[Extensions UI] Add a placeholder icon for extensions in the toolbar

extensions/browser/extension_icon_placeholder.cc

+// 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 "extensions/browser/extension_icon_placeholder.h"
+
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "extensions/grit/extensions_browser_resources.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/codec/png_codec.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+#include "ui/gfx/image/canvas_image_source.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace extensions {
+
+namespace {
+
+// Returns the FontStyle to use for the given icon |size|.
+ui::ResourceBundle::FontStyle GetFontStyleForIconSize(
+    extension_misc::ExtensionIcons size) {
+  switch (size) {
+    case extension_misc::EXTENSION_ICON_INVALID:
+    case extension_misc::EXTENSION_ICON_BITTY:
+      return ui::ResourceBundle::SmallFont;
+    case extension_misc::EXTENSION_ICON_ACTION:
+    case extension_misc::EXTENSION_ICON_SMALLISH:
+    case extension_misc::EXTENSION_ICON_SMALL:
+      return ui::ResourceBundle::MediumFont;
+    case extension_misc::EXTENSION_ICON_MEDIUM:
+    case extension_misc::EXTENSION_ICON_LARGE:
+    case extension_misc::EXTENSION_ICON_EXTRA_LARGE:
+    case extension_misc::EXTENSION_ICON_GIGANTOR:
+      return ui::ResourceBundle::LargeFont;
+  }
+  NOTREACHED();
+  return ui::ResourceBundle::MediumFont;
+}
+
+// Returns the background image to use for the given icon |size|.
+gfx::Image GetBackgroundImageForIconSize(extension_misc::ExtensionIcons size) {
+  int resource_id = 0;
+  // Right now, we have resources for a 19x19 (action) and a 48x48 (extensions
+  // page icon). The implementation of the placeholder scales these correctly,
+  // so it's not a big deal to use these for other sizes, but if it's something
+  // that will be done frequently, we should probably make a devoted assest for

[Finnur, 2015/05/13 15:46:37]

nit: s/assest/asset/

[Devlin, 2015/05/14 20:23:48]

Done.

+  // that size.
+  switch (size) {
+    case extension_misc::EXTENSION_ICON_INVALID:
+    case extension_misc::EXTENSION_ICON_BITTY:
+    case extension_misc::EXTENSION_ICON_ACTION:
+    case extension_misc::EXTENSION_ICON_SMALLISH:
+    case extension_misc::EXTENSION_ICON_SMALL:
+      resource_id = IDR_EXTENSION_ANONYMOUS_ACTION_BACKGROUND;

[Finnur, 2015/05/13 15:46:37]

nit: This naming bugs me a bit. It's not for a background action that is
anonymous. It's also not for an extension that is anonymous (especially since
you are using the first letter of the name to draw upon it). What about just:

IDR_EXTENSION_ICON_PLAIN_BACKGROUND
IDR_EXTENSION_ACTION_PLAIN_BACKGROUND

... and png file names to match?

[Devlin, 2015/05/14 20:23:48]

Yeah, that sounds better. :)  Done.

+      break;
+    case extension_misc::EXTENSION_ICON_MEDIUM:
+    case extension_misc::EXTENSION_ICON_LARGE:
+    case extension_misc::EXTENSION_ICON_EXTRA_LARGE:
+    case extension_misc::EXTENSION_ICON_GIGANTOR:
+      resource_id = IDR_EXTENSION_ANONYMOUS_ICON_BACKGROUND;
+      break;
+  }
+  return ui::ResourceBundle::GetSharedInstance().GetImageNamed(resource_id);
+}
+
+}  // namespace
+
+ExtensionIconPlaceholder::ExtensionIconPlaceholder(
+    extension_misc::ExtensionIcons size,
+    const std::string& letter)
+    : gfx::CanvasImageSource(gfx::Size(size, size), false),
+      icon_size_(size),
+      letter_(StringToUpperASCII(base::UTF8ToUTF16(letter.substr(0, 1)))),

[Finnur, 2015/05/13 15:46:37]

Does this work well (considering localization)?

[Devlin, 2015/05/14 20:23:48]

Good catch.  Probably not.  Moving to ASCII at all is lossy, so removing the
StringToUpperASCII call - which is probably fine anyway, since if an extension
really wants a lower-cased name, that's probably okay.  Taking the first
character and UTF8 -> UTF16 should be okay, though, I think.

+      base_image_(GetBackgroundImageForIconSize(size)) {
+}
+
+ExtensionIconPlaceholder::~ExtensionIconPlaceholder() {
+}
+
+gfx::Image ExtensionIconPlaceholder::CreateImage(
+    extension_misc::ExtensionIcons size,
+    const std::string& name) {
+  return gfx::Image(gfx::ImageSkia(new ExtensionIconPlaceholder(size, name),
+                                   gfx::Size(size, size)));
+}
+
+void ExtensionIconPlaceholder::Draw(gfx::Canvas* canvas) {
+  // Draw the background image, correctly scaled.
+  canvas->DrawImageInt(*base_image_.ToImageSkia(), 0, 0,
+                       base_image_.Size().width(), base_image_.Size().height(),
+                       0, 0, size().width(), size().height(), true);
+  gfx::Rect bounds(size().width(), size().height());
+  // Draw the letter on top.
+  canvas->DrawStringRectWithFlags(
+      letter_, ui::ResourceBundle::GetSharedInstance().GetFontList(
+                   GetFontStyleForIconSize(icon_size_)),
+      SK_ColorWHITE, bounds, gfx::Canvas::TEXT_ALIGN_CENTER);
+}
+
+}  // namespace extensions