visibility

问题 I looked at the manual, but I can't seem to find the answer. What is the default visibility in PHP for methods without a visibility declaration? Does PHP have a package visibility like in Java? For example, in the following code, is go() public or private? class test { function go() { } } The reason I asked is that I've seen many constructors code written as function __construct() and some as public function __construct() . Are they equivalent? 回答1: Default is public. Class methods may be

问题 How can I ensure that a button's Tooltip is only visible when the button is disabled? What can I bind the tooltip's visibility to? 回答1: You will need to set ToolTipService.ShowOnDisabled to True on the Button in order to have the Tooltip visible at all when the Button is disabled. You can bind ToolTipService.IsEnabled on the Button to enable and disable the Tooltip. 回答2: This is the full XAML of the Button (based on the answer of @Quartermeister) <Button x:Name="btnAdd" Content="Add"

问题 The Java compiler doesn't complain when I override a protected method with a public method. What's really happening here? Is it overriding or hiding the parent method since the parent method has lower visibility? 回答1: A sub-class can always widen the access modifier, because it is still a valid substitution for the super-class. From the Java specification about Requirements in Overriding and Hiding: The access modifier (§6.6) of an overriding or hiding method must provide at least as much

问题 If the visibility property of the style of an HTML element is set to hidden , is it still clickable? When the display property is set to none , the element is not even part of the DOM tree, so that is not a problem. But I was wondering if a hidden element still responds to mouse events. 回答1: With display: none it is still part of the DOM. It just isn't rendered in the viewport. As for clicks on elements with visibility: hidden , the events are not fired. jsFiddle. $('div').click(function() {

问题 Consider the following piece of code: class foo { private function m() { echo 'foo->m() '; } public function call() { $this->m(); } } class bar extends foo { private function m() { echo 'bar->m() '; } public function callbar() { $this->m(); } } $bar = new bar; $bar->call(); $bar->callbar(); Now, changing the visibility of the m() method, I get: ( + for public , - for private ) Visibility bar->call() bar->callbar() ====================================================== -foo->m(), -bar->m() foo

问题 What are differences between Visibility.Collapsed and Visibility.Hidden in WPF? 回答1: The difference is that Visibility.Hidden hides the control, but reserves the space it occupies in the layout. So it renders whitespace instead of the control. Visibilty.Collapsed does not render the control and does not reserve the whitespace. The space the control would take is 'collapsed', hence the name. The exact text from the MSDN: Collapsed : Do not display the element, and do not reserve space for it

问题 I'm using a BooleanToVisibilityConverter in WPF to bind the Visibility property of a control to a Boolean . This works fine, but I'd like one of the controls to hide if the boolean is true , and show if it's false . 回答1: Implement your own implementation of IValueConverter. A sample implementation is at http://msdn.microsoft.com/en-us/library/system.windows.data.ivalueconverter.aspx In your Convert method, have it return the values you'd like instead of the defaults. 回答2: Instead of inverting

问题 This question already has answers here : Check if element is visible in DOM (19 answers) Closed 3 years ago . In JavaScript, how would you check if an element is actually visible? I don't just mean checking the visibility and display attributes. I mean, checking that the element is not visibility: hidden or display: none underneath another element scrolled off the edge of the screen For technical reasons I can't include any scripts. I can however use Prototype as it is on the page already.

问题 This question already has answers here : Check if element is visible in DOM (19 answers) Closed 3 years ago . In JavaScript, how would you check if an element is actually visible? I don't just mean checking the visibility and display attributes. I mean, checking that the element is not visibility: hidden or display: none underneath another element scrolled off the edge of the screen For technical reasons I can't include any scripts. I can however use Prototype as it is on the page already.

问题 How can I hide a column in a WPF DataGrid through a Binding? This is what I did: <DataGridTextColumn Header="Column header" Binding="{Binding ColumnValue}" Width="100" ElementStyle="{StaticResource DataGridRightAlign}" Visibility="{Binding MyColumnVisibility}" /> And this is what I got (besides the column still visible): System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=MyColumnVisibility; DataItem=null;