cscg24-guacamole

CSCG 2024 Challenge 'Guacamole Mashup'
git clone https://git.sinitax.com/sinitax/cscg24-guacamole
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hash.h (2116B)

      1/*
      2 * Licensed to the Apache Software Foundation (ASF) under one
      3 * or more contributor license agreements.  See the NOTICE file
      4 * distributed with this work for additional information
      5 * regarding copyright ownership.  The ASF licenses this file
      6 * to you under the Apache License, Version 2.0 (the
      7 * "License"); you may not use this file except in compliance
      8 * with the License.  You may obtain a copy of the License at
      9 *
     10 *   http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing,
     13 * software distributed under the License is distributed on an
     14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     15 * KIND, either express or implied.  See the License for the
     16 * specific language governing permissions and limitations
     17 * under the License.
     18 */
     19
     20
     21#ifndef _GUAC_HASH_H
     22#define _GUAC_HASH_H
     23
     24/**
     25 * Provides functions and structures for producing likely-to-be-unique hash
     26 * values for images.
     27 *
     28 * @file hash.h
     29 */
     30
     31#include <cairo/cairo.h>
     32
     33/**
     34 * Produces a 24-bit hash value from all pixels of the given surface. The
     35 * surface provided must be RGB or ARGB with each pixel stored in 32 bits.
     36 * The hashing algorithm used is a variant of the cyclic polynomial rolling
     37 * hash.
     38 *
     39 * @param surface The Cairo surface to hash.
     40 * @return An arbitrary 24-bit unsigned integer value intended to be well
     41 *         distributed across different images.
     42 */
     43unsigned int guac_hash_surface(cairo_surface_t* surface);
     44
     45/**
     46 * Given two Cairo surfaces, returns zero if the data contained within each
     47 * is identical, and a positive or negative value if the value of the first
     48 * is found to be lexically greater or less than the second respectively.
     49 *
     50 * @param a The first Cairo surface to compare.
     51 * @param b The Cairo surface to compare the first surface against.
     52 * @return Zero if the data contained within each is identical, and a positive
     53 *         or negative value if the value of the first is found to be lexically
     54 *         greater or less than the second respectively.
     55 */
     56int guac_surface_cmp(cairo_surface_t* a, cairo_surface_t* b);
     57
     58#endif
     59