[Spice-devel] [vdagent-win PATCH v8 3/5] Write code to decode PNG format
Christophe Fergeau
cfergeau at redhat.com
Fri Jul 21 12:48:09 UTC 2017
On Wed, Jul 19, 2017 at 09:42:41AM +0100, Frediano Ziglio wrote:
> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
> Makefile.am | 6 +-
> configure.ac | 3 +
> vdagent/image.cpp | 8 +-
> vdagent/imagepng.cpp | 237 +++++++++++++++++++++++++++++++++++++++++++++++++++
> vdagent/imagepng.h | 25 ++++++
> 5 files changed, 270 insertions(+), 9 deletions(-)
> create mode 100644 vdagent/imagepng.cpp
> create mode 100644 vdagent/imagepng.h
>
> diff --git a/Makefile.am b/Makefile.am
> index b35dd57..175d8f7 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -23,8 +23,8 @@ LIBS = -lversion
>
> bin_PROGRAMS = vdagent vdservice
>
> -vdagent_LDADD = -lwtsapi32 -lgdi32 vdagent_rc.$(OBJEXT)
> -vdagent_CXXFLAGS = $(AM_CXXFLAGS)
> +vdagent_LDADD = $(LIBPNG_LIBS) $(ZLIB_LIBS) -lwtsapi32 -lgdi32 vdagent_rc.$(OBJEXT)
> +vdagent_CXXFLAGS = $(AM_CXXFLAGS) $(LIBPNG_CFLAGS)
> vdagent_LDFLAGS = $(AM_LDFLAGS) -Wl,--subsystem,windows
> vdagent_SOURCES = \
> common/vdcommon.cpp \
> @@ -44,6 +44,8 @@ vdagent_SOURCES = \
> vdagent/as_user.h \
> vdagent/image.cpp \
> vdagent/image.h \
> + vdagent/imagepng.cpp \
> + vdagent/imagepng.h \
> $(NULL)
>
> vdagent_rc.$(OBJEXT): vdagent/vdagent.rc
> diff --git a/configure.ac b/configure.ac
> index 4eac4b4..bb33075 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -101,6 +101,9 @@ dnl ---------------------------------------------------------------------------
> dnl - Check library dependencies
> dnl ---------------------------------------------------------------------------
>
> +PKG_CHECK_MODULES(LIBPNG, [libpng])
> +PKG_CHECK_MODULES(ZLIB, [zlib])
> +
> dnl ---------------------------------------------------------------------------
> dnl - Makefiles, etc.
> dnl ---------------------------------------------------------------------------
> diff --git a/vdagent/image.cpp b/vdagent/image.cpp
> index faec18f..82cfb0e 100644
> --- a/vdagent/image.cpp
> +++ b/vdagent/image.cpp
> @@ -21,9 +21,9 @@
>
> #include "vdcommon.h"
> #include "image.h"
> +#include "imagepng.h"
>
> ImageCoder *create_bitmap_coder();
> -ImageCoder *create_png_coder();
>
> static ImageCoder *get_coder(uint32_t vdagent_type)
> {
> @@ -172,9 +172,3 @@ ImageCoder *create_bitmap_coder()
> {
> return new BitmapCoder();
> }
> -
> -// TODO
> -ImageCoder *create_png_coder()
> -{
> - return NULL;
> -}
> diff --git a/vdagent/imagepng.cpp b/vdagent/imagepng.cpp
> new file mode 100644
> index 0000000..9530d71
> --- /dev/null
> +++ b/vdagent/imagepng.cpp
> @@ -0,0 +1,237 @@
> +/*
> + Copyright (C) 2017 Red Hat, Inc.
> +
> + This program is free software; you can redistribute it and/or
> + modify it under the terms of the GNU General Public License as
> + published by the Free Software Foundation; either version 2 of
> + the License, or (at your option) any later version.
> +
> + This program is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + GNU General Public License for more details.
> +
> + You should have received a copy of the GNU General Public License
> + along with this program. If not, see <http://www.gnu.org/licenses/>.
> +*/
> +
> +#include "vdcommon.h"
> +
> +#include <png.h>
> +#include <algorithm>
> +
> +#include "imagepng.h"
> +
> +class PngCoder: public ImageCoder
> +{
> +public:
> + PngCoder() {};
> + size_t get_dib_size(const uint8_t *data, size_t size);
> + void get_dib_data(uint8_t *dib, const uint8_t *data, size_t size);
> + uint8_t *from_bitmap(const BITMAPINFO& info, const void *bits, long &size);
> +private:
> + size_t convert_to_dib(uint8_t *out_buf, const uint8_t *data, size_t size);
> +};
> +
> +struct BufferIo {
> + uint8_t *buf;
> + uint32_t pos, size;
> + BufferIo(uint8_t *_buf, uint32_t _size):
> + buf(_buf), pos(0), size(_size)
> + {}
> +};
> +
> +static void read_from_bufio(png_structp png, png_bytep out, png_size_t size)
> +{
> + BufferIo& io(*(BufferIo*)png_get_io_ptr(png));
> + if (io.pos + size > io.size)
> + png_error(png, "read past end");
> + memcpy(out, io.buf+io.pos, size);
> + io.pos += size;
> +}
> +
> +size_t PngCoder::get_dib_size(const uint8_t *data, size_t size)
> +{
> + return convert_to_dib(NULL, data, size);
> +}
> +
> +typedef void line_fixup_t(uint8_t *line, unsigned int width);
> +
> +static void line_fixup_none(uint8_t *line, unsigned int width)
> +{
> +}
> +
> +static void line_fixup_2bpp_to_4bpp(uint8_t *line, unsigned int width)
> +{
> + width = (width + 3) / 4u;
> + while (width--) {
> + uint8_t from = line[width];
> + line[width*2+1] = ((from & 0x03) << 0) | ((from & 0x0c) << 2);
> + line[width*2+0] = ((from & 0x30) >> 4) | ((from & 0xc0) >> 2);
> + }
> +}
This is used in the 2bpp greyscale case, and will convert this way:
00b -> 0000b
01b -> 0001b
10b -> 0010b
11b -> 0011b
We'll then generate a palette this way:
+ const unsigned int colors = 1 << out_bits;
+ const unsigned int mult = 255 / (colors - 1);
+ for (unsigned int color = 0; color < colors; ++color) {
+ rgb->rgbBlue = rgb->rgbGreen = rgb->rgbRed = color * mult;
+ rgb->rgbReserved = 0;
+ ++rgb;
+ }
This means in particular that 11b will not be mapped to 1111b, so I
suspect we might be making 2bpp images paler than they should?
