I am currently working on a messaging platform and previously, we just load all the messages at once as there are not that many messages. Now that that there are many messages, it is starting to take a long time to load everything.
As such, I would like to implement lazy loading but I can't find any documentation explaining how I can do load the latest 20 messages and load more when I scroll up to view the earlier messages (Just like any messaging platform). Is there any way to implement this?
So I am trying to create the waveform shape in react native while recording an audio, I looked up many packages but they all need an audio url so they don't support realtime recording, I tried creating one by myself which i used a package that provides me with the decibals value when recording and then push the value to state array but it cause too many lags since I setstate every 0.5 sec.
Any suggestion?
This package audio-react-recorder provides the recording interface as well as a somewhat customisable waveform. I think it's a good place to start. I used it a few times, it works quite well.
Here's a demo
Let me know if it works out for you.
I am new to adobe Analytics. I am trying to track form errors that are occurring when the user submitting the form without filling the required fields.
So here what I did was, passed form values to list prop to capture the values. But I am not getting how to implement events to track against these values.
Can anyone please help me with how to implement rules and events in the adobe launch for tracking?
Yes, there are a few ways to do it.
The recommended way is to ask the Front-end team to send an error event that Launch can listen to. It can be done in a few ways. It's considered the best practice to install the adobeDataLayer extension: https://experienceleague.adobe.com/docs/launch/using/extensions-ref/adobe-extension/acdl/overview.html?lang=en
The extension provides ability to use a dataLayer very similar to GTM. Very comfortable.
The other way to do it is ask the devs to send a simple JS customEvent with error details in the detail property of the event.
Launch can natively listen to JS events and gives access to the event object.
Finally, the worst kind of implementation, that should be mostly considered as a hack, is the become visible trigger:
you're supposed to detect the actual error message with this trigger. I suggest not using it since the enters viewport listener is a bit heavy. And it also depends on the DOM structure since you'll have to provide the CSS selector for the error message.
This is not all, surely. You can build your own settimeout polling logic to look for the errors manually, or ask devs to send direct calls, but those are even worse solutions, so I'm not elaborating on them.
I have large WPF application which also uses MEF.
I want to trigger an Audio alert on certain condition and repeat it for the times specified by user. audio file can be .wav or .mp3.
I am making use of SoundPlayer to play the audio.
I am not sure which timer to use for repeat intervals.
I dont want to block UI thread when audio is playing and also want it to be threadsafe.
thanks in advance.
Why not consider using Event Aggregation, which is an implementation of publisher subscriber pattern. Whenever your application encounters a condition where it wants to play audio, it would publish its intensions via the event aggregator.
There would be a listener who listens for these events and would play the correct audio based on the type of the event. If there are multiple requests, the listener may play them in parallel or in a sequence. You can implement the desired threading model within the listener and standard thread-sleep
This way, you get to keep all you audio configuration and logic tucked behind a single module. All the other modules will just ‘tell’ this module what they want to play (and optionally for how long)
On the other hand, unless your application is large enough the above approach would be an overkill
A good write-up on event aggregation
http://codebetter.com/glennblock/2009/02/23/event-aggregation-with-mef-with-and-without-eventaggregator/
I can't understand, Why HTML/Web UI response slower than WinForms/WPF/Android View/Native UI?
The Native UI also have styles, elements nesting, events than the CSS, DOM, javascript events of the Web UI.
Event response time includes: focus changing, dropdown, scrolling, animation moving, animation resizing, etc.
The DOM tree insertion/replacing is also slow, inserting 10000 chars html will cost 100 ms in google chrome in android 4.0 while parsing its template only cost 20 ms(jQuery micro template).
I releazied maybe the biggest factor that slowdown event response is:
The UI locking between parallel javascript processes;
The rendering engine is too slow to process the new UI changing messages from javascript workers, especially when the browser rendering engine is busy with the last UI updating(because of the point 3);
The html layout method (for example: css cascading, inline flow layout, responsive layout etc) may slow down partial UI updating.
Parsing html/xml cost long time, a hint: Android view inflation relies heavily on pre-processing of XML files that is done at build time(http://developer.android.com/reference/android/view/LayoutInflater.html)
A subset of HTML and CSS standards maybe the future solution for webview app development:
http://www.silexlabs.org/haxe/cocktail/
http://www.terrainformatica.com/htmlayout/
http://www.nativecss.com/
http://www.pixate.com/
https://github.com/tombenner/nui
http://steelratstory.com/steelrat-products/wrathwebkit
http://trac.webkit.org/wiki/EFLWebKit
https://github.com/WebKitNix/webkitnix
http://qt-project.org/doc/qt-4.8/richtext-html-subset.html
http://sealedabstract.com/rants/why-mobile-web-apps-are-slow/
A pile of native UI markup languages: http://en.wikipedia.org/wiki/User_interface_markup_language
why there is not a simplified HTML standard and a simplified Webcore layout engine to replace these native UIML?
Maybe we could realize a subset html in kivy.org project.
PC, android browser = application thread + ui thread
iOS browser = application thread + ui data thread + ui hardware thread(CoreAnimation/OpenGL ES)
In ios browser, application thread could directly call ui hardware thread.
If Web UI is completely implemented by JavaScript on the client side, the difference from WinForms/Native UI will be trivial.
However, in most cases, the Web UI triggers some Web request to the Web server, then it has to go through the following steps to achieve the same effect as a WinForms/Native app:
Send a HTTP request (GET/POST/...) to the Web server
The Web server is an executable (in the format of an external app or a service) listening to one or multiple ports. When it receives the request, parses it, and finds the Web application.
