Support pixel antialising in DirectWrite.

src/ports/SkScalerContext_win_dw.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTypes.h"
 #if defined(SK_BUILD_FOR_WIN32)
 
@@ skipping 194 matching lines @@
 }
 
 SkScalerContext_DW::SkScalerContext_DW(DWriteFontTypeface* typeface,
                                        const SkScalerContextEffects& effects,
                                        const SkDescriptor* desc)
         : SkScalerContext(typeface, effects, desc)
         , fTypeface(SkRef(typeface))
         , fGlyphCount(-1) {
 
 #if SK_HAS_DWRITE_2_H
-    fTypeface->fFactory->QueryInterface<IDWriteFactory2>(&fFactory2);
-
-    SkTScopedComPtr<IDWriteFontFace2> fontFace2;
-    fTypeface->fDWriteFontFace->QueryInterface<IDWriteFontFace2>(&fontFace2);
-    fIsColorFont = fFactory2.get() && fontFace2.get() && fontFace2->IsColorFont();
+    fIsColorFont = fTypeface->fFactory2 &&
+                   fTypeface->fDWriteFontFace2 &&
+                   fTypeface->fDWriteFontFace2->IsColorFont();
 #endif
 
     // In general, all glyphs should use CLEARTYPE_NATURAL_SYMMETRIC
     // except when bi-level rendering is requested or there are embedded
     // bi-level bitmaps (and the embedded bitmap flag is set and no rotation).
     //
     // DirectWrite's IDWriteFontFace::GetRecommendedRenderingMode does not do
     // this. As a result, determine the actual size of the text and then see if
     // there are any embedded bi-level bitmaps of that size. If there are, then
     // force bitmaps by requesting bi-level rendering.
@@ skipping 87 matching lines @@
 
     // The normal case is to use natural symmetric rendering and linear metrics.
     } else {
         fTextSizeRender = realTextSize;
         fRenderingMode = DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL_SYMMETRIC;
         fTextureType = DWRITE_TEXTURE_CLEARTYPE_3x1;
         fTextSizeMeasure = realTextSize;
         fMeasuringMode = DWRITE_MEASURING_MODE_NATURAL;
     }
 
+    // DirectWrite2 allows for grayscale hinting.
+#if SK_HAS_DWRITE_2_H
+    fAntiAliasMode = DWRITE_TEXT_ANTIALIAS_MODE_CLEARTYPE;
+    if (fTypeface->fFactory2 && fTypeface->fDWriteFontFace2 &&
+        !isLCD(fRec) && !(fRec.fFlags & SkScalerContext::kGenA8FromLCD_Flag))
+    {
+        // DWRITE_TEXTURE_ALIASED_1x1 is not misnamed, it must also be used with grayscale.

[bungeman-skia, 2016/06/14 14:40:52]

s/not/now, will fix

+        fTextureType = DWRITE_TEXTURE_ALIASED_1x1;
+        fAntiAliasMode = DWRITE_TEXT_ANTIALIAS_MODE_GRAYSCALE;
+    }
+#endif
+
+    // DirectWrite2 allows hinting to be disabled.
+#if SK_HAS_DWRITE_2_H
+    fGridFitMode = DWRITE_GRID_FIT_MODE_ENABLED;
+    if (fTypeface->fFactory2 && fTypeface->fDWriteFontFace2 &&
+        fRec.getHinting() == SkPaint::kNo_Hinting)
+    {
+        fGridFitMode = DWRITE_GRID_FIT_MODE_DISABLED;
+    }
+#endif
+
     if (this->isSubpixel()) {
         fTextSizeMeasure = realTextSize;
         fMeasuringMode = DWRITE_MEASURING_MODE_NATURAL;
     }
 }
 
 SkScalerContext_DW::~SkScalerContext_DW() {
 }
 
 unsigned SkScalerContext_DW::generateGlyphCount() {
@@ skipping 88 matching lines @@
     run.fontFace = fTypeface->fDWriteFontFace.get();
     run.fontEmSize = SkScalarToFloat(fTextSizeRender);
     run.bidiLevel = 0;
     run.glyphIndices = &glyphId;
     run.isSideways = FALSE;
     run.glyphOffsets = &offset;
 
