NSUndoManager：redo不工作 [英] NSUndoManager: redo not working

问题描述

我正在做一个简单的应用程序，使用NSSlider，可以把它的最大值或最小值与两个按钮。恢复管理器将跟踪所有更改，并允许撤消/重做所有更改使用这两个按钮。 br>
这里是界面：

I am making a simple application that uses a NSSlider, which can be put to it's max or min value with two buttons.The undo manager shall track all changes and allow to undo/redo all changes made using these two buttons.
Here is the interface:

#import <Cocoa/Cocoa.h>

@interface AppDelegate : NSObject <NSApplicationDelegate>
{
@private
    NSUndoManager* undoManager;
}

@property (assign) IBOutlet NSWindow *window;
@property (weak) IBOutlet NSSlider *slider;


- (IBAction)putToMax:(id)sender;
- (IBAction)putToMin:(id)sender;
- (void) setSliderValue: (float) value;

@end

实施：

#import "AppDelegate.h"

@implementation AppDelegate

@synthesize window = _window;
@synthesize slider = _slider;

- (NSUndoManager*) windowWillReturnUndoManager: (NSWindow*) window
{
    return undoManager;
}

- (IBAction)putToMax:(id)sender 
{
    float value= [_slider floatValue];
    [ [undoManager prepareWithInvocationTarget: self] setSliderValue: value];
    if(![undoManager isUndoing])
        [undoManager setActionName: @"Put to Max"];
    NSLog(@"%f value added to the stack",value);
    [_slider setFloatValue: 100.0];
}

- (IBAction)putToMin:(id)sender 
{
    float value= [_slider floatValue];
    [ [undoManager prepareWithInvocationTarget: self] setSliderValue: value];
    if(![undoManager isUndoing])
        [undoManager setActionName: @"Put to Min"];
    NSLog(@"%f value added to the stack",value);
    [_slider setFloatValue: 0.0];
}

- (void) setSliderValue: (float) value
{
    [_slider setFloatValue: value];
}

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
}

- (id) init
{
    self=[super init];
    if(self)
    {
        undoManager=[[NSUndoManager alloc]init];
    }
    return self;
}


@end

应用程式的萤幕撷取画面：

And a screenshot of the application:

撤消可以正常工作，但我有重做的问题。

The undo works fine, but I have problems with redo.

例如在启动应用程序后：

For example after launching the application:

• - >

滑块返回到原来的位置。

The slider goes back where it was.

但如果我转到菜单编辑 - >重做放到最大，滑块不会回到它的最大位置。

But if I go to menu Edit -> Redo put to max, the slider doesn't go back to it's max position. And I don't understand why.

推荐答案

当撤销系统执行撤销操作时，它希望您注册重做操作使用与撤消相同的代码，（除了 NSUndoManager 知道它是倒带 - 但你不应该关心）。

When the Undo system performs an undo action, it expects you to register the redo actions using the same code as for undo, (except that the NSUndoManager knows it's rewinding - but you should not care).

因此在 -setSliderValue中添加正确的NSUndoManager调用：

这篇关于NSUndoManager：redo不工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！