如何帮助阻止我的用户在Cocoa中意外启动拖动？ [英] How do I help prevent my users from initiating a drag accidentally in Cocoa?

问题描述

我有一个集合视图，我已经子类化，允许我通过拖放重新排序集合视图项。我的拖拽代码设置的Pasterboard目前在mouseDragged：

   - （void）mouseDragged：（NSEvent *）aEvent {
 
 if（！dragInProgress）{
 dragInProgress = YES; 
 
 NSPasteboard * pboard = [NSPasteboard pasteboardWithName：NSDragPboard]; 
 
 ... setup pboard，declare types，setData ... 
 ...创建拖动图像.... 
 
 [self dragImage：image 
 at：position 
 offset：NSZeroSize 
 event：aEvent 
 pasteboard：pboard 
 source：self 
 slideBack：YES]; 
} 
} 
  

我想只在用户已经拖动了一定长度，所以他们不会意外启动拖拽。是否有一个设置在Cocoa中执行此操作，或者需要将此代码移动到mouseMoved：并检查拖动开始位置和鼠标当前位置之间的距离。

locationInWindow ）在 mouseDown： ）。在 mouseDragged：中，从鼠标拖动事件的位置中减去鼠标按下事件的位置，并将该差异与 HIMouseTrackingGetParameters 与 kMouseParamsDragInitiation 选择器。

I have a collection view that I've subclassed that allows me to reorder the collection view items via drag and drop. My drag code that sets up the pasterboard is currently in mouseDragged:

- (void)mouseDragged:(NSEvent *)aEvent {

    if(!dragInProgress) {
        dragInProgress = YES;

        NSPasteboard *pboard = [NSPasteboard pasteboardWithName:NSDragPboard];        

            ... setup pboard, declare types, setData ...
            ... create drag image ....

        [self  dragImage: image
                      at: position
                  offset: NSZeroSize
                   event: aEvent
              pasteboard: pboard
                  source: self
               slideBack: YES];
    }
}

I would like to only initiate a drag if the user has dragged for a certain length, so they don't initiate a drag accidentally. Is there a setting to do this in Cocoa, or do I need to move this code to mouseMoved: and check the distance between where the drag started and where the mouse is currently?

解决方案

In mouseDown:, remember where the mouse went down (locationInWindow). In mouseDragged:, subtract the location of the mouse-down event from the location of the mouse-dragged event, and compare the difference to the size returned by HIMouseTrackingGetParameters with the kMouseParamsDragInitiation selector.

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