Fix RTL and complex script title in print preview header/footer.

chrome/renderer/print_web_view_helper.cc

Index: chrome/renderer/print_web_view_helper.cc
diff --git a/chrome/renderer/print_web_view_helper.cc b/chrome/renderer/print_web_view_helper.cc
index b31cd851cfe5213c2219515b3dde4681cd01e5f7..64693732a28ffc87b70d4d350c3a5c0b1a3f8df5 100644
--- a/chrome/renderer/print_web_view_helper.cc
+++ b/chrome/renderer/print_web_view_helper.cc
@@ -49,6 +49,10 @@
 #include "skia/ext/vector_canvas.h"
 #include "skia/ext/vector_platform_device_skia.h"
 #include "third_party/skia/include/core/SkTypeface.h"
+#if defined(OS_WIN)  // Currently Windows only
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/render_text.h"
+#endif  // USE_SKIA && defined(OS_WIN)
 #elif defined(OS_MACOSX)
 #include <CoreGraphics/CGContext.h>
 
@@ -394,6 +398,60 @@ SkPoint GetHeaderFooterPosition(
   return point;
 }
 
+#if defined(USE_SKIA) && defined(OS_WIN)
+void PrintHeaderFooterByRenderText(
+    const string16& text,
+    WebKit::WebCanvas* canvas,
+    HeaderFooterPaint paint,
+    float webkit_scale_factor,
+    const PageSizeMargins& page_layout,
+    printing::HorizontalHeaderFooterPosition horizontal_position,
+    printing::VerticalHeaderFooterPosition vertical_position,
+    double offset_to_baseline) {
+  // TODO(arthurhsu): Following code works on Windows only so far.
+  // See crbug.com/108599 and its blockers for more information.
+  scoped_ptr<gfx::RenderText> render_text(gfx::RenderText::CreateRenderText());
+  render_text->SetText(text);
+  int font_size = printing::kSettingHeaderFooterFontSize / webkit_scale_factor;
+  render_text->SetFontSize(font_size);
+  gfx::Size text_size = render_text->GetStringSize();
+  int text_height = text_size.height() / webkit_scale_factor;

[Alexei Svitkine (slow), 2012/05/03 19:04:41]

The scaling still looks incorrect to me.

You take "printing::kSettingHeaderFooterFontSize" and divide it by
webkit_scale_factor and set that as the font size.

Then you get the text_size from render_text and divide the height from that
again by webkit_scale_factor.

That looks wrong - you're dividing both the input and the output by it -
essentially it seems like you're dividing it twice. Did you mean to multiply the
output instead?

[arthurhsu, 2012/05/07 17:28:06]

Ah yeah nice catch.  The division by webkit_scale_factor is to transform context
coordinates to skia coordinates, so the text_size got from RenderText does not
need to be transformed again since it's already in skia coordinates.

On 2012/05/03 19:04:41, Alexei Svitkine wrote:

+  int y_offset = text_height - font_size;
+  SkScalar margin_left = page_layout.margin_left / webkit_scale_factor;
+  SkScalar margin_top = page_layout.margin_top / webkit_scale_factor;
+  SkScalar content_height = page_layout.content_height / webkit_scale_factor;
+
+  int save_count = canvas->save();
+  canvas->translate(-margin_left, -margin_top);

[Alexei Svitkine (slow), 2012/05/03 19:04:41]

Move these two canvas operations further down, just before actually drawing the
text.

[arthurhsu, 2012/05/07 17:28:06]

Done.

+  int text_width = text_size.width() / webkit_scale_factor;
+  SkPoint point = GetHeaderFooterPosition(webkit_scale_factor, page_layout,
+                                          horizontal_position,
+                                          vertical_position, offset_to_baseline,
+                                          SkScalarToDouble(text_width));
+  point.set(point.x() + margin_left, point.y() + margin_top);
+  // Workaround clipping issue of RenderText by adjusting the y_offset to make
+  // sure that display rect overlaps with content area.
+  if (vertical_position == printing::TOP) {
+    // Bottom of display rect must overlap with content.
+    if (point.y() - y_offset + text_height < margin_top + 1) {

[Alexei Svitkine (slow), 2012/05/03 19:04:41]

I still think this can made clearer by the using of aptly named intermediate
variables (see my previous comment).

[arthurhsu, 2012/05/07 17:28:06]

Done.

+      y_offset = point.y() + text_height - margin_top - 1;
+    }
+  } else {  // BOTTOM
+    // Top of display rect must overlap with content.
+    if (point.y() - y_offset > margin_top + content_height - 1) {
+      y_offset = point.y() - margin_top - content_height + 1;
+    }
+  }
+
+  gfx::Rect rect(point.x(), point.y() - y_offset, text_width, text_height);
+  render_text->SetDisplayRect(rect);
+  scoped_ptr<gfx::Canvas> gfx_canvas(new gfx::Canvas(canvas));
+  render_text->Draw(gfx_canvas.get());
+  gfx_canvas.reset();
+  canvas->restoreToCount(save_count);
+}
+#endif
+
 // Given a text, the positions, and the paint object, this method gets the
 // coordinates and prints the text at those coordinates on the canvas.
 void PrintHeaderFooterText(
@@ -406,6 +464,12 @@ void PrintHeaderFooterText(
     printing::VerticalHeaderFooterPosition vertical_position,
     double offset_to_baseline) {
 #if defined(USE_SKIA)
+#if defined(OS_WIN)
+  PrintHeaderFooterByRenderText(text, canvas, paint, webkit_scale_factor,
+      page_layout, horizontal_position, vertical_position, offset_to_baseline);
+#else
+  // TODO(arthurhsu): following code has issues with i18n BiDi, see
+  //                  crbug.com/108599.
   size_t text_byte_length = text.length() * sizeof(char16);
   double text_width_in_points = SkScalarToDouble(paint.measureText(
       text.c_str(), text_byte_length));
@@ -417,6 +481,7 @@ void PrintHeaderFooterText(
       paint.getTextSize() / webkit_scale_factor));
   canvas->drawText(text.c_str(), text_byte_length, point.x(), point.y(),
                    paint);
+#endif  // USE_SKIA && OS_WIN
 #elif defined(OS_MACOSX)
   ScopedCFTypeRef<CFStringRef> cf_text(base::SysUTF16ToCFStringRef(text));
   ScopedCFTypeRef<CFAttributedStringRef> cf_attr_text(