Revert of remove unused (by clients) SkUnitMapper (https://codereview.chromium.org/283273002/)

Reason for revert:
does not address all legacy callsites in chrome.

e.g.

[13:45:32.091872] ../../ui/native_theme/native_theme_base.cc:608:76: error: no matching function for call to ‘SkGradientShader::CreateLinear(SkPoint [3], SkColor [3], NULL, int, SkShader::TileMode, NULL)’
[13:45:32.091919]            gradient_bounds, colors, NULL, 3, SkShader::kClamp_TileMode, NULL));


Original issue's description:
> remove unused (by clients) SkUnitMapper
>
> BUG=skia:
>
> Committed: http://code.google.com/p/skia/source/detail?r=14761

R=robertphillips@google.com, scroggo@google.com, george@mozilla.com
TBR=george@mozilla.com, robertphillips@google.com, scroggo@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Author: reed@google.com

Review URL: https://codereview.chromium.org/287063009

git-svn-id: http://skia.googlecode.com/svn/trunk@14763 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 52 insertions, 3 deletions

diff --git a/src/animator/SkDrawGradient.cpp b/src/animator/SkDrawGradient.cpp
index 70e5e4493e..c11559581b 100644
--- a/src/animator/SkDrawGradient.cpp
+++ b/src/animator/SkDrawGradient.cpp
@@ -11,6 +11,49 @@
 #include "SkAnimateMaker.h"
 #include "SkAnimatorScript.h"
 #include "SkGradientShader.h"
+#include "SkUnitMapper.h"
+
+static SkScalar SkUnitToScalar(U16CPU x) {
+    return x / 65535.0f;
+}
+
+static U16CPU SkScalarToUnit(SkScalar x) {
+    SkScalar pin =  SkScalarPin(x, 0, SK_Scalar1);
+    return (int) (pin * 65535.0f);
+}
+
+class SkDrawGradientUnitMapper : public SkUnitMapper {
+public:
+    SkDrawGradientUnitMapper(SkAnimateMaker* maker, const char* script) : fMaker(maker), fScript(script) {
+    }
+
+    SK_DECLARE_UNFLATTENABLE_OBJECT()
+
+protected:
+    virtual uint16_t mapUnit16(uint16_t x) {
+        fUnit = SkUnitToScalar(x);
+        SkScriptValue value;
+        SkAnimatorScript engine(*fMaker, NULL, SkType_Float);
+        engine.propertyCallBack(GetUnitValue, &fUnit);
+        if (engine.evaluate(fScript, &value, SkType_Float))
+            x = SkScalarToUnit(value.fOperand.fScalar);
+        return x;
+    }
+
+    static bool GetUnitValue(const char* token, size_t len, void* unitPtr, SkScriptValue* value) {
+        if (SK_LITERAL_STR_EQUAL("unit", token, len)) {
+            value->fOperand.fScalar = *(SkScalar*) unitPtr;
+            value->fType = SkType_Float;
+            return true;
+        }
+        return false;
+    }
+
+    SkAnimateMaker* fMaker;
+    const char* fScript;
+    SkScalar fUnit;
+};
+
 
 #if SK_USE_CONDENSED_INFO == 0
 
@@ -24,12 +67,13 @@ const SkMemberInfo SkDrawGradient::fInfo[] = {
 
 DEFINE_GET_MEMBER(SkDrawGradient);
 
-SkDrawGradient::SkDrawGradient() {
+SkDrawGradient::SkDrawGradient() : fUnitMapper(NULL) {
 }
 
 SkDrawGradient::~SkDrawGradient() {
     for (int index = 0; index < fDrawColors.count(); index++)
         delete fDrawColors[index];
+    delete fUnitMapper;
 }
 
 bool SkDrawGradient::addChild(SkAnimateMaker& , SkDisplayable* child) {
@@ -94,6 +138,8 @@ void SkDrawGradient::onEndElement(SkAnimateMaker& maker) {
             }
         }
     }
+    if (unitMapper.size() > 0)
+        fUnitMapper = new SkDrawGradientUnitMapper(&maker, unitMapper.c_str());
     INHERITED::onEndElement(maker);
 }
 
@@ -130,7 +176,7 @@ SkShader* SkDrawLinearGradient::getShader() {
         return NULL;
     SkShader* shader = SkGradientShader::CreateLinear((SkPoint*)points.begin(),
         fColors.begin(), offsets.begin(), fColors.count(), (SkShader::TileMode) tileMode,
-        0, getMatrix());
+        fUnitMapper, 0, getMatrix());
     SkAutoTDelete<SkShader> autoDel(shader);
     (void)autoDel.detach();
     return shader;
@@ -165,7 +211,7 @@ SkShader* SkDrawRadialGradient::getShader() {
         return NULL;
     SkShader* shader = SkGradientShader::CreateRadial(center,
         radius, fColors.begin(), offsets.begin(), fColors.count(), (SkShader::TileMode) tileMode,
-        0, getMatrix());
+        fUnitMapper, 0, getMatrix());
     SkAutoTDelete<SkShader> autoDel(shader);
     (void)autoDel.detach();
     return shader;
diff --git a/src/animator/SkDrawGradient.h b/src/animator/SkDrawGradient.h
index fa46a9e629..ff79e3fb91 100644
--- a/src/animator/SkDrawGradient.h
+++ b/src/animator/SkDrawGradient.h
@@ -14,6 +14,8 @@
 #include "SkDrawShader.h"
 #include "SkIntArray.h"
 
+class SkUnitMapper;
+
 class SkDrawGradient : public SkDrawShader {
     DECLARE_PRIVATE_MEMBER_INFO(DrawGradient);
     SkDrawGradient();
@@ -28,6 +30,7 @@ protected:
     SkString unitMapper;
     SkTDColorArray fColors;
     SkTDDrawColorArray fDrawColors;
+    SkUnitMapper* fUnitMapper;
     int addPrelude();
 private:
     typedef SkDrawShader INHERITED;