Add regular polygon shapes to display component (#6108)

esphome/components/display/display.cpp

@@ -257,6 +257,67 @@ void Display::filled_triangle(int x1, int y1, int x2, int y2, int x3, int y3, Co
     this->filled_flat_side_triangle_(x3, y3, x2, y2, x_temp, y_temp, color);
   }
 }
+void HOT Display::get_regular_polygon_vertex(int vertex_id, int *vertex_x, int *vertex_y, int center_x, int center_y,
+                                             int radius, int edges, RegularPolygonVariation variation,
+                                             float rotation_degrees) {
+  if (edges >= 2) {
+    // Given the orientation of the display component, an angle is measured clockwise from the x axis.
+    // For a regular polygon, the human reference would be the top of the polygon,
+    // hence we rotate the shape by 270° to orient the polygon up.
+    rotation_degrees += ROTATION_270_DEGREES;
+    // Convert the rotation to radians, easier to use in trigonometrical calculations
+    float rotation_radians = rotation_degrees * PI / 180;
+    // A pointy top variation means the first vertex of the polygon is at the top center of the shape, this requires no
+    // additional rotation of the shape.
+    // A flat top variation means the first point of the polygon has to be rotated so that the first edge is horizontal,
+    // this requires to rotate the shape by π/edges radians counter-clockwise so that the first point is located on the
+    // left side of the first horizontal edge.
+    rotation_radians -= (variation == VARIATION_FLAT_TOP) ? PI / edges : 0.0;
+
+    float vertex_angle = ((float) vertex_id) / edges * 2 * PI + rotation_radians;
+    *vertex_x = (int) round(cos(vertex_angle) * radius) + center_x;
+    *vertex_y = (int) round(sin(vertex_angle) * radius) + center_y;
+  }
+}
+
+void HOT Display::regular_polygon(int x, int y, int radius, int edges, RegularPolygonVariation variation,
+                                  float rotation_degrees, Color color, RegularPolygonDrawing drawing) {
+  if (edges >= 2) {
+    int previous_vertex_x, previous_vertex_y;
+    for (int current_vertex_id = 0; current_vertex_id <= edges; current_vertex_id++) {
+      int current_vertex_x, current_vertex_y;
+      get_regular_polygon_vertex(current_vertex_id, &current_vertex_x, &current_vertex_y, x, y, radius, edges,
+                                 variation, rotation_degrees);
+      if (current_vertex_id > 0) {  // Start drawing after the 2nd vertex coordinates has been calculated
+        if (drawing == DRAWING_FILLED) {
+          this->filled_triangle(x, y, previous_vertex_x, previous_vertex_y, current_vertex_x, current_vertex_y, color);
+        } else if (drawing == DRAWING_OUTLINE) {
+          this->line(previous_vertex_x, previous_vertex_y, current_vertex_x, current_vertex_y, color);
+        }
+      }
+      previous_vertex_x = current_vertex_x;
+      previous_vertex_y = current_vertex_y;
+    }
+  }
+}
+void HOT Display::regular_polygon(int x, int y, int radius, int edges, RegularPolygonVariation variation, Color color,
+                                  RegularPolygonDrawing drawing) {
+  regular_polygon(x, y, radius, edges, variation, ROTATION_0_DEGREES, color, drawing);
+}
+void HOT Display::regular_polygon(int x, int y, int radius, int edges, Color color, RegularPolygonDrawing drawing) {
+  regular_polygon(x, y, radius, edges, VARIATION_POINTY_TOP, ROTATION_0_DEGREES, color, drawing);
+}
+void Display::filled_regular_polygon(int x, int y, int radius, int edges, RegularPolygonVariation variation,
+                                     float rotation_degrees, Color color) {
+  regular_polygon(x, y, radius, edges, variation, rotation_degrees, color, DRAWING_FILLED);
+}
+void Display::filled_regular_polygon(int x, int y, int radius, int edges, RegularPolygonVariation variation,
+                                     Color color) {
+  regular_polygon(x, y, radius, edges, variation, ROTATION_0_DEGREES, color, DRAWING_FILLED);
+}
+void Display::filled_regular_polygon(int x, int y, int radius, int edges, Color color) {
+  regular_polygon(x, y, radius, edges, VARIATION_POINTY_TOP, ROTATION_0_DEGREES, color, DRAWING_FILLED);
+}
 
 void Display::print(int x, int y, BaseFont *font, Color color, TextAlign align, const char *text) {
   int x_start, y_start;