adding circle and ellipse drawing functions

Author: leonardocavagnis

docs/api.md

@@ -539,6 +539,83 @@ YourScreen.endDraw();
 ```
 
 
+### `circle()`
+
+#### Description
+
+
+Stroke and fill a circle, uses the stroke color set in stroke() and the fill color set in fill().
+
+#### Syntax
+
+```
+YourScreen.circle(x, y, diameter)
+
+```
+
+
+#### Parameters
+
+
+- x: x center position of the circle
+- y: y center position of the circle
+- diameter: diameter of the circle
+
+#### Returns
+
+Nothing
+
+#### Example
+
+```
+YourScreen.beginDraw();
+YourScreen.clear();
+YourScreen.noStroke();
+YourScreen.fill(255, 255, 0);
+YourScreen.circle(YourScreen.width()/2, YourScreen.height()/2, YourScreen.height());
+YourScreen.endDraw();
+```
+
+
+### `ellipse()`
+
+#### Description
+
+
+Stroke and fill an ellipse, uses the stroke color set in stroke() and the fill color set in fill().
+
+#### Syntax
+
+```
+YourScreen.ellipse(x, y, width, height)
+
+```
+
+
+#### Parameters
+
+
+- x: x center position of the ellipse
+- y: y center position of the ellipse
+- width: width of the ellipse
+- height: height of the ellipse
+
+#### Returns
+
+Nothing
+
+#### Example
+
+```
+YourScreen.beginDraw();
+YourScreen.clear();
+YourScreen.noStroke();
+YourScreen.fill(255, 255, 0);
+YourScreen.ellipse(YourScreen.width()/2, YourScreen.height()/2, YourScreen.width(), YourScreen.height());
+YourScreen.endDraw();
+```
+
+
 ### `text()`
 
 #### Description

keywords.txt

@@ -33,6 +33,8 @@ line	KEYWORD2
 point	KEYWORD2
 quad	KEYWORD2
 rect	KEYWORD2
+circle	KEYWORD2
+ellipse	KEYWORD2
 
 text	KEYWORD2
 textFont	KEYWORD2

src/ArduinoGraphics.cpp

@@ -59,6 +59,12 @@ int ArduinoGraphics::height()
   return _height;
 }
 
+uint32_t ArduinoGraphics::background() 
+{
+  uint32_t bg = (uint32_t)((uint32_t)(_backgroundR << 16) | (uint32_t)(_backgroundG << 8) | (uint32_t)(_backgroundB << 0));
+  return bg;
+}
+
 void ArduinoGraphics::beginDraw()
 {
 }
@@ -124,6 +130,47 @@ void ArduinoGraphics::noStroke()
   _stroke = false;
 }
 
+void ArduinoGraphics::circle(int x, int y, int diameter)
+{
+  ellipse(x, y, diameter, diameter);
+}
+
+void ArduinoGraphics::ellipse(int x, int y, int width, int height) 
+{
+  if (!_stroke && !_fill) {
+    return;
+  }
+
+  int32_t a = width / 2;
+  int32_t b = height / 2;
+  int64_t a2 = a * a;
+  int64_t b2 = b * b;
+  int64_t i, j;
+  
+  if (_fill) {
+      for (j = -b; j <= b; j++) {
+          for (i = -a; i <= a; i++) {
+              if (i*i*b2 + j*j*a2 <= a2*b2) {
+                  set(x + i, y + j, _fillR, _fillG, _fillB);
+              }
+          }
+      }
+  }
+  if (_stroke) {
+      int x_val, y_val;
+      for (i = -a; i <= a; i++) {
+          y_val = b * sqrt(1 - (double)i*i / a2);
+          set(x + i, y + y_val, _strokeR, _strokeG, _strokeB);
+          set(x + i, y - y_val, _strokeR, _strokeG, _strokeB);
+      }
+      for (j = -b; j <= b; j++) {
+          x_val = a * sqrt(1 - (double)j*j / b2);
+          set(x + x_val, y + j, _strokeR, _strokeG, _strokeB);
+          set(x - x_val, y + j, _strokeR, _strokeG, _strokeB);
+      }
+  }
+}
+
 void ArduinoGraphics::line(int x1, int y1, int x2, int y2)
 {
   if (!_stroke) {

src/ArduinoGraphics.h

@@ -43,6 +43,7 @@ class ArduinoGraphics : public Print {
 
   int width();
   int height();
+  uint32_t background();
 
   virtual void beginDraw();
   virtual void endDraw();
@@ -58,7 +59,8 @@ class ArduinoGraphics : public Print {
   void noStroke();
 
   //virtual void arc(int x, int y, int width, int height, int start, int stop);
-  //virtual void ellipse(int x, int y, int width, int height);
+  virtual void circle(int x, int y, int diameter);
+  virtual void ellipse(int x, int y, int width, int height);
   virtual void line(int x1, int y1, int x2, int y2);
   virtual void point(int x, int y);
   //virtual void quad(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4);