     SkTScopedComPtr<IDWriteGlyphRunAnalysis> glyphRunAnalysis;
     {
         SkAutoExclusive l(DWriteFactoryMutex);
-        HRM(fTypeface->fFactory->CreateGlyphRunAnalysis(
-            &run,
-            1.0f, // pixelsPerDip,
-            &fXform,
-            renderingMode,
-            fMeasuringMode,
-            0.0f, // baselineOriginX,
-            0.0f, // baselineOriginY,
-            &glyphRunAnalysis),
-            "Could not create glyph run analysis.");
+        if (fTypeface->fFactory2) {
+#if SK_HAS_DWRITE_2_H
+            HRNM(fTypeface->fFactory2->CreateGlyphRunAnalysis(
+                     &run,
+                     &fXform,
+                     renderingMode,
+                     fMeasuringMode,
+                     fGridFitMode,
+                     fAntiAliasMode,
+                     0.0f, // baselineOriginX,
+                     0.0f, // baselineOriginY,
+                     &glyphRunAnalysis),
+                 "Could not create DW2 glyph run analysis.");
+#else
+#  pragma message("No dwrite_2.h is available, pixel antialiased glyph quality may be affected.")
+#endif
+        } else {
+            HRNM(fTypeface->fFactory->CreateGlyphRunAnalysis(&run,
+                     1.0f, // pixelsPerDip,
+                     &fXform,
+                     renderingMode,
+                     fMeasuringMode,
+                     0.0f, // baselineOriginX,
+                     0.0f, // baselineOriginY,
+                     &glyphRunAnalysis),
+                "Could not create glyph run analysis.");
+        }
     }
     {
         Shared l(DWriteFactoryMutex);
         HRM(glyphRunAnalysis->GetAlphaTextureBounds(textureType, bbox),
             "Could not get texture bounds.");
     }
     return S_OK;
 }
 
 /** GetAlphaTextureBounds succeeds but sometimes returns empty bounds like
@@ skipping 36 matching lines @@
     DWRITE_GLYPH_RUN run;
     run.glyphCount = 1;
     run.glyphAdvances = &advance;
     run.fontFace = fTypeface->fDWriteFontFace.get();
     run.fontEmSize = SkScalarToFloat(fTextSizeRender);
     run.bidiLevel = 0;
     run.glyphIndices = &glyphId;
     run.isSideways = FALSE;
     run.glyphOffsets = &offset;
 
-    HRESULT hr = fFactory2->TranslateColorGlyphRun(
+    HRESULT hr = fTypeface->fFactory2->TranslateColorGlyphRun(
         0, 0, &run, nullptr, fMeasuringMode, &fXform, 0, colorGlyph);
     if (hr == DWRITE_E_NOCOLOR) {
         return false;
     }
     HRBM(hr, "Failed to translate color glyph run");
     return true;
 }
 #endif
 
 void SkScalerContext_DW::generateMetrics(SkGlyph* glyph) {
@@ skipping 137 matching lines @@
                 mask >>= 1;
             }
             dst[byteCount] = byte;
         }
         src += bitCount;
         dst += dstRB;
     }
 }
 
 template<bool APPLY_PREBLEND>
+static void grayscale_to_a8(const uint8_t* SK_RESTRICT src, const SkGlyph& glyph,
+                            const uint8_t* table8) {
+    const size_t dstRB = glyph.rowBytes();
+    const U16CPU width = glyph.fWidth;
+    uint8_t* SK_RESTRICT dst = static_cast<uint8_t*>(glyph.fImage);
+
+    for (U16CPU y = 0; y < glyph.fHeight; y++) {
+        for (U16CPU i = 0; i < width; i++) {
+            U8CPU a = *(src++);
+            dst[i] = sk_apply_lut_if<APPLY_PREBLEND>(a, table8);
+        }
+        dst = SkTAddOffset<uint8_t>(dst, dstRB);
+    }
+}
+
+template<bool APPLY_PREBLEND>
 static void rgb_to_a8(const uint8_t* SK_RESTRICT src, const SkGlyph& glyph, const uint8_t* table8) {
     const size_t dstRB = glyph.rowBytes();
     const U16CPU width = glyph.fWidth;
     uint8_t* SK_RESTRICT dst = static_cast<uint8_t*>(glyph.fImage);
 
