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 25 26 27 /* An abstraction providing a scrolling viewport. */ 28 29 typedef struct 30 { 31 /* Display configuration. */ 32 33 display_config_t *cfg; 34 35 /* Scrolling positions for each frame. */ 36 37 int *xorigins, *yorigins; 38 39 /* Scrolling position. */ 40 41 int xorigin, yorigin; 42 43 /* Scaling factors, translating the origin coordinates to display columns 44 and rows. */ 45 46 int xscale, yscale; 47 48 /* Update function after scrolling. */ 49 50 void (*update)(); 51 52 } viewport_t; 53 54 55 56 /* Initialise a viewport. 57 58 Viewport(<name>, display_config_t *cfg, int xscale, int yscale, void (*update)()) 59 */ 60 61 #define Viewport(NAME, CFG, XSCALE, YSCALE, UPDATE) \ 62 int __##NAME##_xorigins[(CFG)->frames]; \ 63 int __##NAME##_yorigins[(CFG)->frames]; \ 64 viewport_t NAME = { \ 65 .cfg=CFG, \ 66 .xorigins=__##NAME##_xorigins, \ 67 .yorigins=__##NAME##_yorigins, \ 68 .xorigin=0, \ 69 .yorigin=0, \ 70 .xscale=XSCALE, \ 71 .yscale=YSCALE, \ 72 .update=UPDATE}; 73 74 /* Viewport operations. */ 75 76 void viewport_set_origin(viewport_t *v, int xorigin, int yorigin); 77 78 void viewport_update_origin(viewport_t *v, int dx, int dy); 79 80 #endif /* __VIEWPORT_H__ */