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Add quarter circle draw-with-fill method #488

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Add quarter circle draw-with-fill method #488

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1c59350
Add quarter circle draw method
BillMerryman Nov 7, 2025
18e6e8b
Add quarter circle draw method (formatting)
BillMerryman Nov 7, 2025
5ec6f8e
Add quarter circle draw method (update briefs)
BillMerryman Nov 7, 2025
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68 changes: 68 additions & 0 deletions Adafruit_GFX.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -625,6 +625,74 @@ void Adafruit_GFX::fillCircleHelper(int16_t x0, int16_t y0, int16_t r,
}
}

/**************************************************************************/
/*!
@brief Quarter-circle drawer with fill.
@param x0 Center-point x coordinate
@param y0 Center-point y coordinate
@param r Radius of circle
@param corners Mask bits 0x1, 0x2, 0x4, and 0x8 to indicate which quarters
of the circle to fill: 0x1 = top-left, 0x2 = top-right,
0x4 = bottom-right, 0x8 = bottom-left
@param delta Offset from center-point. Elongates the horizontal face (by
extending the vertical lines) if desired.
@param color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::fillQuarterCircle(int16_t x0, int16_t y0, int16_t r,
uint8_t corners, int16_t delta,
uint16_t color) {

int16_t f = 1 - r;
int16_t ddF_x = 1;
int16_t ddF_y = -2 * r;
int16_t x = 0;
int16_t y = r;
int16_t px = x;
int16_t py = y;

if (corners & (0x2 | 0x1))
writeFastVLine(x0, y0 - r, r + 1, color);
if (corners & (0x8 | 0x4))
writeFastVLine(x0, y0, r + 1, color);

delta++;

while (x < y) {
if (f >= 0) {
y--;
ddF_y += 2;
f += ddF_y;
}
x++;
ddF_x += 2;
f += ddF_x;

if (x < (y + 1)) {
if (corners & 0x4)
writeFastVLine(x0 + x, y0, y + delta, color);
if (corners & 0x2)
writeFastVLine(x0 + x, y0 - y, y + delta, color);
if (corners & 0x8)
writeFastVLine(x0 - x, y0, y + delta, color);
if (corners & 0x1)
writeFastVLine(x0 - x, y0 - y, y + delta, color);
}
if (y != py) {
if (corners & 0x4)
writeFastVLine(x0 + py, y0, px + delta, color);
if (corners & 0x2)
writeFastVLine(x0 + py, y0 - px, px + delta, color);
if (corners & 0x8)
writeFastVLine(x0 - py, y0, px + delta, color);
if (corners & 0x1)
writeFastVLine(x0 - py, y0 - px, px + delta, color);
py = y;
}
px = x;
}
}

/**************************************************************************/
/*!
@brief Draw a rectangle with no fill color
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2 changes: 2 additions & 0 deletions Adafruit_GFX.h
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Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,8 @@ 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 fillQuarterCircle(int16_t x0, int16_t y0, int16_t r, uint8_t corners,
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,
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