[Favicon] Add new fallback icon rendering flow.

components/favicon_base/fallback_icon_service.cc

Index: components/favicon_base/fallback_icon_service.cc
diff --git a/components/favicon_base/fallback_icon_service.cc b/components/favicon_base/fallback_icon_service.cc
new file mode 100644
index 0000000000000000000000000000000000000000..98446a1a0da6098ec2de9fd0e4e88a1ba59cf2a5
--- /dev/null
+++ b/components/favicon_base/fallback_icon_service.cc
@@ -0,0 +1,103 @@
+// Copyright 2015 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 "components/favicon_base/fallback_icon_service.h"
+
+#include <algorithm>
+
+#include "base/i18n/case_conversion.h"
+#include "base/strings/utf_string_conversions.h"
+#include "components/favicon_base/favicon_types.h"
+#include "grit/platform_locale_settings.h"
+#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
+#include "third_party/skia/include/core/SkPaint.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/codec/png_codec.h"
+#include "ui/gfx/font_list.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+#include "url/gurl.h"
+
+namespace favicon_base {
+
+namespace {
+
+const int kMaxFallbackFaviconSize = 288;
+
+// Returns a single character to represent a fallback URL. To do this we take
+// the first letter in a domain's name and make it upper case. Currently we do
+// not handle non-ASCII domain names.

[pkotwicz, 2015/01/23 16:00:48]

Nit: fallback URL -> page URL

[huangs, 2015/01/23 19:47:52]

Done, updated comment to have TODO(huangs) for non-ASCII domain names.

+base::string16 GetFallbackIconText(const GURL& url) {
+  std::string domain = net::registry_controlled_domains::GetDomainAndRegistry(
+        url, net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES);
+  return domain.empty() ? base::string16() :
+      base::i18n::ToUpper(base::ASCIIToUTF16(std::string(1, domain[0])));
+}
+
+}  // namespace
+
+FallbackIconService::FallbackIconService() {
+  std::string font_name =
+      l10n_util::GetStringUTF8(IDS_SANS_SERIF_FONT_FAMILY);
+#if defined(OS_CHROMEOS)
+  const std::string kChromeOSFontFamily = "Noto Sans";
+  font_name = kChromeOSFontFamily;
+#endif
+  fallback_icon_font_list_.push_back(font_name);
+}
+
+FallbackIconService::~FallbackIconService() {
+}
+
+std::vector<unsigned char> FallbackIconService::RenderFallbackIconBitmap(
+    const GURL& icon_url,
+    int size_in_pixels,
+    const FallbackIconStyle& style) {
+  size_in_pixels = std::min(kMaxFallbackFaviconSize, size_in_pixels);
+  gfx::Canvas canvas(gfx::Size(size_in_pixels, size_in_pixels), 1.0f, false);
+  DrawFallbackIcon(icon_url, 0, 0, size_in_pixels, style, &canvas);
+
+  std::vector<unsigned char> bitmap_data;
+  if (!gfx::PNGCodec::EncodeBGRASkBitmap(canvas.ExtractImageRep().sk_bitmap(),
+                                         false, &bitmap_data)) {
+    bitmap_data.clear();
+  }
+  return bitmap_data;
+}
+

[pkotwicz, 2015/01/23 16:00:48]

Nit: Skip |x| and |y| for now.

Btw, I think the |display_rect| parameter in DrawStringRectWithFlags() needs to
take into account |x| and |y|

[huangs, 2015/01/23 19:47:52]

Done.  Will add them later if needed.  Nice catch on the
DrawStringRectWithFlags().  Made |x| and |y| const 0 to show relation.

+void FallbackIconService::DrawFallbackIcon(const GURL& icon_url,
+                                           int x,
+                                           int y,
+                                           int size_in_pixels,

[pkotwicz, 2015/01/23 16:00:48]

Nit: |size_in_pixels| -> |size|

[huangs, 2015/01/23 19:47:52]

Done.  Note I updated RenderFallbackIconBitmap() as well.

+                                           const FallbackIconStyle& style,
+                                           gfx::Canvas* canvas) {
+  SkPaint paint;
+  paint.setStyle(SkPaint::kFill_Style);
+  paint.setAntiAlias(true);
+
+  // Draw a filled, colored rounded square.
+  paint.setColor(style.background_color);
+  int corner_radius = static_cast<int>(
+      size_in_pixels * style.roundness * 0.5 + 0.5);
+  canvas->DrawRoundRect(gfx::Rect(x, y, size_in_pixels, size_in_pixels),
+      corner_radius, paint);
+
+  // Draw text.
+  base::string16 icon_text = GetFallbackIconText(icon_url);
+  if (!icon_text.empty()) {
+    int font_size = static_cast<int>(size_in_pixels * style.font_size_ratio);
+    if (font_size > 0) {
+      // TODO(huangs): See how expensive gfx::FontList() is, and possibly cache.
+      canvas->DrawStringRectWithFlags(
+          icon_text,
+          gfx::FontList(fallback_icon_font_list_, gfx::Font::NORMAL, font_size),
+          style.text_color,
+          gfx::Rect(0, 0, size_in_pixels, size_in_pixels),
+          gfx::Canvas::TEXT_ALIGN_CENTER);
+    }
+  }
+}
+
+}  // namespace favicon_base