在OSX 10.8 SDK / objective-c中拖动一个按钮

2 回答

• 4

  我为死灵法术道歉，但我在试图自己实现这个问题时偶然发现了这个问题，并希望分享答案，因为它可能对其他人有用 .

  此解决方案使用 NSActionCell 和 NSControl 上的类别，因为我需要能够拖动多个控件类型，而不仅仅是按钮 . 您可以根据自己的需求/课程进行调整 .

  在隐藏/取消隐藏控件时，我已经注释了与不希望的淡入淡出动画的变通方法有关的代码 . 我摆弄着隐含的动画等，但无法想出更好的方法 . 黑客确实运行良好，但我离开了窗口实现代码 .

  @implementation NSControl (DragControl)
  
  - (NSDraggingSession*)beginDraggingSessionWithDraggingCell:(NSActionCell <NSDraggingSource> *)cell event:(NSEvent*) theEvent
  {
      NSImage* image = [self imageForCell:cell];
      NSDraggingItem* di = [[NSDraggingItem alloc] initWithPasteboardWriter:image];
      NSRect dragFrame = [self frameForCell:cell];
      dragFrame.size = image.size;
      [di setDraggingFrame:dragFrame contents:image];
  
      NSArray* items = [NSArray arrayWithObject:di];
  
      [self setHidden:YES];
      return [self beginDraggingSessionWithItems:items event:theEvent source:cell];
  }
  
  - (NSRect)frameForCell:(NSCell*)cell
  {
      // override in multi-cell cubclasses!
      return self.bounds;
  }
  
  - (NSImage*)imageForCell:(NSCell*)cell
  {
      return [self imageForCell:cell highlighted:[cell isHighlighted]];
  }
  
  - (NSImage*)imageForCell:(NSCell*)cell highlighted:(BOOL) highlight
  {
      // override in multicell cubclasses to just get an image of the dragged cell.
      // for any single cell control we can just make sure that cell is the controls cell
  
      if (cell == self.cell || cell == nil) { // nil signifies entire control
                                              // basically a bitmap of the control
                                              // NOTE: the cell is irrelevant when dealing with a single cell control
          BOOL isHighlighted = [cell isHighlighted];
          [cell setHighlighted:highlight];
  
          NSRect cellFrame = [self frameForCell:cell];
  
          // We COULD just draw the cell, to an NSImage, but button cells draw their content
          // in a special way that would complicate that implementation (ex text alignment).
          // subclasses that have multiple cells may wish to override this to only draw the cell
          NSBitmapImageRep* rep = [self bitmapImageRepForCachingDisplayInRect:cellFrame];
          NSImage* image = [[NSImage alloc] initWithSize:rep.size];
  
          [self cacheDisplayInRect:cellFrame toBitmapImageRep:rep];
          [image addRepresentation:rep];
          // reset the original cell state
          [cell setHighlighted:isHighlighted];
          return image;
      }
      // cell doesnt belong to this control!
      return nil;
  }
  
  #pragma mark NSDraggingDestination
  // message forwarding doesnt work for NSDraggingDestination methods
  // because NSView implements empty methods for the protocol
  /*
  - (NSDragOperation)draggingEntered:(id < NSDraggingInfo >)sender
  {
      return [self.cell draggingEntered:sender];
  }
  
  - (void)draggingExited:(id < NSDraggingInfo >)sender
  {
      [self.cell draggingExited:sender];
  }
  
  - (BOOL)prepareForDragOperation:(id < NSDraggingInfo >)sender
  {
      return [self.cell prepareForDragOperation:sender];
  }
  
  - (BOOL)performDragOperation:(id < NSDraggingInfo >)sender
  {
      return [self.cell performDragOperation:sender];
  }
  
  - (void)concludeDragOperation:(id < NSDraggingInfo >)sender
  {
      return [self.cell concludeDragOperation:sender];
  }
  */
  - (void)draggingEnded:(id < NSDraggingInfo >)sender
  {
      // implement whatever you want to do here.
      [self setHidden:NO];
  }
  
  @end
  
  
  static NSPoint _dragImageOffset;
  @implementation NSActionCell (DragCell)
  
  - (void)setControlView:(NSView *)view
  {
      // this is a bit of a hack, but the easiest way to make the control dragging work.
      // force the control to accept image drags.
      // the control will forward us the drag destination events via our DragControl category
  
      [view registerForDraggedTypes:[NSImage imagePasteboardTypes]];
      [super setControlView:view];
  }
  
  - (BOOL)trackMouse:(NSEvent *)theEvent inRect:(NSRect)cellFrame ofView:(NSView *)controlView untilMouseUp:(BOOL)untilMouseUp
  {
      BOOL result = NO;
      NSPoint currentPoint = theEvent.locationInWindow;
      BOOL done = NO;
      BOOL trackContinously = [self startTrackingAt:currentPoint inView:controlView];
  
