Re-land: Use a common font baseline in RenderText classes.

This ensures the text in different runs gets aligned
along a common bottom baseline and that the correct
font's baseline gets used in case of font fallback.

Original CL: http://codereview.chromium.org/9968040/

BUG=105550
TEST=none
TBR=msw
Review URL: https://chromiumcodereview.appspot.com/9982001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@130618 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 27 insertions, 15 deletions

diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index aad57f4..7af7690 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -732,16 +732,14 @@ Point RenderText::GetAlignmentOffset() {
   return Point();
 }
 
-Point RenderText::GetOriginForSkiaDrawing() {
+Point RenderText::GetOriginForDrawing() {
   Point origin(GetTextOrigin());
-  // TODO(msw): Establish a vertical baseline for strings of mixed font heights.
+  // TODO(asvitkine): Use GetStringSize().height() here instead.
   const Font& font = GetFont();
   int height = font.GetHeight();
   DCHECK_LE(height, display_rect().height());
   // Center the text vertically in the display area.
   origin.Offset(0, (display_rect().height() - height) / 2);
-  // Offset to account for Skia expecting y to be the baseline.
-  origin.Offset(0, font.GetBaseline());
   return origin;
 }
 
diff --git a/ui/gfx/render_text.h b/ui/gfx/render_text.h
index 9573494..1e32489 100644
--- a/ui/gfx/render_text.h
+++ b/ui/gfx/render_text.h
@@ -332,8 +332,9 @@ class UI_EXPORT RenderText {
   // Returns display offset based on current text alignment.
   Point GetAlignmentOffset();
 
-  // Returns the origin point for drawing text via Skia.
-  Point GetOriginForSkiaDrawing();
+  // Returns the origin point for drawing text. Does not account for font
+  // baseline, as needed by Skia.
+  Point GetOriginForDrawing();
 
   // Applies fade effects to |renderer|.
   void ApplyFadeEffects(internal::SkiaTextRenderer* renderer);
@@ -354,7 +355,7 @@ class UI_EXPORT RenderText {
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, PasswordCensorship);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, GraphemePositions);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, EdgeSelectionModels);
-  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, OriginForSkiaDrawing);
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, OriginForDrawing);
 
   // Set the cursor to |position|, with the caret trailing the previous
   // grapheme, or if there is no previous grapheme, leading the cursor position.
diff --git a/ui/gfx/render_text_linux.cc b/ui/gfx/render_text_linux.cc
index f5c3a9b..e411cd9 100644
--- a/ui/gfx/render_text_linux.cc
+++ b/ui/gfx/render_text_linux.cc
@@ -359,7 +359,10 @@ void RenderTextLinux::SetupPangoAttributes(PangoLayout* layout) {
 void RenderTextLinux::DrawVisualText(Canvas* canvas) {
   DCHECK(layout_);
 
-  Point offset(GetOriginForSkiaDrawing());
+  Point offset(GetOriginForDrawing());
+  // Skia will draw glyphs with respect to the baseline.
+  offset.Offset(0, PANGO_PIXELS(pango_layout_get_baseline(layout_)));
+
   SkScalar x = SkIntToScalar(offset.x());
   SkScalar y = SkIntToScalar(offset.y());
 
diff --git a/ui/gfx/render_text_unittest.cc b/ui/gfx/render_text_unittest.cc
index 88ca60f..5769fe1 100644
--- a/ui/gfx/render_text_unittest.cc
+++ b/ui/gfx/render_text_unittest.cc
@@ -993,27 +993,27 @@ TEST_F(RenderTextTest, CursorBoundsInReplacementMode) {
   EXPECT_EQ(cursor_around_b.right(), cursor_before_c.x());
 }
 
-TEST_F(RenderTextTest, OriginForSkiaDrawing) {
+TEST_F(RenderTextTest, OriginForDrawing) {
   scoped_ptr<RenderText> render_text(RenderText::CreateRenderText());
   render_text->SetText(ASCIIToUTF16("abcdefg"));
   render_text->SetFontList(FontList("Arial, 13px"));
 
