Revert "Revert "WIP: Skia support library for ICC tasks""

This reverts commit eb733fbf56538838a36814c75cd03f917462cb22.

Reason for revert: Revert patch was automatically merged incorrectly?

Original change's description:
> Revert "WIP: Skia support library for ICC tasks"
> 
> This reverts commit fc8dc3194acb959ee5980b41766660ca0644bcab.
> 
> Reason for revert: Breaks Build-Mac-Clang-Arm7-{Debug,Release}-iOS builds.
> Example tasks:
> * https://chromium-swarm.appspot.com/task?id=3322f668620b9e10&refresh=10
> * https://chromium-swarm.appspot.com/task?id=332296146331e810&refresh=10
> 
> Original change's description:
> > WIP: Skia support library for ICC tasks
> > 
> > As a starting point, this would be mostly trivial to implement using
> > SkColorSpace.
> > 
> > This also would give us the flexibility to begin to move all of
> > the ICC related code from SkColorSpace to SkICC.
> > 
> > What are the advantages of moving this away from SkColorSpace?
> > (1) A long term goal (once Chrome uses SkCodec), might be to
> > move SkColorSpace::MakeICC() out of the public API.  That way,
> > we can guarantee that we can draw to/from *any* SkColorSpace.
> > (2) Keeps SkColorSpace separate from ICC-specific representations
> > like SkColorSpaceTransferFn etc.
> > 
> > BUG=skia:
> > 
> > Change-Id: Iddeb9903221fb57fbfc01218d8641c928b4a5165
> > Reviewed-on: https://skia-review.googlesource.com/5676
> > Commit-Queue: Matt Sarett <msarett@google.com>
> > Reviewed-by: Brian Osman <brianosman@google.com>
> > Reviewed-by: Mike Reed <reed@google.com>
> > 
> 
> TBR=mtklein@google.com,msarett@google.com,brianosman@google.com,reed@google.com,reviews@skia.org
> BUG=skia:
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> 
> Change-Id: Ibdf272fce25892402bd3e85595fb8814cdf59856
> Reviewed-on: https://skia-review.googlesource.com/6232
> Commit-Queue: Ravi Mistry <rmistry@google.com>
> Reviewed-by: Ravi Mistry <rmistry@google.com>
> 

TBR=mtklein@google.com,rmistry@google.com,msarett@google.com,reviews@skia.org,brianosman@google.com,reed@google.com
BUG=skia:
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I68b1624cfab8adfe31b17e1193a7766507dec8b0
Reviewed-on: https://skia-review.googlesource.com/6233
Commit-Queue: Ravi Mistry <rmistry@google.com>
Reviewed-by: Ravi Mistry <rmistry@google.com>

1 files changed, 50 insertions, 1 deletions

diff --git a/src/core/SkColorSpacePriv.h b/src/core/SkColorSpacePriv.h
index 73038738ff..32981ae875 100644
--- a/src/core/SkColorSpacePriv.h
+++ b/src/core/SkColorSpacePriv.h
@@ -5,14 +5,22 @@
  * found in the LICENSE file.
  */
 
+#include <math.h>
+
 #define SkColorSpacePrintf(...)
 
 static inline bool color_space_almost_equal(float a, float b) {
     return SkTAbs(a - b) < 0.01f;
 }
 
+static inline float add_epsilon(float v) {
+    return v + FLT_MIN;
+}
+
 static inline bool is_zero_to_one(float v) {
-    return (0.0f <= v) && (v <= 1.0f);
+    // Because we allow a value just barely larger than 1, the client can use an
+    // entirely linear transfer function.
+    return (0.0f <= v) && (v <= add_epsilon(1.0f));
 }
 
 static inline bool is_valid_transfer_fn(const SkColorSpaceTransferFn& coeffs) {
@@ -84,3 +92,44 @@ static inline bool is_almost_2dot2(const SkColorSpaceTransferFn& coeffs) {
            color_space_almost_equal(0.0f, coeffs.fF) &&
            color_space_almost_equal(2.2f, coeffs.fG);
 }
+
+static inline void value_to_parametric(SkColorSpaceTransferFn* coeffs, float exponent) {
+    coeffs->fA = 1.0f;
+    coeffs->fB = 0.0f;
+    coeffs->fC = 0.0f;
+    coeffs->fD = 0.0f;
+    coeffs->fE = 0.0f;
+    coeffs->fF = 0.0f;
+    coeffs->fG = exponent;
+}
+
+static inline bool named_to_parametric(SkColorSpaceTransferFn* coeffs,
+                                       SkGammaNamed gammaNamed) {
+    switch (gammaNamed) {
+        case kSRGB_SkGammaNamed:
+            coeffs->fA = 1.0f / 1.055f;
+            coeffs->fB = 0.055f / 1.055f;
+            coeffs->fC = 0.0f;
+            coeffs->fD = 0.04045f;
+            coeffs->fE = 1.0f / 12.92f;
+            coeffs->fF = 0.0f;
+            coeffs->fG = 2.4f;
+            return true;
+        case k2Dot2Curve_SkGammaNamed:
+            value_to_parametric(coeffs, 2.2f);
+            return true;
+        case kLinear_SkGammaNamed:
+            coeffs->fA = 0.0f;
+            coeffs->fB = 0.0f;
+            coeffs->fC = 0.0f;
+            // Make sure that we use the linear segment of the transfer function even
+            // when the x-value is 1.0f.
+            coeffs->fD = add_epsilon(1.0f);
+            coeffs->fE = 1.0f;
+            coeffs->fF = 0.0f;
+            coeffs->fG = 0.0f;
+            return true;
+        default:
+            return false;
+    }
+}