Web server executes backend (server-side) logic within application.
Web application such as ASP.NET is pre-compiled. Time complexity of this step could be very close to a Windows app.
Web server renders the result into markup and sends it back to the client
Client (Browser) parses the result and updates the UI if necessary.
Controls/images/other resources in a Web page normally take a little longer to render within a browser than a Windows app renders its display.
Even the Web server is local, the cost generated the data parsing/formatting/transfer cannot be simply ignored.
On the other hand, an application with WinForms/Native UI typically maintains a message loop, which is active and hosted in machine code. A UI request normally just triggers a lookup in the message table and then execute the backend logic (Step 2 in the above)
When it returns result and updates UI, it can be simply binary data structure (doesn't need to be in markup), and doesn't reply another application(browser) to render to the screen.
Lastly, a WinForms/Native application normally has full control to maintain multiple threads to update UI gradually, while a Web application has no direct control over that type of server-side resources.
UPDATE:When we compare a Web application and a Windows/WPF (or native) application consuming a same Web service to partially update their UIs
The two UIs should respond and refresh with ignorable speed difference. The implementation difference between binary & scripting execution to respond and refresh UI is almost nothing.
Neither of the UIs needs to reconstruct the control tree and refresh entire appearance. Given same conditions, they could have same CPU priority, memory/virtual memory caching, and same/close number of kernel object & GDI handles at process/thread level.
In this case, as you described, there should be almost no visual difference.
UPDATE 2:
Actually event handling mechanisms in Web and Windows apps are similar. DOM has event bubbling. Similarly, MFC has command routing; Winforms has its event flow; WPF has event bubbling and tunnelling, and so on. The idea is a UI event might not strictly belong to one control and a control has some way to claim an event has been "handled". For standard controls, focus changing, text changing, dropdown, scrolling events should have similar client-side response time for both Web and Windows apps.
Performancewise, rendering is the biggest difference. Web apps have limited control of "device context" because a Web page is hosted by an external application - the Web browser. Windows applications can implement animation effects using GPU resources like WPF and speed up rendering by refreshing the "device context" partially. That's why HTML5 canvas makes Web developers excited while Windows game developers have been using OpenGL/DirectX for over 10 years.
UPDATE 3:
Each Web browser engine (http://en.wikipedia.org/wiki/Layout_engine) has its own implementation of rendering DOM, CSS; and implementation of (CSS) selectors. Moving and resizing elements within a Web page is changing DOM, CSS (tree) setup. The selector and rendering performance highly depends on the Web browser engine.
UI operations could make selectors go through unnecessary steps to update UI.
A Web page doesn't have control to inform the browser to do partial rendering.
which make fancy JavaScript controls (some jQuery UI, dojo, Ext JS) cannot be real-time fast, usually slower than Flash controls.
The time spent on the client is negligible compared to the time the data spends travelling over the network. The actual render time of a Windows form or a webpage in a browser is measured in (tens or maybe hundreds) of microseconds. Sending a request to a server and getting the result back is measured in milliseconds.
You can confirm this quite easily:
Create a simple Winforms application, time it.
Create a similar Web-based application. Run it on the webserver on your own PC, I.E. //localhost/myapp.asp and time it.
Run it on a remote webserver and time it.
You'll see that 1 is fastest followed closely by 2 (a little slower, interpreting the HTML, the CSS etc) and 3 is vastly slower because of the network time.
To answer your question, the difference due almost entirely to network delays, which are an order of magnitude greater than local processing time.
EDIT: It would be kind of the downvoters to add a comment explaining why.
3 big differences
WebUI apps are run within a browser, which then depends on how well the browser is optimized.
The browser also has its own javascript jvm. another process that has to run and interpret the code before it runs.
All of this is an extra layer that is on top of the native OS. If you were to bring up the activity monitor of you computer and bring up a web page in your browser, you will notice what a resource hog web browsers are.
Native UI elements have graphics acceleration support. depending on the os, native ui templates are compiled to a native format that does not have to be parsed for rendering.
One thing to keep in mind is that the browser itself is a native application, so anything built for the browser to run is inherently written with (at least) one additional layer of abstraction, versus something written directly for native execution.
It's also worth noting such dynamics as this:
300ms tap delay, gone away
http://updates.html5rocks.com/2013/12/300ms-tap-delay-gone-away
The initial impetus for this artificial delay was to support pinch-zooming vs other touch interactions -- that is, slower responsiveness in this case was a deliberate way to disambiguate different user actions.
Granted, while this is a rather specific use-case, the general concept does serve as an example of the different considerations for browser-based vs native implementations. That is, browser-based experiences include some of the usual framework cost of solving for a wide variety of interactions and content, whereas native experiences are naturally tailored more specifically to only listen for / respond to the desired interaction models.
Throughout the implementation, many tiny parts (such as this) are slimmer and more focused in a raw native version, which can contribute to the general effect of better responsiveness.
Only in substandard browsers (this includes all Android browsers, all Mac OS browsers, all Linux browsers, and worst of all every version of Google Chrome). These are badly written, unoptimised browsers with no concern for touchscreen latency, UI responsiveness and smooth scrolling. They lock up and stutter during any kind of CPU activity, disk or network I/O and user input.
Superior browsers such as Internet Explorer 11 or iOS Safari are sometimes even more responsive than unoptimised native apps.
Basically only Windows 8.1 and iOS have responsive browsers. All other browsers are inferior as far as UI responsiveness is concerned. The difference is really huge. IE11 and iOS Safari obliterate other browsers in UI latency and smoothness.