QuickLook使用者作为来自NSViewController的委托 [英] QuickLook consumer as a delegate from an NSViewController

问题描述

我在 NSView 中的表格中实现了 QuickLook 功能的一些问题。 QuickLook 的有限文档根本不起作用。

阅读完 Google文档（针对自定义生成器和插件），我结束了请参阅 QuickLookDownloader示例代码。这段代码基于一个基于文档的应用程序，但似乎是对我来说是正确的方法（毕竟它是苹果的代码，它在他们的项目中工作）。

在我的实现中，我可以得到 QuickLook面板显示得很好，我可以解雇它就像很容易。然而，面板本身从来不调用我的 NSViewController 中的委托方法。因此，我从来没有得到显示对象，只是措辞没有选择项目。

我试着调用 setDelegate ，但是如果我继续下去，路由...

[QL] QLError（）： - [QLPreviewPanel setDelegate：]当面板没有控制器时调用 - 这将很快升高。
查看QLPreviewPanel.h中对-acceptsPreviewPanelControl的注释：/ - beginPreviewPanelControl：/ - endPreviewPanelControl：。

是的，我已经读了头，这确认了我应该设置委托后，我赢得了面板（见下面的代码）。

下面是我的代码，它与示例代码非常匹配，除了a）我从中获取数据从 NSArrayController ）和b）在那里我得到我的预览项目（我直接从我的模型对象 - 或应该反正）

  @interface MyViewController：NSViewController 
< QLPreviewPanelDataSource，QLPreviewPanelDelegate& {
 
 QLPreviewPanel * previewPanel; 
 NSArrayController * myArrayController; 
 NSTableView * myTable; 
 
 // [...]其他实例vars 
} 
 
 @implementation MyViewController 
 
 // [...]其他方法，init，dealloc等... 
 
  - （IBAction）togglePreviewPanel：（id）previewPanel {
 
 if（[QLPreviewPanel sharedPreviewPanelExists]&& 
 [[QLPreviewPanel sharedPreviewPanel] isVisible]）
 {
 [[QLPreviewPanel sharedPreviewPanel] orderOut：nil]; 
} 
 else 
 {
 [[QLPreviewPanel sharedPreviewPanel] makeKeyAndOrderFront：nil]; 
} 
} 
 
  - （BOOL）acceptsPreviewPanelControl：（QLPreviewPanel *）panel 
 {
 return YES; 
} 
 
 //此文档现在负责预览面板。 
 //允许设置委托，数据源和刷新面板。 
 
  - （void）beginPreviewPanelControl：（QLPreviewPanel *）panel 
 {
 
 if（DEBUG）NSLog（@QuickLook panel control did BEGIN）; 
 
 previewPanel = [panel retain]; 
 panel.delegate = self; 
 panel.dataSource = self; 
} 
 
 //此文档在预览面板上失去了响应性。 
 //直到下一次调用-beginPreviewPanelControl：它不能改变
 //面板的委托，数据源或刷新它。 
 
  - （void）endPreviewPanelControl：（QLPreviewPanel *）panel 
 {
 [previewPanel release]; 
 previewPanel = nil; 
 
 if（DEBUG）NSLog（@QuickLook panel control did END）; 
} 
 
 //快速查看面板数据源
 
  - （NSInteger）numberOfPreviewItemsInPreviewPanel：（QLPreviewPanel *）panel 
 {
 
 if（DEBUG）NSLog（@QuickLook preview count called）; 
 
 return [[myArrayController selectedObjects] count]; 
} 
 
  - （id< QLPreviewItem>）previewPanel：（QLPreviewPanel *）panel 
 previewItemAtIndex：（NSInteger）index 
 {
 
 if（DEBUG）NSLog（@QuickLook预览选择项调用）; 
 
 return [[displayAC selectedObjects] objectAtIndex：index]; 
} 
 
  - （BOOL）previewPanel：（QLPreviewPanel *）panel handleEvent：（NSEvent *）event {
 
 if（DEBUG）NSLog错误处理程序称为）; 
 
