Revert of Revert of Revert of add gamma/sRGB to SkImageInfo (patchset #1 of https://codereview.chromium.org/511363002/)

Reason for revert:
android builder in chrome reveals the caller using { } initialization for SkImageInfo, which this CL now makes illegal. Will have to fix the call site before I can re-land this

Original issue's description:
> Revert of Revert of add gamma/sRGB to SkImageInfo (patchset #1 of https://codereview.chromium.org/512243002/)
>
> Reason for revert:
> this revert was premature -- the chrome canary I looked at is old, and newer ones were green. So trying again...
>
> Original issue's description:
> > Revert of add gamma/sRGB to SkImageInfo (patchset #4 of https://codereview.chromium.org/514753002/)
> >
> > Reason for revert:
> > breaks linker on chrome -- may need SK_API, but not sure.
> >
> > Original issue's description:
> > > add gamma/sRGB to SkImageInfo
> > >
> > > BUG=skia:
> > >
> > > Committed: https://skia.googlesource.com/skia/+/615c369777258231054840a88cdb74c68c382485
> >
> > TBR=bungeman@google.com,bsalomon@google.com
> > NOTREECHECKS=true
> > NOTRY=true
> > BUG=skia:
> >
> > Committed: https://skia.googlesource.com/skia/+/dc53701216c0e9f98eacf6c0cda769ebbd200b59
>
> TBR=bungeman@google.com,bsalomon@google.com
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/e759a2662273fdf52ebbb3822229945eda317e46

R=bungeman@google.com, bsalomon@google.com
TBR=bsalomon@google.com, bungeman@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Author: reed@google.com

Review URL: https://codereview.chromium.org/517113002

1 files changed, 21 insertions, 111 deletions

diff --git a/src/core/SkImageInfo.cpp b/src/core/SkImageInfo.cpp
index 44fd808dc8..e61cd7d45f 100644
--- a/src/core/SkImageInfo.cpp
+++ b/src/core/SkImageInfo.cpp
@@ -9,53 +9,34 @@
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 
-static bool color_type_supports_sRGB(SkColorType colorType) {
-    switch (colorType) {
-        case kRGBA_8888_SkColorType:
-        case kBGRA_8888_SkColorType:
-            return true;
-        default:
-            return false;
-    }
+static bool alpha_type_is_valid(SkAlphaType alphaType) {
+    return (alphaType >= 0) && (alphaType <= kLastEnum_SkAlphaType);
 }
 
-static bool color_type_supports_gamma(SkColorType colorType) {
-    switch (colorType) {
-        case kRGBA_8888_SkColorType:
-        case kBGRA_8888_SkColorType:
-        // case kLuminance ...
-            return true;
-        default:
-            return false;
-    }
+static bool color_type_is_valid(SkColorType colorType) {
+    return (colorType >= 0) && (colorType <= kLastEnum_SkColorType);
 }
 
-static float pin_gamma_to_legal(float gamma) {
-    if (!SkScalarIsFinite(gamma)) {
-        return 1;
-    }
-    // these limits are just made up -- feel free to change them within reason
-    const float min_gamma = 0.01f;
-    const float max_gamma = 4.0;
-    return SkScalarPin(gamma, min_gamma, max_gamma);
-}
+void SkImageInfo::unflatten(SkReadBuffer& buffer) {
+    fWidth = buffer.read32();
+    fHeight = buffer.read32();
 
-SkImageInfo SkImageInfo::MakeSRGB(int width, int height, SkColorType ct, SkAlphaType at) {
-    Profile p = color_type_supports_sRGB(ct) ? kSRGB_Profile : kUnknown_Profile;
-    return SkImageInfo(width, height, ct, at, p, 0);
+    uint32_t packed = buffer.read32();
+    SkASSERT(0 == (packed >> 16));
+    fAlphaType = (SkAlphaType)((packed >> 8) & 0xFF);
+    fColorType = (SkColorType)((packed >> 0) & 0xFF);
+    buffer.validate(alpha_type_is_valid(fAlphaType) &&
+                    color_type_is_valid(fColorType));
 }
 
