event-handling | 易学教程

mouseover circle HTML5 canvas

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问题 I am wondering how to set an area as a semi-complex shape (circle) defined in the canvas so when the user mouse overs the shape, a function will be called. I do not wish to use libraries at all such as KineticJS etc. Currently I have added an event listener to the canvas element so that on mouse move I call multiple functions; one of which works out the mouse x/y coordinates relative to the canvas. As such, any rectangular shape is easy to 'listen' for using a basic if statement (as the

Can't use jquery's click event handler to detect right click

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问题 In trying to detect a right mouse click with jquery, I noticed that the click event handler doesn't seem to be fired off with a right mouse click, while the mousedown or mouseup event handler's do. For example, after a right click on the test div, the following alerts 'testing!': $('#test').mousedown(function(e) { alert('testing'); }); However, the following does not : $('#test').click(function(e) { alert('testing!'); }); Does anyone know why? 回答1: As this article puts it: There are no click

Event_Handler of the Done button of a picker

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问题 I have a xamarin picker with a list of items and I want to remove the picker when the "done" button is pressed on iPhone and "Oke" button on android. I have the code to remove the picker. But i don't know what event_Handler that might by. Code: Picker picker = new Picker { Title = "What's in the slot?", VerticalOptions = LayoutOptions.CenterAndExpand //HorizontalOptions = LayoutOptions.Center }; private void Displaypickerview(int row, int column) { if (status == "filling board") { foreach

How to add event handler to local variable in VB.NET

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问题 I have a form in VB.NET that is used as a dialog in a mainform. Its instances are always locally defined, there's no field for it. When the user clicks the OK button in the dialog, it will fire an event with exactly one argument, an instance of one of my classes. Since it is always a local variable, how can I add an event handler for that event? I've searched for myself and found something but I can't really figure it out... Code for the event, a field in MyDialog : public Event ObjectCreated

Why no constraint on EventHandler<TEventArgs>?

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问题 I just figured out by accident (when something compiled that I didn't think would compile) that EventHandler is not constrained to the type System.EventArgs. Here's the inline docs: #region Assembly mscorlib.dll, v4.0.0.0 // C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5\mscorlib.dll #endregion namespace System { // Summary: // Represents the method that will handle an event. // // Parameters: // sender: // The source of the event. // // e: // An System

How to attach a function to popover dismiss event (Twitter Bootstrap)

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问题 I've done some searching and I've only been able to figure that I can attach events to the buttons that cause it to close. However, this doesn't handle the case when the user just clicks somewhere else. I would like to trigger an event as the popover is fading and being removed. Anyone have any suggestions? Update: I've tried the answer below and was unable to get it to work, although it clearly should from the jsfiddle example. There may be some conflicts with the libraries and setup I'm

Invoke SharePoint Workflow after EventReceiver

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i got a question regarding sharepoint workflows and event receivers. i got an event receiver that is setting metadata on an element. after that, i use a workflow to copy item metadata to a list. unfortunately the workflow does not copy the metadata set by the event receiver. i think because it is executed before the event receiver. is there a possibility to change the order, so that the workflow will execute after the event receiver? the receiver ist bound to the ItemAdded and ItemUpdated Events i a syncrounous manner. Thank you for your help! Patrick You can use SPWorkFlowAssociation to run

PyQt Event Handling and QErrorMessage: detect the source of the click

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I'm new to Python and Qt, and I have the following problem: I have rewritten the event handler of class mywin(QMainWindow): , so that when I click on it, a command should execute. Howewer, when the command returns an error, I would like to show an error message using QErrorMessage . Howewer, when I click on the OK button of the Error Message, an other click event is registred and the command reexecutes, errors and shows a new error message, so I can't ever quit the error messages (Everytime I close on, an other one reopens). def eventFilter(self, source, event): if event.type() == QEvent

Process after grid was loaded completely using ExtJS

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问题 I am using ExtJS to load data to a grid, and I want to add some additional processes after data was put on grid completely. My context is, after data was put on grid, I will check all rows, and mark some of them as disabled based on a specified condition and put tooltip to row (explain why it is disabled). I tried to use 2 events: 'afterrender' of Grid, and 'load' of grid's store, but they did not work. Because grid's 'afterrender' was fired when first grid initialization, not concern to data

Delphi: Test event handler assignment

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问题 I want to assign an event handler in constructor, if it does not have one assigned. Consequentially I want to remove the eventually assigned event handler in destructor. I wrote the code as follows, but cannot be compiled. constructor TSomeControl.Create(Panel: TPanel); begin inherited Create; FPanel := Panel; if not Assigned(FPanel.OnResize) then FPanel.OnResize := HandlePanelResize; end; destructor TSomeControl.Destroy; begin if @FPanel.OnResize = @HandlePanelResize then // [dcc32 Error]