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#ifndef PNGTILE_CACHE_H

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#define PNGTILE_CACHE_H

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/**

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 * @file

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 *

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 * Internal image cache implementation

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 */

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#include "image.h"

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#include "png.h"

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#include <stdint.h>

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#include <stdbool.h>

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/**

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 * Cache format version

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 */

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#define PT_CACHE_VERSION 2

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/**

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 * Size used to store the cache header

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 */

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#define PT_CACHE_HEADER_SIZE 4096

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/**

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 * On-disk header

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 */

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struct pt_cache_header {

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    /** Set to PT_CACHE_VERSION */

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    uint16_t version;

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    /** Image format */

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    enum pt_img_format {

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        PT_IMG_PNG,     ///< @see pt_png

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    } format;

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    /** Data header by format  */

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    union {

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        struct pt_png_header png;

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    };

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    /** Parameters used */

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    struct pt_image_params params;

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    /** Size of the data segment */

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    size_t data_size;

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};

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/**

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 */

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struct pt_cache_file {

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    /** Header */

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    struct pt_cache_header header;

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    /** Padding for data */

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    uint8_t padding[PT_CACHE_HEADER_SIZE - sizeof(struct pt_cache_header)];

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    /** Data follows, header.data_size bytes */

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    uint8_t data[];

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};

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/**

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 * Cache state

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 */

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struct pt_cache {

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    /** Filesystem path to cache file */

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    char *path;

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    /** The mode we are operating in, bitmask of PT_IMG_* */

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    int mode;

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    /** Opened file */

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    int fd;

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    /** Size of the data segment in bytes, starting at PT_CACHE_HEADER_SIZE */

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    size_t data_size;

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    /** The mmap'd file */

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    struct pt_cache_file *file;

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};

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/**

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 * Construct the image cache info object associated with the given image.

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 */

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int pt_cache_new (struct pt_cache **cache_ptr, const char *path, int mode);

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/**

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 * Verify if the cached data eixsts, or has become stale compared to the given original file.

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 *

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 * @return one of pt_cache_status; <0 on error, 0 if fresh, >0 otherwise

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 */

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int pt_cache_status (struct pt_cache *cache, const char *img_path);

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/**

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 * Get info for the cached image.

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 *

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 * Does not open it if not yet opened.

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 */

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void pt_cache_info (struct pt_cache *cache, struct pt_image_info *info);

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/**

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 * Update the cache data from the given image data

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 */

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int pt_cache_update (struct pt_cache *cache, struct pt_png_img *img, const struct pt_image_params *params);

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/**

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 * Open the existing .cache for use. If already opened, does nothing.

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 */

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int pt_cache_open (struct pt_cache *cache);

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/**

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 * Render out the given tile

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 *

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 * If the cache is not yet open, this will open it

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 */

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int pt_cache_tile (struct pt_cache *cache, struct pt_tile *tile);

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/**

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 * Close the cache, if opened

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 */

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int pt_cache_close (struct pt_cache *cache);

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/**

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 * Release all resources associated with the given cache object without any cleanup.

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 */

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void pt_cache_destroy (struct pt_cache *cache);

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#endif