image_extract.c

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/*****************************************************************************
 * ugBASIC - an isomorphic BASIC language compiler for retrocomputers        *
 *****************************************************************************
 * Copyright 2021-2026 Marco Spedaletti (asimov@mclink.it)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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/****************************************************************************
 * INCLUDE SECTION 
 ****************************************************************************/
 
#include "../../ugbc.h"
 
/****************************************************************************
 * CODE SECTION 
 ****************************************************************************/

/* <usermanual>
@keyword IMAGE (function)
 
@english
The ''IMAGE'' command allows you to extract an image from a collection of images 
stored in an ''IMAGES'' or ''SEQUENCE'' variable. Note that extraction occurs at compile 
time: therefore, no extra resources are allocated in the compiled program. This command 
is intended for all those commands that need an image to function, but want to exploit a
graphic resource already loaded and optimized. If ''resource'' is a TILESET, you 
can look for a specific frame by name, unsing the ''NAMED'' parameter.
 
@italian
Il comando ''IMAGE'' consente di estrarre un'immagine da una raccolta di immagini 
memorizzate in una variabile ''IMAGES'' o ''SEQUENCE''. Si noti che l'estrazione 
avviene al momento della compilazione: pertanto, non viene allocata alcuna risorsa 
suppletiva nel programma compilato. Questo comando è inteso per tutti quei comandi 
che hanno bisogno di una immagine per poter funzionare, ma si vuole sfruttare una 
risorsa grafica già caricata e ottimizzata. Se ''resource'' è un TILESET, puoi 
cercare un frame specifico per nome, usando il parametro ''NAMED''.
 
@syntax = IMAGE( resource FRAME num )
@syntax = IMAGE( resource STRIP seq FRAME num )
@syntax = IMAGE( resource NAMED name )
 
@example starship = IMAGE( LOAD IMAGES(("tiles.png") FRAME SIZE(32,32) FRAME 1 )
@example starship = IMAGE( LOAD SEQUENCE("tiles.png") FRAME SIZE(32, 32) STRIP 1 FRAME 2 )
@example tile = IMAGE( LOAD TILESET("tiles.tsx") NAMED pavimento )
 
</usermanual> */
Variable * image_extract( Environment * _environment, char * _images, int _frame, int * _sequence ) {
 
    Variable * result = variable_temporary( _environment, VT_IMAGE, 0 );
 
    Variable * images = variable_retrieve( _environment, _images );
 
    if ( images->type != VT_IMAGES && images->type != VT_SEQUENCE ) {
        CRITICAL_IMAGE_EXTRACT_ON_NOT_IMAGES( _images );
    }
 
    int framesPerRow = images->originalWidth / images->frameWidth;
    int frame = _frame;
    int sequence = ( _sequence ) ? *_sequence : 0;
    char * destination = malloc( images->frameWidth * images->frameHeight * images->originalDepth );
    char * target = NULL;
 
    // printf( "framesPerRow = %d / %d = %d\n", images->originalWidth, images->frameWidth, framesPerRow );
 
    switch( images->type ) {
        case VT_IMAGES:
            target = image_extract_subimage( _environment, images->originalBitmap, images->originalWidth, images->originalHeight, images->frameWidth, images->frameHeight, frame % framesPerRow, frame / framesPerRow, images->originalDepth );
            break;
        case VT_SEQUENCE:
            target = image_extract_subimage( _environment, images->originalBitmap, images->originalWidth, images->originalHeight, images->frameWidth, images->frameHeight, frame, sequence, images->originalDepth );
            break;
    }
 
    // printf( "Before image extract = %d colors\n", images->originalColors );
 
    result->originalBitmap = target;
    result->originalWidth = images->frameWidth;
    result->originalHeight = images->frameHeight;
    result->originalDepth = images->originalDepth;
    result->originalColors = palette_extract( _environment, result->originalBitmap, result->originalWidth, result->originalHeight, result->originalDepth, 0 /* flags */, result->originalPalette );
    
    result->readonly = 1;
 
    // printf( "After image extract = %d colors\n", result->originalColors );
 
    return result;
 
}