grab from latest android
git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/SkUnitMappers.cpp b/src/utils/SkUnitMappers.cpp
new file mode 100644
index 0000000..0363a2b
--- /dev/null
+++ b/src/utils/SkUnitMappers.cpp
@@ -0,0 +1,80 @@
+#include "SkUnitMappers.h"
+
+SkDiscreteMapper::SkDiscreteMapper(int segments)
+{
+ if (segments < 2)
+ {
+ fSegments = 0;
+ fScale = 0;
+ }
+ else
+ {
+ if (segments > 0xFFFF)
+ segments = 0xFFFF;
+ fSegments = segments;
+ fScale = SK_Fract1 / (segments - 1);
+ }
+}
+
+uint16_t SkDiscreteMapper::mapUnit16(uint16_t input)
+{
+ SkFixed x = input * fSegments >> 16;
+ x = x * fScale >> 14;
+ x += x << 15 >> 31; // map 0x10000 to 0xFFFF
+ return SkToU16(x);
+}
+
+SkDiscreteMapper::SkDiscreteMapper(SkFlattenableReadBuffer& rb)
+ : SkUnitMapper(rb)
+{
+ fSegments = rb.readU32();
+ fScale = rb.readU32();
+}
+
+SkFlattenable::Factory SkDiscreteMapper::getFactory()
+{
+ return Create;
+}
+
+SkFlattenable* SkDiscreteMapper::Create(SkFlattenableReadBuffer& rb)
+{
+ return SkNEW_ARGS(SkDiscreteMapper, (rb));
+}
+
+void SkDiscreteMapper::flatten(SkFlattenableWriteBuffer& wb)
+{
+ this->INHERITED::flatten(wb);
+
+ wb.write32(fSegments);
+ wb.write32(fScale);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+uint16_t SkCosineMapper::mapUnit16(uint16_t input)
+{
+ /* we want to call cosine(input * pi/2) treating input as [0...1)
+ however, the straight multitply would overflow 32bits since input is
+ 16bits and pi/2 is 17bits, so we shift down our pi const before we mul
+ */
+ SkFixed rads = (unsigned)(input * (SK_FixedPI >> 2)) >> 15;
+ SkFixed x = SkFixedCos(rads);
+ x += x << 15 >> 31; // map 0x10000 to 0xFFFF
+ return SkToU16(x);
+}
+
+SkCosineMapper::SkCosineMapper(SkFlattenableReadBuffer& rb)
+ : SkUnitMapper(rb)
+{
+}
+
+SkFlattenable::Factory SkCosineMapper::getFactory()
+{
+ return Create;
+}
+
+SkFlattenable* SkCosineMapper::Create(SkFlattenableReadBuffer& rb)
+{
+ return SkNEW_ARGS(SkCosineMapper, (rb));
+}
+