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      1 // Copyright 2014 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 CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_VIEW_OVERSCROLL_ANIMATOR_MAC_H_
      6 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_VIEW_OVERSCROLL_ANIMATOR_MAC_H_
      7 
      8 #import <Cocoa/Cocoa.h>
      9 
     10 namespace content {
     11 class WebContentsImpl;
     12 
     13 // The direction of the overscroll animations. Backwards means that the user
     14 // wants to navigate backwards in the navigation history. The opposite applies
     15 // to forwards.
     16 enum OverscrollAnimatorDirection {
     17   OVERSCROLL_ANIMATOR_DIRECTION_BACKWARDS,
     18   OVERSCROLL_ANIMATOR_DIRECTION_FORWARDS,
     19 };
     20 }  // namespace content
     21 
     22 // NSViews that intend to manage the animation associated with an overscroll
     23 // must implement this protocol.
     24 @protocol WebContentsOverscrollAnimator
     25 // Some implementations require the WebContentsView to supply a snapshot of a
     26 // previous navigation state. This method determines whether the snapshot passed
     27 // to the overscroll animator is expected to be non-nil.
     28 - (BOOL)needsNavigationSnapshot;
     29 
     30 // Begin an overscroll animation. The method -needsNavigationSnapshot determines
     31 // whether |snapshot| can be nil.
     32 - (void)beginOverscrollInDirection:
     33             (content::OverscrollAnimatorDirection)direction
     34                 navigationSnapshot:(NSImage*)snapshot;
     35 
     36 // Due to the nature of some of the overscroll animations, implementators of
     37 // this protocol must have control over the layout of the RenderWidgetHost's
     38 // NativeView. When there is no overscroll animation in progress, the
     39 // implementor must guarantee that the frame of the RenderWidgetHost's
     40 // NativeView in screen coordinates is the same as its own frame in screen
     41 // coordinates.
     42 // Due to the odd ownership cycles of the RenderWidgetHost's NativeView, it is
     43 // important that its presence in the NSView hierarchy is the only strong
     44 // reference, and that when it gets removed from the NSView hierarchy, it will
     45 // be dealloc'ed shortly thereafter.
     46 - (void)addRenderWidgetHostNativeView:(NSView*)view;
     47 
     48 // During an overscroll animation, |progress| ranges from 0 to 2, and indicates
     49 // how close the overscroll is to completing. If the overscroll ends with
     50 // |progress| >= 1, then the overscroll is considered completed.
     51 - (void)updateOverscrollProgress:(CGFloat)progress;
     52 
     53 // Animate the finish of the overscroll and perform a navigation. The navigation
     54 // may not happen synchronously, but is guaranteed to eventually occur.
     55 - (void)completeOverscroll:(content::WebContentsImpl*)webContents;
     56 
     57 // Animate the cancellation of the overscroll.
     58 - (void)cancelOverscroll;
     59 @end
     60 
     61 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_VIEW_OVERSCROLL_ANIMATOR_MAC_H_
     62