[ios] Snapshot for WebState

ios/web/public/web_state/web_state.h

 // Copyright 2013 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_WEB_PUBLIC_WEB_STATE_WEB_STATE_H_
 #define IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 17 matching lines @@
 @protocol CRWWebViewProxy;
 typedef id<CRWWebViewProxy> CRWWebViewProxyType;
 @class UIView;
 typedef UIView<CRWScrollableContent> CRWContentView;
 
 namespace base {
 class DictionaryValue;
 class Value;
 }
 
+namespace gfx {
+class Image;
+}
+
 namespace web {
 
 class BrowserState;
 class NavigationManager;
 class SessionCertificatePolicyCache;
 class WebInterstitial;
 class WebStateDelegate;
 class WebStateInterfaceProvider;
 class WebStateObserver;
 class WebStatePolicyDecider;
@@ skipping 193 matching lines @@
   // Returns the current CRWWebViewProxy object.
   virtual CRWWebViewProxyType GetWebViewProxy() const = 0;
 
   // Returns Mojo interface registry for this WebState.
   virtual WebStateInterfaceProvider* GetWebStateInterfaceProvider() = 0;
 
   // Returns whether this WebState was created with an opener.  See
   // CreateParams::created_with_opener for more details.
   virtual bool HasOpener() const = 0;
 
+  // Takes a full-resolution snapshot of this WebState.

[marq (ping after 24h), 2017/06/21 11:13:23]

Document when |callback| will be called?

[kkhorimoto, 2017/06/21 20:06:52]

You should also document that this API is asynchronous on iOS 11, but
synchronous for previous versions of iOS.

[edchin, 2017/06/22 07:01:07]

Done.

[edchin, 2017/06/22 07:01:07]

Made this asynchronous in pre-ios-11 versions as well. Used SequencedTaskRunner.

+  virtual void TakeSnapshot(

[Eugene But (OOO till 7-30), 2017/06/21 22:11:29]

Do you want to pass width argument? Not every client will need view's size. 

[edchin, 2017/06/22 07:01:07]

Resizing will take place elsewhere. That place will have the infrastructure to
make operations cancellable. So let's keep web simple and move such 
complexity elsewhere.

[Eugene But (OOO till 7-30), 2017/06/22 19:34:14]

What is the advantage of resizing elsewhere? Changing graphics context size will
not make code complex and WKWebView already supports width argument.

[edchin, 2017/06/23 19:03:10]

Per our offline discussion, I've added a CGSize argument. This improves memory 
and runtime efficiency over taking a full-res, full-size snapshot and then
resizing.

+      const base::Callback<void(const gfx::Image& snapshot)>& callback)

[kkhorimoto, 2017/06/21 20:06:52]

Optional: There's some precedent for typedefing Callbacks in web (e.g.
java_script_dialog_callback.h).  You might want to do the same here to make
formatting a little easier.

[edchin, 2017/06/22 07:01:07]

Done.

+      const = 0;
+
  protected:
   friend class WebStateObserver;
   friend class WebStatePolicyDecider;
 
   // Adds and removes observers for page navigation notifications. The order in
   // which notifications are sent to observers is undefined. Clients must be
   // sure to remove the observer before they go away.
   // TODO(droger): Move these methods to WebStateImpl once it is in ios/.
   virtual void AddObserver(WebStateObserver* observer) = 0;
   virtual void RemoveObserver(WebStateObserver* observer) = 0;
@@ skipping 12 matching lines @@
 
   // Returns a WeakPtr<WebState> to the current WebState. Must remain private
   // and only call must be in WebStateWeakPtrFactory. Please consult that class
   // for more details. Remove as part of http://crbug.com/556736.
   virtual base::WeakPtr<WebState> AsWeakPtr() = 0;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_H_