detect web-fonts, and force gray-antialiasing for them, regardless of the system's FONTSMOOTHING se…

Source/core/platform/graphics/chromium/FontPlatformDataChromiumWin.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Computer, Inc.
  * Copyright (c) 2006, 2007, 2008, 2009, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 17 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/platform/graphics/FontPlatformData.h"
 
 #include <windows.h>
 #include <mlang.h>
 #include <objidl.h>
+#include "core/platform/LayoutTestSupport.h"
 #include "core/platform/SharedBuffer.h"
 #include "core/platform/graphics/FontCache.h"
 #include "core/platform/graphics/skia/SkiaFontWin.h"
 #include "core/platform/win/HWndDC.h"
 #include "public/platform/Platform.h"
 #include "public/platform/win/WebSandboxSupport.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "third_party/skia/include/ports/SkTypeface_win.h"
 #include "wtf/PassOwnPtr.h"
@@ skipping 27 matching lines @@
             if (SystemParametersInfo(SPI_GETFONTSMOOTHINGTYPE, 0, &smoothType, 0)) {
                 if (FE_FONTSMOOTHINGCLEARTYPE == smoothType)
                     gFlags |= SkPaint::kLCDRenderText_Flag;
             }
         }
         gInited = true;
     }
     return gFlags;
 }
 
+static bool isWebFont(const LOGFONT& lf)
+{
+    // web-fonts have artifical names constructed to always be
+    // 1. 24 characters, followed by a '\0'
+    // 2. the last two characters are '=='

[f(malita), 2013/09/13 15:28:02]

Don't know much about LOGFONT, but I assume lfFaceName's storage is guaranteed
>= 25 chars? A quick search seems to confirm it.

+    return '=' == lf.lfFaceName[22] && '=' == lf.lfFaceName[23] && '\0' == lf.lfFaceName[24];
+}
+
 static int computePaintTextFlags(const LOGFONT& lf)
 {
     int textFlags = 0;
     switch (lf.lfQuality) {
     case NONANTIALIASED_QUALITY:
         textFlags = 0;
         break;
     case ANTIALIASED_QUALITY:
         textFlags = SkPaint::kAntiAlias_Flag;
         break;
     case CLEARTYPE_QUALITY:
         textFlags = (SkPaint::kAntiAlias_Flag | SkPaint::kLCDRenderText_Flag);
         break;
     default:
         textFlags = getDefaultGDITextFlags();
         break;
     }
 
     // only allow features that SystemParametersInfo allows
-    return textFlags & getDefaultGDITextFlags();
+    textFlags &= getDefaultGDITextFlags();
+
+    /*
+     *  FontPlatformData(...) will read our logfont, and try to honor the the lfQuality
+     *  setting (computing the corresponding SkPaint flags for AA and LCD). However, it
+     *  will limit the quality based on its query of SPI_GETFONTSMOOTHING. This could mean
+     *  we end up drawing the text in BW, even though our lfQuality requested antialiasing.
+     *
+     *  Many web-fonts are so poorly hinted that they are terrible to read when drawn in BW.
+     *  In these cases, we have decided to FORCE these fonts to be drawn with at least grayscale AA,
+     *  even when the System (getDefaultGDITextFlags) tells us to draw only in BW.
+     */
+    if (isWebFont(lf) && !isRunningLayoutTest())
+        textFlags |= SkPaint::kAntiAlias_Flag;
+    return textFlags;
 }
 
 PassRefPtr<SkTypeface> CreateTypefaceFromHFont(HFONT hfont, int* size, int* paintTextFlags)
 {
     LOGFONT info;
     GetObject(hfont, sizeof(info), &info);
     if (size) {
         int height = info.lfHeight;
         if (height < 0)
             height = -height;
@@ skipping 195 matching lines @@
 
 bool FontPlatformData::ensureFontLoaded(HFONT font)
 {
     WebKit::WebSandboxSupport* sandboxSupport = WebKit::Platform::current()->sandboxSupport();
     // if there is no sandbox, then we can assume the font
     // was able to be loaded successfully already
     return sandboxSupport ? sandboxSupport->ensureFontLoaded(font) : true;
 }
 
 }