if SK_USE_COLOR_LUMINANCE is defined, then we store 2 bits of each component

to create a per-component-luminance value for the fonthost to use. Only supported
on Mac at the moment (but still disabled by default)



git-svn-id: http://skia.googlecode.com/svn/trunk@3180 2bbb7eff-a529-9590-31e7-b0007b416f81

3 files changed, 36 insertions, 29 deletions

diff --git a/include/core/SkScalerContext.h b/include/core/SkScalerContext.h
index 7a83bd79ad..43baedf799 100644
--- a/include/core/SkScalerContext.h
+++ b/include/core/SkScalerContext.h
@@ -17,7 +17,6 @@
 #include "SkPoint.h"
 
 //#define SK_USE_COLOR_LUMINANCE
-//#define USE_FULL_LUMI
 
 class SkDescriptor;
 class SkMaskFilter;
@@ -236,34 +235,12 @@ public:
         }
         
 #ifdef SK_USE_COLOR_LUMINANCE
-        static unsigned ColorToLumBits(U8CPU x) {
-            SkASSERT(x <= 0xFF);
-            return x >> 7;
-        }
-        static U8CPU LumBitsToColor(unsigned x) {
-            SkASSERT(x <= 1);
-            return x * 0xFF;
-        }
-
         SkColor getLuminanceColor() const {
-#ifdef USE_FULL_LUMI
             return fLumBits;
-#else
-            unsigned bits = fLumBits;
-            return SkColorSetRGB(LumBitsToColor((bits >> 2) & 1),
-                                 LumBitsToColor((bits >> 1) & 1),
-                                 LumBitsToColor((bits >> 0) & 1));
-#endif
         }
         
         void setLuminanceColor(SkColor c) {
-#ifdef USE_FULL_LUMI
             fLumBits = c;
-#else
-            fLumBits =  (ColorToLumBits(SkColorGetR(c)) << 2) |
-                        (ColorToLumBits(SkColorGetG(c)) << 1) |
-                        (ColorToLumBits(SkColorGetB(c)) << 0);
-#endif
         }
 #else
         unsigned getLuminanceBits() const {
diff --git a/src/core/SkPaint.cpp b/src/core/SkPaint.cpp
index 4026acbae4..86bc49ed54 100644
--- a/src/core/SkPaint.cpp
+++ b/src/core/SkPaint.cpp
@@ -1301,6 +1301,14 @@ static SkColor computeLuminanceColor(const SkPaint& paint) {
     }
     return c;
 }
+
+static U8CPU reduce_lumbits(U8CPU x) {
+    static const uint8_t gReduceBits[] = {
+        0x0, 0x55, 0xAA, 0xFF
+    };
+    return gReduceBits[x >> 6];
+}
+
 #else
 // returns 0..kLuminance_Max
 static unsigned computeLuminance(const SkPaint& paint) {
@@ -1476,6 +1484,15 @@ void SkScalerContext::MakeRec(const SkPaint& paint,
 #else
         rec->setLuminanceBits(0);
 #endif
+    } else {
+#ifdef SK_USE_COLOR_LUMINANCE
+        // filter down the luminance color to a finite number of bits
+        SkColor c = rec->getLuminanceColor();
+        c = SkColorSetRGB(reduce_lumbits(SkColorGetR(c)),
+                          reduce_lumbits(SkColorGetG(c)),
+                          reduce_lumbits(SkColorGetB(c)));
+        rec->setLuminanceColor(c);
+#endif
     }
 }
 
diff --git a/src/ports/SkFontHost_mac_coretext.cpp b/src/ports/SkFontHost_mac_coretext.cpp
index 0500508383..19b91ad298 100644
--- a/src/ports/SkFontHost_mac_coretext.cpp
+++ b/src/ports/SkFontHost_mac_coretext.cpp
@@ -31,6 +31,7 @@
 
 class SkScalerContext_Mac;
 
+
 // inline versions of these rect helpers
 
 static bool CGRectIsEmpty_inline(const CGRect& rect) {
@@ -464,6 +465,12 @@ static SkTypeface* GetDefaultFace() {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+extern CTFontRef SkTypeface_GetCTFontRef(const SkTypeface* face);
+CTFontRef SkTypeface_GetCTFontRef(const SkTypeface* face) {
+    const SkTypeface_Mac* macface = (const SkTypeface_Mac*)face;
+    return macface ? macface->fFontRef : NULL;
+}
+
 /*  This function is visible on the outside. It first searches the cache, and if
  *  not found, returns a new entry (after adding it to the cache).
  */
@@ -1230,13 +1237,13 @@ void SkScalerContext_Mac::generateImage(const SkGlyph& glyph) {
         CGRGBPixel* bkPixels = NULL;
         bool needBlack = true;
         bool needWhite = true;
-        
+
         if (!isLCD || (SK_ColorWHITE == lumBits)) {
             needBlack = false;
         } else if (SK_ColorBLACK == lumBits) {
             needWhite = false;
         }
-
+        
         if (needBlack) {
             bkPixels = fBlackScreen.getCG(*this, glyph, false, cgGlyph, &cgRowBytes);
             cgPixels = bkPixels;
@@ -1793,10 +1800,16 @@ void SkFontHost::FilterRec(SkScalerContext::Rec* rec) {
     }
     rec->setHinting(h);
 
-    // for compatibility at the moment, discretize luminance to 3 settings
-    // black, white, gray. This helps with fontcache utilization, since we
-    // won't create multiple entries that in the end map to the same results.
-#ifndef SK_USE_COLOR_LUMINANCE
+#ifdef SK_USE_COLOR_LUMINANCE
+    {
+        SkColor c = rec->getLuminanceColor();
+        // apply our chosen scaling between Black and White cg output
+        int r = SkColorGetR(c)*2/3;
+        int g = SkColorGetG(c)*2/3;
+        int b = SkColorGetB(c)*2/3;
+        rec->setLuminanceColor(SkColorSetRGB(r, g, b));
+    }
+#else
     {
         unsigned lum = rec->getLuminanceByte();
         if (lum <= BLACK_LUMINANCE_LIMIT) {