event-handling | 易学教程

Is it possible to use multiple callbacks in the WindowButtonMotionFcn?

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问题 I created a class which adds functionality to a figure on construction. This class creates a listener for the WindowMouseMotion event; however, to get this event to fire I had to add a dummy callback function for the figure's WindowButtonMotionFcn property. I first check if this property is already populated. If it isn't then I set it to a dummy callback function that does nothing. Instead of checking if the property is already set or not, can I simply add this dummy callback to any existing

What is the best practice to not to override other bound functions to window.onresize?

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How much I dig into JavaScript, I find myself asking that much. For example we have window.onresize event handler and if I say: window.onresize = resize; function resize() { console.log("resize event detected!"); } Wouldn't that kill all other functions which is connected to the same event and just log my message in console? If so I think there should be another notifier which tells me about window resize event - or a workaround maybe - without overriding other functions which are bound to same event. Or am I totally confused by its usage? You can save the old onresize function and call that

Difference between Events and Functions?

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问题 I am new to Node, and I am struggling to understand the main difference between Events and Functions. Both need to be triggered, so why do we need an Event at all if we have to trigger it anyway? How is it different than having a Function triggered? Example code: var events = require('events'); var eventEmitter = new events.EventEmitter(); eventEmitter.on('event1', function () { console.log('Event 1 executed.'); eventEmitter.emit('event2'); }); eventEmitter.on('event2', function() { console

c# WPF how to repeat MediaElement playback from mediaended event handler without declaring new source?

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问题 im playing a video in WPF.i want it to loop so what i did is when the mediaended event fires, i play back my video. so this will get me a loop. prob is why do u i have to create new source again? why cant i just call 'play'? i dont want to do it in XAML as for some reason. have a look at my code snippet: string startPath System.IO.Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName); public Window1() { InitializeComponent(); media.Source = new Uri(startPath + @"playlist.wpl"

Object to process touch event but also let it through

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I want to create an object that will work like MultiPointTouchArea (so it will have touchUpdated signal) but also it would not steal touches, so that objects placed beneath it will receive the touch events as well. The solution may require creating C++ object. Is there a simple way to create such object? Is it possible to process (touch) events without "stealing" them? Any hint will be appreciated. Here is an example of what I am trying to do. I want to touch top Rectangle but at the same time I want both MultiPointTouchArea s process touches: import QtQuick 2.3 import QtQuick.Window 2.2

Threads & Event loop in the Qt application [closed]

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问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 3 years ago . Can anyone explain difference in the Threads and Event loop, and how can I use this in the QT application. where can I use move to the thread and complete thread class.? 回答1: Each thread processes its own event loop, you normally do not need to worry about this - its taken care of

Best way to get the name of a button that called an event?

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问题 In the following code (inspired by this snippet), I use a single event handler buttonClick to change the title of the window. Currently, I need to evaluate if the Id of the event corresponds to the Id of the button. If I decide to add 50 buttons instead of 2, this method could become cumbersome. Is there a better way to do this? import wx class MyFrame(wx.Frame): def __init__(self): wx.Frame.__init__(self, None, wx.ID_ANY, 'wxBitmapButton', pos=(300, 150), size=(300, 350)) self.panel1 = wx

Threads & Event loop in the Qt application [closed]

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Can anyone explain difference in the Threads and Event loop, and how can I use this in the QT application. where can I use move to the thread and complete thread class.? code_fodder Each thread processes its own event loop, you normally do not need to worry about this - its taken care of for you and unless you have a specific reason to its meant to be left alone. QThread is a class provided by Qt for you to use to control the operation of a thread. The method of "putting" object into that thread is to use the moveToThread() function. You should not inherit the QThread class in order to run

dynamically created list of link buttons, link buttons not posting back

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问题 Hi I am dynamically creating link buttons in a 'ul li' list. I am then trying to tie each link button to a click event where i set a label to the text of the link button clicked. however the event that should fire doesnt get fired? if (!Page.IsPostBack) { int listItemIds = 0; foreach (Node productcolour in product.Children) { HtmlGenericControl li = new HtmlGenericControl("li"); LinkButton lnk = new LinkButton(); lnk.ID = "lnk" + listItemIds; lnk.Text = productcolour.Name; lnk.Click += new

Event handling for dynamic controls in VB6

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How can i achieve event handling for dynamic controls in VB6? Any ideas? The easiest way is to declare a module-level variable of the same type as the control, and use the WithEvents keyword. For example Option Explicit ' Declare object variable as CommandButton and handle the events.' Private WithEvents cmdObject As CommandButton Private Sub Form_Load() 'Add button control and keep a reference in the WithEvents variable' Set cmdObject = Form1.Controls.Add("VB.CommandButton", "cmdOne") cmdObject.Visible = True cmdObject.Caption = "Dynamic CommandButton" End Sub 'Handle the events of the