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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 <stdint.h>

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#include <stdbool.h>

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#include <png.h>

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/**

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 * State for cache access

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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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    /** The mmap'd header */

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    struct pt_cache_header *header;

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    /** Memory-mapped file data, starting at PT_CACHE_HEADER_SIZE */

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    uint8_t *data;

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

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    size_t size;

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};

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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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    /** Pixel dimensions of image */

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    uint32_t width, height;

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    /** Pixel format */

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    uint8_t bit_depth, color_type;

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    /** Number of png_color entries that follow */

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    uint16_t num_palette;

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    /** Number of bytes per row */

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    uint32_t row_bytes;

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    /** Number of bytes per pixel */

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    uint8_t col_bytes;

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    /** Palette entries, up to 256 entries used */

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    png_color palette[PNG_MAX_PALETTE_LENGTH];

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    /** Parameters used */

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    struct pt_image_params params;

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};

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/**

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 * Handle sparse data at this granularity (pixels)

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 */

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#define PT_CACHE_BLOCK_SIZE 64

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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, open it if not already open.

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 */

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int 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 PNG image.

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 */

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int pt_cache_update_png (struct pt_cache *cache, png_structp png, png_infop info, 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 a PNG tile as given, into the established png object, up to (but not including) the png_write_end.

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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_png (struct pt_cache *cache, png_structp png, png_infop info, const struct pt_tile_info *ti);

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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