Use more fields from OutlineFontMEtrics: linegap, bbox.

src/ports/SkFontHost_win.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkAdvancedTypefaceMetrics.h"
 #include "SkBase64.h"
@@ skipping 81 matching lines @@
 using namespace skia_advanced_typeface_metrics_utils;
 
 static const uint16_t BUFFERSIZE = (16384 - 32);
 static uint8_t glyphbuf[BUFFERSIZE];
 
 /**
  *  Since LOGFONT wants its textsize as an int, and we support fractional sizes,
  *  and since we have a cache of LOGFONTs for our tyepfaces, we always set the
  *  lfHeight to a canonical size, and then we use the 2x2 matrix to achieve the
  *  actual requested size.
+ *
+ *  Not critical to match the font's upem, but we want it big enough to avoid
+ *  precision loss for GDI calls that return ints (e.g. GetOutlineFontMetrics).
  */
-static const int gCanonicalTextSize = 64;
+static const int gCanonicalTextSize = 2048;
 
 static void tchar_to_skstring(const TCHAR t[], SkString* s) {
 #ifdef UNICODE
     size_t sSize = WideCharToMultiByte(CP_UTF8, 0, t, -1, NULL, 0, NULL, NULL);
     s->resize(sSize);
     WideCharToMultiByte(CP_UTF8, 0, t, -1, s->writable_str(), sSize, NULL, NULL);
 #else
     s->set(t);
 #endif
 }
@@ skipping 714 matching lines @@
             SkPoint advance;
             fHiResMatrix.mapXY(SkIntToScalar(gm.gmCellIncX), SkIntToScalar(gm.gmCellIncY), &advance);
             glyph->fAdvanceX = SkScalarToFixed(advance.fX);
             glyph->fAdvanceY = SkScalarToFixed(advance.fY);
         }
         SelectObject(fDDC, fFont);
     }
 }
 
 void SkScalerContext_Windows::generateFontMetrics(SkPaint::FontMetrics* mx, SkPaint::FontMetrics* my) {
-// Note: This code was borrowed from generateLineHeight, which has a note
-// stating that it may be incorrect.
-    if (!(mx || my))
+    if (!(mx || my)) {
       return;
+    }
+
+    if (mx) {
+        sk_bzero(mx, sizeof(*mx));
+    }
+    if (my) {
+        sk_bzero(my, sizeof(*my));
+    }
 
     SkASSERT(fDDC);
 
     if (fType == SkScalerContext_Windows::kBitmap_Type) {
         if (mx) {
             mx->fTop = SkIntToScalar(-fTM.tmAscent);
             mx->fAscent = SkIntToScalar(-fTM.tmAscent);
             mx->fDescent = -SkIntToScalar(fTM.tmDescent);
             mx->fBottom = SkIntToScalar(fTM.tmDescent);
-            mx->fLeading = SkIntToScalar(fTM.tmInternalLeading
-                                         + fTM.tmExternalLeading);
+            mx->fLeading = SkIntToScalar(fTM.tmExternalLeading);
         }
 
         if (my) {
             my->fTop = SkIntToScalar(-fTM.tmAscent);
             my->fAscent = SkIntToScalar(-fTM.tmAscent);
             my->fDescent = SkIntToScalar(-fTM.tmDescent);
             my->fBottom = SkIntToScalar(fTM.tmDescent);
-            my->fLeading = SkIntToScalar(fTM.tmInternalLeading
-                                         + fTM.tmExternalLeading);
+            my->fLeading = SkIntToScalar(fTM.tmExternalLeading);

[bungeman-skia, 2013/05/08 02:40:40]

tmAveCharWidth is also available here. There is no xheight, however. Blink
currently uses tmAscent * 0.56f as a guess.

Apparently the avg and max character widths are used to size text boxes. The
xheight is semi-optional and is mostly used as the basis of the css ex unit, but
is also used to attempt vertical centering.

         }
         return;
     }
 
     OUTLINETEXTMETRIC otm;
 
     uint32_t ret = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
     if (GDI_ERROR == ret) {
         LogFontTypeface::EnsureAccessible(this->getTypeface());
         ret = GetOutlineTextMetrics(fDDC, sizeof(otm), &otm);
     }
     if (sizeof(otm) != ret) {
         return;
     }
 
     if (mx) {
-        mx->fTop = -fScale * otm.otmTextMetrics.tmAscent;
+        mx->fTop = -fScale * otm.otmrcFontBox.left;
         mx->fAscent = -fScale * otm.otmAscent;
         mx->fDescent = -fScale * otm.otmDescent;
-        mx->fBottom = fScale * otm.otmTextMetrics.tmDescent;
-        mx->fLeading = fScale * (otm.otmTextMetrics.tmInternalLeading
-                                 + otm.otmTextMetrics.tmExternalLeading);
+        mx->fBottom = fScale * otm.otmrcFontBox.right;
+        mx->fLeading = fScale * otm.otmLineGap;
     }
 
     if (my) {
-        my->fTop = -fScale * otm.otmTextMetrics.tmAscent;
+        my->fTop = -fScale * otm.otmrcFontBox.top;
         my->fAscent = -fScale * otm.otmAscent;
         my->fDescent = -fScale * otm.otmDescent;
-        my->fBottom = fScale * otm.otmTextMetrics.tmDescent;
-        my->fLeading = fScale * (otm.otmTextMetrics.tmInternalLeading
-                                 + otm.otmTextMetrics.tmExternalLeading);
+        my->fBottom = fScale * otm.otmrcFontBox.bottom;
+        my->fLeading = fScale * otm.otmLineGap;
+        my->fAvgCharWidth = fScale * otm.otmTextMetrics.tmAveCharWidth;
+        my->fXHeight = fScale * otm.otmsXHeight;
     }
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////
 
 static void build_power_table(uint8_t table[], float ee) {
     for (int i = 0; i < 256; i++) {
         float x = i / 255.f;
         x = sk_float_pow(x, ee);
         int xx = SkScalarRound(SkFloatToScalar(x * 255));
@@ skipping 955 matching lines @@
         return this->createFromStream(stream);
     }
 
 private:
     SkTDArray<ENUMLOGFONTEX> fLogFontArray;
 };
 
 SkFontMgr* SkFontMgr::Factory() {
     return SkNEW(SkFontMgrGDI);
 }