gp_container.h

// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * Copyright (C) 2009-2013 Cyril Hrubis <metan@ucw.cz>
 */
 
 /*
 
   Container is an abstraction for file formats that can include several images
   in one file. For example gif, tiff, apng, cbr, cbz, etc.
 
  */
 
#ifndef LOADERS_GP_CONTAINER_H
#define LOADERS_GP_CONTAINER_H
 
#include <core/gp_types.h>
#include <core/gp_progress_callback.h>
#include <utils/gp_seek.h>
#include <loaders/gp_types.h>
 
#include <loaders/gp_data_storage.h>
 
struct gp_container_ops {
        /*
         * Loads next image from container, use the inline function defined
         * below.
         */
        gp_pixmap *(*load_next)(gp_container *self, gp_progress_cb *callback);
 
        /*
         * Just loads current image, does not advance to the next image.
         */
        int (*load_ex)(gp_container *self, gp_pixmap **img,
                       gp_storage *storage, gp_progress_cb *callback);
 
        /*
         * Close callback, use the inline function defined below.
         */
        void (*close)(gp_container *self);
 
        /*
         * Seeks to the offset from whence.
         *
         * Returns 0 on success, errno on failure.
         */
        int (*seek)(gp_container *self, ssize_t offset,
                    enum gp_seek_whence whence);
 
 
        int (*match)(const void *buf);
 
        /*
         * Initializes container.
         */
        gp_container *(*init)(gp_io *io);
 
        /* Short format name */
        const char *fmt_name;
 
        /* NULL terminated list of file extensions */
        const char *const extensions[];
};
 
struct gp_container {
        /*
         * Image counter. This is set to number of images, or to -1 if number
         * of images in container is not known prior to parsing the whole
         * file.
         */
        unsigned int img_count;
 
        /*
         * Current image counter, do not change from application.
         */
        unsigned int cur_img;
 
        /*
         * Contains container callbacks
         */
        const struct gp_container_ops *ops;
 
        char priv[];
};
 
#define GP_CONTAINER_PRIV(c) ((void*)(c)->priv)
 
/*
 * Behaves just like gp_load_image, but takes pointer to opened container instead.
 */
static inline gp_pixmap *gp_container_load_next(gp_container *self,
                                                gp_progress_cb *callback)
{
        return self->ops->load_next(self, callback);
}
 
/*
 * Just loads current image, does not advance to the next one.
 */
int gp_container_load_ex(gp_container *self, gp_pixmap **img,
                         gp_storage *storage, gp_progress_cb *callback);
 
static inline gp_pixmap *gp_container_load(gp_container *self,
                                           gp_progress_cb *callback)
{
        gp_pixmap *ret = NULL;
 
        gp_container_load_ex(self, &ret, NULL, callback);
 
        return ret;
}
 
int gp_container_seek(gp_container *self, ssize_t offset,
                      enum gp_seek_whence whence);
 
static inline void gp_container_close(gp_container *self)
{
        self->ops->close(self);
}
 
gp_container *gp_container_open(const char *path);
 
#endif /* LOADERS_GP_CONTAINER_H */