I am using thread and progressbar in xamarin android. I am using the following code for progress. But the progressbar is still showing after the thread has completed.
Could anyone help me to resolve this:
ProgressBar probar=view.FindViewById<ProgressBar>(Resource.Id.progressBar1);
probar.Visibility = ViewStates.Invisible;
Button btnref = view.FindViewById<Button>(Resource.Id.btnrefresh);
btnref.Click += delegate {
probar.Visibility = ViewStates.Visible;
System.Threading.ThreadStart th = new System.Threading.ThreadStart(imagesetting);
Thread myThread = new Thread(th);
myThread.Start();
probar.Visibility = ViewStates.Invisible;
};
private void imagesetting() {
string uri = "example.com/xxx.svc" + Vid + "";
-----
}
Thanks in Advance,
Manthiram C
1) Make method that hides/show probar on main thread
private void ShowProgressBar(bool show) {
RunOnUiThread(() => {
ProgressBar probar=view.FindViewById<ProgressBar>(Resource.Id.progressBar1);
probar.Visibility = show ? ViewStates.Visible : ViewStates.Invisible;
});
}
2) Show probar before starting task thread by calling ShowProgressBar(true)
btnref.Click += delegate {
ShowProgressBar(true);
System.Threading.ThreadStart th = new System.Threading.ThreadStart(imagesetting);
Thread myThread = new Thread(th);
myThread.Start();
};
3) Hide probar by calling ShowProgressBar(false) at the end of imagesetting
private void imagesetting() {
string uri = "example.com/xxx.svc" + Vid + "";
*some code*
ShowProgressBar(false);
}
Related
I am trying to print web page in xamarin forms. I am using DependencyService to print webview, which I have implemented in android successfully.
For Windows UWP,
I referred to this link:
https://forums.xamarin.com/discussion/91163/problem-with-printing-webview-in-uwp-phone
The approach used in this is printing only the first page of the webpage.
Edit :
I created an interface IPrint providing only the html source to the function.
public interface IPrint
{
void PrintAsync(string htmlSource);
}
In PrintAsync function (in Windows UWP project),
async void IPrint.PrintAsync(string htmlSource)
{
ViewToPrint.NavigateToString(htmlSource);
ViewToPrint.LoadCompleted += ViewToPrint_LoadCompleteAsync;
}
When WebView is completely loaded,
private async void ViewToPrint_LoadCompleteAsync(object sender, Windows.UI.Xaml.Navigation.NavigationEventArgs e)
{
if (PrintDoc != null)
{
printDoc.AddPages -= PrintDoc_AddPages;
printDoc.GetPreviewPage -= PrintDoc_GetPreviewPage;
printDoc.Paginate -= PrintDoc_Paginate;
}
this.printDoc = new PrintDocument();
try
{
printDoc.AddPages += PrintDoc_AddPages;
printDoc.GetPreviewPage += PrintDoc_GetPreviewPage;
printDoc.Paginate += PrintDoc_Paginate;
bool showprint = await PrintManager.ShowPrintUIAsync();
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
PrintDoc = null;
GC.Collect();
}
To add pages in PrintDocument,
private void PrintDoc_AddPages(object sender, AddPagesEventArgs e)
{
printDoc.AddPage(ViewToPrint);
printDoc.AddPagesComplete();
}
To implement multiple pages printing,
I referred this link : https://stackoverflow.com/a/17222629/6366591
I changed AddPages function to the following, but it doesn't seem to work for me.
private void PrintDoc_AddPages(object sender, AddPagesEventArgs e)
{
rectangleList = GetWebPages(ViewToPrint, new Windows.Foundation.Size(100d, 150d));
foreach (Windows.UI.Xaml.Shapes.Rectangle rectangle in rectangleList)
{
printDoc.AddPage(rectangle);
}
printDoc.AddPagesComplete();
}
You can find GetWebPages() function here.