     for (U16CPU y = 0; y < glyph.fHeight; y++) {
         for (U16CPU i = 0; i < width; i++) {
             U8CPU r = *(src++);
             U8CPU g = *(src++);
             U8CPU b = *(src++);
             dst[i] = sk_apply_lut_if<APPLY_PREBLEND>((r + g + b) / 3, table8);
         }
-        dst = (uint8_t*)((char*)dst + dstRB);
+        dst = SkTAddOffset<uint8_t>(dst, dstRB);
     }
 }
 
 template<bool APPLY_PREBLEND, bool RGB>
 static void rgb_to_lcd16(const uint8_t* SK_RESTRICT src, const SkGlyph& glyph,
                          const uint8_t* tableR, const uint8_t* tableG, const uint8_t* tableB) {
     const size_t dstRB = glyph.rowBytes();
     const U16CPU width = glyph.fWidth;
     uint16_t* SK_RESTRICT dst = static_cast<uint16_t*>(glyph.fImage);
 
     for (U16CPU y = 0; y < glyph.fHeight; y++) {
         for (U16CPU i = 0; i < width; i++) {
             U8CPU r, g, b;
             if (RGB) {
                 r = sk_apply_lut_if<APPLY_PREBLEND>(*(src++), tableR);
                 g = sk_apply_lut_if<APPLY_PREBLEND>(*(src++), tableG);
                 b = sk_apply_lut_if<APPLY_PREBLEND>(*(src++), tableB);
             } else {
                 b = sk_apply_lut_if<APPLY_PREBLEND>(*(src++), tableB);
                 g = sk_apply_lut_if<APPLY_PREBLEND>(*(src++), tableG);
                 r = sk_apply_lut_if<APPLY_PREBLEND>(*(src++), tableR);
             }
             dst[i] = SkPack888ToRGB16(r, g, b);
         }
-        dst = (uint16_t*)((char*)dst + dstRB);
+        dst = SkTAddOffset<uint16_t>(dst, dstRB);
     }
 }
 
 const void* SkScalerContext_DW::drawDWMask(const SkGlyph& glyph,
                                            DWRITE_RENDERING_MODE renderingMode,
                                            DWRITE_TEXTURE_TYPE textureType)
 {
     int sizeNeeded = glyph.fWidth * glyph.fHeight;
-    if (DWRITE_RENDERING_MODE_ALIASED != renderingMode) {
+    if (DWRITE_TEXTURE_CLEARTYPE_3x1 == textureType) {
         sizeNeeded *= 3;
     }
     if (sizeNeeded > fBits.count()) {
         fBits.setCount(sizeNeeded);
     }
 
     // erase
     memset(fBits.begin(), 0, sizeNeeded);
 
