clip.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
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *----------------------------------------------------------------------------
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 * (la "Licenza"); è proibito usare questo file se non in conformità alla
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 * Se non richiesto dalla legislazione vigente o concordato per iscritto,
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/****************************************************************************
 * INCLUDE SECTION 
 ****************************************************************************/
 
#include "../../ugbc.h"
 
/****************************************************************************
 * CODE SECTION 
 ****************************************************************************/

/* <usermanual>
@keyword CLIP
 
@english
 
The ''CLIP'' instruction allows you to delimit the area in which the graphics 
are actually drawn. In general, the area corresponds to the entire surface 
of the screen ''(0,0)-(SCREEN WIDTH-1,SCREEN HEIGHT-1)''. However, it is possible 
to limit the drawing to a sub area, to ensure that the area outside this crop 
area is not altered or modified. The area is bounded by the coordinate ''(x1, y1)'' 
to the coordinate ''(x2, y2)''. If components are omitted, the screen limits will be used.
 
@italian
L'istruzione ''CLIP'' permette di delimitare l'area nella quale la grafica 
viene effettivamente disegnata. In generale, l'area corrisponde all'intera 
superficie dello schermo. E' tuttavia possibile limitare il disegno a una sotto 
area, di modo da garantire che l'are al di fuori di tale area di ritaglio non 
venga alterata o modificata. L'area viene delimitata dalla coordinata ''(x1,y1)'' 
alla coordinata ''(x2,y2)''. In mancanza di componenti, l'intero schermo sarà
considerato.
 
@syntax CLIP x1,y1 TO x2, x2
 
@example CLIP 42,42 TO 84,84
@usedInExample graphics_clip_01.bas
 
@target all
</usermanual> */
void clip( Environment * _environment, char * _x1, char * _y1, char * _x2, char * _y2 ) {
 
    Variable * c;
    
    c = variable_retrieve( _environment, "CLIPX1" );
    if ( _x1 ) {
        Variable * x = variable_retrieve_or_define( _environment, _x1, VT_POSITION, 0 );
        variable_move( _environment, x->name, c->name );
    } else {
        variable_store( _environment, c->name, 0 );
    }
 
    c = variable_retrieve( _environment, "CLIPY1" );
    if ( _y1 ) {
        Variable * x = variable_retrieve_or_define( _environment, _y1, VT_POSITION, 0 );
        variable_move( _environment, x->name, c->name );
    } else {
        variable_store( _environment, c->name, 0 );
    }
 
    c = variable_retrieve( _environment, "CLIPX2" );
    if ( _x2 ) {
        Variable * x = variable_retrieve_or_define( _environment, _x2, VT_POSITION, 0 );
        variable_move( _environment, x->name, c->name );
    } else {
        variable_move( _environment, screen_get_width( _environment )->name, c->name );
    }
 
    c = variable_retrieve( _environment, "CLIPY2" );
    if ( _y2 ) {
        Variable * x = variable_retrieve_or_define( _environment, _y2, VT_POSITION, 0 );
        variable_move( _environment, x->name, c->name );
    } else {
        variable_move( _environment, screen_get_height( _environment )->name, c->name );
    }
 
}