Detect that we're drawing to a device that has per-pixel alpha, and if so,

disable LCD text.

Add experimental flag to force AA in fontscaler (windows-only). Hope to remove
this later.



git-svn-id: http://skia.googlecode.com/svn/trunk@2387 2bbb7eff-a529-9590-31e7-b0007b416f81

3 files changed, 26 insertions, 21 deletions

diff --git a/src/core/SkBlitter_ARGB32.cpp b/src/core/SkBlitter_ARGB32.cpp
index af55aba951..4e2916af0e 100644
--- a/src/core/SkBlitter_ARGB32.cpp
+++ b/src/core/SkBlitter_ARGB32.cpp
@@ -60,18 +60,16 @@ static void blit_lcd16_row(SkPMColor dst[], const uint16_t src[],
         maskG = maskG * srcA >> 8;
         maskB = maskB * srcA >> 8;
 
-        int maskA = SkMax32(SkMax32(maskR, maskG), maskB);
-
-        int dstA = SkGetPackedA32(d);
         int dstR = SkGetPackedR32(d);
         int dstG = SkGetPackedG32(d);
         int dstB = SkGetPackedB32(d);
 
-        // nocheck version for now, until we cleanup GDI's garbage bits
-        dst[i] = SkPackARGB32NoCheck(blend32(0xFF, dstA, maskA),
-                                     blend32(srcR, dstR, maskR),
-                                     blend32(srcG, dstG, maskG),
-                                     blend32(srcB, dstB, maskB));
+        // LCD blitting is only supported if the dst is known/required\
+        // to be opaque
+        dst[i] = SkPackARGB32(0xFF,
+                              blend32(srcR, dstR, maskR),
+                              blend32(srcG, dstG, maskG),
+                              blend32(srcB, dstB, maskB));
     }
 }
 
@@ -105,18 +103,16 @@ static void blit_lcd16_opaque_row(SkPMColor dst[], const uint16_t src[],
         maskG = upscale31To32(maskG);
         maskB = upscale31To32(maskB);
 
-        int maskA = SkMax32(SkMax32(maskR, maskG), maskB);
-
-        int dstA = SkGetPackedA32(d);
         int dstR = SkGetPackedR32(d);
         int dstG = SkGetPackedG32(d);
         int dstB = SkGetPackedB32(d);
 
-        // nocheck version for now, until we cleanup GDI's garbage bits
-        dst[i] = SkPackARGB32NoCheck(blend32(0xFF, dstA, maskA),
-                                     blend32(srcR, dstR, maskR),
-                                     blend32(srcG, dstG, maskG),
-                                     blend32(srcB, dstB, maskB));
+        // LCD blitting is only supported if the dst is known/required
+        // to be opaque
+        dst[i] = SkPackARGB32(0xFF,
+                              blend32(srcR, dstR, maskR),
+                              blend32(srcG, dstG, maskG),
+                              blend32(srcB, dstB, maskB));
     }
 }
 
@@ -150,14 +146,13 @@ static void blit_lcd32_row(SkPMColor dst[], const uint32_t src[],
         maskG = maskG * srcA >> 8;
         maskB = maskB * srcA >> 8;
 
-        int maskA = SkMax32(SkMax32(maskR, maskG), maskB);
-
-        int dstA = SkGetPackedA32(d);
         int dstR = SkGetPackedR32(d);
         int dstG = SkGetPackedG32(d);
         int dstB = SkGetPackedB32(d);
 
-        dst[i] = SkPackARGB32(SkAlphaBlend(0xFF, dstA, maskA),
+        // LCD blitting is only supported if the dst is known/required
+        // to be opaque
+        dst[i] = SkPackARGB32(0xFF,
                               SkAlphaBlend(srcR, dstR, maskR),
                               SkAlphaBlend(srcG, dstG, maskG),
                               SkAlphaBlend(srcB, dstB, maskB));
diff --git a/src/core/SkDevice.cpp b/src/core/SkDevice.cpp
index 69f86ccf52..c88ad9afb7 100644
--- a/src/core/SkDevice.cpp
+++ b/src/core/SkDevice.cpp
@@ -219,12 +219,13 @@ void SkDevice::drawDevice(const SkDraw& draw, SkDevice* device,
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkDevice::filterTextFlags(const SkPaint& paint, TextFlags* flags) {
-    if (!paint.isLCDRenderText()) {
+    if (!paint.isLCDRenderText() || !paint.isAntiAlias()) {
         // we're cool with the paint as is
         return false;
     }
 
     if (SkBitmap::kARGB_8888_Config != fBitmap.config() ||
+        !fBitmap.isOpaque() ||
         paint.getShader() ||
         paint.getXfermode() || // unless its srcover
         paint.getMaskFilter() ||
@@ -235,6 +236,10 @@ bool SkDevice::filterTextFlags(const SkPaint& paint, TextFlags* flags) {
         paint.getStyle() != SkPaint::kFill_Style) {
         // turn off lcd
         flags->fFlags = paint.getFlags() & ~SkPaint::kLCDRenderText_Flag;
+#ifdef SK_BUILD_FOR_WIN
+        // flag that we *really* want AA
+        flags->fFlags |= SkPaint::kForceAAText_Flag;
+#endif
         flags->fHinting = paint.getHinting();
         return true;
     }
diff --git a/src/core/SkPaint.cpp b/src/core/SkPaint.cpp
index 9197adde0f..b2f5d8e0e1 100644
--- a/src/core/SkPaint.cpp
+++ b/src/core/SkPaint.cpp
@@ -1340,6 +1340,11 @@ void SkScalerContext::MakeRec(const SkPaint& paint,
     if (paint.isAutohinted()) {
         flags |= SkScalerContext::kAutohinting_Flag;
     }
+#ifdef SK_BUILD_FOR_WIN
+    if (paint.getFlags() & SkPaint::kForceAAText_Flag) {
+        flags |= SkScalerContext::kForceAA_Flag;
+    }
+#endif
     rec->fFlags = SkToU16(flags);
 
     // setHinting modifies fFlags, so do this last