List<Windows.UI.Xaml.Shapes.Rectangle> GetWebPages(Windows.UI.Xaml.Controls.WebView webView, Windows.Foundation.Size page)
{
// ask the content its width
var _WidthString = webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollWidth.toString()" }).GetResults();
int _ContentWidth;
if (!int.TryParse(_WidthString, out _ContentWidth))
throw new Exception(string.Format("failure/width:{0}", _WidthString));
webView.Width = _ContentWidth;
// ask the content its height
var _HeightString = webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollHeight.toString()" }).GetResults();
int _ContentHeight;
if (!int.TryParse(_HeightString, out _ContentHeight))
throw new Exception(string.Format("failure/height:{0}", _HeightString));
webView.Height = _ContentHeight;
// how many pages will there be?
var _Scale = page.Width / _ContentWidth;
var _ScaledHeight = (_ContentHeight * _Scale);
var _PageCount = (double)_ScaledHeight / page.Height;
_PageCount = _PageCount + ((_PageCount > (int)_PageCount) ? 1 : 0);
// create the pages
var _Pages = new List<Windows.UI.Xaml.Shapes.Rectangle>();
for (int i = 0; i < (int)_PageCount; i++)
{
var _TranslateY = -page.Height * i;
var _Page = new Windows.UI.Xaml.Shapes.Rectangle
{
Height = page.Height,
Width = page.Width,
Margin = new Windows.UI.Xaml.Thickness(5),
Tag = new Windows.UI.Xaml.Media.TranslateTransform { Y = _TranslateY },
};
_Page.Loaded += (s, e) =>
{
var _Rectangle = s as Windows.UI.Xaml.Shapes.Rectangle;
var _Brush = GetWebViewBrush(webView);
_Brush.Stretch = Windows.UI.Xaml.Media.Stretch.UniformToFill;
_Brush.AlignmentY = Windows.UI.Xaml.Media.AlignmentY.Top;
_Brush.Transform = _Rectangle.Tag as Windows.UI.Xaml.Media.TranslateTransform;
_Rectangle.Fill = _Brush;
};
_Pages.Add(_Page);
}
return _Pages;
}
WebViewBrush GetWebViewBrush(Windows.UI.Xaml.Controls.WebView webView)
{
// resize width to content
var _OriginalWidth = webView.Width;
var _WidthString = webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollWidth.toString()" }).GetResults();
int _ContentWidth;
if (!int.TryParse(_WidthString, out _ContentWidth))
throw new Exception(string.Format("failure/width:{0}", _WidthString));
webView.Width = _ContentWidth;
// resize height to content
var _OriginalHeight = webView.Height;
var _HeightString = webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollHeight.toString()" }).GetResults();
int _ContentHeight;
if (!int.TryParse(_HeightString, out _ContentHeight))
throw new Exception(string.Format("failure/height:{0}", _HeightString));
webView.Height = _ContentHeight;
// create brush
var _OriginalVisibilty = webView.Visibility;
webView.Visibility = Windows.UI.Xaml.Visibility.Visible;
var _Brush = new WebViewBrush
{
SourceName = webView.Name,
Stretch = Windows.UI.Xaml.Media.Stretch.Uniform
};
_Brush.Redraw();
// reset, return
webView.Width = _OriginalWidth;
webView.Height = _OriginalHeight;
webView.Visibility = _OriginalVisibilty;
return _Brush;
}
#Jerry Nixon's method worked well on my side. Since his code sample was posted on that thread about five years ago. For current UWP APIs, I just done a little changes(e.g, webView.InvokeScriptAsync). I also saw that you call the webView.InvokeScriptAsync method in your code. That's good. But you call the GetResults() method, I did not suggest you call GetResults() method. Because invoking javascript code sometimes will take you a lot of time. You might get the exception A method was called at an unexpected time.
Then, I also noticed that your printing flow is a bit of a mess. Please read Print from your app to learn the standardized printing process.
You could check the official code sample Printing sample for details.
The following was the updated code of your code snippet:
async Task<List<Windows.UI.Xaml.Shapes.Rectangle>> GetWebPages(Windows.UI.Xaml.Controls.WebView webView, Windows.Foundation.Size page)
{
// ask the content its width
var _WidthString = await webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollWidth.toString()" });
int _ContentWidth;
if (!int.TryParse(_WidthString, out _ContentWidth))
throw new Exception(string.Format("failure/width:{0}", _WidthString));
webView.Width = _ContentWidth;
// ask the content its height
var _HeightString = await webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollHeight.toString()" });
int _ContentHeight;
if (!int.TryParse(_HeightString, out _ContentHeight))
throw new Exception(string.Format("failure/height:{0}", _HeightString));
webView.Height = _ContentHeight;
// how many pages will there be?
