Get additional DW font metrics when available.

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"
 #undef GetGlyphIndices
 
 #include "SkDWrite.h"
 #include "SkDWriteGeometrySink.h"
 #include "SkEndian.h"
 #include "SkGlyph.h"
 #include "SkHRESULT.h"
 #include "SkMaskGamma.h"
 #include "SkMatrix22.h"
 #include "SkOTTable_EBLC.h"
 #include "SkOTTable_EBSC.h"
 #include "SkOTTable_gasp.h"
 #include "SkOTTable_maxp.h"
 #include "SkPath.h"
 #include "SkScalerContext.h"
 #include "SkScalerContext_win_dw.h"
 #include "SkTScopedComPtr.h"
 #include "SkTypeface_win_dw.h"
 
 #include <dwrite.h>
+#include <dwrite_1.h>
 
 static bool isLCD(const SkScalerContext::Rec& rec) {
     return SkMask::kLCD16_Format == rec.fMaskFormat ||
            SkMask::kLCD32_Format == rec.fMaskFormat;
 }
 
 static bool is_hinted_without_gasp(DWriteFontTypeface* typeface) {
     AutoTDWriteTable<SkOTTableMaximumProfile> maxp(typeface->fDWriteFontFace.get());
     if (!maxp.fExists) {
         return false;
@@ skipping 402 matching lines @@
          "Could not get texture bounds.");
 
     glyph->fWidth = SkToU16(bbox.right - bbox.left);
     glyph->fHeight = SkToU16(bbox.bottom - bbox.top);
     glyph->fLeft = SkToS16(bbox.left);
     glyph->fTop = SkToS16(bbox.top);
 }
 
 void SkScalerContext_DW::generateFontMetrics(SkPaint::FontMetrics* metrics) {
     if (NULL == metrics) {
-      return;
+        return;
     }
 
     sk_bzero(metrics, sizeof(*metrics));
 
     DWRITE_FONT_METRICS dwfm;
     if (DWRITE_MEASURING_MODE_GDI_CLASSIC == fMeasuringMode ||
         DWRITE_MEASURING_MODE_GDI_NATURAL == fMeasuringMode)
     {
         fTypeface->fDWriteFontFace->GetGdiCompatibleMetrics(
              fTextSizeRender,
              1.0f, // pixelsPerDip
              &fXform,
              &dwfm);
     } else {
         fTypeface->fDWriteFontFace->GetMetrics(&dwfm);
     }
 
     SkScalar upem = SkIntToScalar(dwfm.designUnitsPerEm);
 
-    metrics->fTop = -fTextSizeRender * SkIntToScalar(dwfm.ascent) / upem;
-    metrics->fAscent = metrics->fTop;
+    metrics->fAscent = -fTextSizeRender * SkIntToScalar(dwfm.ascent) / upem;
     metrics->fDescent = fTextSizeRender * SkIntToScalar(dwfm.descent) / upem;
-    metrics->fBottom = metrics->fDescent;
     metrics->fLeading = fTextSizeRender * SkIntToScalar(dwfm.lineGap) / upem;
     metrics->fXHeight = fTextSizeRender * SkIntToScalar(dwfm.xHeight) / upem;
     metrics->fUnderlineThickness = fTextSizeRender * SkIntToScalar(dwfm.underlineThickness) / upem;
     metrics->fUnderlinePosition = -(fTextSizeRender * SkIntToScalar(dwfm.underlinePosition) / upem);
 
     metrics->fFlags |= SkPaint::FontMetrics::kUnderlineThinknessIsValid_Flag;
     metrics->fFlags |= SkPaint::FontMetrics::kUnderlinePositionIsValid_Flag;
+
+    if (NULL != fTypeface->fDWriteFontFace1.get()) {
+        DWRITE_FONT_METRICS1 dwfm1;
+        fTypeface->fDWriteFontFace1->GetMetrics(&dwfm1);
+        metrics->fTop = -fTextSizeRender * SkIntToScalar(dwfm1.glyphBoxTop) / upem;
+        metrics->fBottom = -fTextSizeRender * SkIntToScalar(dwfm1.glyphBoxBottom) / upem;
+        metrics->fXMin = fTextSizeRender * SkIntToScalar(dwfm1.glyphBoxLeft) / upem;
+        metrics->fXMax = fTextSizeRender * SkIntToScalar(dwfm1.glyphBoxRight) / upem;
+
+        metrics->fMaxCharWidth = metrics->fXMax - metrics->fXMin;
+    } else {
+        AutoTDWriteTable<SkOTTableHead> head(fTypeface->fDWriteFontFace.get());
+        if (head.fExists &&
+            head.fSize >= sizeof(SkOTTableHead) &&
+            head->version == SkOTTableHead::version1)
+        {
+            metrics->fTop = -fTextSizeRender * (int16_t)SkEndian_SwapBE16(head->yMax) / upem;
+            metrics->fBottom = -fTextSizeRender * (int16_t)SkEndian_SwapBE16(head->yMin) / upem;
+            metrics->fXMin = fTextSizeRender * (int16_t)SkEndian_SwapBE16(head->xMin) / upem;
+            metrics->fXMax = fTextSizeRender * (int16_t)SkEndian_SwapBE16(head->xMax) / upem;
+
+            metrics->fMaxCharWidth = metrics->fXMax - metrics->fXMin;
+        } else {
+            metrics->fTop = metrics->fAscent;
+            metrics->fBottom = metrics->fDescent;
+        }
+    }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "SkColorPriv.h"
 
 static void bilevel_to_bw(const uint8_t* SK_RESTRICT src, const SkGlyph& glyph) {
     const int width = glyph.fWidth;
     const size_t dstRB = (width + 7) >> 3;
     uint8_t* SK_RESTRICT dst = static_cast<uint8_t*>(glyph.fImage);
@@ skipping 194 matching lines @@
                                        NULL, //advances
                                        NULL, //offsets
                                        1, //num glyphs
                                        FALSE, //sideways
                                        FALSE, //rtl
                                        geometryToPath.get()),
          "Could not create glyph outline.");
 
     path->transform(fSkXform);
 }