Custom convertMaskToAlpha for #431

src/basics/alleg5.d

@@ -124,6 +124,45 @@ Albit albitCreateSmoothlyScalable(in int xl, in int yl)
  bool isTargetBitmap(in Albit b) { return al_get_target_bitmap() == b; }
 }
 
+/*
+ * My custom variant of al_convert_mask_to_alpha to debug github issue #431:
+ * Magic pink won't become transparent on macOS (both Intel and ARM64)
+ */
+void convertPinkToAlpha(Albit bitmap)
+{
+ auto region = LockReadWrite(bitmap);
+ auto target = TargetBitmap(bitmap);
+ immutable xl = bitmap.xl;
+ immutable yl = bitmap.yl;
+ immutable Alcol transp = al_map_rgba(0, 0, 0, 0);
+ for (int y = 0; y < yl; y++) {
+ for (int x = 0; x < xl; x++) {
+ immutable Alcol pixel = al_get_pixel(bitmap, x, y);
+ if (pixel.r == 1f && pixel.g == 0f && pixel.b == 1f) {
+ al_put_pixel(x, y, transp);
+ }
+ }
+ }
+}
+
+/*
+ * The reason for above custom variant of al_convert_mask_to_alpha() is
+ * that A5's version compares colors with memcmp, but memcmp fails for float
+ * color components +0 and -0 which must compare equal as color components:
+ */
+unittest {
+ union Float {
+ float f;
+ ubyte[4] arr;
+ }
+ Float a;
+ Float b;
+ a.f = +0f;
+ b.f = -0f;
+ assert (a.f == b.f);
+ assert (a.arr != b.arr);
+}
+
 // The following structs implement RAII.
 struct TargetBitmap
 {

src/graphic/color.d

@@ -1,7 +1,5 @@
 module graphic.color;
 
-import std.random;
-
 public import basics.alleg5 :
  Alcol,
  al_map_rgb, al_unmap_rgb, al_map_rgb_f, al_unmap_rgb_f,
@@ -40,15 +38,6 @@ void computeColors(in int r, in int g, in int b)
 }
 
 private class ColorPrivate {
-
- @property Alcol random()
- {
- alias rnd = uniform01!float;
- float[] arr = [rnd(), 0.7 + 0.3 * rnd(), 0.3 * rnd()];
- arr.randomShuffle();
- return al_map_rgb_f(arr[0], arr[1], arr[2]);
- }
-
  // This can't be an alias to al_map_rgb because al_map_rgb expects ubytes.
  Alcol makecol(in int r, in int g, in int b)
  {

src/graphic/cutbit.d

@@ -79,8 +79,9 @@ public:
  {
  // Try loading the file. If not found, don't crash, but log.
  bitmap = al_load_bitmap(fn.stringForReading.toStringz);
- if (bitmap)
- al_convert_mask_to_alpha(bitmap, color.pink);
+ if (bitmap) {
+ bitmap.convertPinkToAlpha();
+ }
  this(bitmap, cut);
  }
 

src/graphic/internal/loadfile.d

@@ -10,7 +10,6 @@ import std.algorithm; // find
 import basics.alleg5;
 import basics.globals : dirDataBitmap;
 import file.filename;
-import graphic.color;
 import graphic.cutbit;
 import graphic.internal.getters;
 import graphic.internal.names;
@@ -33,7 +32,7 @@ do {
  return;
  }
  loadedCutbitMayBeScaled[id] = new Cutbit(fn, Cutbit.Cut.ifGridExists);
- al_convert_mask_to_alpha(loadedCutbitMayBeScaled[id].albit, color.pink);
+ loadedCutbitMayBeScaled[id].albit.convertPinkToAlpha();
  if (id.needGuiRecoloring) {
  eidrecol(loadedCutbitMayBeScaled[id], 0);
  }