var _Scale = page.Width / _ContentWidth;
var _ScaledHeight = (_ContentHeight * _Scale);
var _PageCount = (double)_ScaledHeight / page.Height;
_PageCount = _PageCount + ((_PageCount > (int)_PageCount) ? 1 : 0);
// create the pages
var _Pages = new List<Windows.UI.Xaml.Shapes.Rectangle>();
for (int i = 0; i < (int)_PageCount; i++)
{
var _TranslateY = -page.Height * i;
var _Page = new Windows.UI.Xaml.Shapes.Rectangle
{
Height = page.Height,
Width = page.Width,
Margin = new Windows.UI.Xaml.Thickness(5),
Tag = new Windows.UI.Xaml.Media.TranslateTransform { Y = _TranslateY },
};
_Page.Loaded +=async (s, e) =>
{
var _Rectangle = s as Windows.UI.Xaml.Shapes.Rectangle;
var _Brush = await GetWebViewBrush(webView);
_Brush.Stretch = Windows.UI.Xaml.Media.Stretch.UniformToFill;
_Brush.AlignmentY = Windows.UI.Xaml.Media.AlignmentY.Top;
_Brush.Transform = _Rectangle.Tag as Windows.UI.Xaml.Media.TranslateTransform;
_Rectangle.Fill = _Brush;
};
_Pages.Add(_Page);
}
return _Pages;
}
async Task<WebViewBrush> GetWebViewBrush(Windows.UI.Xaml.Controls.WebView webView)
{
// resize width to content
var _OriginalWidth = webView.Width;
var _WidthString = await webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollWidth.toString()" });
int _ContentWidth;
if (!int.TryParse(_WidthString, out _ContentWidth))
throw new Exception(string.Format("failure/width:{0}", _WidthString));
webView.Width = _ContentWidth;
// resize height to content
var _OriginalHeight = webView.Height;
var _HeightString = await webView.InvokeScriptAsync("eval",
new[] { "document.body.scrollHeight.toString()" });
int _ContentHeight;
if (!int.TryParse(_HeightString, out _ContentHeight))
throw new Exception(string.Format("failure/height:{0}", _HeightString));
webView.Height = _ContentHeight;
// create brush
var _OriginalVisibilty = webView.Visibility;
webView.Visibility = Windows.UI.Xaml.Visibility.Visible;
var _Brush = new WebViewBrush
{
SourceName = webView.Name,
Stretch = Windows.UI.Xaml.Media.Stretch.Uniform
};
_Brush.Redraw();
// reset, return
webView.Width = _OriginalWidth;
webView.Height = _OriginalHeight;
webView.Visibility = _OriginalVisibilty;
return _Brush;
}
I used the Printing sample and put my above updated code in it and do some relevant changes, then I could print all web pages successfully.
I have already try to understand the API doc, the articles about them, and this post: How do you create a Stream in Dart
I'm making a simple web app using WebSocket. Actually, it's working well, but I want add a feature (enjoy learn).
This is my class (can be optimized I guess)
library Ask;
import 'dart:html';
import 'dart:async';
import 'dart:convert';
class Ask {
final String addr;
String _protocol;
String _port;
WebSocket _ws;
bool openned;
Map<int, Completer> _completer_list = {};
int _counter = 0;
static final Map<String, Ask> _cache = <String, Ask>{};
factory Ask(String addr) {
if (_cache.containsKey(addr)) {
return _cache[addr];
} else {
final ask_server = new Ask._internal(addr);
_cache[addr] = ask_server;
return ask_server;
}
}
Ask._internal(this.addr);
Future<bool> open() {
if (openned)
return true;
_completer_list[0] = new Completer();
if (window.location.protocol == 'http:') {
_port = ':8080/ws';
_protocol = 'ws://';
} else {
_port = ':8443/ws';
_protocol = 'wss://';
}
_ws = new WebSocket(_protocol + addr + _port);
_ws.onOpen.listen((e) {
_get_data();
_get_close();
openned = true;
_completer_list[0].complete(true);
});
return _completer_list[0].future;
}
Future<String> send(Map data) {
bool check = false;
int id;
_completer_list.forEach((k, v) {
if (v.isCompleted) {
id = data['ws_id'] = k;
_completer_list[k] = new Completer();
_ws.send(JSON.encode(data));
check = true;
}
});
if (!check) {
_counter++;
id = data['ws_id'] = _counter;
_completer_list[id] = new Completer();
_ws.send(JSON.encode(data));
}
return _completer_list[id].future;
}
void _get_data() {
_ws.onMessage.listen((MessageEvent data) {
var response = JSON.decode(data.data);
_completer_list[response['ws_id']].complete(response);
});
}
void _get_close() {
_ws.onClose.listen((_) {
print('Server have been lost. Try to reconnect in 3 seconds.');
new Timer(new Duration(seconds: 3), () {
_ws = new WebSocket(_protocol + addr + _port);
_get_data();
_get_close();
_ws.onOpen.listen((e) => print('Server is alive again.'));
});
});
}
}
Example of use:
void showIndex() {
Element main = querySelector('main');
Ask connect = new Ask('127.0.0.1');
Map request = {};
request['index'] = true;
connect.open().then((_) {
connect.send(request).then((data) {
main.setInnerHtml(data['response']);
});
});
}
I would replace the then by a listen who will be canceled when the message will completed. By this way, I can add a progress bar, I think...
