Switch RenderTextMac to use point font sizes instead of pixel font sizes.

The previous implementation tried to use pixel sizes for consistency with
implementations of RenderText on other platforms. However, it turns out
that Skia itself uses point font sizes on Mac as does gfx::Font, so it
makes more sense to use point sizes throughout.

BUG=125664, 137033
TEST=Patch in http://codereview.chromium.org/10879069/ and bring up a
print preview on www.google.com. Letter spacing for the header and
footer text should be the same as what's produced by current Canary.

Review URL: https://chromiumcodereview.appspot.com/10874066

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@153599 0039d316-1c4b-4281-b951-d872f2087c98

ui/gfx/render_text_mac.cc

@@ -14,71 +14,6 @@
 #include "base/sys_string_conversions.h"
 #include "skia/ext/skia_utils_mac.h"
 
-namespace {
-
-// Returns the pixel height of |ct_font|.
-CGFloat GetCTFontPixelSize(CTFontRef ct_font) {
-  return CTFontGetAscent(ct_font) + CTFontGetDescent(ct_font);
-}
-
-// Creates a CTFont with the given font name and pixel size. Ownership is
-// transferred to the caller.
-//
-// Note: This code makes use of pixel sizes (rather than view coordinate sizes)
-// because it draws to an underlying Skia canvas, which is normally pixel based.
-CTFontRef CreateCTFontWithPixelSize(const std::string& font_name,
-                                    const int target_pixel_size) {
-  // Epsilon value used for comparing font sizes.
-  const CGFloat kEpsilon = 0.001;
-  // The observed pixel to points ratio for Lucida Grande on 10.6. Other fonts
-  // have other ratios and the documentation doesn't provide a guarantee that
-  // the relation is linear. So this ratio is used as a first try before
-  // falling back to the bisection method.
-  const CGFloat kPixelsToPointsRatio = 0.849088;
-
-  base::mac::ScopedCFTypeRef<CFStringRef> font_name_cf_string(
-      base::SysUTF8ToCFStringRef(font_name));
-
-  // First, try using |kPixelsToPointsRatio|.
-  CGFloat point_size = target_pixel_size * kPixelsToPointsRatio;
-  base::mac::ScopedCFTypeRef<CTFontRef> ct_font(
-      CTFontCreateWithName(font_name_cf_string, point_size, NULL));
-  CGFloat actual_pixel_size = GetCTFontPixelSize(ct_font);
-  if (std::fabs(actual_pixel_size - target_pixel_size) < kEpsilon)
-    return ct_font.release();
-
-  // |kPixelsToPointsRatio| wasn't correct. Use the bisection method to find the
-  // right size.
-
-  // First, find the initial bisection range, so that the point size that
-  // corresponds to |target_pixel_size| is between |lo| and |hi|.
-  CGFloat lo = 0;
-  CGFloat hi = point_size;
-  while (actual_pixel_size < target_pixel_size) {
-    lo = hi;
-    hi *= 2;
-    ct_font.reset(CTFontCreateWithName(font_name_cf_string, hi, NULL));
-    actual_pixel_size = GetCTFontPixelSize(ct_font);
-  }
-
-  // Now, bisect to find the right size.
-  while (lo < hi) {
-    point_size = (hi - lo) * 0.5 + lo;
-    ct_font.reset(CTFontCreateWithName(font_name_cf_string, point_size, NULL));
-    actual_pixel_size = GetCTFontPixelSize(ct_font);
-    if (std::fabs(actual_pixel_size - target_pixel_size) < kEpsilon)
-      break;
-    if (target_pixel_size > actual_pixel_size)
-      lo = point_size;
-    else
-      hi = point_size;
-  }
-
-  return ct_font.release();
-}
-
-}  // namespace
-
 namespace gfx {
 
 RenderTextMac::RenderTextMac() : common_baseline_(0), runs_valid_(false) {
@@ -163,8 +98,10 @@ void RenderTextMac::EnsureLayout() {
   runs_valid_ = false;
 
   const Font& font = GetFont();
+  base::mac::ScopedCFTypeRef<CFStringRef> font_name_cf_string(
+      base::SysUTF8ToCFStringRef(font.GetFontName()));
   base::mac::ScopedCFTypeRef<CTFontRef> ct_font(
-      CreateCTFontWithPixelSize(font.GetFontName(), font.GetFontSize()));
+      CTFontCreateWithName(font_name_cf_string, font.GetFontSize(), NULL));
 
   const void* keys[] = { kCTFontAttributeName };
   const void* values[] = { ct_font };
@@ -344,7 +281,7 @@ void RenderTextMac::ComputeRuns() {
     base::mac::ScopedCFTypeRef<CFStringRef> font_name_ref(
         CTFontCopyFamilyName(ct_font));
     run->font_name = base::SysCFStringRefToUTF8(font_name_ref);
-    run->text_size = GetCTFontPixelSize(ct_font);
+    run->text_size = CTFontGetSize(ct_font);
 
     CTFontSymbolicTraits traits = CTFontGetSymbolicTraits(ct_font);
     if (traits & kCTFontBoldTrait)