Add RenderText DirectionalityMode enum and support; etc.

ui/views/controls/label.cc

Index: ui/views/controls/label.cc
diff --git a/ui/views/controls/label.cc b/ui/views/controls/label.cc
index 9412a6ab792a2827454cdbd828ea5ca720eb9828..69375a4392726de1742f4fb60de13ef3c677f9ac 100644
--- a/ui/views/controls/label.cc
+++ b/ui/views/controls/label.cc
@@ -22,6 +22,7 @@
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/font.h"
 #include "ui/gfx/insets.h"
+#include "ui/gfx/text_constants.h"
 #include "ui/views/background.h"
 
 namespace views {
@@ -102,10 +103,10 @@ void Label::ClearEmbellishing() {
 
 void Label::SetHorizontalAlignment(Alignment alignment) {
   // If the View's UI layout is right-to-left and directionality_mode_ is
-  // USE_UI_DIRECTIONALITY, we need to flip the alignment so that the alignment
-  // settings take into account the text directionality.
-  if (base::i18n::IsRTL() && (directionality_mode_ == USE_UI_DIRECTIONALITY) &&
-      (alignment != ALIGN_CENTER))
+  // gfx::DIRECTIONALITY_FROM_UI, we need to flip the alignment so that the
+  // alignment settings take into account the text directionality.
+  if (base::i18n::IsRTL() && (alignment != ALIGN_CENTER) &&
+      (directionality_mode_ == gfx::DIRECTIONALITY_FROM_UI))

[xji, 2012/07/30 18:32:16]

I can see that you are trying to re-use gfx::DirectionalityMode, but I feel the
name is pretty confusing here (at least I was confused at first).

The gfx::DIRECTIONALITY_FROM_UI/TEXT here is used to control whether the
alignment is going to be flipped or not (or whether the label's
directionality_mode is a forced one or not).
But in RenderText, in the current implementation, DIRECTIONALITY_FROM_TEXT is
the default, DIRECTIONALITY_FROM_UI means text directionality is based on UI.

the combinations are as following:
Label's DIRECTIONALITY_FROM_UI --> (falls to) RenderText's
DIRECTIONALTY_FROM_TEXT.
Label's DIRECTIONALITY_FROM_TEXT --> (falls to) RenderText's
DIRECTIONALITY_FORCE_xxx.

[msw, 2012/07/31 03:03:06]

You're right; Label doesn't currently support gfx::DIRECTIONALITY_FROM_UI.
I reverted this portion of the CL and will followup in a separate CL.

     alignment = (alignment == ALIGN_LEFT) ? ALIGN_RIGHT : ALIGN_LEFT;
   if (horiz_alignment_ != alignment) {
     horiz_alignment_ = alignment;
@@ -362,7 +363,7 @@ void Label::Init(const string16& text, const gfx::Font& font) {
   elide_in_middle_ = false;
   is_email_ = false;
   collapse_when_hidden_ = false;
-  directionality_mode_ = USE_UI_DIRECTIONALITY;
+  directionality_mode_ = gfx::DIRECTIONALITY_FROM_UI;
   paint_as_focused_ = false;
   has_focus_border_ = false;
   enabled_shadow_color_ = 0;
@@ -433,8 +434,8 @@ int Label::ComputeDrawStringFlags() const {
   if (SkColorGetA(background_color_) != 0xFF)
     flags |= gfx::Canvas::NO_SUBPIXEL_RENDERING;
 
-  if (directionality_mode_ == AUTO_DETECT_DIRECTIONALITY) {
-    base::i18n::TextDirection direction =
+  if (directionality_mode_ == gfx::DIRECTIONALITY_FROM_TEXT) {
+    const base::i18n::TextDirection direction =

[xji, 2012/07/30 19:00:04]

if we introduce gfx::Canvas::DIRECTIONALITY_FROM_TEXT, then, we do not need the
computation here. we can just do: 
flags |= gfx::Canvas::DIRECTIONALITY_FROM_TEXT

And in "bool AdjustStringDirection()" in canvas_skia.cc,
we need to add:

else if (flags & gfx::Canvas::DIRECTIONALITY_FROM_TEXT)
  render_text->SetDirectionalityMode(gfx::DIRECTIONALITY_FROM_TEXT);


So far, there is no real usage of FORCE directionality (they are actually the
current DIRECTIONALITY_FROM_TEXT. They were introduced before is because we
previously use DIRECTIONALITY_FROM_UI as default).
But I think the forced directionality might be useful later for the title page
case (http://code.google.com/p/chromium/issues/detail?id=27094). 

[msw, 2012/07/31 03:03:06]

I've reverted these changes in this CL and I'll follup in a separate CL.
(DIRECTIONALITY_FROM_TEXT is the default underlying behavior and this class
currently doesn't actually propagate DIRECTIONALITY_FROM_UI, so this block can
be removed altogether).

         base::i18n::GetFirstStrongCharacterDirection(text_);
     if (direction == base::i18n::RIGHT_TO_LEFT)
       flags |= gfx::Canvas::FORCE_RTL_DIRECTIONALITY;