commit 7e54e3083fba9b0f07536c155e91eab6dcc84f91
author Dominik Röttsches <drott@chromium.org> Tue Oct 12 18:21:17 2021 +0300
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> Tue Oct 12 19:04:03 2021 +0000
tree 17dcfa091a2b1235fd329e6f739734a4d7642e48
parent a3a3ea97b43444a6ff1f8757e0361f07b9294258

Allow Windows simulations for fonts with EBDT/EBLC bitmap strikes

Korean fonts Gulim, Dotum, Batang, Gungsuh have bitmap strikes that get
artifically emboldened by Windows without antialiasing. Korean users
prefer these over the synthetic boldening performed by Skia. So let's
make an exception for fonts with bitmap strikes and allow passing
through Windows simulations for those, until Skia provides more control
over simulations in font matching.

Fixed: chromium:1258378
Change-Id: I66d7cfd5bc5a4262db401b51aad4d384a2b11d25
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/458536
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

src/ports/SkFontMgr_win_dw.cpp

diff --git a/src/ports/SkFontMgr_win_dw.cpp b/src/ports/SkFontMgr_win_dw.cpp
index 79fb263..58fc6e7 100644
--- a/src/ports/SkFontMgr_win_dw.cpp
+++ b/src/ports/SkFontMgr_win_dw.cpp
@@ -267,6 +267,21 @@
 
 namespace {
 
+// Korean fonts Gulim, Dotum, Batang, Gungsuh have bitmap strikes that get
+// artifically emboldened by Windows without antialiasing. Korean users prefer
+// these over the synthetic boldening performed by Skia. So let's make an
+// exception for fonts with bitmap strikes and allow passing through Windows
+// simulations for those, until Skia provides more control over simulations in
+// font matching, see https://crbug.com/1258378
+bool HasBitmapStrikes(const SkTScopedComPtr<IDWriteFont>& font) {
+  SkTScopedComPtr<IDWriteFontFace> fontFace;
+  HRB(font->CreateFontFace(&fontFace));
+
+  AutoDWriteTable ebdtTable(fontFace.get(),
+                            SkEndian_SwapBE32(SkSetFourByteTag('E', 'B', 'D', 'T')));
+  return ebdtTable.fExists;
+}
+
 // Iterate calls to GetFirstMatchingFont incrementally removing bold or italic
 // styling that can trigger the simulations. Implementing it this way gets us a
 // IDWriteFont that can be used as before and has the correct information on its
@@ -288,7 +303,8 @@
 #ifdef SK_WIN_FONTMGR_NO_SIMULATIONS
         noSimulations = simulations == DWRITE_FONT_SIMULATIONS_NONE ||
                         (dwStyle.fWeight == DWRITE_FONT_WEIGHT_REGULAR &&
-                         dwStyle.fSlant == DWRITE_FONT_STYLE_NORMAL);
+                         dwStyle.fSlant == DWRITE_FONT_STYLE_NORMAL) ||
+                        HasBitmapStrikes(searchFont);
 #else
         noSimulations = true;
 #endif
@@ -631,7 +647,8 @@
             fResolvedTypeface = fOuter->makeTypefaceFromDWriteFont(glyphRun->fontFace,
                                                                    font.get(),
                                                                    fontFamily.get());
-            fHasSimulations = font->GetSimulations() != DWRITE_FONT_SIMULATIONS_NONE;
+            fHasSimulations = (font->GetSimulations() != DWRITE_FONT_SIMULATIONS_NONE) &&
+                              !HasBitmapStrikes(font);
         }
 
         return S_OK;
@@ -880,7 +897,7 @@
         DWRITE_FONT_SIMULATIONS simulations = font->GetSimulations();
 
 #ifdef SK_WIN_FONTMGR_NO_SIMULATIONS
-        noSimulations = simulations == DWRITE_FONT_SIMULATIONS_NONE;
+        noSimulations = simulations == DWRITE_FONT_SIMULATIONS_NONE || HasBitmapStrikes(font);
 #else
         noSimulations = true;
 #endif