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| author | Robin Watts <robin.watts@artifex.com> | 2017-11-07 17:32:15 +0000 |
|---|---|---|
| committer | Robin Watts <robin.watts@artifex.com> | 2017-11-08 12:57:18 +0000 |
| commit | 3119f69dd9536cdaab0719fba2898be894e8fc01 (patch) | |
| tree | 7e034de6e3d83ca163ce656b328e29c1b55a03e4 /source/fitz/output-tga.c | |
| parent | 520cc26d18c9ee245b56e9e91f9d4fcae02be5f0 (diff) | |
| download | mupdf-3119f69dd9536cdaab0719fba2898be894e8fc01.tar.xz | |
Pixmap writers for formats with alpha should handle premultiplied data.
Any pixmap writers that can handle data with an alpha plane
should accept that data in premultiplied form, and write it out
appropriately for the file format.
This avoids the need to unpremultiply data in mudraw, and solves
the issue we were seeing where we want the png writer to be able
to cope with premultiplied data (such as for the debug blending
routines) and unpremultiplied data (such as that given after
mudraw has unpremultiplied the data).
Diffstat (limited to 'source/fitz/output-tga.c')
| -rw-r--r-- | source/fitz/output-tga.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/source/fitz/output-tga.c b/source/fitz/output-tga.c index 3bee3640..0e7a213c 100644 --- a/source/fitz/output-tga.c +++ b/source/fitz/output-tga.c @@ -13,19 +13,22 @@ typedef struct { static inline void tga_put_pixel(fz_context *ctx, fz_output *out, const unsigned char *data, int n, int is_bgr) { + int a, inva; switch(n) { case 4: /* RGBA or BGRA */ + a = data[3]; + inva = a ? 256 * 255 / a : 0; if (!is_bgr) { - fz_write_byte(ctx, out, data[2]); - fz_write_byte(ctx, out, data[1]); - fz_write_byte(ctx, out, data[0]); + fz_write_byte(ctx, out, (data[2] * inva + 128)>>8); + fz_write_byte(ctx, out, (data[1] * inva + 128)>>8); + fz_write_byte(ctx, out, (data[0] * inva + 128)>>8); } else { - fz_write_byte(ctx, out, data[0]); - fz_write_byte(ctx, out, data[1]); - fz_write_byte(ctx, out, data[2]); + fz_write_byte(ctx, out, (data[0] * inva + 128)>>8); + fz_write_byte(ctx, out, (data[1] * inva + 128)>>8); + fz_write_byte(ctx, out, (data[2] * inva + 128)>>8); } - fz_write_byte(ctx, out, data[3]); + fz_write_byte(ctx, out, a); break; case 3: /* RGB or BGR */ if (!is_bgr) { @@ -39,10 +42,13 @@ static inline void tga_put_pixel(fz_context *ctx, fz_output *out, const unsigned } break; case 2: /* GA */ - fz_write_byte(ctx, out, data[0]); - fz_write_byte(ctx, out, data[0]); - fz_write_byte(ctx, out, data[0]); - fz_write_byte(ctx, out, data[1]); + a = data[1]; + inva = a ? 256 * 255 / a : 0; + inva = (data[0] * inva + 128)>>8; + fz_write_byte(ctx, out, inva); + fz_write_byte(ctx, out, inva); + fz_write_byte(ctx, out, inva); + fz_write_byte(ctx, out, a); break; case 1: /* G */ fz_write_byte(ctx, out, data[0]); |