grab from latest android

git-svn-id: http://skia.googlecode.com/svn/trunk/src@27 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 80 insertions, 0 deletions

diff --git a/utils/SkUnitMappers.cpp b/utils/SkUnitMappers.cpp
new file mode 100644
index 00000000..0363a2b8
--- /dev/null
+++ b/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));
+}
+