vectorio: speed up polygon

This change takes polygon from 126k pixels per second fill to 240k pps fill
  on a reference 5 point star 50x66px polygon, updating both location and shape
  at 10hz.  Tested on an m4 express feather.

As a curiosity, the flat-out fill rate of a shape whose get_pixel is `return 0;`
  fills just shy of 375k pixels per second.

3 files changed, 65 insertions, 61 deletions

diff --git a/shared-bindings/vectorio/Polygon.c b/shared-bindings/vectorio/Polygon.c
index 5f4d85e21..e9e90942a 100644
--- a/shared-bindings/vectorio/Polygon.c
+++ b/shared-bindings/vectorio/Polygon.c
@@ -15,41 +15,6 @@
 // #define VECTORIO_POLYGON_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)
 
 
-// Converts a list of points tuples to a flat list of ints for speedier internal use.
-// Also validates the points.
-static mp_obj_t _to_points_list(mp_obj_t points_tuple_list) {
-    size_t len = 0;
-    mp_obj_t *items;
-    mp_obj_list_get(points_tuple_list, &len, &items);
-    VECTORIO_POLYGON_DEBUG("polygon_points_list len: %d\n", len);
-
-    if ( len == 0 ) {
-        mp_raise_TypeError_varg(translate("empty %q list"), MP_QSTR_point);
-    }
-
-    mp_obj_t points_list = mp_obj_new_list(0, NULL);
-
-    for ( size_t i = 0; i < len; ++i) {
-        size_t tuple_len = 0;
-        mp_obj_t *tuple_items;
-        mp_obj_tuple_get(items[i], &tuple_len, &tuple_items);
-
-        if (tuple_len != 2) {
-            mp_raise_ValueError_varg(translate("%q must be a tuple of length 2"), MP_QSTR_point);
-        }
-        int value;
-        if (!mp_obj_get_int_maybe(tuple_items[0], &value)) {
-            mp_raise_ValueError_varg(translate("unsupported %q type"), MP_QSTR_point);
-        }
-        mp_obj_list_append(points_list, MP_OBJ_NEW_SMALL_INT(value));
-        if (!mp_obj_get_int_maybe(tuple_items[1], &value)) {
-            mp_raise_ValueError_varg(translate("unsupported %q type"), MP_QSTR_point);
-        }
-        mp_obj_list_append(points_list, MP_OBJ_NEW_SMALL_INT(value));
-    }
-    return points_list;
-}
-//| from typing import List, Tuple
 //|
 //| class Polygon:
 //|     def __init__(self, points: List[ Tuple[ x, y ], ... ] ):
@@ -68,12 +33,11 @@ static mp_obj_t vectorio_polygon_make_new(const mp_obj_type_t *type, size_t n_ar
     if (!MP_OBJ_IS_TYPE(args[ARG_points_list].u_obj, &mp_type_list)) {
         mp_raise_TypeError_varg(translate("%q list must be a list"), MP_QSTR_point);
     }
-    mp_obj_t points_list = _to_points_list(args[ARG_points_list].u_obj);
 
     vectorio_polygon_t *self = m_new_obj(vectorio_polygon_t);
     self->base.type = &vectorio_polygon_type;
 
-    common_hal_vectorio_polygon_construct(self, points_list);
+    common_hal_vectorio_polygon_construct(self, args[ARG_points_list].u_obj);
 
     return MP_OBJ_FROM_PTR(self);
 }
@@ -104,9 +68,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(vectorio_polygon_get_points_obj, vectorio_polygon_obj_
 STATIC mp_obj_t vectorio_polygon_obj_set_points(mp_obj_t self_in, mp_obj_t points) {
     vectorio_polygon_t *self = MP_OBJ_TO_PTR(self_in);
 
-    mp_obj_t points_list = _to_points_list(points);
-
-    common_hal_vectorio_polygon_set_points(self, points_list);
+    common_hal_vectorio_polygon_set_points(self, points);
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_2(vectorio_polygon_set_points_obj, vectorio_polygon_obj_set_points);
diff --git a/shared-module/vectorio/Polygon.c b/shared-module/vectorio/Polygon.c
index 6722912c2..7e3a3acfe 100644
--- a/shared-module/vectorio/Polygon.c
+++ b/shared-module/vectorio/Polygon.c
@@ -4,6 +4,8 @@
 #include "shared-module/displayio/area.h"
 
