Get all font unittests running with DirectWrite on Windows 7+

ui/gfx/platform_font_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/platform_font_win.h"
 
 #include <algorithm>
 #include <dwrite.h>
 #include <math.h>
 #include <windows.h>
@@ skipping 212 matching lines @@
     int font_size = font.GetFontSize();
     while (font_height > height && font_size != min_font_size) {
       font = font.Derive(-1, style);
       if (font_height == font.GetHeight() && font_size == font.GetFontSize())
         break;
       font_height = font.GetHeight();
       font_size = font.GetFontSize();
     }
     return font;
   }
-
-  LOGFONT font_info;
-  GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
-  font_info.lfHeight = height;
-  SetLogFontStyle(style, &font_info);
-
-  HFONT hfont = CreateFontIndirect(&font_info);
-  return DeriveWithCorrectedSize(hfont);
+  // We derive a font with a size delta of 0 initially, i.e the derived font

[msw, 2015/01/12 21:30:55]

Is this necessary given the early return at lines 214/215?

[msw, 2015/01/12 21:30:55]

nit: add a blank line above.

[ananta, 2015/01/12 22:14:15]

Done.

[ananta, 2015/01/12 22:14:15]

The function has changed. 

[ananta, 2015/01/12 22:14:15]

Removed the comment. The function has changed a bit.

+  // starts off with the height of the current font instance.
+  // This is to ensure that we honor the contract of this function which is
+  // to return a font with with height less than or equal to the desired
+  // height.
+  Font font = DeriveFont(0, style);
+  while (font.GetHeight() < height) {
+    Font derived_font = font.Derive(1, style);

[msw, 2015/01/12 21:30:55]

I'm curious about the performance impact here, but I'm not aware of related
perftests. Perhaps an initial CreateFontIndirect would avoid 90% of the
DeriveFont iterations for both loops. Maybe Alexei or Dan have some thoughts?

[ananta, 2015/01/12 22:14:15]

Done. Removed the starting 2 lines which check for whether the current font is
of the desired height. This is as per our discussion that we want to iterate and
return the next available font with the desired height.

+    if (derived_font.GetHeight() > height)
+      break;
+    font = derived_font;
+  }
+  return font;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformFontWin, PlatformFont implementation:
 
 Font PlatformFontWin::DeriveFont(int size_delta, int style) const {
   LOGFONT font_info;
   GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
   const int requested_font_size = font_ref_->requested_font_size();
   font_info.lfHeight = AdjustFontSize(-requested_font_size, size_delta);
@@ skipping 260 matching lines @@
   SkPaint paint;
   paint.setAntiAlias(!!antialiasing);
   paint.setTypeface(skia_face.get());
   paint.setTextSize(-font_info.lfHeight);
   SkPaint::FontMetrics skia_metrics;
   paint.getFontMetrics(&skia_metrics);
 
   // The calculations below are similar to those in the CreateHFontRef
   // function. The height, baseline and cap height are rounded up to ensure
   // that they match up closely with GDI.
-  const int height = std::ceil(
-      skia_metrics.fDescent - skia_metrics.fAscent + skia_metrics.fLeading);
+  const int height = std::ceil(skia_metrics.fDescent - skia_metrics.fAscent);
   const int baseline = std::max<int>(1, std::ceil(-skia_metrics.fAscent));
   const int cap_height = std::ceil(paint.getTextSize() *
       static_cast<double>(dwrite_font_metrics.capHeight) /
           dwrite_font_metrics.designUnitsPerEm);
 
   // The metrics retrieved from skia don't have the average character width. In
   // any case if we get the average character width from skia then use that or
   // use the text extent technique as documented by microsoft. See
   // GetAverageCharWidthInDialogUnits for details.
   const int ave_char_width =
@@ skipping 87 matching lines @@
   return new PlatformFontWin(native_font);
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontWin(font_name, font_size);
 }
 
 }  // namespace gfx