 //将所有按键事件重定向到表视图
 
 if（[event type] == NSKeyDown）{
 [myTable keyDown：event]; 
 return YES; 
} 
 
 return NO; 
} 
  

问题似乎是 acceptsPreviewPanelControl 永远不会被调用，所以代理不会被使用（他们从不被调用）。

我确定这是一个简单的步骤， m缺少，但在解剖示例代码和冲刷文档后，我没有看到答案。

是因为这是所有从NSViewController看到没有理由为什么这应该进入方程）？

任何和所有的帮助非常感激。

解决方案更新

感谢Peter的观察，这个修正是一个快速的修正。你不讨厌它，当调试器中的错误消息意味着它说什么？ ： - ）

在我装载 MyViewController 的类中，我只需要添加三行代码来解决问题。

  // mainWindow是一个IBOutlet到我的窗口，因为调用类
 //是一个简单的对象一个NSWindowController否则我可以
 //使用`self`而不是`mainWindow` 
 
 NSResponder * aNextResponder = [mainWindow nextResponder]; 
 
 [mainWindow setNextResponder：myViewControllerInstance]; 
 [myViewControllerInstance setNextResponder：aNextResponder]; 
  

工作完成:-)感谢Peter。

解决方案

为什么你期望它发送代理消息，如果你还不是它的委托？

我试图调用 setDelegate ，但如果我沿着该路线继续，就会收到警告。

] 当面板没有控制器时调用QLError（）： - [QLPreviewPanel setDelegate：] 提高很快。请参阅QLPreviewPanel.h中对 -acceptsPreviewPanelControl： / -beginPreviewPanelControl： / 的评论--endPreviewPanelControl：







无控制器。

对该标题的注释，特别是 acceptedPreviewPanelControl： QLPreviewPanel实例方法 updateController ，建议面板的控制器，当它有一个，是响应器链中的一个对象。因此，如果您的控制器没有成为面板的控制器，那是因为您的控制器不在响应器链中。

因此，修复它，然后它会工作。

我想象你的视图控制器应该在响应链中，只要它的视图或其任何子视图在响应链中，但也许不是这样。 文档不说。如果所有其他失败，设置自己作为一些视图的下一个响应者显式（和其上一个下一个响应者作为下一个响应者），然后发送预览面板 updateController 消息。 >

I am having some problems implementing QuickLook functionality from a table in an NSView. The limited documentation on QuickLook really doesn't help at all.

After reading through the Apple Docs (which are geared heavily towards custom generators and plugins), I ended up looking at the QuickLookDownloader sample code. This code is based upon a document-based application, but appears to be the right method for me (after all it is Apple's code and it does work in their project).

In my implementation I can get the QuickLook panel to show up just fine, and I can dismiss it just as easy. However, the panel itself never calls the delegate methods from within my NSViewController. As a result I never even get to displaying objects, just the wording "No items selected". And I am stumped.

I tried calling a setDelegate, but get warned about impending doom if I continue down that route...

[QL] QLError(): -[QLPreviewPanel setDelegate:] called while the panel has no controller - Fix this or this will raise soon. See comments in QLPreviewPanel.h for -acceptsPreviewPanelControl:/-beginPreviewPanelControl:/-endPreviewPanelControl:.

And then doom happens anyway with a dealloc when trying to respond to one of the delegate methods.

And yes I did read the header which confirms that I should be setting the delegate after I won the panel (see code below).

So here's my code, which pretty much matches the sample code with the exception of a) where I get my data from (I get it from an NSArrayController) and the b) where I get my preview item from (mine comes directly from my model object - or should anyway)

@interface MyViewController : NSViewController 
    <QLPreviewPanelDataSource, QLPreviewPanelDelegate> {

    QLPreviewPanel * previewPanel;
    NSArrayController * myArrayController;
    NSTableView * myTable;

    // [...] Other instance vars
}

@implementation MyViewController

// [...] all the other methods, init, dealloc etc...

