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    width  width of rectangle
+    @param    height  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::drawRotatedRectangle(int16_t cenX, int16_t cenY,
+                                        int16_t width, int16_t height,
+                                        int16_t angleDeg, uint16_t color) {
+
+  int16_t halfW = width / 2;
+  int16_t halfH = height / 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    width  width of rectangle
+    @param    height  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::fillRotatedRectangle(int16_t cenX, int16_t cenY,
+                                        int16_t width, int16_t height,
+                                        int16_t angleDeg, uint16_t color) {
+
+  int16_t halfW = width / 2;
+  int16_t halfH = height / 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 drawRotatedRectangle(int16_t cenX, int16_t cenY, int16_t width,
+                            int16_t height, int16_t angleDeg, uint16_t color);
+  void fillRotatedRectangle(int16_t cenX, int16_t cenY, int16_t width,
+                            int16_t height, 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/RotatedRectangleTest/RotatedRectangleTest.ino

@@ -0,0 +1,52 @@
+#include <SPI.h>
+#include <Adafruit_GFX.h>
+#include <Adafruit_ST7789.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          320
+#define SCREEN_HEIGHT         240
+
+#define SERIAL_SPEED          9600
+
+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(ST77XX_BLACK);
+  canvas.drawRotatedRectangle(44, 44, 40, 30, angle, 0xFFFF);
+  canvas.fillRotatedRectangle(84, 84, 40, 30, angle, ST77XX_GREEN);
+  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);
+  tft.fillScreen(ST77XX_BLACK);
+  tft.setCursor(0, 0);
+  tft.setTextColor(ST77XX_WHITE);
+  tft.setTextSize(1);
+
+  Serial.println("TFT initialized.");
+  tft.println("TFT initialized.");
+}