create alternative fillCircleHelper

Author: BillMerryman

Adafruit_GFX.cpp

@@ -514,7 +514,7 @@ void Adafruit_GFX::drawCircle(int16_t x0, int16_t y0, int16_t r,
     @param    x0   Center-point x coordinate
     @param    y0   Center-point y coordinate
     @param    r   Radius of circle
-    @param    cornername  Mask bit #1 or bit #2 to indicate which quarters of
+    @param    cornername  Mask bit #1, #2, #4, and #8 to indicate which quarters of
    the circle we're doing
     @param    color 16-bit 5-6-5 Color to draw with
 */
@@ -574,11 +574,12 @@ void Adafruit_GFX::fillCircle(int16_t x0, int16_t y0, int16_t r,
 
 /**************************************************************************/
 /*!
-    @brief  Quarter-circle drawer with fill, used for circles and roundrects
+    @brief  Half-circle drawer with fill, used for circles and roundrects
     @param  x0       Center-point x coordinate
     @param  y0       Center-point y coordinate
     @param  r        Radius of circle
-    @param  corners  Mask bits indicating which quarters we're doing
+    @param  corners  Mask bits indicating which sides of the circle we are doing,
+                        left and/or right
     @param  delta    Offset from center-point, used for round-rects
     @param  color    16-bit 5-6-5 Color to fill with
 */
@@ -625,6 +626,79 @@ void Adafruit_GFX::fillCircleHelper(int16_t x0, int16_t y0, int16_t r,
   }
 }
 
+/**************************************************************************/
+/*!
+    @brief  Quarter-circle drawer with fill.
+    @param  useLegacy       uses the half-circle implementation if desired
+    @param  x0       Center-point x coordinate
+    @param  y0       Center-point y coordinate
+    @param  r        Radius of circle
+    @param  corners  Mask bit #1, #2, #4, and #8 to indicate which quarters of
+   the circle we're doing
+    @param  delta    Offset from center-point. Elongates the horizontal face if desired.
+    @param  color    16-bit 5-6-5 Color to fill with
+*/
+/**************************************************************************/
+void Adafruit_GFX::fillCircleHelper(bool useLegacy, 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(useLegacy){
+      fillCircleHelper(x0, y0, r, corners, delta, color);
+      return;
+  }
+  
+  if (corners & (0x2 | 0x1))
+    writeFastVLine(x0, y0 - r, r + 1, color);
+  if (corners & (0x8 | 0x4))
+    writeFastVLine(x0, y0, r + 1, color);
+
+  delta++; // Avoid some +1's in the loop
+
+  while (x < y) {
+    if (f >= 0) {
+      y--;
+      ddF_y += 2;
+      f += ddF_y;
+    }
+    x++;
+    ddF_x += 2;
+    f += ddF_x;
+    // These checks avoid double-drawing certain lines, important
+    // for the SSD1306 library which has an INVERT drawing mode.
+    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

Adafruit_GFX.h

@@ -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 fillCircleHelper(bool useLegacy, 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,