      BOOL mouseIsUp = NO;
      NSEvent *event = nil;
      while (!done)
      {
          NSPoint lastPoint = currentPoint;
  
          event = [NSApp nextEventMatchingMask:(NSLeftMouseUpMask|NSLeftMouseDraggedMask)
                                     untilDate:[NSDate distantFuture]
                                        inMode:NSEventTrackingRunLoopMode
                                       dequeue:YES];
  
          if (event)
          {
              currentPoint = event.locationInWindow;
  
              // Send continueTracking.../stopTracking...
              if (trackContinously)
              {
                  if (![self continueTracking:lastPoint
                                           at:currentPoint
                                       inView:controlView])
                  {
                      done = YES;
                      [self stopTracking:lastPoint
                                      at:currentPoint
                                  inView:controlView
                               mouseIsUp:mouseIsUp];
                  }
                  if (self.isContinuous)
                  {
                      [NSApp sendAction:self.action
                                     to:self.target
                                   from:controlView];
                  }
              }
  
              mouseIsUp = (event.type == NSLeftMouseUp);
              done = done || mouseIsUp;
  
              if (untilMouseUp)
              {
                  result = mouseIsUp;
              } else {
                  // Check if the mouse left our cell rect
                  result = NSPointInRect([controlView
                                          convertPoint:currentPoint
                                          fromView:nil], cellFrame);
                  if (!result)
                      done = YES;
              }
  
              if (done && result && ![self isContinuous])
                  [NSApp sendAction:self.action
                                 to:self.target
                               from:controlView];
              else {
                  done = YES;
                  result = YES;
  
                  // this initiates the control drag event using NSDragging protocols
                  NSControl* cv = (NSControl*)self.controlView;
                  NSDraggingSession* session = [cv beginDraggingSessionWithDraggingCell:self
                                                                                  event:theEvent];
                  // _dragImageOffset = [cv convertPoint:[theEvent locationInWindow] fromView:nil];
                  // Note that you will get an ugly flash effect when the image returns if this is set to yes
                  // you can work around it by setting NO and faking the release by animating an NSWindowSubclass with the image as the content
                  // create the window in the drag ended method for NSDragOperationNone
                  // there is [probably a better and easier way around this behavior by playing with view animation properties.
                  session.animatesToStartingPositionsOnCancelOrFail = YES;
              }
  
          }
      }
      return result;
  }
  
  #pragma mark - NSDraggingSource Methods
  - (NSDragOperation)draggingSession:(NSDraggingSession *)session sourceOperationMaskForDraggingContext:(NSDraggingContext)context
  {
      switch(context) {
          case NSDraggingContextOutsideApplication:
              return NSDragOperationNone;
              break;
  
          case NSDraggingContextWithinApplication:
          default:
              return NSDragOperationPrivate;
              break;
      }
  }
  /*
  - (void)draggingSession:(NSDraggingSession *)session willBeginAtPoint:(NSPoint)screenPoint
  {
      DragAnimationWindow* dw = [DragAnimationWindow sharedAnimationWindow];
      NSControl* cv = (NSControl*)self.controlView;
  
      NSImage* image = [[NSImage alloc] initWithPasteboard:session.draggingPasteboard];
      [dw setupDragAnimationWith:cv usingDragImage:image];
      [image release];
      NSRect frame = [cv frameForCell:self];
      frame = [cv convertRect:frame toView:nil];
      [dw setFrame:[cv.window convertRectToScreen:frame] display:NO];
  }
  */
  - (void)draggingSession:(NSDraggingSession *)session endedAtPoint:(NSPoint)screenPoint operation:(NSDragOperation)operation
  {
      /*
      if (operation == NSDragOperationNone) {
          DragAnimationWindow* dw = [DragAnimationWindow sharedAnimationWindow];
          NSRect frame = dw.frame;
  
          NSPoint start = screenPoint;
          start.y += _dragImageOffset.y;
          start.x -= _dragImageOffset.x;
  
          [dw setFrameTopLeftPoint:start];
          [dw animateToFrame:frame];
      }*/
      // now tell the control view the drag ended so it can do any cleanup it needs
      // this is somewhat hackish
      [self.controlView draggingEnded:nil];
  }
  
  @end
  

  回复于 2024-05-02T06:47:41+08:00
• 2

  可能问题是你用 NSPasteboardTypeString 调用 -setDataProvider:forTypes: 但是你的 -pasteboard:item:provideDataForType: 在传递那种类型时什么都不做？

  回复于 2024-05-02T06:47:41+08:00