Draw text via Skia in RenderTextLinux.

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
===================================================================
--- ui/gfx/render_text.cc	(revision 112983)
+++ ui/gfx/render_text.cc	(working copy)
@@ -9,6 +9,7 @@
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
+#include "third_party/skia/include/core/SkTypeface.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/canvas_skia.h"
 #include "unicode/uchar.h"
@@ -79,6 +80,83 @@
 
 namespace gfx {
 
+namespace internal {
+
+SkiaTextRenderer::SkiaTextRenderer(Canvas* canvas)
+    : canvas_skia_(canvas->GetSkCanvas()) {
+  DCHECK(canvas_skia_);
+}
+
+SkiaTextRenderer::~SkiaTextRenderer() {
+}
+
+void SkiaTextRenderer::Init() {
+  paint_.setTextEncoding(SkPaint::kGlyphID_TextEncoding);

[msw, 2011/12/06 18:40:56]

Why not roll this into the ctor?

[Alexei Svitkine (slow), 2011/12/06 19:10:12]

I guess I followed our style that we shouldn't do too much work in the
constructor. Though, since this is just setting properties, I see your point
that it's not really doing serious work, so done.

+  paint_.setStyle(SkPaint::kFill_Style);
+  paint_.setAntiAlias(true);
+  paint_.setSubpixelText(true);
+  paint_.setLCDRenderText(true);
+}
+
+void SkiaTextRenderer::SetFont(const gfx::Font& font) {
+  SkTypeface* typeface =
+      SkTypeface::CreateFromName(font.GetFontName().c_str(),
+                                 SkTypeface::kNormal);
+  if (typeface) {
+    paint_.setTypeface(typeface);
+    // |paint_| adds its own ref. Release the ref from |CreateFromName()|.

[msw, 2011/12/06 18:40:56]

Then shouldn't |typeface| be a scoped refptr or something?

[Alexei Svitkine (slow), 2011/12/06 19:10:12]

The Chromium scoped_refptr won't work, since its a Skia ref-counted object. I've
made it use SkAutoTUnref() instead. I'm not sure its much better, since it still
needs the comment to explain why it uses .get() rather than .release().

[msw, 2011/12/07 01:08:45]

Thanks for enlightening me!

+    typeface->unref();
+  }
+  paint_.setTextSize(font.GetFontSize());
+}
+
+void SkiaTextRenderer::SetForegroundColor(SkColor foreground) {
+  paint_.setColor(foreground);
+}
+
+void SkiaTextRenderer::DrawPosText(const SkPoint* pos,
+                 const uint16* glyphs,

[msw, 2011/12/06 18:40:56]

Indent these args.

[Alexei Svitkine (slow), 2011/12/06 19:10:12]

Done.

+                 size_t glyph_count) {
+  size_t byte_length = glyph_count * sizeof(glyphs[0]);

[xji, 2011/12/05 23:47:09]

Will uint16 cause problem? PangoGlyph is a guint32.

http://developer.gnome.org/pango/stable/pango-Glyph-Storage.html#PangoGlyph

[Alexei Svitkine (slow), 2011/12/06 19:10:12]

It's a good question. |drawPosText()| seems to only take uint16 indices - I'll
have to ask Mike Reed about this.

+  canvas_skia_->drawPosText(&glyphs[0], byte_length, &pos[0], paint_);
+}
+
+// Draw underline and strike through text decorations.
+// Based on |SkCanvas::DrawTextDecorations()| and constants from:
+//   third_party/skia/src/core/SkTextFormatParams.h
+void SkiaTextRenderer::DrawDecorations(int x, int y, int width,
+                                       bool underline, bool strike) {
+  // Fraction of the text size to lower a strike through below the baseline.
+  const SkScalar kStrikeThroughOffset = (-SK_Scalar1 * 6 / 21);
+  // Fraction of the text size to lower an underline below the baseline.
+  const SkScalar kUnderlineOffset = (SK_Scalar1 / 9);
+  // Fraction of the text size to use for a strike through or under-line.
+  const SkScalar kLineThickness = (SK_Scalar1 / 18);
+
+  SkScalar text_size = paint_.getTextSize();
+  SkScalar height = SkScalarMul(text_size, kLineThickness);
+  SkRect r;
+
+  r.fLeft = x;
+  r.fRight = x + width;
+
+  if (underline) {
+    SkScalar offset = SkScalarMulAdd(text_size, kUnderlineOffset, y);
+    r.fTop = offset;
+    r.fBottom = offset + height;
+    canvas_skia_->drawRect(r, paint_);
+  }
+  if (strike) {
+    SkScalar offset = SkScalarMulAdd(text_size, kStrikeThroughOffset, y);
+    r.fTop = offset;
+    r.fBottom = offset + height;
+    canvas_skia_->drawRect(r, paint_);
+  }
+}
+
+}  // namespace internal
+
+
 StyleRange::StyleRange()
     : font(),
       foreground(SK_ColorBLACK),