Merge pull request #5616 from jepler/bitmaptools-bugfixes

Bitmaptools bugfixes

Author: tannewt

shared-bindings/bitmaptools/__init__.c

@@ -664,7 +664,7 @@ MP_DEFINE_CONST_FUN_OBJ_KW(bitmaptools_readinto_obj, 0, bitmaptools_readinto);
 //|     """The Floyd-Stenberg dither"""
 //|
 MAKE_ENUM_VALUE(bitmaptools_dither_algorithm_type, dither_algorithm, Atkinson, DITHER_ALGORITHM_ATKINSON);
-MAKE_ENUM_VALUE(bitmaptools_dither_algorithm_type, dither_algorithm, FloydStenberg, DITHER_ALGORITHM_ATKINSON);
+MAKE_ENUM_VALUE(bitmaptools_dither_algorithm_type, dither_algorithm, FloydStenberg, DITHER_ALGORITHM_FLOYD_STENBERG);
 
 MAKE_ENUM_MAP(bitmaptools_dither_algorithm) {
     MAKE_ENUM_MAP_ENTRY(dither_algorithm, Atkinson),

shared-module/bitmaptools/__init__.c

@@ -749,9 +749,9 @@ void common_hal_bitmaptools_dither(displayio_bitmap_t *dest_bitmap, displayio_bi
                 int x1 = x + info->terms[i].dx;
                 int dy = info->terms[i].dy;
 
-                rows[dy][x1] = ((info->terms[i].dl * err) >> 8) + rows[dy][x1];
+                rows[dy][x1] = ((info->terms[i].dl * err) / 256) + rows[dy][x1];
             }
-            err = err * info->dl >> 8;
+            err = (err * info->dl) / 256;
         }
         write_pixels(dest_bitmap, y, out);
 
@@ -761,13 +761,13 @@ void common_hal_bitmaptools_dither(displayio_bitmap_t *dest_bitmap, displayio_bi
         rows[1] = rows[2];
         rows[2] = tmp;
 
-        fill_row(source_bitmap, swap, rows[2], y + 2, info->mx);
-
         y++;
         if (y == height) {
             break;
         }
 
+        fill_row(source_bitmap, swap, rows[2], y + 2, info->mx);
+
         // Serpentine dither.   Going right-to-left...
         for (int x = width; x--;) {
             int16_t pixel_in = rows[0][x] + err;
@@ -779,9 +779,9 @@ void common_hal_bitmaptools_dither(displayio_bitmap_t *dest_bitmap, displayio_bi
                 int x1 = x - info->terms[i].dx;
                 int dy = info->terms[i].dy;
 
-                rows[dy][x1] = ((info->terms[i].dl * err) >> 8) + rows[dy][x1];
+                rows[dy][x1] = ((info->terms[i].dl * err) / 256) + rows[dy][x1];
             }
-            err = err * info->dl >> 8;
+            err = (err * info->dl) / 256;
         }
         write_pixels(dest_bitmap, y, out);
 
@@ -790,7 +790,7 @@ void common_hal_bitmaptools_dither(displayio_bitmap_t *dest_bitmap, displayio_bi
         rows[1] = rows[2];
         rows[2] = tmp;
 
-        fill_row(source_bitmap, swap, rows[2], y + 2, info->mx);
+        fill_row(source_bitmap, swap, rows[2], y + 3, info->mx);
     }
 
     displayio_area_t a = { 0, 0, width, height, NULL };

tests/circuitpython-manual/_bmp16.py renamed to tests/circuitpython-manual/bitmaptools/_bmp16.py

@@ -0,0 +1,18 @@
+import bitmaptools
+import displayio
+import _bmp16
+
+if "/" in __file__:
+    here = __file__.rsplit("/", 1)[0]
+else:
+    here = "."
+
+c = displayio.Colorspace.BGR565
+
+b1 = _bmp16.loadbmp16(here + "/minerva16.bmp")
+b3 = displayio.Bitmap(320, 240, 65536)
+
+bitmaptools.dither(b3, b1, c)
+_bmp16.writebmp16(f"dither-atkinson.bmp", b3)
+bitmaptools.dither(b3, b1, c, bitmaptools.DitherAlgorithm.FloydStenberg)
+_bmp16.writebmp16(f"dither-floydstenberg.bmp", b3)