Gamma correction for distance field text.

src/core/SkPaint.cpp

Index: src/core/SkPaint.cpp
diff --git a/src/core/SkPaint.cpp b/src/core/SkPaint.cpp
index f3bf01bfafc5ca30e0507190a8ffee37f8a5efaa..fcd95054bdf33711f9fb0216dfc24cb1e9478f75 100644
--- a/src/core/SkPaint.cpp
+++ b/src/core/SkPaint.cpp
@@ -1773,7 +1773,7 @@ static const SkMaskGamma& cachedMaskGamma(SkScalar contrast, SkScalar paintGamma
 /**
  *  We ensure that the rec is self-consistent and efficient (where possible)
  */
-void SkScalerContext::PostMakeRec(const SkPaint&, SkScalerContext::Rec* rec) {
+void SkScalerContext::PostMakeRec(const SkPaint& paint, SkScalerContext::Rec* rec) {
     /**
      *  If we're asking for A8, we force the colorlum to be gray, since that
      *  limits the number of unique entries, and the scaler will only look at
@@ -1809,6 +1809,23 @@ void SkScalerContext::PostMakeRec(const SkPaint&, SkScalerContext::Rec* rec) {
             rec->ignorePreBlend();
             break;
     }
+
+    /**
+     *  If we're using distance fields we need to reset the rec to default values
+     */
+    if (paint.isDistanceFieldTextTEMP()) {
+        rec->ignorePreBlend();
+
+        rec->fFlags |= SkScalerContext::kSubpixelPositioning_Flag;
+        rec->fFlags &= ~SkScalerContext::kForceAutohinting_Flag;

[reed1, 2014/05/28 19:45:17]

other than preblend, this rest of this change seems unrelated to gamma. How were
we working before w/o wacking all of these flags?

[jvanverth1, 2014/05/29 18:53:49]

This was done in GrDistanceFieldTextContext::init(), by clearing the flags in
the local copy of SkPaint before getting the SkGlyphCache. I think I could do
that and back up the parameters I need from the SkPaint and DeviceProperties
(the current color, the gamma) if that seems better.

+
+        if (SkMask::kLCD16_Format == rec->fMaskFormat ||
+            SkMask::kLCD32_Format == rec->fMaskFormat) {
+            rec->fMaskFormat = SkMask::kA8_Format;
+        }
+        rec->setHinting(SkPaint::kNo_Hinting);
+    }
+
 }
 
 #define MIN_SIZE_FOR_EFFECT_BUFFER  1024
@@ -1974,6 +1991,21 @@ SkMaskGamma::PreBlend SkScalerContext::GetMaskPreBlend(const SkScalerContext::Re
     return maskGamma.preBlend(rec.getLuminanceColor());
 }
 
+void* SkScalerContext::getGammaLUTData(int& width, int& height, SkScalar contrast,

[reed1, 2014/05/28 19:45:17]

style again: use pointers for out-params

[jvanverth1, 2014/05/29 18:53:49]

Done.

+                                       SkScalar paintGamma, SkScalar deviceGamma) {
+    SkAutoMutexAcquire ama(gMaskGammaCacheMutex);
+    const SkMaskGamma& maskGamma = cachedMaskGamma(contrast,
+                                                   paintGamma,
+                                                   deviceGamma);
+    const uint8_t* gammaTables = maskGamma.getGammaTables(width, height);
+    size_t size = width*height*sizeof(uint8_t);
+    void* data = SkNEW_ARRAY(uint8_t, size);
+    memcpy(data, gammaTables, size);
+
+    return data;
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "SkStream.h"