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# cairo_jpg
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2016-01-01 13:49:39 +01:00
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## Introduction
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This is an implementation of functions to import and export Cairo surfaces from
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and to JPEG files. It uses the same function prototypes as Cairo's [PNG
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support](http://www.cairographics.org/manual/cairo-PNG-Support.html).
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## Description
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The implementation is done on top of the Cairo API. It does not access
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Cairo-internal functions.
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2018-02-16 11:40:03 +01:00
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For compression and decompression a JPEG library is used. It compiles against
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[libjpeg-turbo](https://libjpeg-turbo.org/) or the original
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[libjpeg](http://www.ijg.org/).
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2016-01-01 13:49:39 +01:00
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2018-02-16 11:40:03 +01:00
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The following prototypes are implemented. Their functionality is equal to the
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2016-01-01 13:49:39 +01:00
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PNG functions of Cairo with the advance that there are memory-buffer-based
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functions as well.
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```C
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cairo_status_t cairo_image_surface_write_to_jpeg_mem(cairo_surface_t *sfc, unsigned char **data, size_t *len, int quality);
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cairo_status_t cairo_image_surface_write_to_jpeg_stream(cairo_surface_t *sfc, cairo_write_func_t write_func, void *closure, int quality);
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cairo_status_t cairo_image_surface_write_to_jpeg(cairo_surface_t *sfc, const char *filename, int quality);
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cairo_surface_t *cairo_image_surface_create_from_jpeg_mem(void *data, size_t len);
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cairo_surface_t *cairo_image_surface_create_from_jpeg_stream(cairo_read_func_t read_func, void *closure);
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cairo_surface_t *cairo_image_surface_create_from_jpeg(const char *filename);
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```
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To compile this code you need to have installed the packages libcairo2-dev
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and libjpeg-dev. Compile with the following command to create an object file
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linkable to your code:
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```Shell
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gcc -Wall -c `pkg-config cairo libjpeg --cflags --libs` cairo_jpg.c
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```
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Please have a look at the comments within the source files for further details.
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Don't hesitate to contact me at [bf@abenteuerland.at](mailto:bf@abenteuerland.at).
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2018-02-16 11:40:03 +01:00
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## Testing
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There is a ```main()``` function implemented which serves as demonstrational
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purpose and for testing. To compile with the ```main()``` function run the
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following statement:
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```Shell
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gcc -Wall -o cairo_jpg -DCAIRO_JPEG_MAIN `pkg-config cairo libjpeg --cflags --libs` cairo_jpg.c
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```
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