So my question, my send function can be a stream and keep my concept of one websocket for all ? (yes, if my function is used when a request is in progress, it's sent and if she's finish before the first, I recovered her properly. Thank you ws_id).
Thank you.
I think what you need is a StreamController
https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart-async.StreamController
I am having a problem trying to load an image and display it using System.Threading.Task
My Code is as follows
Task DownloadTask { get; set; }
public string Instrument { get; set; }
public PriceChartViewController(string Instrument) {
this.Instrument = Instrument;
DownloadTask = Task.Factory.StartNew(() => { });
}
private void LoadChart(ChartType chartType) {
NSData data = new NSData();
DownloadTask = DownloadTask.ContinueWith(prevTask => {
try {
UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true;
NSUrl nsUrl = new NSUrl(chartType.Uri(Instrument));
data = NSData.FromUrl(nsUrl);
}
finally {
UIApplication.SharedApplication.NetworkActivityIndicatorVisible = false;
}
});
DownloadTask = DownloadTask.ContinueWith(t => {
UIImage image = new UIImage(data);
chartImageView = new UIImageView(image);
chartImageView.ContentScaleFactor = 2f;
View.AddSubview(chartImageView);
this.Title = chartType.Title;
}, CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.FromCurrentSynchronizationContext());
}
The second Continue with does not seem to be being called?
Initially my code looked like the following without the background processing and it worked perfectly.
private void oldLoadChart(ChartType chartType) {
UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true;
NSUrl nsUrl = new NSUrl(chartType.Uri(Instrument));
NSData data = NSData.FromUrl(nsUrl);
UIImage image = new UIImage(data);
chartImageView = new UIImageView(image);
chartImageView.ContentScaleFactor = 2f;
View.AddSubview(chartImageView);
this.Title = chartType.Title;
UIApplication.SharedApplication.NetworkActivityIndicatorVisible = false;
}
Does anyone know what I am doing wrong?
Your first part of the thread is crashing, that's why it is never getting to the second:
You are calling UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true;
from a non-UI thread. Setting the network activity indicator is a UI operation and may only be executed on the main thread. You'll have to wrap it in InvokeOnMainThread().
If you add a try-catch, you'll see the exception.
Add catch before finally. Maybe you just have an exception so workflow doesn't go any further.
When I run my method from the constructor of the mainscreen it works, but if invoked in the timer then I get the error.
Here is my method:
public void buildDesc(){
try {
JSONObject event = array.getJSONObject(currentPage);
String title = event.getString("title");
String by = event.getString("by");
String by_name = event.getString("by_name");
String summary = event.getString("summary");
int nid = event.getInt("nid");
vfm.add(new LabelField(title));
System.out.println("The Title:"+title);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
And the timer:
timer = new Timer();//Create the timer to loop the events every 5 seconds
timer.scheduleAtFixedRate(new TimerTask(){
public void run() {
currentPage++;
if(currentPage > 3){
currentPage = 0;
}
System.out.println("Page Position:"+pagePosition(currentPage+1));
gallery.setHorizontalScroll(pagePosition(currentPage));
buildDesc();
}
}, 0, 10000);
I read a Android question that says, perhaps, I can't make changes to the UI if not on the UIThread?
I think your hunch is right, in BlackBerry you shouldn't do any work on the Ui thread. I guess the Timer thread is getting terminated for it's behaviour which is why you are getting an IllegalStateException. A quick guide to the UI thread can be found here.
Try :
timer = new Timer();//Create the timer to loop the events every 5 seconds
timer.scheduleAtFixedRate(new TimerTask(){
public void run() {
currentPage++;
if(currentPage > 3){
currentPage = 0;
}
System.out.println("Page Position:"+pagePosition(currentPage+1));
synchronized(UiApplication.getUiApplication().getEventLock())) {
// UI Code here
gallery.setHorizontalScroll(pagePosition(currentPage));
buildDesc();
}
}
}, 0, 10000);
Note: The above is untested.
