How to use SpaceBar button inside an application to invoke quick look

Question

i had displayed some images in collectionview. now i want to select the image and press space button. If i pressed Space button , the image should quicklook in a seperate window. any idea?

Answer 1

On your view, do this:

- (void)keyDown:(NSEvent *)event
{
  unichar firstChar = 0;
  if ([[event charactersIgnoringModifiers] length] > 0)
    firstChar = [[event charactersIgnoringModifiers] characterAtIndex:0];

  if (firstChar == ' ')
  {
    if ([QLPreviewPanel sharedPreviewPanelExists]
        && [[QLPreviewPanel sharedPreviewPanel] isVisible])
    {
      [[QLPreviewPanel sharedPreviewPanel] orderOut:nil];
    }
    else
    {
      [[QLPreviewPanel sharedPreviewPanel] makeKeyAndOrderFront:nil];
      [[NSApp mainWindow] makeKeyWindow];
    }
  }
  else if (firstChar == NSRightArrowFunctionKey)
  {
    if ([QLPreviewPanel sharedPreviewPanelExists]
        && [[QLPreviewPanel sharedPreviewPanel] isVisible])
    {
      [[QLPreviewPanel sharedPreviewPanel] selectNextItem];
      return;
    }
  }
  else if (firstChar == NSLeftArrowFunctionKey)
  {
    if ([QLPreviewPanel sharedPreviewPanelExists]
        && [[QLPreviewPanel sharedPreviewPanel] isVisible])
    {
      [[QLPreviewPanel sharedPreviewPanel] selectPreviousItem];
      return;
    }
  }
  else
    [super keyDown:event];
}

Then, I do this in my app's delegate (AppDelegate.m):

- (BOOL)acceptsPreviewPanelControl:(QLPreviewPanel *)panel
{
  //note that this methods indeed gets called because NSApp's
  //delegate is in the responder chain.
  return YES;
}

- (void)beginPreviewPanelControl:(QLPreviewPanel *)panel
{
  previewPanel = panel; //set an ivar
  [panel setDataSource:self];
}

- (void)endPreviewPanelControl:(QLPreviewPanel *)panel
{
  previewPanel = nil;
}

- (NSInteger)numberOfPreviewItemsInPreviewPanel:(QLPreviewPanel *)panel
{
  //return a number of your choice (depends on your own app)
}

- (id <QLPreviewItem>)previewPanel:(QLPreviewPanel *)panel
                previewItemAtIndex:(NSInteger)index
{
  //return an object of your choice (depends on your app)
}

- (void)handleCurrentFileItemsSelectionChange:(NSNotification *)note
{
  [previewPanel reloadData]; //referring to the ivar
}