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Merged
merged 2 commits into from
Sep 14, 2025
Merged

Added drawEllipse and fillEllipse functions #477

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ff66950
Added drawEllipse and fillEllipse functions
DS-Aditya-928 Sep 13, 2025
1418af1
Formatting fixes
DS-Aditya-928 Sep 13, 2025
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116 changes: 116 additions & 0 deletions Adafruit_GFX.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -345,6 +345,122 @@ void Adafruit_GFX::drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1,
}
}

/**************************************************************************/
/*!
@brief Draw an ellipse outline
@param x0 Center-point x coordinate
@param y0 Center-point y coordinate
@param rw Horizontal radius of ellipse
@param rh Vertical radius of ellipse
@param color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
void Adafruit_GFX::drawEllipse(int16_t x0, int16_t y0, int16_t rw, int16_t rh,
uint16_t color) {
#if defined(ESP8266)
yield();
#endif
// Bresenham's ellipse algorithm
int16_t x = 0, y = rh;
int32_t rw2 = rw * rw, rh2 = rh * rh;
int32_t twoRw2 = 2 * rw2, twoRh2 = 2 * rh2;

int32_t decision = rh2 - (rw2 * rh) + (rw2 / 4);

startWrite();

// region 1
while ((twoRh2 * x) < (twoRw2 * y)) {
writePixel(x0 + x, y0 + y, color);
writePixel(x0 - x, y0 + y, color);
writePixel(x0 + x, y0 - y, color);
writePixel(x0 - x, y0 - y, color);
x++;
if (decision < 0) {
decision += rh2 + (twoRh2 * x);
} else {
decision += rh2 + (twoRh2 * x) - (twoRw2 * y);
y--;
}
}

// region 2
decision = ((rh2 * (2 * x + 1) * (2 * x + 1)) >> 2) +
(rw2 * (y - 1) * (y - 1)) - (rw2 * rh2);
while (y >= 0) {
writePixel(x0 + x, y0 + y, color);
writePixel(x0 - x, y0 + y, color);
writePixel(x0 + x, y0 - y, color);
writePixel(x0 - x, y0 - y, color);
y--;
if (decision > 0) {
decision += rw2 - (twoRw2 * y);
} else {
decision += rw2 + (twoRh2 * x) - (twoRw2 * y);
x++;
}
}

endWrite();
}

/**************************************************************************/
/*!
@brief Draw an ellipse with filled colour
@param x0 Center-point x coordinate
@param y0 Center-point y coordinate
@param rw Horizontal radius of ellipse
@param rh Vertical radius of ellipse
@param color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
void Adafruit_GFX::fillEllipse(int16_t x0, int16_t y0, int16_t rw, int16_t rh,
uint16_t color) {
#if defined(ESP8266)
yield();
#endif
// Bresenham's ellipse algorithm
int16_t x = 0, y = rh;
int32_t rw2 = rw * rw, rh2 = rh * rh;
int32_t twoRw2 = 2 * rw2, twoRh2 = 2 * rh2;

int32_t decision = rh2 - (rw2 * rh) + (rw2 / 4);

startWrite();

// region 1
while ((twoRh2 * x) < (twoRw2 * y)) {
drawFastHLine(x0 - x, y0 + y, 2 * x + 1, color);
drawFastHLine(x0 - x, y0 - y, 2 * x + 1, color);

x++;
if (decision < 0) {
decision += rh2 + (twoRh2 * x);
} else {
decision += rh2 + (twoRh2 * x) - (twoRw2 * y);
y--;
}
}

// region 2
decision = ((rh2 * (2 * x + 1) * (2 * x + 1)) >> 2) +
(rw2 * (y - 1) * (y - 1)) - (rw2 * rh2);
while (y >= 0) {
drawFastHLine(x0 - x, y0 + y, 2 * x + 1, color);
drawFastHLine(x0 - x, y0 - y, 2 * x + 1, color);

y--;
if (decision > 0) {
decision += rw2 - (twoRw2 * y);
} else {
decision += rw2 + (twoRh2 * x) - (twoRw2 * y);
x++;
}
}

endWrite();
}

/**************************************************************************/
/*!
@brief Draw a circle outline
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4 changes: 4 additions & 0 deletions Adafruit_GFX.h
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Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,10 @@ class Adafruit_GFX : public Print {
void fillCircle(int16_t x0, int16_t y0, int16_t r, uint16_t color);
void fillCircleHelper(int16_t x0, int16_t y0, int16_t r, uint8_t cornername,
int16_t delta, uint16_t color);
void drawEllipse(int16_t x0, int16_t y0, int16_t rw, int16_t rh,
uint16_t color);
void fillEllipse(int16_t x0, int16_t y0, int16_t rw, int16_t rh,
uint16_t color);
void drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2,
int16_t y2, uint16_t color);
void fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2,
Expand Down