   // Set display area's height equals to font height.
-  int font_height = render_text->GetFont().GetHeight();
+  const int font_height = render_text->GetStringSize().height();
   Rect display_rect(0, 0, 100, font_height);
   render_text->SetDisplayRect(display_rect);
 
-  Point origin = render_text->GetOriginForSkiaDrawing();
+  Point origin = render_text->GetOriginForDrawing();
   EXPECT_EQ(origin.x(), 0);
-  EXPECT_EQ(origin.y(), render_text->GetFont().GetBaseline());
+  EXPECT_EQ(origin.y(), 0);
 
   // Set display area's height greater than font height.
   display_rect = Rect(0, 0, 100, font_height + 2);
   render_text->SetDisplayRect(display_rect);
 
-  origin = render_text->GetOriginForSkiaDrawing();
+  origin = render_text->GetOriginForDrawing();
   EXPECT_EQ(origin.x(), 0);
-  EXPECT_EQ(origin.y(), render_text->GetFont().GetBaseline() + 1);
+  EXPECT_EQ(origin.y(), 1);
 }
 
 TEST_F(RenderTextTest, DisplayRectShowsCursorLTR) {
diff --git a/ui/gfx/render_text_win.cc b/ui/gfx/render_text_win.cc
index 58c4d13..cee9738 100644
--- a/ui/gfx/render_text_win.cc
+++ b/ui/gfx/render_text_win.cc
@@ -179,6 +179,7 @@ std::map<std::string, std::vector<Font> > RenderTextWin::cached_linked_fonts_;
 
 RenderTextWin::RenderTextWin()
     : RenderText(),
+      common_baseline_(0),
       needs_layout_(false) {
   memset(&script_control_, 0, sizeof(script_control_));
   memset(&script_state_, 0, sizeof(script_state_));
@@ -464,7 +465,10 @@ void RenderTextWin::EnsureLayout() {
 void RenderTextWin::DrawVisualText(Canvas* canvas) {
   DCHECK(!needs_layout_);
 
-  Point offset(GetOriginForSkiaDrawing());
+  Point offset(GetOriginForDrawing());
+  // Skia will draw glyphs with respect to the baseline.
+  offset.Offset(0, common_baseline_);
+
   SkScalar x = SkIntToScalar(offset.x());
   SkScalar y = SkIntToScalar(offset.y());
 
@@ -518,6 +522,7 @@ void RenderTextWin::ItemizeLogicalText() {
   STLDeleteContainerPointers(runs_.begin(), runs_.end());
   runs_.clear();
   string_size_ = Size(0, GetFont().GetHeight());
+  common_baseline_ = 0;
   if (text().empty())
     return;
 
@@ -684,6 +689,7 @@ void RenderTextWin::LayoutVisualText() {
     DCHECK(SUCCEEDED(hr));
     string_size_.set_height(std::max(string_size_.height(),
                                      run->font.GetHeight()));
+    common_baseline_ = std::max(common_baseline_, run->font.GetBaseline());
 
     if (run->glyph_count > 0) {
       run->advance_widths.reset(new int[run->glyph_count]);
diff --git a/ui/gfx/render_text_win.h b/ui/gfx/render_text_win.h
index d85e9ef..d79c877 100644
--- a/ui/gfx/render_text_win.h
+++ b/ui/gfx/render_text_win.h
@@ -121,6 +121,10 @@ class RenderTextWin : public RenderText {
   std::vector<internal::TextRun*> runs_;
   Size string_size_;
 
+  // A common vertical baseline for all the text runs. This is computed as the
+  // largest baseline over all the runs' fonts.
+  int common_baseline_;
+
   scoped_array<int> visual_to_logical_;
   scoped_array<int> logical_to_visual_;