[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..1aa6b2376ee19d807332e8455bfc4f68989636a7
--- /dev/null
+++ b/components/favicon_base/fallback_icon_service.cc
@@ -0,0 +1,115 @@
+// 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 "base/bind.h"
+#include "base/i18n/case_conversion.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop_proxy.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/favicon_size.h"
+#include "ui/gfx/font_list.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+#include "ui/gfx/image/image_skia.h"
+#include "url/gurl.h"
+
+namespace favicon_base {
+
+namespace {
+
+// 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.
+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);

[pkotwicz, 2015/01/19 04:32:02]

You should cache the gfx::FontList. Creating the gfx::FontList object is very
expensive for some fonts. (e.g. "ui-sans" on ChromeOS)

[huangs, 2015/01/20 22:20:41]

Would this add extra memory footprint, and would this be premature optimization?

Since this feature is not used yet, I'd rather keep it simple.  Adding TODO
though.

+}
+
+FallbackIconService::~FallbackIconService() {
+}
+
+void FallbackIconService::DrawFallbackIcon(const GURL& icon_url,
+                                           int x,
+                                           int y,
+                                           int size_in_pixels,
+                                           const FallbackIconSpecs& specs,
+                                           gfx::Canvas* canvas) {
+  SkPaint paint;
+  paint.setStyle(SkPaint::kFill_Style);
+  paint.setAntiAlias(true);
+
+  // Draw a filled, colored rounded square.
+  paint.setColor(specs.background_color);
+  int corner_radius = static_cast<int>(
+      size_in_pixels * specs.corner_radius_ratio + 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 * specs.font_size_ratio);
+    if (font_size > 0) {
+      canvas->DrawStringRectWithFlags(
+          icon_text,
+          gfx::FontList(fallback_icon_font_list_, gfx::Font::NORMAL, font_size),
+          specs.text_color,
+          gfx::Rect(0, 0, size_in_pixels, size_in_pixels),
+          gfx::Canvas::TEXT_ALIGN_CENTER);
+    }
+  }
+}
+
+base::CancelableTaskTracker::TaskId FallbackIconService::GetFallbackIcon(
+    const GURL& icon_url,
+    int size_in_pixels,
+    const FallbackIconSpecs& specs,
+    const FaviconResultsCallback& callback,
+    base::CancelableTaskTracker* tracker) {
+
+  FaviconRawBitmapResult result;

[pkotwicz, 2015/01/19 04:36:22]

Having the fallback icon codepath separate from the main favicon codepathallows
you to:
- avoid using FaviconRawBitmapResult
- make this function synchronous

[huangs, 2015/01/20 22:20:41]

Done.

+  result.expired = false;
+  result.pixel_size.SetSize(size_in_pixels, size_in_pixels);
+  result.icon_url = icon_url;
+  result.icon_type = FAVICON;
+
+  gfx::Canvas canvas(gfx::Size(size_in_pixels, size_in_pixels), 1.0f, false);
+  DrawFallbackIcon(icon_url, 0, 0, size_in_pixels, specs, &canvas);
+
+  std::vector<unsigned char> bitmap_data;
+  if (gfx::PNGCodec::EncodeBGRASkBitmap(canvas.ExtractImageRep().sk_bitmap(),
+                                        false, &bitmap_data)) {
+    result.bitmap_data = base::RefCountedBytes::TakeVector(&bitmap_data);
+  }
+
+  return tracker->PostTask(
+      base::MessageLoopProxy::current().get(),
+      FROM_HERE,
+      Bind(callback, std::vector<FaviconRawBitmapResult>(1, result)));
+}
+
+}  // namespace favicon_base