1 files changed, 110 insertions, 0 deletions
diff --git a/shared-module/vectorio/Polygon.c b/shared-module/vectorio/Polygon.c
new file mode 100644
index 000000000..6722912c2
--- /dev/null
+++ b/shared-module/vectorio/Polygon.c
@@ -0,0 +1,110 @@
+
+#include "shared-module/vectorio/__init__.h"
+#include "shared-bindings/vectorio/Polygon.h"
+#include "shared-module/displayio/area.h"
+
+#include "py/runtime.h"
+#include "stdlib.h"
+#include <stdio.h>
+
+
+#define VECTORIO_POLYGON_DEBUG(...) (void)0
+// #define VECTORIO_POLYGON_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)
+
+
+void common_hal_vectorio_polygon_construct(vectorio_polygon_t *self, mp_obj_t points_list) {
+    VECTORIO_POLYGON_DEBUG("%p polygon_construct\n", self);
+    self->points_list = points_list;
+    self->on_dirty.obj = NULL;
+}
+
+
+mp_obj_t common_hal_vectorio_polygon_get_points(vectorio_polygon_t *self) {
+    return self->points_list;
+}
+void common_hal_vectorio_polygon_set_points(vectorio_polygon_t *self, mp_obj_t points_list) {
+    self->points_list = points_list;
+    if (self->on_dirty.obj != NULL) {
+        self->on_dirty.event(self->on_dirty.obj);
+    }
+}
+
+void common_hal_vectorio_polygon_set_on_dirty(vectorio_polygon_t *self, vectorio_event_t notification) {
+    if ( self->on_dirty.obj != NULL ) {
+        mp_raise_TypeError(translate("polygon can only be registered in one parent"));
+    }
+    self->on_dirty = notification;
+}
+
+
+void common_hal_vectorio_polygon_get_area(void *polygon, displayio_area_t *area) {
+    VECTORIO_POLYGON_DEBUG("%p polygon get_area", polygon);
+    vectorio_polygon_t *self = polygon;
+    size_t len;
+    mp_obj_t *points;
+    mp_obj_list_get(self->points_list, &len, &points);
+    VECTORIO_POLYGON_DEBUG(" len: %2d, points: %d\n", len, len/2);
+
+    area->x1 = SHRT_MAX;
+    area->y1 = SHRT_MAX;
+    area->x2 = SHRT_MIN;
+    area->y2 = SHRT_MIN;
+    for (size_t i=0; i < len; ++i) {
+        mp_int_t x = mp_obj_get_int(points[i]);
+        ++i;
+        mp_int_t y = mp_obj_get_int(points[i]);
+        if (x <= area->x1) area->x1 = x-1;
+        if (y <= area->y1) area->y1 = y-1;
+        if (x >= area->x2) area->x2 = x+1;
+        if (y >= area->y2) area->y2 = y+1;
+    }
+}
+
+
+// <0 if the point is to the left of the line vector
+//  0 if the point is on the line
+// >0 if the point is to the right of the line vector
+__attribute__((always_inline)) static inline int line_side( mp_int_t x1, mp_int_t y1, mp_int_t x2, mp_int_t y2, int16_t px, int16_t py ) {
+    return (px - x1) * (y2 - y1)
+         - (py - y1) * (x2 - x1);
+}
+
+
+uint32_t common_hal_vectorio_polygon_get_pixel(void *obj, int16_t x, int16_t y) {
+    VECTORIO_POLYGON_DEBUG("%p polygon get_pixel %d, %d\n", obj, x, y);
+    vectorio_polygon_t *self = obj;
+    size_t len;
+    mp_obj_t *points;
+    mp_obj_list_get(self->points_list, &len, &points);
+
+    if (len == 0) {
+        return 0;
+    }
+
+    int winding_number = 0;
+    mp_int_t x1 = mp_obj_get_int(points[0]);
+    mp_int_t y1 = mp_obj_get_int(points[1]);
+    for (size_t i=2; i <= len + 1; ++i) {
+        VECTORIO_POLYGON_DEBUG("  {(%3d, %3d),", x1, y1);
+        mp_int_t x2 = mp_obj_get_int(points[i % len]);
+        ++i;
+        mp_int_t y2 = mp_obj_get_int(points[i % len]);
+        VECTORIO_POLYGON_DEBUG(" (%3d, %3d)}\n", x2, y2);
+        if ( y1 <= y ) {
+            if ( y2 > y && line_side(x1, y1, x2, y2, x, y) > 0 ) {
+                // Wind up, point is to the right of the edge vector
+                ++winding_number;
+                VECTORIO_POLYGON_DEBUG("    wind:%2d winding_number:%2d\n", 1, winding_number);
+            }
+        } else if ( y2 <= y && line_side(x1, y1, x2, y2, x, y) < 0 ) {
+            // Wind down, point is to the left of the edge vector
+            --winding_number;
+            VECTORIO_POLYGON_DEBUG("    wind:%2d winding_number:%2d\n", -1, winding_number); 
+        }
+
+        x1 = x2;
+        y1 = y2;
+    }
+    return winding_number == 0 ? 0 : 1;
+}
+