RenderText: Only clip if necessary to workaround a Skia bug in the PDF path.

ui/gfx/render_text.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
@@ skipping 588 matching lines @@
 }
 
 VisualCursorDirection RenderText::GetVisualDirectionOfLogicalEnd() {
   return GetTextDirection() == base::i18n::LEFT_TO_RIGHT ?
       CURSOR_RIGHT : CURSOR_LEFT;
 }
 
 void RenderText::Draw(Canvas* canvas) {
   EnsureLayout();
 
-  gfx::Rect clip_rect(display_rect());
-  clip_rect.Inset(ShadowValue::GetMargin(text_shadows_));
+  // Normally, always clipping is harmless. However, there is a Skia bug with
+  // the PDF path (http://crbug.com/133548) that results in incorrect clipping
+  // when drawing to the document margins. Workaround the issue by only clipping
+  // when necessary, since the PDF print path does not require clipping.
+  //
+  // TODO(asvitkine): Remove this logic once http://crbug.com/133548 is fixed
+  //                  on the Skia side.
+  const Size size = GetStringSize();
+  const bool need_to_clip = display_rect().width() < size.width() ||

[msw, 2012/06/22 19:30:13]

This doesn't account for display_offset_ or other impetus to clip (does
GetStringSize include underline adornment bounds?). That said, I don't know a
specific case where this would actually regress clipping, so it's probably okay
as a temporary workaround.

+                            display_rect().height() < size.height();
+  if (need_to_clip) {
+    gfx::Rect clip_rect(display_rect());
+    clip_rect.Inset(ShadowValue::GetMargin(text_shadows_));
 
-  canvas->Save();
-  canvas->ClipRect(clip_rect);
+    canvas->Save();
+    canvas->ClipRect(clip_rect);
+  }
 
   if (!text().empty())
     DrawSelection(canvas);
 
   DrawCursor(canvas);
 
   if (!text().empty())
     DrawVisualText(canvas);
-  canvas->Restore();
+
+  if (need_to_clip)
+    canvas->Restore();
 }
 
 Rect RenderText::GetCursorBounds(const SelectionModel& caret,
                                  bool insert_mode) {
   EnsureLayout();
 
   size_t caret_pos = caret.caret_pos();
   // In overtype mode, ignore the affinity and always indicate that we will
   // overtype the next character.
   LogicalCursorDirection caret_affinity =
@@ skipping 328 matching lines @@
   if (cursor_enabled() && cursor_visible() && focused()) {
     const Rect& bounds = GetUpdatedCursorBounds();
     if (bounds.width() != 0)
       canvas->FillRect(bounds, cursor_color_);
     else
       canvas->DrawRect(bounds, cursor_color_);
   }
 }
 
 }  // namespace gfx