1 /* 2 * Common viewport-related functions. 3 * 4 * Copyright (C) 2018 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software: you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation, either version 3 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program. If not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 #ifndef __VIEWPORT_H__ 21 #define __VIEWPORT_H__ 22 23 #include "display.h" 24 #include "image.h" 25 26 27 28 /* An abstraction providing a scrolling viewport. */ 29 30 typedef struct 31 { 32 /* Display configuration. */ 33 34 display_config_t *cfg; 35 36 /* Scrolling positions for each frame. */ 37 38 int *xorigins, *yorigins; 39 40 /* Scrolling position. */ 41 42 int xorigin, yorigin; 43 44 /* Scaling factors, translating the origin coordinates to display columns 45 and rows. */ 46 47 int xscale, yscale; 48 49 /* Update function after scrolling. */ 50 51 void (*update)(); 52 53 } viewport_t; 54 55 56 57 /* Initialise a viewport. 58 59 Viewport(<name>, display_config_t *cfg, int xscale, int yscale, void (*update)()) 60 */ 61 62 #define Viewport(NAME, CFG, XSCALE, YSCALE, UPDATE) \ 63 int __##NAME##_xorigins[(CFG)->frames]; \ 64 int __##NAME##_yorigins[(CFG)->frames]; \ 65 viewport_t NAME = { \ 66 .cfg=CFG, \ 67 .xorigins=__##NAME##_xorigins, \ 68 .yorigins=__##NAME##_yorigins, \ 69 .xorigin=0, \ 70 .yorigin=0, \ 71 .xscale=XSCALE, \ 72 .yscale=YSCALE, \ 73 .update=UPDATE}; 74 75 /* Viewport operations. */ 76 77 void viewport_set_origin(viewport_t *v, int xorigin, int yorigin); 78 79 void viewport_update_origin(viewport_t *v, int dx, int dy); 80 81 /* Update operations. */ 82 83 void viewport_unplot_sprite_from_image(viewport_t *v, sprite_t *s, sprite_t *bg); 84 85 #endif /* __VIEWPORT_H__ */