Always aligns text at vertically center (Textfield, Label).

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index fc8bad161ba30d97809619e18a56736a8315985c..dae0c616834f987d623c0fa850e00d2b59e7fbd5 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -5,6 +5,7 @@
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
+#include <limits>
 
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
@@ -44,6 +45,36 @@ const SkScalar kLineThickness = (SK_Scalar1 / 18);
 // Fraction of the text size to use for a top margin of a diagonal strike.
 const SkScalar kDiagonalStrikeMarginOffset = (SK_Scalar1 / 4);
 
+// Invalid value of baseline.  Assigning this value to |baseline_| causes
+// re-calculation of baseline.
+const int kInvalidBaseline = std::numeric_limits<int>::max();
+
+// Returns the baseline, with which the text best appears vertically centered.
+int DetermineBaselineCenteringText(const Rect& display_rect,
+                                   const FontList& font_list) {
+  const int display_height = display_rect.height();
+  const int font_height = font_list.GetHeight();
+  // Lower and upper bound of baseline shift as we try to show as much area of
+  // text as possible.  In particular case of |display_height| == |font_height|,
+  // we do not want to shift the baseline.
+  int min_shift;
+  int max_shift;
+  if (display_height < font_height) {
+    min_shift = display_height - font_height;
+    max_shift = font_height - display_height;
+  } else {
+    min_shift = 0;
+    max_shift = display_height - font_height;
+  }
+  const int baseline = font_list.GetBaseline();
+  const int cap_height = font_list.GetCapHeight();
+  const int internal_leading = baseline - cap_height;
+  const int baseline_shift =
+      std::max(min_shift, std::min(max_shift,
+          (display_height - cap_height) / 2 - internal_leading));
+  return baseline + baseline_shift;

[Alexei Svitkine (slow), 2013/10/24 15:03:55]

Nit: I think this is more readable:

  const int baseline_shift =
      (display_height - cap_height) / 2 - internal_leading;
  return baseline + std::max(min_shift, std::min(max_shift, baseline_shift));

[Yuki, 2013/10/24 15:17:36]

Done.

+}
+
 // Converts |gfx::Font::FontStyle| flags to |SkTypeface::Style| flags.
 SkTypeface::Style ConvertFontStyleToSkiaTypefaceStyle(int font_style) {
   int skia_style = SkTypeface::kNormal;
@@ -348,16 +379,9 @@ void RenderText::SetHorizontalAlignment(HorizontalAlignment alignment) {
   }
 }
 
-void RenderText::SetVerticalAlignment(VerticalAlignment alignment) {
-  if (vertical_alignment_ != alignment) {
-    vertical_alignment_ = alignment;
-    display_offset_ = Vector2d();
-    cached_bounds_and_offset_valid_ = false;
-  }
-}
-
 void RenderText::SetFontList(const FontList& font_list) {
   font_list_ = font_list;
+  baseline_ = kInvalidBaseline;
   cached_bounds_and_offset_valid_ = false;
   ResetLayout();
 }
@@ -414,6 +438,7 @@ void RenderText::SetMultiline(bool multiline) {
 
 void RenderText::SetDisplayRect(const Rect& r) {
   display_rect_ = r;
+  baseline_ = kInvalidBaseline;
   cached_bounds_and_offset_valid_ = false;
   lines_.clear();
 }
@@ -653,6 +678,12 @@ int RenderText::GetContentWidth() {
   return GetStringSize().width() + (cursor_enabled_ ? 1 : 0);
 }
 
+int RenderText::GetBaseline() {
+  if (baseline_ == kInvalidBaseline)
+    baseline_ = DetermineBaselineCenteringText(display_rect(), font_list());

[Alexei Svitkine (slow), 2013/10/24 15:03:55]

Nit: Add DCHECK_NE(kInvalidBaseline, baseline_);

[Yuki, 2013/10/24 15:17:36]

Done.

+  return baseline_;
+}
+
 void RenderText::Draw(Canvas* canvas) {
   EnsureLayout();
 
@@ -784,7 +815,6 @@ void RenderText::SetTextShadows(const ShadowValues& shadows) {
 
 RenderText::RenderText()
     : horizontal_alignment_(base::i18n::IsRTL() ? ALIGN_RIGHT : ALIGN_LEFT),
-      vertical_alignment_(ALIGN_VCENTER),
       directionality_mode_(DIRECTIONALITY_FROM_TEXT),
       text_direction_(base::i18n::UNKNOWN_DIRECTION),
       cursor_enabled_(true),
@@ -806,6 +836,7 @@ RenderText::RenderText()
       fade_tail_(false),
       background_is_transparent_(false),
       clip_to_display_rect_(true),
+      baseline_(kInvalidBaseline),
       cached_bounds_and_offset_valid_(false) {
 }
 
@@ -969,11 +1000,7 @@ Vector2d RenderText::GetAlignmentOffset(size_t line_number) {
     if (horizontal_alignment_ == ALIGN_CENTER)
       offset.set_x(offset.x() / 2);
   }
-  if (vertical_alignment_ != ALIGN_TOP) {
-    offset.set_y(display_rect().height() - GetStringSize().height());
-    if (vertical_alignment_ == ALIGN_VCENTER)
-      offset.set_y(offset.y() / 2);
-  }
+  offset.set_y(GetBaseline() - GetLayoutTextBaseline());
   return offset;
 }