Add rotated rectangle draw and fill methods

Adafruit_GFX.cpp

@@ -700,6 +700,111 @@ void Adafruit_GFX::fillRoundRect(int16_t x, int16_t y, int16_t w, int16_t h,
   endWrite();
 }
 
+/**************************************************************************/
+/*!
+   @brief     Draw a rotated rectangle
+    @param    cenX  x coordinate of center of rectangle
+    @param    cenY  y coordinate of center of rectangle
+    @param    w  width of rectangle
+    @param    h  height of rectangle
+    @param    angleDeg  angle of rotation of rectangle
+    @param    color 16-bit 5-6-5 Color to fill/draw with
+*/
+/**************************************************************************/
+void Adafruit_GFX::drawRotatedRect(int16_t cenX, int16_t cenY, int16_t w,
+                                   int16_t h, int16_t angleDeg,
+                                   uint16_t color) {
+
+  int16_t halfW = w / 2;
+  int16_t halfH = h / 2;
+
+  int16_t x0 = cenX - halfW; // top-left
+  int16_t y0 = cenY - halfH; // top-left
+  int16_t x1 = cenX + halfW; // top-right
+  int16_t y1 = cenY - halfH; // top-right
+  int16_t x2 = cenX - halfW; // bottom-left
+  int16_t y2 = cenY + halfH; // bottom-left
+  int16_t x3 = cenX + halfW; // bottom-right
+  int16_t y3 = cenY + halfH; // bottom-right
+
+  rotatePoint(x0, y0, cenX, cenY, angleDeg);
+  rotatePoint(x1, y1, cenX, cenY, angleDeg);
+  rotatePoint(x2, y2, cenX, cenY, angleDeg);
+  rotatePoint(x3, y3, cenX, cenY, angleDeg);
+
+  drawLine(x0, y0, x1, y1, color); // top left to top right
+  drawLine(x0, y0, x2, y2, color); // top left to bottom left
+  drawLine(x1, y1, x3, y3, color); // top right to bottom right
+  drawLine(x2, y2, x3, y3, color); // bottom left to bottom right
+}
+
+/**************************************************************************/
+/*!
+   @brief     Draw a filled rotated rectangle
+    @param    cenX  x coordinate of center of rectangle
+    @param    cenY  y coordinate of center of rectangle
+    @param    w  width of rectangle
+    @param    h  height of rectangle
+    @param    angleDeg  angle of rotation of rectangle
+    @param    color 16-bit 5-6-5 Color to fill/draw with
+*/
+/**************************************************************************/
+void Adafruit_GFX::fillRotatedRect(int16_t cenX, int16_t cenY, int16_t w,
+                                   int16_t h, int16_t angleDeg,
+                                   uint16_t color) {
+
+  int16_t halfW = w / 2;
+  int16_t halfH = h / 2;
+
+  int16_t x0 = cenX - halfW; // top-left
+  int16_t y0 = cenY - halfH; // top-left
+  int16_t x1 = cenX + halfW; // top-right
+  int16_t y1 = cenY - halfH; // top-right
+  int16_t x2 = cenX - halfW; // bottom-left
+  int16_t y2 = cenY + halfH; // bottom-left
+  int16_t x3 = cenX + halfW; // bottom-right
+  int16_t y3 = cenY + halfH; // bottom-right
+
+  rotatePoint(x0, y0, cenX, cenY, angleDeg);
+  rotatePoint(x1, y1, cenX, cenY, angleDeg);
+  rotatePoint(x2, y2, cenX, cenY, angleDeg);
+  rotatePoint(x3, y3, cenX, cenY, angleDeg);
+
+  fillTriangle(x0, y0, x1, y1, x2, y2, color);
+  fillTriangle(x1, y1, x2, y2, x3, y3, color);
+}
+
+/**************************************************************************/
+/*!
+   @brief     Rotate a point around another point
+    @param    x0  x coordinate of point to rotate. This is passed by reference
+                  and updated upon return
+    @param    y0  y coordinate of point to rotate. This is passed by reference
+                  and updated upon return
+    @param    orgX  x coordinate of point to be rotated around
+    @param    orgY  y coordinate of point to be rotated around
+    @param    angleDeg  angle of rotation of rectangle
+*/
+/**************************************************************************/
+void Adafruit_GFX::rotatePoint(int16_t &x0, int16_t &y0, int16_t orgX,
+                               int16_t orgY, int16_t angleDeg) {
+  float angleRad = radians(angleDeg);
+  float s = sin(angleRad);
+  float c = cos(angleRad);
+
+  // Translate to standard position
+  int16_t xStan = x0 - orgX;
+  int16_t yStan = y0 - orgY;
+
+  // Rotate point
+  int16_t xRot = (int16_t)((float)xStan * c - (float)yStan * s);
+  int16_t yRot = (int16_t)((float)xStan * s + (float)yStan * c);
+
+  // Translate back
+  x0 = xRot + orgX;
+  y0 = yRot + orgY;
+}
+
 /**************************************************************************/
 /*!
    @brief   Draw a triangle with no fill color

