When transparency is present, it's not enough to just write 32bpp samples.
One need to use the full BITMAPV3INFOHEADER syntax and specify the
masks for BGRA.
see https://en.wikipedia.org/wiki/BMP_file_format#Pixel_storage
Also remove the height-flip trick and write samples bottom-to-top instead.
Change-Id: If5d92c11453b96764b5bfbf19e9678e632bc911f
(cherry picked from commit 480cd51de6)
Define macros in examples/unicode.h to use Unicode argv
on Windows. Keep char everywhere on Unix since it handles
UTF-8 without any change.
Impact:
- All fopen () and SHCreateStreamOnFile(),
- All fprintf() printing file paths,
- All strcmp() used with "-",
- File path parsing,
- Gif reading.
Concerned executables from examples/ and extras/:
anim_diff, anim_dump, vwebp, vwebp_sdl,
cwebp, dwebp, gif2webp, img2webp,
webpmux, webpinfo, webp_quality, get_disto
When compiled on Windows with Unicode enabled, webpmux and
img2webp will not work when used with an argument file and
will print "Reading arguments from a file is a feature
unavailable with Unicode binaries."
BUG=webp:398
Change-Id: Ic55d222a3ce1a715f9c4cce57ecbe2705d5ce317
this quiets a -Wclobbered warning on const has_alpha under gcc-7 and
brings the variables closer to their first use.
Change-Id: I8a24f275b7ff34a94d47b576bcf276dbedac2121
Encoder:
We were always using ExtraSamples=1, which means associated-alpha.
But we don't need the (lossy) excursion to rgbA format. We can save
the samples as RGBA directly, by changing ExtraSamples to '2'.
The TIFF encoder now checks the colorspace properly, to handle
premultiplied format as well as non-premultiplied.
Decoder:
The result of TIFFReadRGBAImageOriented() is always pre-multiply.
So, in case an alpha channel is present, we need to unmultiply it before
calling WebPPictureImportRGBA().
See:
https://www.itu.int/itudoc/itu-t/com16/tiff-fx/docs/tiff6.pdf (page 31)
and also http://www.asmail.be/msg0055469184.html
Change-Id: I3258bfdb0eb2e1a53d6c04414f55edb2926c938c
