Experimental app list: "All apps" button has a folder-like icon.

ui/app_list/folder_image.cc

+// Copyright 2014 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 "ui/app_list/folder_image.h"
+
+#include "ui/app_list/app_list_constants.h"
+#include "ui/app_list/app_list_item.h"
+#include "ui/app_list/app_list_item_list.h"
+#include "ui/app_list/folder_image_source.h"
+#include "ui/app_list/views/contents_view.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/image/image_skia.h"
+#include "ui/strings/grit/ui_strings.h"
+
+namespace app_list {
+
+FolderImage::FolderImage(AppListItemList* item_list) : item_list_(item_list) {
+  item_list_->AddObserver(this);
+}
+
+FolderImage::~FolderImage() {
+  for (size_t i = 0; i < top_items_.size(); ++i)
+    top_items_[i]->RemoveObserver(this);
+  item_list_->RemoveObserver(this);
+}
+
+void FolderImage::UpdateIcon() {
+  for (size_t i = 0; i < top_items_.size(); ++i)
+    top_items_[i]->RemoveObserver(this);
+  top_items_.clear();
+
+  for (size_t i = 0; i < kNumFolderTopItems && i < item_list_->item_count();
+       ++i) {
+    AppListItem* item = item_list_->item_at(i);
+    item->AddObserver(this);
+    top_items_.push_back(item);
+  }
+  UpdateImageOnly();

[calamity, 2014/10/28 05:12:57]

As discussed, avoiding a copy of 4 pointers is probably not worth splitting this
method in two.

Or at least change the name to RedrawIconAndNotify().

[Matt Giuca, 2014/10/29 07:11:23]

Done.

[calamity, 2014/11/03 00:37:45]

I think this got missed.

[Matt Giuca, 2014/11/03 05:23:16]

Sorry, I misunderstood this (thought it was about storing the image in the
class).

So after a lot of investigation, it turns out that it's not possible to call
UpdateIcon from ItemIconChanged (because it would modify the observer list that
is currently being iterated over --- normally this is OK but here it puts it
into an infinite loop). Added a comment explaining this and abandoned the idea.

Renamed to RedrawIconAndNotify.

+}
+
+const gfx::ImageSkia& FolderImage::GetTopIcon(size_t item_index) {
+  DCHECK(item_index <= top_items_.size());
+  return top_items_[item_index]->icon();
+}
+
+gfx::Rect FolderImage::GetTargetIconRectInFolderForItem(
+    AppListItem* item,
+    const gfx::Rect& folder_icon_bounds) {
+  for (size_t i = 0; i < top_items_.size(); ++i) {
+    if (item->id() == top_items_[i]->id()) {
+      std::vector<gfx::Rect> rects =
+          FolderImageSource::GetTopIconsBounds(folder_icon_bounds);
+      return rects[i];
+    }
+  }
+
+  gfx::Rect target_rect(folder_icon_bounds);
+  target_rect.ClampToCenteredSize(FolderImageSource::ItemIconSize());
+  return target_rect;
+}
+
+void FolderImage::AddObserver(FolderImageObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void FolderImage::RemoveObserver(FolderImageObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void FolderImage::ItemIconChanged() {
+  UpdateImageOnly();
+}
+
+void FolderImage::OnListItemAdded(size_t index, AppListItem* item) {
+  if (index <= kNumFolderTopItems)
+    UpdateIcon();
+}
+
+void FolderImage::OnListItemRemoved(size_t index, AppListItem* item) {
+  if (index <= kNumFolderTopItems)
+    UpdateIcon();
+}
+
+void FolderImage::OnListItemMoved(size_t from_index,
+                                  size_t to_index,
+                                  AppListItem* item) {
+  if (from_index <= kNumFolderTopItems || to_index <= kNumFolderTopItems)
+    UpdateIcon();
+}
+
+void FolderImage::UpdateImageOnly() {
+  FolderImageSource::Icons top_icons;
+  for (size_t i = 0; i < top_items_.size(); ++i)
+    top_icons.push_back(top_items_[i]->icon());
+
+  const gfx::Size icon_size = gfx::Size(kGridIconDimension, kGridIconDimension);
+  gfx::ImageSkia icon =
+      gfx::ImageSkia(new FolderImageSource(top_icons, icon_size), icon_size);
+
+  FOR_EACH_OBSERVER(
+      FolderImageObserver, observers_, OnFolderImageUpdated(icon));
+}
+
+}  // namespace app_list