morph: accommodate fractional add values

jepler · jepler · commit 7e1c05edf5ed · 2024-01-09T17:11:53.000-06:00
diff --git a/shared-bindings/bitmapfilter/__init__.c b/shared-bindings/bitmapfilter/__init__.c
@@ -35,7 +35,7 @@
 //|     bitmap: displayio.Bitmap,
 //|     weights: Sequence[int],
 //|     mul: float = 1.0,
-//|     add: int = 0,
+//|     add: float = 0,
 //|     mask: displayio.Bitmap | None = None,
 //|     threshold=False,
 //|     offset: int = 0,
@@ -112,7 +112,7 @@ STATIC mp_obj_t bitmapfilter_morph(size_t n_args, const mp_obj_t *pos_args, mp_m
         mask = MP_OBJ_TO_PTR(args[ARG_mask].u_obj);
     }
 
-    mp_int_t b = mp_obj_get_int(args[ARG_add].u_obj);
+    mp_float_t b = mp_obj_get_float(args[ARG_add].u_obj);
 
     mp_obj_t weights = args[ARG_weights].u_obj;
     mp_obj_t obj_len = mp_obj_len(weights);
@@ -137,7 +137,7 @@ STATIC mp_obj_t bitmapfilter_morph(size_t n_args, const mp_obj_t *pos_args, mp_m
 
     mp_float_t m = args[ARG_mul].u_obj != mp_const_none ? mp_obj_get_float(args[ARG_mul].u_obj) : 1 / (mp_float_t)weight_sum;
 
-    shared_module_bitmapfilter_morph(bitmap, mask, sq_n_weights / 2, iweights, (float)m, b,
+    shared_module_bitmapfilter_morph(bitmap, mask, sq_n_weights / 2, iweights, m, b,
         args[ARG_threshold].u_bool, args[ARG_offset].u_bool, args[ARG_invert].u_bool);
     return mp_const_none;
 }
diff --git a/shared-bindings/bitmapfilter/__init__.h b/shared-bindings/bitmapfilter/__init__.h
@@ -33,8 +33,8 @@ void shared_module_bitmapfilter_morph(
     displayio_bitmap_t *mask,
     const int ksize,
     const int *krn,
-    const float m,
-    const int b,
+    const mp_float_t m,
+    const mp_float_t b,
     bool threshold,
     int offset,
     bool invert);
diff --git a/shared-module/bitmapfilter/__init__.c b/shared-module/bitmapfilter/__init__.c
@@ -140,15 +140,16 @@ void shared_module_bitmapfilter_morph(
     displayio_bitmap_t *mask,
     const int ksize,
     const int *krn,
-    const float m,
-    const int b,
+    const mp_float_t m,
+    const mp_float_t b,
     bool threshold,
     int offset,
     bool invert) {
 
     int brows = ksize + 1;
 
     const int32_t m_int = (int32_t)MICROPY_FLOAT_C_FUN(round)(65536 * m);
+    const int32_t b_int = (int32_t)MICROPY_FLOAT_C_FUN(round)(65536 * COLOR_G6_MAX * b);
 
     check_matching_details(bitmap, bitmap);
 
@@ -169,7 +170,7 @@ void shared_module_bitmapfilter_morph(
                         continue; // Short circuit.
 
                     }
-                    int32_t tmp, r_acc = 0, g_acc = 0, b_acc = 0, ptr = 0;
+                    int32_t r_acc = 0, g_acc = 0, b_acc = 0, ptr = 0;
 
                     if (x >= ksize && x < bitmap->width - ksize && y >= ksize && y < bitmap->height - ksize) {
                         for (int j = -ksize; j <= ksize; j++) {
@@ -194,22 +195,19 @@ void shared_module_bitmapfilter_morph(
                             }
                         }
                     }
-                    tmp = (r_acc * m_int) >> 16;
-                    r_acc = tmp + b;
+                    r_acc = (r_acc * m_int + b_int) >> 16;
                     if (r_acc > COLOR_R5_MAX) {
                         r_acc = COLOR_R5_MAX;
                     } else if (r_acc < 0) {
                         r_acc = 0;
                     }
-                    tmp = (g_acc * m_int) >> 16;
-                    g_acc = tmp + b;
+                    g_acc = (g_acc * m_int + b_int * 2) >> 16;
                     if (g_acc > COLOR_G6_MAX) {
                         g_acc = COLOR_G6_MAX;
                     } else if (g_acc < 0) {
                         g_acc = 0;
                     }
-                    tmp = (b_acc * m_int) >> 16;
-                    b_acc = tmp + b;
+                    b_acc = (b_acc * m_int + b_int) >> 16;
                     if (b_acc > COLOR_B5_MAX) {
                         b_acc = COLOR_B5_MAX;
                     } else if (b_acc < 0) {
diff --git a/tests/circuitpython/bitmapfilter_morph.py b/tests/circuitpython/bitmapfilter_morph.py
@@ -32,10 +32,10 @@ def make_quadrant_bitmap():
 b = make_circle_bitmap()
 q = make_quadrant_bitmap()
 dump_bitmap(q)
-bitmapfilter.morph(b, mask=q, weights=blur, add=32)
+bitmapfilter.morph(b, mask=q, weights=blur, add=1 / 4)
 dump_bitmap(b)
 
 # This is a kind of edge filter
 b = make_circle_bitmap()
-bitmapfilter.morph(b, weights=sharpen, threshold=True, add=8, invert=True)
+bitmapfilter.morph(b, weights=sharpen, threshold=True, add=0.125, invert=True)
 dump_bitmap(b)
