Add vectorio: for drawing shapes

vectorio builds on m4 express feather

Concrete shapes are composed into a VectorShape which is put into a displayio Group for display.

VectorShape provides transpose and x/y positioning for shape implementations.

Included Shapes:

* Circle
  - A radius; Circle is positioned at its axis in the VectorShape.
  - You can freely modify the radius to grow and shrink the circle in-place.

* Polygon
  - An ordered list of points.
  - Beteween each successive point an edge is inferred.  A final edge closing the shape is inferred between the last
    point and the first point.
  - You can modify the points in a Polygon.  The points' coordinate system is relative to (0, 0) so if you'd like a
      top-center justified 10x20 rectangle you can do points [(-5, 0), (5, 0), (5, 20), (0, 20)] and your VectorShape
      x and y properties will position the rectangle relative to its top center point

* Rectangle
  A width and a height.

1 files changed, 51 insertions, 0 deletions

diff --git a/shared-module/vectorio/VectorShape.h b/shared-module/vectorio/VectorShape.h
new file mode 100644
index 000000000..ac60e5b98
--- /dev/null
+++ b/shared-module/vectorio/VectorShape.h
@@ -0,0 +1,51 @@
+
+#ifndef MICROPY_INCLUDED_SHARED_MODULE_VECTORIO_SHAPE_H
+#define MICROPY_INCLUDED_SHARED_MODULE_VECTORIO_SHAPE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "py/obj.h"
+#include "shared-module/displayio/area.h"
+#include "shared-module/displayio/Palette.h"
+
+typedef void get_area_function(mp_obj_t shape, displayio_area_t *out_area);
+typedef uint32_t get_pixel_function(mp_obj_t shape, int16_t x, int16_t y);
+
+// This struct binds a shape's common Shape support functions (its vector shape interface)
+//   to its instance pointer.  We only check at construction time what the type of the
+//   associated shape is and link the correct functions up.
+// Later when using the shape for drawing logic these functions may be invoked
+//   unconditionally.  This simplifies the addition of new types and restricts the
+//   respective responsibilities of VectorShape and actual shape implementations.
+typedef struct {
+    mp_obj_t shape;
+    get_area_function *get_area;
+    get_pixel_function *get_pixel;
+} vectorio_ishape_t;
+
+typedef struct {
+    mp_obj_base_t base;
+    vectorio_ishape_t ishape;
+    mp_obj_t pixel_shader;
+    int16_t x;
+    int16_t y;
+    bool transpose_xy;
+    bool dirty;  // True if we need to draw
+    // Tracks current shape footprint and expands outward as the shape dirties and changes.
+    // This is suboptimal if you move your shape far.  Could add more state to only redraw
+    //   exactly what we left behind.
+    displayio_area_t ephemeral_dirty_area;
+} vectorio_vector_shape_t;
+
+displayio_area_t* vectorio_vector_shape_get_refresh_areas(vectorio_vector_shape_t *self, displayio_area_t* tail);
+
+// Area is always in absolute screen coordinates.
+bool vectorio_vector_shape_fill_area(vectorio_vector_shape_t *self, const _displayio_colorspace_t *colorspace, const displayio_area_t *area, uint32_t *mask, uint32_t *buffer);
+
+// Fills in out_area with the maximum bounds of all related pixels in the last rendered frame. Returns
+// false if the vector shape wasn't rendered in the last frame.
+bool vectorio_vector_shape_get_previous_area(vectorio_vector_shape_t *self, displayio_area_t *out_area);
+void vectorio_vector_shape_finish_refresh(vectorio_vector_shape_t *self);
+
+#endif // MICROPY_INCLUDED_SHARED_MODULE_VECTORIO_SHAPE_H