Added a flag to the Canvas class which allows forcing an RTL directionality

on text drawn using Canvas::DrawStringInt(). Using this flag, it is possible to
render RTL text correctly on platforms where LRE/PDF chars are not supported (e.g.
Windows XP with no RTL fonts installed).

BUG=23425
TEST=Run chrome and enter Hebrew text into the omnibox (see bug description). Make sure suggestions are formatted correctly. Verify in both RTL and LTR UIs.

Review URL: http://codereview.chromium.org/384018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31619 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 19 insertions, 5 deletions

diff --git a/app/gfx/canvas.h b/app/gfx/canvas.h
index 90cfad8..e6b07a1 100644
--- a/app/gfx/canvas.h
+++ b/app/gfx/canvas.h
@@ -66,6 +66,16 @@ class Canvas : public skia::PlatformCanvas {
     // Specifies if words can be split by new lines.
     // This only works with MULTI_LINE.
     CHARACTER_BREAK = 1024,
+
+    // Instructs DrawStringInt() to render the text using RTL directionality.
+    // In most cases, passing this flag is not necessary because information
+    // about the text directionality is going to be embedded within the string
+    // in the form of special Unicode characters. However, we don't insert
+    // directionality characters into strings if the locale is LTR because some
+    // platforms (for example, an English Windows XP with no RTL fonts
+    // installed) don't support these characters. Thus, this flag should be
+    // used to render text using RTL directionality when the locale is LTR.
+    FORCE_RTL_DIRECTIONALITY = 2048,
   };
 
   // Creates an empty Canvas. Callers must use initialize before using the
diff --git a/app/gfx/canvas_win.cc b/app/gfx/canvas_win.cc
index 9f70136..8b5e685 100644
--- a/app/gfx/canvas_win.cc
+++ b/app/gfx/canvas_win.cc
@@ -106,12 +106,16 @@ int ComputeFormatFlags(int flags, const std::wstring& text) {
   // Caveat: If the string is purely LTR, don't set DTL_RTLREADING since when
   // the flag is set, LRE-PDF don't have the desired effect of rendering
   // multiline English-only text as LTR.
-  if (l10n_util::GetTextDirection() == l10n_util::RIGHT_TO_LEFT &&
-      (f & DT_RIGHT)) {
-    if (l10n_util::StringContainsStrongRTLChars(text)) {
-      f |= DT_RTLREADING;
-    }
+  //
+  // Note that if the caller is explicitly requesting displaying the text
+  // using RTL directionality then we respect that and pass DT_RTLREADING to
+  // ::DrawText even if the locale is LTR.
+  if ((flags & gfx::Canvas::FORCE_RTL_DIRECTIONALITY) ||
+      ((l10n_util::GetTextDirection() == l10n_util::RIGHT_TO_LEFT) &&
+       (f & DT_RIGHT) && l10n_util::StringContainsStrongRTLChars(text))) {
+    f |= DT_RTLREADING;
   }
+
   return f;
 }