1// Copyright (c) 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 CHROME_BROWSER_UI_COCOA_DRAGGABLE_BUTTON_MIXIN_H_ 6#define CHROME_BROWSER_UI_COCOA_DRAGGABLE_BUTTON_MIXIN_H_ 7 8#import <Cocoa/Cocoa.h> 9 10// The design of this class is extraordinarily poor. Apologies to all clients in 11// advance. Unfortunately, the lack of multiple inheritance and our desire to 12// avoid runtime hacks makes this convoluted dance necessary. 13// 14// Buttons that want to be draggable should implement the Mixin protocol below 15// and keep an instance of the Impl as an ivar. The button should forward mouse 16// events to the impl, which will tell the button whether or not to call super 17// and let the event be handled normally. 18// 19// If the impl decides to do work on the event, methods of the mixin protocol 20// may be called. Some of the methods declared in that protocol have base 21// implementations. If the method is not implemented by the button, that base 22// implementation will be called. Otherwise, the button's implementation will 23// be called first and the DraggableButtonResult will be used to determine 24// whether the base implementation should be called. This requires the client to 25// understand what the base does. 26 27enum DraggableButtonResult { 28 // Return values for Impl methods. 29 kDraggableButtonImplDidWork, 30 kDraggableButtonMixinCallSuper, 31 32 // Return values for Mixin methods. 33 kDraggableButtonMixinDidWork, 34 kDraggableButtonImplUseBase, 35}; 36 37// Mixin Protocol ////////////////////////////////////////////////////////////// 38 39// Buttons that make use of the below impl need to conform to this protocol. 40@protocol DraggableButtonMixin 41 42@required 43 44// Called when a drag should start. Implement this to do any pasteboard 45// manipulation and begin the drag, usually with 46// -dragImage:at:offset:event:. Subclasses must call one of the blocking 47// -drag* methods of NSView when implementing this method. 48- (void)beginDrag:(NSEvent*)dragEvent; 49 50@optional 51 52// Called if the actsOnMouseDown property is set. Fires the button's action and 53// tracks the click. 54- (DraggableButtonResult)performMouseDownAction:(NSEvent*)theEvent; 55 56// Implement if you want to do any extra work on mouseUp, after a mouseDown 57// action has already fired. 58- (DraggableButtonResult)secondaryMouseUpAction:(BOOL)wasInside; 59 60// Resets the draggable state of the button after dragging is finished. This is 61// called by DraggableButtonImpl when the beginDrag call returns. 62- (DraggableButtonResult)endDrag; 63 64// Decides whether to treat the click as a cue to start dragging, or to instead 65// call the mouseDown/mouseUp handler as appropriate. Implement if you want to 66// do something tricky when making the decision. 67- (DraggableButtonResult)deltaIndicatesDragStartWithXDelta:(float)xDelta 68 yDelta:(float)yDelta 69 xHysteresis:(float)xHysteresis 70 yHysteresis:(float)yHysteresis 71 indicates:(BOOL*)result; 72 73// Decides if there is enough information to stop tracking the mouse. 74// It's deltaIndicatesDragStartWithXDelta, however, that decides whether it's a 75// drag or not. Implement if you want to do something tricky when making the 76// decision. 77- (DraggableButtonResult)deltaIndicatesConclusionReachedWithXDelta:(float)xDelta 78 yDelta:(float)yDelta 79 xHysteresis:(float)xHysteresis 80 yHysteresis:(float)yHysteresis 81 indicates:(BOOL*)result; 82 83@end 84 85// Impl Interface ////////////////////////////////////////////////////////////// 86 87// Implementation of the drag and drop logic. NSButton Mixin subclasses should 88// forward their mouse events to this, which in turn will call out to the mixin 89// protocol. 90@interface DraggableButtonImpl : NSObject { 91 @private 92 // The button for which this class is implementing stuff. 93 NSButton<DraggableButtonMixin>* button_; 94 95 // Is this a draggable type of button? 96 BOOL draggable_; 97 98 // Has the action already fired for this click? 99 BOOL actionHasFired_; 100 101 // Does button action happen on mouse down when possible? 102 BOOL actsOnMouseDown_; 103 104 NSTimeInterval durationMouseWasDown_; 105 NSTimeInterval whenMouseDown_; 106} 107 108@property(nonatomic) NSTimeInterval durationMouseWasDown; 109 110@property(nonatomic) NSTimeInterval whenMouseDown; 111 112// Whether the action has already fired for this click. 113@property(nonatomic) BOOL actionHasFired; 114 115// Enable or disable dragability for special buttons like "Other Bookmarks". 116@property(nonatomic) BOOL draggable; 117 118// If it has a popup menu, for example, we want to perform the action on mouse 119// down, if possible (as long as user still gets chance to drag, if 120// appropriate). 121@property(nonatomic) BOOL actsOnMouseDown; 122 123// Designated initializer. 124- (id)initWithButton:(NSButton<DraggableButtonMixin>*)button; 125 126// NSResponder implementation. NSButton subclasses should invoke these methods 127// and only call super if the return value indicates such. 128- (DraggableButtonResult)mouseDownImpl:(NSEvent*)event; 129- (DraggableButtonResult)mouseUpImpl:(NSEvent*)event; 130 131@end 132 133#endif // CHROME_BROWSER_UI_COCOA_DRAGGABLE_BUTTON_MIXIN_H_ 134