-(IBAction)togglePreviewPanel:(id)previewPanel {

    if ([QLPreviewPanel sharedPreviewPanelExists] && 
          [[QLPreviewPanel sharedPreviewPanel] isVisible])
    {
       [[QLPreviewPanel sharedPreviewPanel] orderOut:nil];
    }
    else
    {
       [[QLPreviewPanel sharedPreviewPanel] makeKeyAndOrderFront:nil];
    }
 }

 -(BOOL)acceptsPreviewPanelControl:(QLPreviewPanel *)panel
 {    
      return YES;
 }

 // This document is now responsible of the preview panel. 
 // It is allowed to set the delegate, data source and refresh panel.

 -(void)beginPreviewPanelControl:(QLPreviewPanel *)panel 
 {

    if (DEBUG) NSLog(@"QuickLook panel control did BEGIN");

    previewPanel = [panel retain];
    panel.delegate = self;
    panel.dataSource = self;
 }

 // This document loses its responsisibility on the preview panel. 
 // Until the next call to -beginPreviewPanelControl: it must not change 
 // the panel's delegate, data source or refresh it.

 -(void)endPreviewPanelControl:(QLPreviewPanel *)panel   
 {
     [previewPanel release];
     previewPanel = nil;

     if (DEBUG) NSLog(@"QuickLook panel control did END");
 }

 // Quick Look panel data source

 -(NSInteger)numberOfPreviewItemsInPreviewPanel:(QLPreviewPanel *)panel 
 {

     if (DEBUG) NSLog(@"QuickLook preview count called");

     return [[myArrayController selectedObjects] count];
 }

 -(id <QLPreviewItem>)previewPanel:(QLPreviewPanel *)panel
        previewItemAtIndex:(NSInteger)index
 {

     if (DEBUG) NSLog(@"QuickLook preview selection of item called");

     return [[displayAC selectedObjects] objectAtIndex:index];
 }

 -(BOOL)previewPanel:(QLPreviewPanel *)panel handleEvent:(NSEvent *)event {

    if (DEBUG) NSLog(@"QuickLook panel error handler called");

// redirect all key down events to the table view

    if ([event type] == NSKeyDown) {
        [myTable keyDown:event];
    return YES;
    }

    return NO;
}

The issue seems to be that the acceptsPreviewPanelControl never gets called, so the delegates never get used (they definitely never get called).

I'm sure this is a simple step that I'm missing, but after dissecting the sample code and scouring over the docs I don't see the answer.

Is it because this is all from within an NSViewController (although I see no reason why that should even come into the equation)?

Any and all help much appreciated.

SOLUTION UPDATE

Thanks to Peter's observation, the fix was a quick one. Don't you hate it when the error message in the debugger means what it says? :-)

In my class that loaded MyViewController I simply needed to add three lines of code to fix the problem.

// mainWindow is an IBOutlet to my window because the calling class 
// is a simple object and not an NSWindowController otherwise I could
// have used `self` instead of `mainWindow`

NSResponder * aNextResponder = [mainWindow nextResponder];

[mainWindow setNextResponder:myViewControllerInstance];
[myViewControllerInstance setNextResponder:aNextResponder];

Job done :-) Thanks Peter.

解决方案

Why would you expect it to send you delegate messages if you aren't (yet) its delegate? If you want it to send you delegate messages, then you need to set yourself as its delegate.

I tried calling a setDelegate, but get warned about impending doom if I continue down that route...

[QL] QLError(): -[QLPreviewPanel setDelegate:] called while the panel has no controller - Fix this or this will raise soon. See comments in QLPreviewPanel.h for -acceptsPreviewPanelControl:/-beginPreviewPanelControl:/-endPreviewPanelControl:.

"No controller", it says. So, you need it to have a controller.

The comments on that header, particularly on acceptsPreviewPanelControl: and the QLPreviewPanel instance method updateController, suggest that the panel's controller, when it has one, is an object that is in the responder chain. Therefore, if your controller is not becoming the panel's controller, it's because your controller isn't in the responder chain.

So, fix that, and then it'll work.

I would imagine that your view controller should be in the responder chain whenever its view or any subview thereof is in the responder chain, but maybe this isn't the case. The documentation doesn't say. If all else fails, set yourself as some view's next responder explicitly (and its previous next responder as your next responder), then send the preview panel an updateController message.

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