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#include "image.h"

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#include "cache.h"

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#include "shared/util.h"

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#include <stdlib.h>

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#include <limits.h> // for _POSIX_PATH_MAX

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#include <png.h>

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static int pt_image_new (struct pt_image **img_ptr, struct pt_ctx *ctx, const char *path)

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{

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    struct pt_image *img;

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    // alloc

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    if ((img = calloc(1, sizeof(*img))) == NULL)

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        return -1;

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    if ((img->path = strdup(path)) == NULL)

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        goto error;

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    // init

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    img->ctx = ctx;

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    // ok

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    *img_ptr = img;

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    return 0;

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error:

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    pt_image_destroy(img);

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    return -1;

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}

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/**

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 * Open the image's FILE

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 */

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static int pt_image_open_file (struct pt_image *img, FILE **file_ptr)

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{

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    FILE *fp;

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    // open

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    if ((fp = fopen(img->path, "rb")) < 0)

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        return -1;

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    // ok

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    *file_ptr = fp;

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    return 0;

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}

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/**

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 * Open the PNG image, setting up the I/O and returning the png_structp and png_infop

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 */

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static int pt_image_open_png (struct pt_image *img, png_structp *png_ptr, png_infop *info_ptr)

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{

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    FILE *fp = NULL;

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    png_structp png = NULL;

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    png_infop info = NULL;

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    // open I/O

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    if (pt_image_open_file(img, &fp))

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        goto error;

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    // create the struct

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    if ((png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)) == NULL)

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        goto error;

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    // create the info

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    if ((info = png_create_info_struct(png)) == NULL)

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        goto error;

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    // setup error trap for the I/O

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    if (setjmp(png_jmpbuf(png)))

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        goto error;

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    // setup I/O to FILE

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    png_init_io(png, fp);

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    // ok

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    // XXX: what to do with fp?

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    *png_ptr = png;

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    *info_ptr = info;

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    return 0;

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error:

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    // cleanup file

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    if (fp) fclose(fp);

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    // cleanup PNG state

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    png_destroy_read_struct(&png, &info, NULL);

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    return -1;

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}

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/**

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 * Open the PNG image, and write out to the cache

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 */

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static int pt_image_update_cache (struct pt_image *img)

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{

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    png_structp png;

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    png_infop info;

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    // open .png

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    if (pt_image_open_png(img, &png, &info))

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        return -1;

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    // setup error trap

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    if (setjmp(png_jmpbuf(png)))

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        goto error;

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    // read meta-info

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    png_read_info(png, info);

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    // pass to cache object

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    if (pt_cache_update_png(img->cache, png, info))

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        goto error;

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    // finish off, ignore trailing data

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    png_read_end(png, NULL);

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    // clean up

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    png_destroy_read_struct(&png, &info, NULL);

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    return 0;

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error:

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    // clean up

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    png_destroy_read_struct(&png, &info, NULL);

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    return -1;

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}

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/**

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 * Build a filesystem path representing the appropriate path for this image's cache entry, and store it in the given

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 * buffer.

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 */

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static int pt_image_cache_path (struct pt_image *image, char *buf, size_t len)

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{

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    return path_with_fext(image->path, buf, len, ".cache"); 

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}

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int pt_image_open (struct pt_image **image_ptr, struct pt_ctx *ctx, const char *path, int cache_mode)

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{

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    struct pt_image *image;

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    char cache_path[_POSIX_PATH_MAX];

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    // XXX: verify that the path exists and looks like a PNG file

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    // alloc

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    if (pt_image_new(&image, ctx, path))

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        return -1;

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    // compute cache file path

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    if (pt_image_cache_path(image, cache_path, sizeof(cache_path)))

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        goto error;

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    // open the cache object for this image

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    if (pt_cache_open(&image->cache, cache_path, cache_mode))

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        goto error;

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    // ok, ready for access

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    *image_ptr = image;

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    return 0;

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error:

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    pt_image_destroy(image);

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    return -1;

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}

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void pt_image_destroy (struct pt_image *image)

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{

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    free(image->path);

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    if (image->cache)

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        pt_cache_destroy(image->cache);

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    free(image);

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}