PlatformFontWin::DeriveFontWithHeight insensitive to base font's height

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 <windows.h>
 #include <math.h>
 
 #include <algorithm>
@@ skipping 98 matching lines @@
     }
     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 Font(new PlatformFontWin(CreateHFontRef(hfont)));
+  Font best_font(new PlatformFontWin(CreateHFontRef(hfont)));
+  int best_font_height = best_font.GetHeight();
+
+  while (best_font_height <= height) {

[msw, 2014/05/29 21:34:41]

Is it possible (and more efficient) to first guess a size change value to more
quickly approach the desired height? Something like:
best_font.Derive(best_font_height - height, style) (though I realize that size
and height aren't directly comparable like that...)

+    Font font = best_font.Derive(1, style);
+    int font_height = font.GetHeight();
+    if (font_height > height) {
+      break;
+    }
+    best_font = font;
+    best_font_height = font_height;
+  }
+
+  return best_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 192 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