erge branch 'main' into shareground

Author: ahyangyi

agrf/graphics/helpers/blend.py

@@ -13,5 +13,6 @@ def blend_alternative_sprites(a, b):
                 continue
             fs = BlendSprite(sa, sb)
             alts.append(fs)
+    assert len(alts) > 0
 
     return grf.AlternativeSprites(*alts)

agrf/graphics/helpers/map.py

@@ -20,11 +20,13 @@ def map_alternative_sprites(a, f, name, xofs=0, yofs=0):
     for scale in [1, 2, 4]:
         for bpp in [8, 32]:
             sa = tuple(b.get_sprite(zoom=SCALE_TO_ZOOM[scale], bpp=bpp) for b in a)
-            if all(x is None for x in sa):
+            if any(x is None for x in sa):
                 continue
             fs = MapSprite(
                 sa, (lambda x, scale=scale, bpp=bpp: f(x, scale, bpp)), name, xofs=xofs * scale, yofs=yofs * scale
             )
             alts.append(fs)
 
+    assert len(alts) > 0
+
     return MapAlternativeSprites(name, a, *alts)

agrf/graphics/layered_image.py

@@ -66,7 +66,13 @@ def copy_from(self, other):
         return self
 
     def apply_mask(self):
-        if self.rgb is None or self.mask is None:
+        if self.mask is None:
+            return
+        if self.rgb is None:
+            self.rgb = NUMPY_PALETTE[self.mask]
+            assert self.alpha is None
+            self.alpha = self.mask > 0
+            self.mask = None
             return
         v = np.min(self.rgb, axis=2, keepdims=True)
         mask_colour = NUMPY_PALETTE[self.mask].astype(np.uint16)