80 lines
1.7 KiB
C
80 lines
1.7 KiB
C
/**
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* @file lv_circ.c
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* Circle drawing algorithm (with Bresenham)
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* Only a 1/8 circle is calculated. Use CIRC_OCT1_X, CIRC_OCT1_Y macros to get
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* the other octets.
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*/
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/*********************
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* INCLUDES
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*********************/
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#include "lv_circ.h"
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/*********************
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* DEFINES
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*********************/
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/**********************
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* TYPEDEFS
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**********************/
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/**********************
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* STATIC PROTOTYPES
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**********************/
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/**********************
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* STATIC VARIABLES
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**********************/
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/**********************
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* MACROS
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**********************/
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/**********************
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* GLOBAL FUNCTIONS
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**********************/
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/**
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* Initialize the circle drawing
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* @param c pointer to a point. The coordinates will be calculated here
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* @param tmp point to a variable. It will store temporary data
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* @param radius radius of the circle
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*/
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void lv_circ_init(lv_point_t * c, lv_coord_t * tmp, lv_coord_t radius)
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{
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c->x = radius;
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c->y = 0;
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*tmp = 1 - radius;
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}
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/**
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* Test the circle drawing is ready or not
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* @param c same as in circ_init
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* @return true if the circle is not ready yet
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*/
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bool lv_circ_cont(lv_point_t * c)
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{
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return c->y <= c->x ? true : false;
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}
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/**
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* Get the next point from the circle
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* @param c same as in circ_init. The next point stored here.
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* @param tmp same as in circ_init.
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*/
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void lv_circ_next(lv_point_t * c, lv_coord_t * tmp)
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{
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c->y++;
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if(*tmp <= 0) {
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(*tmp) += 2 * c->y + 1; // Change in decision criterion for y -> y+1
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} else {
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c->x--;
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(*tmp) += 2 * (c->y - c->x) + 1; // Change for y -> y+1, x -> x-1
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}
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}
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/**********************
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* STATIC FUNCTIONS
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**********************/
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