 #include "py/runtime.h"
+#include "py/gc.h"
+
 #include "stdlib.h"
 #include <stdio.h>
 
@@ -12,10 +14,57 @@
 // #define VECTORIO_POLYGON_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)
 
 
+// Converts a list of points tuples to a flat list of ints for speedier internal use.
+// Also validates the points.
+static void _clobber_points_list(vectorio_polygon_t *self, mp_obj_t points_tuple_list) {
+    size_t len = 0;
+    mp_obj_t *items;
+    mp_obj_list_get(points_tuple_list, &len, &items);
+    VECTORIO_POLYGON_DEBUG("polygon_points_list len: %d\n", len);
+
+    if ( len < 3 ) {
+        mp_raise_TypeError_varg(translate("Polygon needs at least 3 points"));
+    }
+
+    if ( self->len < 2*len ) {
+        if ( self->points_list != NULL ) {
+            gc_free( self->points_list );
+        }
+        self->points_list = gc_alloc( 2 * len * sizeof(int), false, false );
+    }
+    self->len = 2*len;
+
+    for ( size_t i = 0; i < len; ++i) {
+        size_t tuple_len = 0;
+        mp_obj_t *tuple_items;
+        mp_obj_tuple_get(items[i], &tuple_len, &tuple_items);
+
+        if (tuple_len != 2) {
+            mp_raise_ValueError_varg(translate("%q must be a tuple of length 2"), MP_QSTR_point);
+        }
+        if (!mp_obj_get_int_maybe(tuple_items[0], &self->points_list[2*i])) {
+            self->len = 0;
+            gc_free( self->points_list );
+            self->points_list = NULL;
+            mp_raise_ValueError_varg(translate("unsupported %q type"), MP_QSTR_point);
+        }
+        if (!mp_obj_get_int_maybe(tuple_items[1], &self->points_list[2*i + 1])) {
+            self->len = 0;
+            gc_free( self->points_list );
+            self->points_list = NULL;
+            mp_raise_ValueError_varg(translate("unsupported %q type"), MP_QSTR_point);
+        }
+    }
+}
+
+
+
 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->points_list = NULL;
+    self->len = 0;
     self->on_dirty.obj = NULL;
+    _clobber_points_list( self, points_list );
 }
 
 
@@ -23,7 +72,7 @@ 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;
+    _clobber_points_list( self, points_list );
     if (self->on_dirty.obj != NULL) {
         self->on_dirty.event(self->on_dirty.obj);
     }
@@ -38,21 +87,16 @@ void common_hal_vectorio_polygon_set_on_dirty(vectorio_polygon_t *self, vectorio
 
 
 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]);
+    for (size_t i=0; i < self->len; ++i) {
+        int x = self->points_list[i];
         ++i;
-        mp_int_t y = mp_obj_get_int(points[i]);
+        int y = self->points_list[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;
@@ -73,22 +117,19 @@ __attribute__((always_inline)) static inline int line_side( mp_int_t x1, mp_int_
 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) {
+    if (self->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) {
+    int x1 = self->points_list[0];
+    int y1 = self->points_list[1];
+    for (size_t i=2; i <= self->len + 1; ++i) {
         VECTORIO_POLYGON_DEBUG("  {(%3d, %3d),", x1, y1);
-        mp_int_t x2 = mp_obj_get_int(points[i % len]);
+        int x2 = self->points_list[i % self->len];
         ++i;
-        mp_int_t y2 = mp_obj_get_int(points[i % len]);
+        int y2 = self->points_list[i % self->len];
         VECTORIO_POLYGON_DEBUG(" (%3d, %3d)}\n", x2, y2);
         if ( y1 <= y ) {
             if ( y2 > y && line_side(x1, y1, x2, y2, x, y) > 0 ) {
diff --git a/shared-module/vectorio/Polygon.h b/shared-module/vectorio/Polygon.h
index 1aef854a7..70de9036d 100644
--- a/shared-module/vectorio/Polygon.h
+++ b/shared-module/vectorio/Polygon.h
@@ -8,8 +8,9 @@
 
 typedef struct {
     mp_obj_base_t base;
-    // A micropython List[ x, y, ... ]
-    mp_obj_t points_list;
+    // An int array[ x, y, ... ]
+    int *points_list;
+    size_t len;
     vectorio_event_t on_dirty;
 } vectorio_polygon_t;