ios/chrome/browser/net/image_fetcher.h

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef IOS_CHROME_BROWSER_NET_IMAGE_FETCHER_H_
   6 #define IOS_CHROME_BROWSER_NET_IMAGE_FETCHER_H_
   7
   8 #include <map>
   9
  10 #include "base/mac/scoped_block.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "net/url_request/url_fetcher_delegate.h"
  14 #include "net/url_request/url_request.h"
  15
  16 class GURL;
  17 @class NSData;
  18
  19 namespace base {
  20 class TaskRunner;
  21 }
  22
  23 namespace net {
  24 class URLRequestContextGetter;
  25 }
  26
  27 namespace image_fetcher {
  28
  29 // Callback that informs of the download of an image encoded in |data|,
  30 // downloaded from |url|, and with the http status |http_response_code|. If the
  31 // url is a data URL, |http_response_code| is always 200.
  32 using ImageFetchedCallback =
  33     void (^)(const GURL& url, int http_response_code, NSData* data);
  34
  35 // Utility class that will retrieve an image from an URL. The image is returned
  36 // as NSData which can be used with +[UIImage imageWithData:]. This class
  37 // usually returns the raw bytes retrieved from the network without any
  38 // processing, with the exception of WebP encoded images. Those are decoded and
  39 // then reencoded in a format suitable for UIImage.
  40 // An instance of this class can download a number of images at the same time.
  41 class ImageFetcher : public net::URLFetcherDelegate {
  42  public:
  43   // The TaskRunner is used to eventually decode the image.
  44   explicit ImageFetcher(const scoped_refptr<base::TaskRunner>& task_runner);
  45   ~ImageFetcher() override;
  46
  47   // Start downloading the image at the given |url|. The |callback| will be
  48   // called with the downloaded image, or nil if any error happened. The
  49   // |referrer| and |referrer_policy| will be passed on to the underlying
  50   // URLFetcher.
  51   // This method assumes the request context getter has been set.
  52   // (virtual for testing)
  53   virtual void StartDownload(const GURL& url,
  54                              ImageFetchedCallback callback,
  55                              const std::string& referrer,
  56                              net::URLRequest::ReferrerPolicy referrer_policy);
  57
  58   // Helper method to call StartDownload without a referrer.
  59   // (virtual for testing)
  60   virtual void StartDownload(const GURL& url, ImageFetchedCallback callback);
  61
  62   // A valid request context getter is required before starting the download.
  63   // (virtual for testing)
  64   virtual void SetRequestContextGetter(const scoped_refptr<
  65       net::URLRequestContextGetter>& request_context_getter);
  66
  67   // net::URLFetcherDelegate:
  68   void OnURLFetchComplete(const net::URLFetcher* source) override;
  69
  70  private:
  71   // Runs the callback with the given arguments.
  72   void RunCallback(const base::mac::ScopedBlock<ImageFetchedCallback>& callback,
  73                    const GURL& url,
  74                    const int http_response_code,
  75                    NSData* data);
  76
  77   // Tracks open download requests.  The key is the URLFetcher object doing the
  78   // fetch; the value is the callback to use when the download request
  79   // completes. When a download request completes, the URLFetcher must be
  80   // deleted and the callback called and released.
  81   std::map<const net::URLFetcher*, ImageFetchedCallback> downloads_in_progress_;
  82   scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
  83
  84   // The task runner used to decode images if necessary.
  85   const scoped_refptr<base::TaskRunner> task_runner_;
  86
  87   // The WeakPtrFactory is used to cancel callbacks if ImageFetcher is destroyed
  88   // during WebP decoding.
  89   base::WeakPtrFactory<ImageFetcher> weak_factory_;
  90 };
  91
  92 }  // namespace image_fetcher
  93
  94 #endif  // IOS_CHROME_BROWSER_NET_IMAGE_FETCHER_H_