diff options
Diffstat (limited to 'glcd.c')
| -rw-r--r-- | glcd.c | 28 |
1 files changed, 28 insertions, 0 deletions
@@ -319,6 +319,34 @@ void lcdDrawCircle(uint16_t x, uint16_t y, uint16_t radius, uint8_t filled, uint } while(a <= b); } +void lcdDrawEllipse(uint16_t x, uint16_t y, uint16_t a, uint16_t b, uint16_t color) { + int dx = 0, dy = b; /* im I. Quadranten von links oben nach rechts unten */ + long a2 = a*a, b2 = b*b; + long err = b2-(2*b-1)*a2, e2; /* Fehler im 1. Schritt */ + + do { + lcdDrawPixel(x+dx, y+dy, color); /* I. Quadrant */ + lcdDrawPixel(x-dx, y+dy, color); /* II. Quadrant */ + lcdDrawPixel(x-dx, y-dy, color); /* III. Quadrant */ + lcdDrawPixel(x+dx, y-dy, color); /* IV. Quadrant */ + + e2 = 2*err; + if(e2 < (2*dx+1)*b2) { + dx++; + err += (2*dx+1)*b2; + } + if(e2 > -(2*dy-1)*a2) { + dy--; + err -= (2*dy-1)*a2; + } + } while(dy >= 0); + + while(dx++ < a) { /* fehlerhafter Abbruch bei flachen Ellipsen (b=1) */ + lcdDrawPixel(x+dx, y, color); /* -> Spitze der Ellipse vollenden */ + lcdDrawPixel(x-dx, y, color); + } +} + void lcdVerticalScroll(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, int16_t lines) { lld_lcdVerticalScroll(x0,y0,x1,y1,lines); } |