     fXform.dx = SkFixedToFloat(glyph.getSubXFixed());
@@ skipping 10 matching lines @@
     DWRITE_GLYPH_RUN run;
     run.glyphCount = 1;
     run.glyphAdvances = &advance;
     run.fontFace = fTypeface->fDWriteFontFace.get();
     run.fontEmSize = SkScalarToFloat(fTextSizeRender);
     run.bidiLevel = 0;
     run.glyphIndices = &index;
     run.isSideways = FALSE;
     run.glyphOffsets = &offset;
     {
-
         SkTScopedComPtr<IDWriteGlyphRunAnalysis> glyphRunAnalysis;
         {
             SkAutoExclusive l(DWriteFactoryMutex);
-            HRNM(fTypeface->fFactory->CreateGlyphRunAnalysis(&run,
-                1.0f, // pixelsPerDip,
-                &fXform,
-                renderingMode,
-                fMeasuringMode,
-                0.0f, // baselineOriginX,
-                0.0f, // baselineOriginY,
-                &glyphRunAnalysis),
-                "Could not create glyph run analysis.");
+            if (fTypeface->fFactory2) {
+#if SK_HAS_DWRITE_2_H
+                HRNM(fTypeface->fFactory2->CreateGlyphRunAnalysis(&run,
+                         &fXform,
+                         renderingMode,
+                         fMeasuringMode,
+                         fGridFitMode,
+                         fAntiAliasMode,
+                         0.0f, // baselineOriginX,
+                         0.0f, // baselineOriginY,
+                         &glyphRunAnalysis),
+                     "Could not create DW2 glyph run analysis.");
+#else
+#  pragma message("No dwrite_2.h is available, pixel antialiased glyph quality may be affected.")
+#endif
+            } else {
+                HRNM(fTypeface->fFactory->CreateGlyphRunAnalysis(&run,
+                         1.0f, // pixelsPerDip,
+                         &fXform,
+                         renderingMode,
+                         fMeasuringMode,
+                         0.0f, // baselineOriginX,
+                         0.0f, // baselineOriginY,
+                         &glyphRunAnalysis),
+                     "Could not create glyph run analysis.");
+            }
         }
         //NOTE: this assumes that the glyph has already been measured
         //with an exact same glyph run analysis.
         RECT bbox;
         bbox.left = glyph.fLeft;
         bbox.top = glyph.fTop;
         bbox.right = glyph.fLeft + glyph.fWidth;
         bbox.bottom = glyph.fTop + glyph.fHeight;
         {
             Shared l(DWriteFactoryMutex);
@@ skipping 99 matching lines @@
         sk_bzero(glyph.fImage, glyph.computeImageSize());
         return;
     }
 
     //Copy the mask into the glyph.
     const uint8_t* src = (const uint8_t*)bits;
     if (DWRITE_RENDERING_MODE_ALIASED == renderingMode) {
         bilevel_to_bw(src, glyph);
         const_cast<SkGlyph&>(glyph).fMaskFormat = SkMask::kBW_Format;
     } else if (!isLCD(fRec)) {
-        if (fPreBlend.isApplicable()) {
-            rgb_to_a8<true>(src, glyph, fPreBlend.fG);
+        if (textureType == DWRITE_TEXTURE_ALIASED_1x1) {
+            if (fPreBlend.isApplicable()) {
+                grayscale_to_a8<true>(src, glyph, fPreBlend.fG);
+            } else {
+                grayscale_to_a8<false>(src, glyph, fPreBlend.fG);
+            }
         } else {
-            rgb_to_a8<false>(src, glyph, fPreBlend.fG);
+            if (fPreBlend.isApplicable()) {
+                rgb_to_a8<true>(src, glyph, fPreBlend.fG);
+            } else {
+                rgb_to_a8<false>(src, glyph, fPreBlend.fG);
+            }
         }
     } else {
         SkASSERT(SkMask::kLCD16_Format == glyph.fMaskFormat);
         if (fPreBlend.isApplicable()) {
             if (fRec.fFlags & SkScalerContext::kLCD_BGROrder_Flag) {
                 rgb_to_lcd16<true, false>(src, glyph, fPreBlend.fR, fPreBlend.fG, fPreBlend.fB);
             } else {
                 rgb_to_lcd16<true, true>(src, glyph, fPreBlend.fR, fPreBlend.fG, fPreBlend.fB);
             }
         } else {
@@ skipping 27 matching lines @@
             FALSE, //sideways
             FALSE, //rtl
             geometryToPath.get()),
             "Could not create glyph outline.");
     }
 
     path->transform(fSkXform);
 }
 
 #endif//defined(SK_BUILD_FOR_WIN32)