Adafruit_GFX.h

@@ -85,6 +85,12 @@ class Adafruit_GFX : public Print {
                      int16_t radius, uint16_t color);
   void fillRoundRect(int16_t x0, int16_t y0, int16_t w, int16_t h,
                      int16_t radius, uint16_t color);
+  void drawRotatedRect(int16_t cenX, int16_t cenY, int16_t w, int16_t h,
+                       int16_t angleDeg, uint16_t color);
+  void fillRotatedRect(int16_t cenX, int16_t cenY, int16_t w, int16_t h,
+                       int16_t angleDeg, uint16_t color);
+  void rotatePoint(int16_t &x0, int16_t &y0, int16_t orgX, int16_t orgY,
+                   int16_t angleDeg);
   void drawBitmap(int16_t x, int16_t y, const uint8_t bitmap[], int16_t w,
                   int16_t h, uint16_t color);
   void drawBitmap(int16_t x, int16_t y, const uint8_t bitmap[], int16_t w,

examples/RotatedRectTest/RotatedRectTest.ino

@@ -0,0 +1,67 @@
+/***************************************************
+  This is an example to exercise the rotated rectangle
+  methods 'drawRotatedRect' and 'fillRotatedRect'.
+  The commented lines represent hardware-specific
+  details that will need to be customized for the
+  particular display chosen by the end-user.
+ ****************************************************/
+
+// #include <SPI.h>
+// #include <Adafruit_ST7789.h>
+#include <Adafruit_GFX.h>
+
+// #define TFT_RST               D0
+// #define TFT_DC                D1
+// #define TFT_CS                D2
+// #define TFT_BACKLIGHT         D3
+// #define SPI_SPEED             40000000
+// #define ROTATION              1
+
+#define SCREEN_WIDTH          128
+#define SCREEN_HEIGHT         128
+
+#define SERIAL_SPEED          9600
+
+#define DRAW_CIRCLE_X         44
+#define DRAW_CIRCLE_Y         44
+#define FILL_CIRCLE_X         84
+#define FILL_CIRCLE_Y         84
+#define WIDTH                 40
+#define HEIGHT                30
+#define BLACK                 0x0000
+#define WHITE                 0xFFFF
+#define GREEN                 0x07E0
+
+
+//Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);
+GFXcanvas16 canvas = GFXcanvas16(SCREEN_WIDTH, SCREEN_HEIGHT);
+
+int16_t angle = 0;
+
+void setup(void)
+{
+  Serial.begin(SERIAL_SPEED);
+  Serial.println("Start up.");
+  initializeTFT();
+}
+
+void loop()
+{
+  canvas.fillScreen(BLACK);
+  canvas.drawRotatedRect(DRAW_CIRCLE_X, DRAW_CIRCLE_Y, WIDTH, HEIGHT, angle, WHITE);
+  canvas.fillRotatedRect(FILL_CIRCLE_X, FILL_CIRCLE_Y, WIDTH, HEIGHT, angle, GREEN);
+  //Un-comment to display the rotated rectangles on your display
+  //tft.drawRGBBitmap(0, 0, canvas.getBuffer(), SCREEN_WIDTH, SCREEN_HEIGHT);
+  ++angle %= 360;
+}
+
+void initializeTFT(void)
+{
+  // pinMode(TFT_BACKLIGHT, OUTPUT);
+  // digitalWrite(TFT_BACKLIGHT, HIGH);
+  // tft.init(SCREEN_WIDTH, SCREEN_HEIGHT);
+  // tft.setSPISpeed(SPI_SPEED);
+  // tft.setRotation(ROTATION);
+}
+
+