31 Jan 2016 11:05:00 +0100
Fix alpha blending
- "/ 257", because 255 * 257 = UINT16_MAX
- "/ 255", because that's the maximum possible RGB value
Diffstat:
M sent.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
---
DIR diff --git a/sent.c b/sent.c
@@ -258,15 +258,15 @@ int ffread(Image *img)
nbytes += count;
}
for (x = 0; x < rowlen / 2; x += 4) {
- fg_r = ntohs(row[x + 0]) / 256;
- fg_g = ntohs(row[x + 1]) / 256;
- fg_b = ntohs(row[x + 2]) / 256;
- opac = ntohs(row[x + 3]) / 256;
+ fg_r = ntohs(row[x + 0]) / 257;
+ fg_g = ntohs(row[x + 1]) / 257;
+ fg_b = ntohs(row[x + 2]) / 257;
+ opac = ntohs(row[x + 3]) / 257;
/* blend opaque part of image data with window background color to
* emulate transparency */
- img->buf[off++] = (fg_r * opac + bg_r * (255 - opac)) / 256;
- img->buf[off++] = (fg_g * opac + bg_g * (255 - opac)) / 256;
- img->buf[off++] = (fg_b * opac + bg_b * (255 - opac)) / 256;
+ img->buf[off++] = (fg_r * opac + bg_r * (255 - opac)) / 255;
+ img->buf[off++] = (fg_g * opac + bg_g * (255 - opac)) / 255;
+ img->buf[off++] = (fg_b * opac + bg_b * (255 - opac)) / 255;
}
}