Upstream image_fetcher::ImageFetcher

ios/chrome/browser/net/image_fetcher.h

+// Copyright 2011 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.
+
+#ifndef IOS_CHROME_BROWSER_NET_IMAGE_FETCHER_H_
+#define IOS_CHROME_BROWSER_NET_IMAGE_FETCHER_H_
+
+#include <map>
+
+#include "base/compiler_specific.h"
+#include "base/mac/bind_objc_block.h"
+#include "base/mac/scoped_nsobject.h"
+#include "base/memory/weak_ptr.h"
+#include "net/url_request/url_fetcher_delegate.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "url/gurl.h"
+
+@class NSData;
+
+namespace image_fetcher {
+
+// Callback that informs of the download of an image encoded in |data|,
+// downloaded from |url|, and with the http status |http_response_code|. If the
+// url is a data URL, |http_response_code| is always 200.
+typedef void (^Callback)(const GURL& url, int http_response_code, NSData* data);
+
+// Utility class that will retrieve an image from an URL. The image is returned
+// as NSData which can be used with +[UIImage imageWithData:]. This class
+// usually returns the raw bytes retrieved from the network without any
+// processing with the exception of WebP encoded images. Those are decoded and
+// then reencoded in a format suitable for UIImage.
+// An instance of this class can download a number of images at the same time.
+class ImageFetcher : public net::URLFetcherDelegate {
+ public:
+  // The WorkerPool is used to eventually decode the image.
+  explicit ImageFetcher(
+      const scoped_refptr<base::SequencedWorkerPool> decoding_pool);
+  ~ImageFetcher() override;
+
+  // Start downloading the image at the given |url|. The |callback| will be
+  // called with the downloaded image, or nil if any error happened. The
+  // |referrer| and |referrer_policy| will be passed on to the underlying
+  // URLFetcher.
+  // This method assumes the request context getter has been set.
+  // (virtual for testing)
+  virtual void StartDownload(const GURL& url,
+                             Callback callback,
+                             const std::string& referrer,
+                             net::URLRequest::ReferrerPolicy referrer_policy);
+
+  // Helper method to call StartDownload without a referrer.
+  // (virtual for testing)
+  virtual void StartDownload(const GURL& url, Callback callback);
+
+  // A valid request context getter is required before starting the download.
+  // (virtual for testing)
+  virtual void SetRequestContextGetter(
+      net::URLRequestContextGetter* request_context_getter);
+
+  // content::URLFetcherDelegate methods.
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
+
+ private:
+  // Runs the callback with the given arguments.
+  void RunCallback(const base::mac::ScopedBlock<Callback>& callback,
+                   const GURL& url,
+                   const int http_response_code,
+                   NSData* data);
+
+  // Tracks open download requests.  The key is the URLFetcher object doing the
+  // fetch; the value is the callback to use when the download request
+  // completes. When a download request completes, the URLFetcher must be
+  // deleted and the callback called and released.
+  std::map<const net::URLFetcher*, Callback> downloads_in_progress_;
+  scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
+
+  // The WeakPtrFactory is used to cancel callbacks if ImageFetcher is destroyed
+  // during WebP decoding.
+  base::WeakPtrFactory<ImageFetcher> weak_factory_;
+
+  // The pool used to decode images if necessary.
+  const scoped_refptr<base::SequencedWorkerPool> decoding_pool_;
+};
+
+}  // namespace image_fetcher
+
+#endif  // IOS_CHROME_BROWSER_NET_IMAGE_FETCHER_H_