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 193 matching lines @@
   InitWithCopyOfHFONT(native_font);
 }
 
 PlatformFontWin::PlatformFontWin(const std::string& font_name,
                                  int font_size) {
   InitWithFontNameAndSize(font_name, font_size);
 }
 
 Font PlatformFontWin::DeriveFontWithHeight(int height, int style) {
   DCHECK_GE(height, 0);
-  if (GetHeight() == height && GetStyle() == style)
-    return Font(this);
+
+  LOGFONT font_info;

[msw, 2015/01/12 22:29:29]

nit: Add a comment like "Create a font with a height near that of the target
height."

[ananta, 2015/01/12 23:08:02]

Done.

+  GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
+  font_info.lfHeight = height;
+  SetLogFontStyle(style, &font_info);
+
+  HFONT hfont = CreateFontIndirect(&font_info);
+  Font font(new PlatformFontWin(CreateHFontRef(hfont)));
 
   // CreateFontIndirect() doesn't return the largest size for the given height
   // when decreasing the height. Iterate to find it.
-  if (GetHeight() > height) {
+  if (font.GetHeight() > height) {
     const int min_font_size = GetMinimumFontSize();
-    Font font = DeriveFont(-1, style);
+    font = font.Derive(-1, style);
     int font_height = font.GetHeight();
     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);
+  while (font.GetHeight() <= height) {

[Alexei Svitkine (slow), 2015/01/12 23:00:43]

Have you checked whether this extra loop doesn't cause any performance
regressions? In the past, I recall that we have had cases where bad performance
in this function resulted in a degradation of text rendering performance in UI.
Can you check whether this change is performance neutral or not?

[ananta, 2015/01/12 23:08:02]

We start off with a native font created with the target height which ensures
that the loop here will not have too many iterations to cause performance
issues. In the unittest runs the loop runs once at the most which is similar to
current behavior.

+    Font derived_font = font.Derive(1, style);

[msw, 2015/01/12 22:29:29]

nit: The loop above breaks if the derived font isn't any smaller than the
current font. I'm not sure if that's still a problem there, or if something
similar might happen here. If you want to be really safe, you can add a similar
break, otherwise you might want to just add a dcheck here:
DCHECK_GT(derived_font.GetFontSize(), font.GetFontSize());

[ananta, 2015/01/12 23:08:02]

Done.

+    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 165 matching lines @@
     style |= Font::ITALIC;
   if (font_metrics.tmUnderlined)
     style |= Font::UNDERLINE;
   if (font_metrics.tmWeight >= kTextMetricWeightBold)
     style |= Font::BOLD;
 
   return new HFontRef(font, font_size, height, baseline, cap_height,
                       ave_char_width, style);
 }
 
-Font PlatformFontWin::DeriveWithCorrectedSize(HFONT base_font) {
-  base::win::ScopedGetDC screen_dc(NULL);
-  gfx::ScopedSetMapMode mode(screen_dc, MM_TEXT);
-
-  base::win::ScopedGDIObject<HFONT> best_font(base_font);
-  TEXTMETRIC best_font_metrics;
-  GetTextMetricsForFont(screen_dc, best_font, &best_font_metrics);
-
-  LOGFONT font_info;
-  GetObject(base_font, sizeof(LOGFONT), &font_info);
-
-  // Set |lfHeight| to negative value to indicate it's the size, not the height.
-  font_info.lfHeight =
-      -(best_font_metrics.tmHeight - best_font_metrics.tmInternalLeading);
-
-  do {
-    // Increment font size. Prefer font with greater size if its height isn't
-    // greater than height of base font.
-    font_info.lfHeight = AdjustFontSize(font_info.lfHeight, 1);
-    base::win::ScopedGDIObject<HFONT> font(CreateFontIndirect(&font_info));
-    TEXTMETRIC font_metrics;
-    GetTextMetricsForFont(screen_dc, font, &font_metrics);
-    if (font_metrics.tmHeight > best_font_metrics.tmHeight)
-      break;
-    best_font.Set(font.release());
-    best_font_metrics = font_metrics;
-  } while (true);
-
-  return Font(new PlatformFontWin(CreateHFontRef(best_font.release())));
-}
-
 // static
 PlatformFontWin::HFontRef* PlatformFontWin::CreateHFontRefFromSkia(
     HFONT gdi_font,
     const TEXTMETRIC& font_metrics) {
   LOGFONT font_info = {0};
   GetObject(gdi_font, sizeof(LOGFONT), &font_info);
 
   // If the font height is passed in as 0, assume the height to be -1 to ensure
   // that we return the metrics for a 1 point font.
   // If the font height is positive it represents the rasterized font's cell
@@ skipping 44 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