nica/cairo_jpg
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

updated code to also compile against the original libjpeg (and not just libjpeg-turbo)

Browse source
This commit is contained in:
rahra 2018-02-16 11:40:03 +01:00
parent b6b0c5f3d1
commit e71f4f393b
2 changed files with 76 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

16
README.md
View file

@ -10,10 +10,11 @@ support](http://www.cairographics.org/manual/cairo-PNG-Support.html).
The implementation is done on top of the Cairo API. It does not access
Cairo-internal functions.
For compression and decompression [libjpeg](http://libjpeg.sourceforge.net/) is
used.
For compression and decompression a JPEG library is used. It compiles against
[libjpeg-turbo](https://libjpeg-turbo.org/) or the original
[libjpeg](http://www.ijg.org/).
The following prototypes are implemented. Their functionallity is equal to the
The following prototypes are implemented. Their functionality is equal to the
PNG functions of Cairo with the advance that there are memory-buffer-based
functions as well.
@ -36,3 +37,12 @@ gcc -Wall -c `pkg-config cairo libjpeg --cflags --libs` cairo_jpg.c
Please have a look at the comments within the source files for further details.
Don't hesitate to contact me at [bf@abenteuerland.at](mailto:bf@abenteuerland.at).
## Testing
There is a ```main()``` function implemented which serves as demonstrational
purpose and for testing. To compile with the ```main()``` function run the
following statement:
```Shell
gcc -Wall -o cairo_jpg -DCAIRO_JPEG_MAIN `pkg-config cairo libjpeg --cflags --libs` cairo_jpg.c
```

66
src/cairo_jpg.c
View file

@ -15,8 +15,8 @@
* executable for testing of this code:
* gcc -Wall -o cairo_jpg -DCAIRO_JPEG_MAIN `pkg-config cairo libjpeg --cflags --libs` cairo_jpg.c
*
* @author Bernhard R. Fischer, 2048R/5C5FFD47 bf@abenteuerland.at
* @version 2016/01/01 r1922
* @author Bernhard R. Fischer, 4096R/8E24F29D bf@abenteuerland.at
* @version 2018/02/15
* @license This code is free software. Do whatever you like to do with it.
*/
@ -70,6 +70,45 @@
#endif
#ifndef LIBJPEG_TURBO_VERSION
/*! This function makes a covnersion for "odd" pixel sizes which typically is a
* conversion from a 3-byte to a 4-byte (or more) pixel size or vice versa.
* The conversion is done from the source buffer src to the destination buffer
* dst. The caller MUST ensure that src and dst have the correct memory size.
* This is dw * num for dst and sw * num for src. src and dst may point to the
* same memory address.
* @param dst Pointer to destination buffer.
* @param dw Pixel width (in bytes) of pixels in destination buffer, dw >= 3.
* @param src Pointer to source buffer.
* @param sw Pixel width (in bytes) of pixels in source buffer, sw >= 3.
* @param num Number of pixels to convert, num >= 1;
*/
static void pix_conv(unsigned char *dst, int dw, const unsigned char *src, int sw, int num)
{
int si, di;
// safety check
if (dw < 3 || sw < 3 || dst == NULL || src == NULL)
return;
num--;
for (si = num * sw, di = num * dw; si >= 0; si -= sw, di -= dw)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
dst[di + 2] = src[si ];
dst[di + 1] = src[si + 1];
dst[di + 0] = src[si + 2];
#else
// FIXME: This is untested, it may be wrong.
dst[di - 3] = src[si - 3];
dst[di - 2] = src[si - 2];
dst[di - 1] = src[si - 1];
#endif
}
}
#endif
/*! This function creates a JPEG file in memory from a Cairo image surface.
* @param sfc Pointer to a Cairo surface. It should be an image surface of
* either CAIRO_FORMAT_ARGB32 or CAIRO_FORMAT_RGB24. Other formats are
@ -135,6 +174,7 @@ cairo_status_t cairo_image_surface_write_to_jpeg_mem(cairo_surface_t *sfc, unsig
jpeg_mem_dest(&cinfo, data, len);
cinfo.image_width = cairo_image_surface_get_width(sfc);
cinfo.image_height = cairo_image_surface_get_height(sfc);
#ifdef LIBJPEG_TURBO_VERSION
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
//cinfo.in_color_space = JCS_EXT_BGRX;
cinfo.in_color_space = cairo_image_surface_get_format(sfc) == CAIRO_FORMAT_ARGB32 ? JCS_EXT_BGRA : JCS_EXT_BGRX;
@ -143,6 +183,10 @@ cairo_status_t cairo_image_surface_write_to_jpeg_mem(cairo_surface_t *sfc, unsig
cinfo.in_color_space = cairo_image_surface_get_format(sfc) == CAIRO_FORMAT_ARGB32 ? JCS_EXT_ARGB : JCS_EXT_XRGB;
#endif
cinfo.input_components = 4;
#else
cinfo.in_color_space = JCS_RGB;
cinfo.input_components = 3;
#endif
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, quality, TRUE);
@ -152,8 +196,15 @@ cairo_status_t cairo_image_surface_write_to_jpeg_mem(cairo_surface_t *sfc, unsig
// loop over all lines and compress
while (cinfo.next_scanline < cinfo.image_height)
{
#ifdef LIBJPEG_TURBO_VERSION
row_pointer[0] = cairo_image_surface_get_data(sfc) + (cinfo.next_scanline
* cairo_image_surface_get_stride(sfc));
#else
unsigned char row_buf[3 * cinfo.image_width];
pix_conv(row_buf, 3, cairo_image_surface_get_data(sfc) +
(cinfo.next_scanline * cairo_image_surface_get_stride(sfc)), 4, cinfo.image_width);
row_pointer[0] = row_buf;
#endif
(void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
}
@ -243,6 +294,7 @@ cairo_status_t cairo_image_surface_write_to_jpeg(cairo_surface_t *sfc, const cha
}
/*! This function decompresses a JPEG image from a memory buffer and creates a
* Cairo image surface.
* @param data Pointer to JPEG data (i.e. the full contents of a JPEG file read
@ -264,11 +316,15 @@ cairo_surface_t *cairo_image_surface_create_from_jpeg_mem(void *data, size_t len
jpeg_mem_src(&cinfo, data, len);
(void) jpeg_read_header(&cinfo, TRUE);
#ifdef LIBJPEG_TURBO_VERSION
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
cinfo.out_color_space = JCS_EXT_BGRA;
#else
cinfo.out_color_space = JCS_EXT_ARGB;
#endif
#else
cinfo.out_color_space = JCS_RGB;
#endif
// start decompressor
(void) jpeg_start_decompress(&cinfo);
@ -284,9 +340,13 @@ cairo_surface_t *cairo_image_surface_create_from_jpeg_mem(void *data, size_t len
// loop over all scanlines and fill Cairo image surface
while (cinfo.output_scanline < cinfo.output_height)
{
row_pointer[0] = cairo_image_surface_get_data(sfc) +
unsigned char *row_address = cairo_image_surface_get_data(sfc) +
(cinfo.output_scanline * cairo_image_surface_get_stride(sfc));
row_pointer[0] = row_address;
(void) jpeg_read_scanlines(&cinfo, row_pointer, 1);
#ifndef LIBJPEG_TURBO_VERSION
pix_conv(row_address, 4, row_address, 3, cinfo.output_width);
#endif
}
// finish and close everything