-SkImageInfo SkImageInfo::MakeWithGamma(int width, int height, SkColorType ct, SkAlphaType at,
-                                       float gamma) {
-    Profile p;
-    if (color_type_supports_gamma(ct)) {
-        gamma = pin_gamma_to_legal(gamma);
-        p = kExponential_Profile;
-    } else {
-        p = kUnknown_Profile;
-        gamma = 0;
-    }
-    return SkImageInfo(width, height, ct, at, p, gamma);
+void SkImageInfo::flatten(SkWriteBuffer& buffer) const {
+    buffer.write32(fWidth);
+    buffer.write32(fHeight);
+
+    SkASSERT(0 == (fAlphaType & ~0xFF));
+    SkASSERT(0 == (fColorType & ~0xFF));
+    uint32_t packed = (fAlphaType << 8) | fColorType;
+    buffer.write32(packed);
 }
 
 bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
@@ -88,74 +69,3 @@ bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
     }
     return true;
 }
-
-void SkImageInfo::unflatten(SkReadBuffer& buffer) {
-    *this = Unflatten(buffer);
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////
-
-static bool alpha_type_is_valid(SkAlphaType alphaType) {
-    return (alphaType >= 0) && (alphaType <= kLastEnum_SkAlphaType);
-}
-
-static bool color_type_is_valid(SkColorType colorType) {
-    return (colorType >= 0) && (colorType <= kLastEnum_SkColorType);
-}
-
-static float igamma_to_gamma(int gamma3dot9) {
-    return gamma3dot9 / 512.0f;
-}
-
-static unsigned gamma_to_igamma(float gamma) {
-    SkASSERT(gamma >= 0 && gamma < 8);
-    int igamma = SkScalarRoundToInt(gamma * 512);
-    SkASSERT(igamma >= 0 && igamma <= 0xFFF);
-    return igamma;
-}
-
-SkImageInfo SkImageInfo::Unflatten(SkReadBuffer& buffer) {
-    int width = buffer.read32();
-    int height = buffer.read32();
-    uint32_t packed = buffer.read32();
-    
-    SkColorType ct = (SkColorType)((packed >> 0) & 0xFF);   // 8 bits for colortype
-    SkAlphaType at = (SkAlphaType)((packed >> 8) & 0xFF);   // 8 bits for alphatype
-    if (!alpha_type_is_valid(at) || !color_type_is_valid(ct)) {
-        return MakeUnknown();
-    }
-
-    // Earlier formats always stored 0 in the upper 16 bits. That corresponds to
-    // days before we had gamma/profile. That happens to correspond to kUnknown_Profile,
-    // which means we can just ignore the gamma value anyways.
-    //
-    int iprofile = ((packed >> 16) & 0xF);  // 4 bits for profile
-    
-    switch (iprofile) {
-        case kUnknown_Profile:
-            return Make(width, height, ct, at);
-        case kSRGB_Profile:
-            return MakeSRGB(width, height, ct, at);
-        case kExponential_Profile: {
-            int igamma = packed >> 20;      // 12 bits for gamma 3.9
-            float gamma = igamma_to_gamma(igamma);
-            return MakeWithGamma(width, height, ct, at, gamma);
-        }
-        default:
-            (void)buffer.validate(false);
-            return MakeUnknown();
-    }
-}
-
-void SkImageInfo::flatten(SkWriteBuffer& buffer) const {
-    buffer.write32(fWidth);
-    buffer.write32(fHeight);
-    
-    SkASSERT(0 == (fColorType & ~0xFF));    // 8 bits for colortype
-    SkASSERT(0 == (fAlphaType & ~0xFF));    // 8 bits for alphatype
-    SkASSERT(0 == (fProfile & ~0xF));       // 4 bits for profile
-    int igamma = gamma_to_igamma(fGamma);   // 12 bits for gamma (if needed)
- 
-    uint32_t packed = (igamma << 20) | (fProfile << 16) | (fAlphaType << 8) | fColorType;
-    buffer.write32(packed);
-}