Break out manifest icon logic from ShortcutHelper

chrome/browser/android/manifest_icon_selector.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 "chrome/browser/android/manifest_icon_selector.h"
+
+#include <limits>
+
+#include "base/strings/utf_string_conversions.h"
+#include "content/public/browser/web_contents.h"
+#include "net/base/mime_util.h"
+#include "ui/gfx/screen.h"
+
+using content::Manifest;
+
+// static
+bool ManifestIconSelector::IconSizesContainsPreferredSize(
+    const std::vector<gfx::Size>& sizes,
+    int preferred_icon_size_in_px) {
+  for (size_t i = 0; i < sizes.size(); ++i) {
+    if (sizes[i].height() != sizes[i].width())
+      continue;
+    if (sizes[i].width() == preferred_icon_size_in_px)
+      return true;
+  }
+
+  return false;
+}
+
+// static
+bool ManifestIconSelector::IconSizesContainsAny(
+    const std::vector<gfx::Size>& sizes) {
+  for (size_t i = 0; i < sizes.size(); ++i) {
+    if (sizes[i].IsEmpty())
+      return true;
+  }
+
+  return false;
+}
+
+// static
+GURL ManifestIconSelector::FindBestMatchingIcon(
+    const std::vector<Manifest::Icon>& icons,
+    float density,
+    int preferred_icon_size_in_px) {
+  GURL url;
+  int best_delta = std::numeric_limits<int>::min();
+
+  for (size_t i = 0; i < icons.size(); ++i) {
+    if (icons[i].density != density)
+      continue;
+
+    const std::vector<gfx::Size>& sizes = icons[i].sizes;
+    for (size_t j = 0; j < sizes.size(); ++j) {
+      if (sizes[j].height() != sizes[j].width())
+        continue;
+      int delta = sizes[j].width() - preferred_icon_size_in_px;
+      if (delta == 0)
+        return icons[i].src;
+      if (best_delta > 0 && delta < 0)
+        continue;
+      if ((best_delta > 0 && delta < best_delta) ||
+          (best_delta < 0 && delta > best_delta)) {
+        url = icons[i].src;
+        best_delta = delta;
+      }
+    }
+  }
+
+  return url;
+}
+
+// static
+std::vector<Manifest::Icon> ManifestIconSelector::FilterIconsByType(
+    const std::vector<Manifest::Icon>& icons) {
+  std::vector<Manifest::Icon> result;
+
+  for (size_t i = 0; i < icons.size(); ++i) {
+    if (icons[i].type.is_null() ||
+        net::IsSupportedImageMimeType(
+            base::UTF16ToUTF8(icons[i].type.string()))) {
+      result.push_back(icons[i]);
+    }
+  }
+
+  return result;
+}
+
+// static
+GURL ManifestIconSelector::FindBestMatchingIcon(
+    const std::vector<Manifest::Icon>& unfiltered_icons,
+    const float preferred_size_in_dp,
+    content::WebContents* web_contents) {
+  const float device_scale_factor =
+      gfx::Screen::GetScreenFor(web_contents->GetNativeView())->
+          GetPrimaryDisplay().device_scale_factor();
+  const float preferred_size_in_px =
+      preferred_size_in_dp * device_scale_factor;
+
+  GURL url;
+  std::vector<Manifest::Icon> icons = FilterIconsByType(unfiltered_icons);
+
+  // The first pass is to find the ideal icon. That icon is of the right size
+  // with the default density or the device's density.
+  for (size_t i = 0; i < icons.size(); ++i) {
+    if (icons[i].density == device_scale_factor &&
+        IconSizesContainsPreferredSize(icons[i].sizes, preferred_size_in_px)) {
+      return icons[i].src;
+    }
+
+    // If there is an icon with the right size but not the right density, keep
+    // it on the side and only use it if nothing better is found.
+    if (icons[i].density == Manifest::Icon::kDefaultDensity &&
+        IconSizesContainsPreferredSize(icons[i].sizes, preferred_size_in_px)) {
+      url = icons[i].src;
+    }
+  }
+
+  // The second pass is to find an icon with 'any'. The current device scale
+  // factor is preferred. Otherwise, the default scale factor is used.
+  for (size_t i = 0; i < icons.size(); ++i) {
+    if (icons[i].density == device_scale_factor &&
+        IconSizesContainsAny(icons[i].sizes)) {
+      return icons[i].src;
+    }
+
+    // If there is an icon with 'any' but not the right density, keep it on the
+    // side and only use it if nothing better is found.
+    if (icons[i].density == Manifest::Icon::kDefaultDensity &&
+        IconSizesContainsAny(icons[i].sizes)) {
+      url = icons[i].src;
+    }
+  }
+
+  // The last pass will try to find the best suitable icon for the device's
+  // scale factor. If none, another pass will be run using kDefaultDensity.
+  if (!url.is_valid())
+    url = FindBestMatchingIcon(icons,
+                               device_scale_factor,
+                               preferred_size_in_px);
+  if (!url.is_valid())
+    url = FindBestMatchingIcon(icons,
+                               Manifest::Icon::kDefaultDensity,
+                               preferred_size_in_px);
+
+  return url;
+}