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support transparent images - sent - simple plaintext presentation tool |
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git clone git://git.suckless.org/sent |
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--- |
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commit 0798e82d2326fc330168733997006020cc59e215 |
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parent b516f468faa3a80c31932cbcb1ea8ccd1468ffc1 |
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Author: Markus Teich <[email protected]> |
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Date: Tue, 8 Dec 2015 21:46:18 +0100 |
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support transparent images |
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Diffstat: |
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M sent.c | 19 ++++++++++++++++--- |
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1 file changed, 16 insertions(+), 3 deletions(-) |
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--- |
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diff --git a/sent.c b/sent.c |
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@@ -215,6 +215,8 @@ int ffread(Image *img) |
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{ |
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uint32_t y, x; |
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uint16_t *row; |
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+ uint8_t opac; |
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+ uint8_t fg_r, fg_g, fg_b, bg_r, bg_g, bg_b; |
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size_t rowlen, off, nbytes; |
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ssize_t r; |
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@@ -239,6 +241,11 @@ int ffread(Image *img) |
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return 0; |
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} |
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+ /* extract window background color channels for transparency */ |
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+ bg_r = (sc->bg.pix >> 16) % 256; |
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+ bg_g = (sc->bg.pix >> 8) % 256; |
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+ bg_b = (sc->bg.pix >> 0) % 256; |
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+ |
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for (off = 0, y = 0; y < img->bufheight; y++) { |
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nbytes = 0; |
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while (nbytes < rowlen) { |
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@@ -248,9 +255,15 @@ int ffread(Image *img) |
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nbytes += r; |
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} |
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for (x = 0; x < rowlen / 2; x += 4) { |
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- img->buf[off++] = ntohs(row[x + 0]) / 257; |
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- img->buf[off++] = ntohs(row[x + 1]) / 257; |
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- img->buf[off++] = ntohs(row[x + 2]) / 257; |
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+ fg_r = ntohs(row[x + 0]) / 256; |
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+ fg_g = ntohs(row[x + 1]) / 256; |
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+ fg_b = ntohs(row[x + 2]) / 256; |
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+ opac = ntohs(row[x + 3]) / 256; |
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+ /* blend opaque part of image data with window backgro… |
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+ * emulate transparency */ |
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+ img->buf[off++] = (fg_r * opac + bg_r * (255 - opac)) … |
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+ img->buf[off++] = (fg_g * opac + bg_g * (255 - opac)) … |
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+ img->buf[off++] = (fg_b * opac + bg_b * (255 - opac)) … |
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} |
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} |
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