1 files changed, 62 insertions, 0 deletions
diff --git a/gfx/thebes/gfxColor.h b/gfx/thebes/gfxColor.h
new file mode 100644
index 0000000000..eec2b0b70e
--- /dev/null
+++ b/gfx/thebes/gfxColor.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_COLOR_H
+#define GFX_COLOR_H
+
+#include "mozilla/Attributes.h"  // for MOZ_ALWAYS_INLINE
+#include "mozilla/gfx/Types.h"   // for mozilla::gfx::SurfaceFormatBit
+
+/**
+ * Fast approximate division by 255. It has the property that
+ * for all 0 <= n <= 255*255, GFX_DIVIDE_BY_255(n) == n/255.
+ * But it only uses two adds and two shifts instead of an
+ * integer division (which is expensive on many processors).
+ *
+ * equivalent to ((v)/255)
+ */
+#define GFX_DIVIDE_BY_255(v) \
+  (((((unsigned)(v)) << 8) + ((unsigned)(v)) + 255) >> 16)
+
+/**
+ * Fast premultiply
+ *
+ * equivalent to (((c)*(a))/255)
+ */
+uint8_t MOZ_ALWAYS_INLINE gfxPreMultiply(uint8_t c, uint8_t a) {
+  return GFX_DIVIDE_BY_255((c) * (a));
+}
+
+/**
+ * Pack the 4 8-bit channels (A,R,G,B)
+ * into a 32-bit packed NON-premultiplied pixel.
+ */
+uint32_t MOZ_ALWAYS_INLINE gfxPackedPixelNoPreMultiply(uint8_t a, uint8_t r,
+                                                       uint8_t g, uint8_t b) {
+  return (((a) << mozilla::gfx::SurfaceFormatBit::OS_A) |
+          ((r) << mozilla::gfx::SurfaceFormatBit::OS_R) |
+          ((g) << mozilla::gfx::SurfaceFormatBit::OS_G) |
+          ((b) << mozilla::gfx::SurfaceFormatBit::OS_B));
+}
+
+/**
+ * Pack the 4 8-bit channels (A,R,G,B)
+ * into a 32-bit packed premultiplied pixel.
+ */
+uint32_t MOZ_ALWAYS_INLINE gfxPackedPixel(uint8_t a, uint8_t r, uint8_t g,
+                                          uint8_t b) {
+  if (a == 0x00)
+    return 0x00000000;
+  else if (a == 0xFF) {
+    return gfxPackedPixelNoPreMultiply(a, r, g, b);
+  } else {
+    return ((a) << mozilla::gfx::SurfaceFormatBit::OS_A) |
+           (gfxPreMultiply(r, a) << mozilla::gfx::SurfaceFormatBit::OS_R) |
+           (gfxPreMultiply(g, a) << mozilla::gfx::SurfaceFormatBit::OS_G) |
+           (gfxPreMultiply(b, a) << mozilla::gfx::SurfaceFormatBit::OS_B);
+  }
+}
+
+#endif /* _GFX_COLOR_H */