I have url I want to check if it is live. I want to get bool value. How to do such thing?
You can use an URLLoader and listen for the events to check if it loads, and if not what might be the problem. Would be handy to use the AIRMonitor first to make sure the client's computer is online in the first place.
Here is a class I started to write to illustrate the idea:
package
{
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.events.HTTPStatusEvent;
import flash.events.IEventDispatcher;
import flash.events.IOErrorEvent;
import flash.events.SecurityErrorEvent;
import flash.net.URLLoader;
import flash.net.URLRequest;
/**
* ...
* #author George Profenza
*/
public class URLChecker extends EventDispatcher
{
private var _url:String;
private var _request:URLRequest;
private var _loader:URLLoader;
private var _isLive:Boolean;
private var _liveStatuses:Array;
private var _completeEvent:Event;
private var _dispatched:Boolean;
private var _log:String = '';
public function URLChecker(target:IEventDispatcher = null)
{
super(target);
init();
}
private function init():void
{
_loader = new URLLoader();
_loader.addEventListener(Event.COMPLETE, _completeHandler);
_loader.addEventListener(HTTPStatusEvent.HTTP_STATUS, _httpStatusHandler);
_loader.addEventListener(IOErrorEvent.IO_ERROR, _ioErrorEventHandler);
_loader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, _securityErrorHandler);
_completeEvent = new Event(Event.COMPLETE, false, true);
_liveStatuses = [];//add other acceptable http statuses here
}
public function check(url:String = 'http://stackoverflow.com'):void {
_dispatched = false;
_url = url;
_request = new URLRequest(url);
_loader.load(_request);
_log += 'load for ' + _url + ' started : ' + new Date() + '\n';
}
private function _completeHandler(e:Event):void
{
_log += e.toString() + ' at ' + new Date();
_isLive = true;
if (!_dispatched) {
dispatchEvent(_completeEvent);
_dispatched = true;
}
}
private function _httpStatusHandler(e:HTTPStatusEvent):void
{
/* comment this in when you're sure what statuses you're after
var statusesLen:int = _liveStatuses.length;
for (var i:int = statusesLen; i > 0; i--) {
if (e.status == _liveStatuses[i]) {
_isLive = true;
dispatchEvent(_completeEvent);
}
}
*/
//200 range
_log += e.toString() + ' at ' + new Date();
if (e.status >= 200 && e.status < 300) _isLive = true;
else _isLive = false;
if (!_dispatched) {
dispatchEvent(_completeEvent);
_dispatched = true;
}
}
private function _ioErrorEventHandler(e:IOErrorEvent):void
{
_log += e.toString() + ' at ' + new Date();
_isLive = false;
if (!_dispatched) {
dispatchEvent(_completeEvent);
_dispatched = true;
}
}
private function _securityErrorHandler(e:SecurityErrorEvent):void
{
_log += e.toString() + ' at ' + new Date();
_isLive = false;
if (!_dispatched) {
dispatchEvent(_completeEvent);
_dispatched = true;
}
}
public function get isLive():Boolean { return _isLive; }
public function get log():String { return _log; }
}
}
and here's a basic usage example:
var urlChecker:URLChecker = new URLChecker();
urlChecker.addEventListener(Event.COMPLETE, urlChecked);
urlChecker.check('wrong_place.url');
function urlChecked(event:Event):void {
trace('is Live: ' + event.target.isLive);
trace('log: ' + event.target.log);
}
The idea is simple:
1. You create a checked
2. Listen for the COMPLETE event(triggered when it has a result
3. In the handler check if it's live and what it logged.
In the HTTP specs, 200 area seems ok, but depending on what you load, you might need
to adjust the class. Also you need to handle security/cross domain issue better, but at least it's a start.
HTH
An important consideration that George's answer left out is the URLRequestMethod. If one were trying to verify the existence of rather large files (e.g, media files) and not just a webpage, you'd want to make sure to set the method property on the URLRequest to URLRequestMethod.HEAD.
As stated in the HTTP1.1 Protocol:
The HEAD method is identical to GET except that the server MUST NOT return a message-body in the response.
Hence, if you really only want to verify the existence of the URL, this is the way to go.
For those who need the code spelled out:
var _request:URLRequest = URLRequest(url);
_request.method = URLRequestMethod.HEAD; // bandwidth :)
Otherwise, George's answer is a good reference point.
NB: This particular URLRequestMethod is only available in AIR.