(on the other hand, are we going to encounter such images in the wild??)
> +
> +size_t PngCoder::convert_to_dib(uint8_t *out_buf, const uint8_t *data, size_t size)
> +{
> + BufferIo io((uint8_t *)data, size);
> +
> + png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
> + if (!png)
> + return 0;
> +
> + png_infop info = png_create_info_struct(png);
> + if (!info) {
> + png_destroy_read_struct(&png, &info, NULL);
> + return 0;
> + }
> +
> + if (setjmp(png_jmpbuf(png))) {
> + png_destroy_read_struct(&png, &info, NULL);
> + return 0;
> + }
> +
> + png_set_read_fn(png, &io, read_from_bufio);
> +
> + png_read_info(png, info);
> +
> + // not so much precision is supported
> + unsigned int bits = png_get_bit_depth(png, info);
> + if (bits == 16)
> + png_set_strip_16(png);
> +
> + unsigned int out_bits;
> + bool is_gray = false;
> + line_fixup_t *line_fixup = line_fixup_none;
> + switch (png_get_color_type(png, info)) {
> + case PNG_COLOR_TYPE_GRAY:
> + is_gray = true;
> + if (bits == 16) {
> + out_bits = 8;
> + } else if (bits == 2) {
> + line_fixup = line_fixup_2bpp_to_4bpp;
> + out_bits = 4;
> + } else {
> + out_bits = bits;
> + }
> + break;
> + case PNG_COLOR_TYPE_PALETTE:
> + // should return 1, 2, 4 and 8, BMP does not support 2
> + out_bits = bits;
> + if (bits == 2) {
> + line_fixup = line_fixup_2bpp_to_4bpp;
> + out_bits = 4;
> + }
> + break;
> + case PNG_COLOR_TYPE_RGB:
> + png_set_bgr(png);
> + out_bits = 24;
> + break;
> + case PNG_COLOR_TYPE_RGB_ALPHA:
> + png_set_bgr(png);
> + out_bits = 24;
> + png_set_strip_alpha(png);
> + break;
> + case PNG_COLOR_TYPE_GRAY_ALPHA:
> + is_gray = true;
> + // gray with alpha should always be 8 bit but make it sure
> + // in case format change
> + png_set_expand_gray_1_2_4_to_8(png);
> + out_bits = 8;
> + png_set_strip_alpha(png);
> + break;
> + default:
> + png_error(png, "PNG color type not supported");
> + break;
> + }
> +
> + const unsigned int width = png_get_image_width(png, info);
> + const unsigned int height = png_get_image_height(png, info);
> + const size_t stride = compute_dib_stride(width, out_bits);
> + const size_t image_size = stride * height;
> + const size_t palette_size = out_bits > 8 ? 0 : sizeof(RGBQUAD) * (1 << out_bits);
> + const size_t dib_size = sizeof(BITMAPINFOHEADER) + palette_size + image_size;
> +
> + // just called to get the size, return the information
> + if (!out_buf) {
> + png_destroy_read_struct(&png, &info, NULL);
> + return dib_size;
> + }
> +
> + // TODO tests
> + // bits, 1, 2, 4, 8, 16
> + // all color types
> + // alpha/not alpha
> + // indexed with not all colors
> +
> + // fill header
> + BITMAPINFOHEADER& head(*(BITMAPINFOHEADER *)out_buf);
> + memset(&head, 0, sizeof(head));
> + head.biSize = sizeof(head);
> + head.biWidth = width;
> + head.biHeight = height;
> + head.biPlanes = 1;
> + head.biBitCount = out_bits;
> + head.biCompression = BI_RGB;
> + head.biSizeImage = image_size;
> +
> + // copy palette
> + RGBQUAD *rgb = (RGBQUAD *)(out_buf + sizeof(BITMAPINFOHEADER));
> + if (is_gray) {
> + const unsigned int colors = 1 << out_bits;
> + const unsigned int mult = 255 / (colors - 1);
> + for (unsigned int color = 0; color < colors; ++color) {
> + rgb->rgbBlue = rgb->rgbGreen = rgb->rgbRed = color * mult;
> + rgb->rgbReserved = 0;
> + ++rgb;
> + }
> + head.biClrUsed = colors;
Do we have to have a palette for 8bpp greyscale images? (another case
which we might not encounter in practice anyway..)
Looks good otherwise.
Christophe
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